Update direct dependencies where possible

vendor/go.uber.org/zap/zapcore/console_encoder.go

@@ -0,0 +1,147 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"fmt"
+	"sync"
+
+	"go.uber.org/zap/buffer"
+	"go.uber.org/zap/internal/bufferpool"
+)
+
+var _sliceEncoderPool = sync.Pool{
+	New: func() interface{} {
+		return &sliceArrayEncoder{elems: make([]interface{}, 0, 2)}
+	},
+}
+
+func getSliceEncoder() *sliceArrayEncoder {
+	return _sliceEncoderPool.Get().(*sliceArrayEncoder)
+}
+
+func putSliceEncoder(e *sliceArrayEncoder) {
+	e.elems = e.elems[:0]
+	_sliceEncoderPool.Put(e)
+}
+
+type consoleEncoder struct {
+	*jsonEncoder
+}
+
+// NewConsoleEncoder creates an encoder whose output is designed for human -
+// rather than machine - consumption. It serializes the core log entry data
+// (message, level, timestamp, etc.) in a plain-text format and leaves the
+// structured context as JSON.
+//
+// Note that although the console encoder doesn't use the keys specified in the
+// encoder configuration, it will omit any element whose key is set to the empty
+// string.
+func NewConsoleEncoder(cfg EncoderConfig) Encoder {
+	return consoleEncoder{newJSONEncoder(cfg, true)}
+}
+
+func (c consoleEncoder) Clone() Encoder {
+	return consoleEncoder{c.jsonEncoder.Clone().(*jsonEncoder)}
+}
+
+func (c consoleEncoder) EncodeEntry(ent Entry, fields []Field) (*buffer.Buffer, error) {
+	line := bufferpool.Get()
+
+	// We don't want the entry's metadata to be quoted and escaped (if it's
+	// encoded as strings), which means that we can't use the JSON encoder. The
+	// simplest option is to use the memory encoder and fmt.Fprint.
+	//
+	// If this ever becomes a performance bottleneck, we can implement
+	// ArrayEncoder for our plain-text format.
+	arr := getSliceEncoder()
+	if c.TimeKey != "" && c.EncodeTime != nil {
+		c.EncodeTime(ent.Time, arr)
+	}
+	if c.LevelKey != "" && c.EncodeLevel != nil {
+		c.EncodeLevel(ent.Level, arr)
+	}
+	if ent.LoggerName != "" && c.NameKey != "" {
+		nameEncoder := c.EncodeName
+
+		if nameEncoder == nil {
+			// Fall back to FullNameEncoder for backward compatibility.
+			nameEncoder = FullNameEncoder
+		}
+
+		nameEncoder(ent.LoggerName, arr)
+	}
+	if ent.Caller.Defined && c.CallerKey != "" && c.EncodeCaller != nil {
+		c.EncodeCaller(ent.Caller, arr)
+	}
+	for i := range arr.elems {
+		if i > 0 {
+			line.AppendByte('\t')
+		}
+		fmt.Fprint(line, arr.elems[i])
+	}
+	putSliceEncoder(arr)
+
+	// Add the message itself.
+	if c.MessageKey != "" {
+		c.addTabIfNecessary(line)
+		line.AppendString(ent.Message)
+	}
+
+	// Add any structured context.
+	c.writeContext(line, fields)
+
+	// If there's no stacktrace key, honor that; this allows users to force
+	// single-line output.
+	if ent.Stack != "" && c.StacktraceKey != "" {
+		line.AppendByte('\n')
+		line.AppendString(ent.Stack)
+	}
+
+	if c.LineEnding != "" {
+		line.AppendString(c.LineEnding)
+	} else {
+		line.AppendString(DefaultLineEnding)
+	}
+	return line, nil
+}
+
+func (c consoleEncoder) writeContext(line *buffer.Buffer, extra []Field) {
+	context := c.jsonEncoder.Clone().(*jsonEncoder)
+	defer context.buf.Free()
+
+	addFields(context, extra)
+	context.closeOpenNamespaces()
+	if context.buf.Len() == 0 {
+		return
+	}
+
+	c.addTabIfNecessary(line)
+	line.AppendByte('{')
+	line.Write(context.buf.Bytes())
+	line.AppendByte('}')
+}
+
+func (c consoleEncoder) addTabIfNecessary(line *buffer.Buffer) {
+	if line.Len() > 0 {
+		line.AppendByte('\t')
+	}
+}

vendor/go.uber.org/zap/zapcore/core.go

@@ -0,0 +1,113 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+// Core is a minimal, fast logger interface. It's designed for library authors
+// to wrap in a more user-friendly API.
+type Core interface {
+	LevelEnabler
+
+	// With adds structured context to the Core.
+	With([]Field) Core
+	// Check determines whether the supplied Entry should be logged (using the
+	// embedded LevelEnabler and possibly some extra logic). If the entry
+	// should be logged, the Core adds itself to the CheckedEntry and returns
+	// the result.
+	//
+	// Callers must use Check before calling Write.
+	Check(Entry, *CheckedEntry) *CheckedEntry
+	// Write serializes the Entry and any Fields supplied at the log site and
+	// writes them to their destination.
+	//
+	// If called, Write should always log the Entry and Fields; it should not
+	// replicate the logic of Check.
+	Write(Entry, []Field) error
+	// Sync flushes buffered logs (if any).
+	Sync() error
+}
+
+type nopCore struct{}
+
+// NewNopCore returns a no-op Core.
+func NewNopCore() Core                                        { return nopCore{} }
+func (nopCore) Enabled(Level) bool                            { return false }
+func (n nopCore) With([]Field) Core                           { return n }
+func (nopCore) Check(_ Entry, ce *CheckedEntry) *CheckedEntry { return ce }
+func (nopCore) Write(Entry, []Field) error                    { return nil }
+func (nopCore) Sync() error                                   { return nil }
+
+// NewCore creates a Core that writes logs to a WriteSyncer.
+func NewCore(enc Encoder, ws WriteSyncer, enab LevelEnabler) Core {
+	return &ioCore{
+		LevelEnabler: enab,
+		enc:          enc,
+		out:          ws,
+	}
+}
+
+type ioCore struct {
+	LevelEnabler
+	enc Encoder
+	out WriteSyncer
+}
+
+func (c *ioCore) With(fields []Field) Core {
+	clone := c.clone()
+	addFields(clone.enc, fields)
+	return clone
+}
+
+func (c *ioCore) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+	if c.Enabled(ent.Level) {
+		return ce.AddCore(ent, c)
+	}
+	return ce
+}
+
+func (c *ioCore) Write(ent Entry, fields []Field) error {
+	buf, err := c.enc.EncodeEntry(ent, fields)
+	if err != nil {
+		return err
+	}
+	_, err = c.out.Write(buf.Bytes())
+	buf.Free()
+	if err != nil {
+		return err
+	}
+	if ent.Level > ErrorLevel {
+		// Since we may be crashing the program, sync the output. Ignore Sync
+		// errors, pending a clean solution to issue #370.
+		c.Sync()
+	}
+	return nil
+}
+
+func (c *ioCore) Sync() error {
+	return c.out.Sync()
+}
+
+func (c *ioCore) clone() *ioCore {
+	return &ioCore{
+		LevelEnabler: c.LevelEnabler,
+		enc:          c.enc.Clone(),
+		out:          c.out,
+	}
+}

vendor/go.uber.org/zap/zapcore/doc.go

@@ -0,0 +1,24 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package zapcore defines and implements the low-level interfaces upon which
+// zap is built. By providing alternate implementations of these interfaces,
+// external packages can extend zap's capabilities.
+package zapcore // import "go.uber.org/zap/zapcore"

vendor/go.uber.org/zap/zapcore/encoder.go

@@ -0,0 +1,348 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"time"
+
+	"go.uber.org/zap/buffer"
+)
+
+// DefaultLineEnding defines the default line ending when writing logs.
+// Alternate line endings specified in EncoderConfig can override this
+// behavior.
+const DefaultLineEnding = "\n"
+
+// A LevelEncoder serializes a Level to a primitive type.
+type LevelEncoder func(Level, PrimitiveArrayEncoder)
+
+// LowercaseLevelEncoder serializes a Level to a lowercase string. For example,
+// InfoLevel is serialized to "info".
+func LowercaseLevelEncoder(l Level, enc PrimitiveArrayEncoder) {
+	enc.AppendString(l.String())
+}
+
+// LowercaseColorLevelEncoder serializes a Level to a lowercase string and adds coloring.
+// For example, InfoLevel is serialized to "info" and colored blue.
+func LowercaseColorLevelEncoder(l Level, enc PrimitiveArrayEncoder) {
+	s, ok := _levelToLowercaseColorString[l]
+	if !ok {
+		s = _unknownLevelColor.Add(l.String())
+	}
+	enc.AppendString(s)
+}
+
+// CapitalLevelEncoder serializes a Level to an all-caps string. For example,
+// InfoLevel is serialized to "INFO".
+func CapitalLevelEncoder(l Level, enc PrimitiveArrayEncoder) {
+	enc.AppendString(l.CapitalString())
+}
+
+// CapitalColorLevelEncoder serializes a Level to an all-caps string and adds color.
+// For example, InfoLevel is serialized to "INFO" and colored blue.
+func CapitalColorLevelEncoder(l Level, enc PrimitiveArrayEncoder) {
+	s, ok := _levelToCapitalColorString[l]
+	if !ok {
+		s = _unknownLevelColor.Add(l.CapitalString())
+	}
+	enc.AppendString(s)
+}
+
+// UnmarshalText unmarshals text to a LevelEncoder. "capital" is unmarshaled to
+// CapitalLevelEncoder, "coloredCapital" is unmarshaled to CapitalColorLevelEncoder,
+// "colored" is unmarshaled to LowercaseColorLevelEncoder, and anything else
+// is unmarshaled to LowercaseLevelEncoder.
+func (e *LevelEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "capital":
+		*e = CapitalLevelEncoder
+	case "capitalColor":
+		*e = CapitalColorLevelEncoder
+	case "color":
+		*e = LowercaseColorLevelEncoder
+	default:
+		*e = LowercaseLevelEncoder
+	}
+	return nil
+}
+
+// A TimeEncoder serializes a time.Time to a primitive type.
+type TimeEncoder func(time.Time, PrimitiveArrayEncoder)
+
+// EpochTimeEncoder serializes a time.Time to a floating-point number of seconds
+// since the Unix epoch.
+func EpochTimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	nanos := t.UnixNano()
+	sec := float64(nanos) / float64(time.Second)
+	enc.AppendFloat64(sec)
+}
+
+// EpochMillisTimeEncoder serializes a time.Time to a floating-point number of
+// milliseconds since the Unix epoch.
+func EpochMillisTimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	nanos := t.UnixNano()
+	millis := float64(nanos) / float64(time.Millisecond)
+	enc.AppendFloat64(millis)
+}
+
+// EpochNanosTimeEncoder serializes a time.Time to an integer number of
+// nanoseconds since the Unix epoch.
+func EpochNanosTimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	enc.AppendInt64(t.UnixNano())
+}
+
+// ISO8601TimeEncoder serializes a time.Time to an ISO8601-formatted string
+// with millisecond precision.
+func ISO8601TimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	enc.AppendString(t.Format("2006-01-02T15:04:05.000Z0700"))
+}
+
+// UnmarshalText unmarshals text to a TimeEncoder. "iso8601" and "ISO8601" are
+// unmarshaled to ISO8601TimeEncoder, "millis" is unmarshaled to
+// EpochMillisTimeEncoder, and anything else is unmarshaled to EpochTimeEncoder.
+func (e *TimeEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "iso8601", "ISO8601":
+		*e = ISO8601TimeEncoder
+	case "millis":
+		*e = EpochMillisTimeEncoder
+	case "nanos":
+		*e = EpochNanosTimeEncoder
+	default:
+		*e = EpochTimeEncoder
+	}
+	return nil
+}
+
+// A DurationEncoder serializes a time.Duration to a primitive type.
+type DurationEncoder func(time.Duration, PrimitiveArrayEncoder)
+
+// SecondsDurationEncoder serializes a time.Duration to a floating-point number of seconds elapsed.
+func SecondsDurationEncoder(d time.Duration, enc PrimitiveArrayEncoder) {
+	enc.AppendFloat64(float64(d) / float64(time.Second))
+}
+
+// NanosDurationEncoder serializes a time.Duration to an integer number of
+// nanoseconds elapsed.
+func NanosDurationEncoder(d time.Duration, enc PrimitiveArrayEncoder) {
+	enc.AppendInt64(int64(d))
+}
+
+// StringDurationEncoder serializes a time.Duration using its built-in String
+// method.
+func StringDurationEncoder(d time.Duration, enc PrimitiveArrayEncoder) {
+	enc.AppendString(d.String())
+}
+
+// UnmarshalText unmarshals text to a DurationEncoder. "string" is unmarshaled
+// to StringDurationEncoder, and anything else is unmarshaled to
+// NanosDurationEncoder.
+func (e *DurationEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "string":
+		*e = StringDurationEncoder
+	case "nanos":
+		*e = NanosDurationEncoder
+	default:
+		*e = SecondsDurationEncoder
+	}
+	return nil
+}
+
+// A CallerEncoder serializes an EntryCaller to a primitive type.
+type CallerEncoder func(EntryCaller, PrimitiveArrayEncoder)
+
+// FullCallerEncoder serializes a caller in /full/path/to/package/file:line
+// format.
+func FullCallerEncoder(caller EntryCaller, enc PrimitiveArrayEncoder) {
+	// TODO: consider using a byte-oriented API to save an allocation.
+	enc.AppendString(caller.String())
+}
+
+// ShortCallerEncoder serializes a caller in package/file:line format, trimming
+// all but the final directory from the full path.
+func ShortCallerEncoder(caller EntryCaller, enc PrimitiveArrayEncoder) {
+	// TODO: consider using a byte-oriented API to save an allocation.
+	enc.AppendString(caller.TrimmedPath())
+}
+
+// UnmarshalText unmarshals text to a CallerEncoder. "full" is unmarshaled to
+// FullCallerEncoder and anything else is unmarshaled to ShortCallerEncoder.
+func (e *CallerEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "full":
+		*e = FullCallerEncoder
+	default:
+		*e = ShortCallerEncoder
+	}
+	return nil
+}
+
+// A NameEncoder serializes a period-separated logger name to a primitive
+// type.
+type NameEncoder func(string, PrimitiveArrayEncoder)
+
+// FullNameEncoder serializes the logger name as-is.
+func FullNameEncoder(loggerName string, enc PrimitiveArrayEncoder) {
+	enc.AppendString(loggerName)
+}
+
+// UnmarshalText unmarshals text to a NameEncoder. Currently, everything is
+// unmarshaled to FullNameEncoder.
+func (e *NameEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "full":
+		*e = FullNameEncoder
+	default:
+		*e = FullNameEncoder
+	}
+	return nil
+}
+
+// An EncoderConfig allows users to configure the concrete encoders supplied by
+// zapcore.
+type EncoderConfig struct {
+	// Set the keys used for each log entry. If any key is empty, that portion
+	// of the entry is omitted.
+	MessageKey    string `json:"messageKey" yaml:"messageKey"`
+	LevelKey      string `json:"levelKey" yaml:"levelKey"`
+	TimeKey       string `json:"timeKey" yaml:"timeKey"`
+	NameKey       string `json:"nameKey" yaml:"nameKey"`
+	CallerKey     string `json:"callerKey" yaml:"callerKey"`
+	StacktraceKey string `json:"stacktraceKey" yaml:"stacktraceKey"`
+	LineEnding    string `json:"lineEnding" yaml:"lineEnding"`
+	// Configure the primitive representations of common complex types. For
+	// example, some users may want all time.Times serialized as floating-point
+	// seconds since epoch, while others may prefer ISO8601 strings.
+	EncodeLevel    LevelEncoder    `json:"levelEncoder" yaml:"levelEncoder"`
+	EncodeTime     TimeEncoder     `json:"timeEncoder" yaml:"timeEncoder"`
+	EncodeDuration DurationEncoder `json:"durationEncoder" yaml:"durationEncoder"`
+	EncodeCaller   CallerEncoder   `json:"callerEncoder" yaml:"callerEncoder"`
+	// Unlike the other primitive type encoders, EncodeName is optional. The
+	// zero value falls back to FullNameEncoder.
+	EncodeName NameEncoder `json:"nameEncoder" yaml:"nameEncoder"`
+}
+
+// ObjectEncoder is a strongly-typed, encoding-agnostic interface for adding a
+// map- or struct-like object to the logging context. Like maps, ObjectEncoders
+// aren't safe for concurrent use (though typical use shouldn't require locks).
+type ObjectEncoder interface {
+	// Logging-specific marshalers.
+	AddArray(key string, marshaler ArrayMarshaler) error
+	AddObject(key string, marshaler ObjectMarshaler) error
+
+	// Built-in types.
+	AddBinary(key string, value []byte)     // for arbitrary bytes
+	AddByteString(key string, value []byte) // for UTF-8 encoded bytes
+	AddBool(key string, value bool)
+	AddComplex128(key string, value complex128)
+	AddComplex64(key string, value complex64)
+	AddDuration(key string, value time.Duration)
+	AddFloat64(key string, value float64)
+	AddFloat32(key string, value float32)
+	AddInt(key string, value int)
+	AddInt64(key string, value int64)
+	AddInt32(key string, value int32)
+	AddInt16(key string, value int16)
+	AddInt8(key string, value int8)
+	AddString(key, value string)
+	AddTime(key string, value time.Time)
+	AddUint(key string, value uint)
+	AddUint64(key string, value uint64)
+	AddUint32(key string, value uint32)
+	AddUint16(key string, value uint16)
+	AddUint8(key string, value uint8)
+	AddUintptr(key string, value uintptr)
+
+	// AddReflected uses reflection to serialize arbitrary objects, so it's slow
+	// and allocation-heavy.
+	AddReflected(key string, value interface{}) error
+	// OpenNamespace opens an isolated namespace where all subsequent fields will
+	// be added. Applications can use namespaces to prevent key collisions when
+	// injecting loggers into sub-components or third-party libraries.
+	OpenNamespace(key string)
+}
+
+// ArrayEncoder is a strongly-typed, encoding-agnostic interface for adding
+// array-like objects to the logging context. Of note, it supports mixed-type
+// arrays even though they aren't typical in Go. Like slices, ArrayEncoders
+// aren't safe for concurrent use (though typical use shouldn't require locks).
+type ArrayEncoder interface {
+	// Built-in types.
+	PrimitiveArrayEncoder
+
+	// Time-related types.
+	AppendDuration(time.Duration)
+	AppendTime(time.Time)
+
+	// Logging-specific marshalers.
+	AppendArray(ArrayMarshaler) error
+	AppendObject(ObjectMarshaler) error
+
+	// AppendReflected uses reflection to serialize arbitrary objects, so it's
+	// slow and allocation-heavy.
+	AppendReflected(value interface{}) error
+}
+
+// PrimitiveArrayEncoder is the subset of the ArrayEncoder interface that deals
+// only in Go's built-in types. It's included only so that Duration- and
+// TimeEncoders cannot trigger infinite recursion.
+type PrimitiveArrayEncoder interface {
+	// Built-in types.
+	AppendBool(bool)
+	AppendByteString([]byte) // for UTF-8 encoded bytes
+	AppendComplex128(complex128)
+	AppendComplex64(complex64)
+	AppendFloat64(float64)
+	AppendFloat32(float32)
+	AppendInt(int)
+	AppendInt64(int64)
+	AppendInt32(int32)
+	AppendInt16(int16)
+	AppendInt8(int8)
+	AppendString(string)
+	AppendUint(uint)
+	AppendUint64(uint64)
+	AppendUint32(uint32)
+	AppendUint16(uint16)
+	AppendUint8(uint8)
+	AppendUintptr(uintptr)
+}
+
+// Encoder is a format-agnostic interface for all log entry marshalers. Since
+// log encoders don't need to support the same wide range of use cases as
+// general-purpose marshalers, it's possible to make them faster and
+// lower-allocation.
+//
+// Implementations of the ObjectEncoder interface's methods can, of course,
+// freely modify the receiver. However, the Clone and EncodeEntry methods will
+// be called concurrently and shouldn't modify the receiver.
+type Encoder interface {
+	ObjectEncoder
+
+	// Clone copies the encoder, ensuring that adding fields to the copy doesn't
+	// affect the original.
+	Clone() Encoder
+
+	// EncodeEntry encodes an entry and fields, along with any accumulated
+	// context, into a byte buffer and returns it.
+	EncodeEntry(Entry, []Field) (*buffer.Buffer, error)
+}

vendor/go.uber.org/zap/zapcore/entry.go

@@ -0,0 +1,257 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"go.uber.org/zap/internal/bufferpool"
+	"go.uber.org/zap/internal/exit"
+
+	"go.uber.org/multierr"
+)
+
+var (
+	_cePool = sync.Pool{New: func() interface{} {
+		// Pre-allocate some space for cores.
+		return &CheckedEntry{
+			cores: make([]Core, 4),
+		}
+	}}
+)
+
+func getCheckedEntry() *CheckedEntry {
+	ce := _cePool.Get().(*CheckedEntry)
+	ce.reset()
+	return ce
+}
+
+func putCheckedEntry(ce *CheckedEntry) {
+	if ce == nil {
+		return
+	}
+	_cePool.Put(ce)
+}
+
+// NewEntryCaller makes an EntryCaller from the return signature of
+// runtime.Caller.
+func NewEntryCaller(pc uintptr, file string, line int, ok bool) EntryCaller {
+	if !ok {
+		return EntryCaller{}
+	}
+	return EntryCaller{
+		PC:      pc,
+		File:    file,
+		Line:    line,
+		Defined: true,
+	}
+}
+
+// EntryCaller represents the caller of a logging function.
+type EntryCaller struct {
+	Defined bool
+	PC      uintptr
+	File    string
+	Line    int
+}
+
+// String returns the full path and line number of the caller.
+func (ec EntryCaller) String() string {
+	return ec.FullPath()
+}
+
+// FullPath returns a /full/path/to/package/file:line description of the
+// caller.
+func (ec EntryCaller) FullPath() string {
+	if !ec.Defined {
+		return "undefined"
+	}
+	buf := bufferpool.Get()
+	buf.AppendString(ec.File)
+	buf.AppendByte(':')
+	buf.AppendInt(int64(ec.Line))
+	caller := buf.String()
+	buf.Free()
+	return caller
+}
+
+// TrimmedPath returns a package/file:line description of the caller,
+// preserving only the leaf directory name and file name.
+func (ec EntryCaller) TrimmedPath() string {
+	if !ec.Defined {
+		return "undefined"
+	}
+	// nb. To make sure we trim the path correctly on Windows too, we
+	// counter-intuitively need to use '/' and *not* os.PathSeparator here,
+	// because the path given originates from Go stdlib, specifically
+	// runtime.Caller() which (as of Mar/17) returns forward slashes even on
+	// Windows.
+	//
+	// See https://github.com/golang/go/issues/3335
+	// and https://github.com/golang/go/issues/18151
+	//
+	// for discussion on the issue on Go side.
+	//
+	// Find the last separator.
+	//
+	idx := strings.LastIndexByte(ec.File, '/')
+	if idx == -1 {
+		return ec.FullPath()
+	}
+	// Find the penultimate separator.
+	idx = strings.LastIndexByte(ec.File[:idx], '/')
+	if idx == -1 {
+		return ec.FullPath()
+	}
+	buf := bufferpool.Get()
+	// Keep everything after the penultimate separator.
+	buf.AppendString(ec.File[idx+1:])
+	buf.AppendByte(':')
+	buf.AppendInt(int64(ec.Line))
+	caller := buf.String()
+	buf.Free()
+	return caller
+}
+
+// An Entry represents a complete log message. The entry's structured context
+// is already serialized, but the log level, time, message, and call site
+// information are available for inspection and modification.
+//
+// Entries are pooled, so any functions that accept them MUST be careful not to
+// retain references to them.
+type Entry struct {
+	Level      Level
+	Time       time.Time
+	LoggerName string
+	Message    string
+	Caller     EntryCaller
+	Stack      string
+}
+
+// CheckWriteAction indicates what action to take after a log entry is
+// processed. Actions are ordered in increasing severity.
+type CheckWriteAction uint8
+
+const (
+	// WriteThenNoop indicates that nothing special needs to be done. It's the
+	// default behavior.
+	WriteThenNoop CheckWriteAction = iota
+	// WriteThenPanic causes a panic after Write.
+	WriteThenPanic
+	// WriteThenFatal causes a fatal os.Exit after Write.
+	WriteThenFatal
+)
+
+// CheckedEntry is an Entry together with a collection of Cores that have
+// already agreed to log it.
+//
+// CheckedEntry references should be created by calling AddCore or Should on a
+// nil *CheckedEntry. References are returned to a pool after Write, and MUST
+// NOT be retained after calling their Write method.
+type CheckedEntry struct {
+	Entry
+	ErrorOutput WriteSyncer
+	dirty       bool // best-effort detection of pool misuse
+	should      CheckWriteAction
+	cores       []Core
+}
+
+func (ce *CheckedEntry) reset() {
+	ce.Entry = Entry{}
+	ce.ErrorOutput = nil
+	ce.dirty = false
+	ce.should = WriteThenNoop
+	for i := range ce.cores {
+		// don't keep references to cores
+		ce.cores[i] = nil
+	}
+	ce.cores = ce.cores[:0]
+}
+
+// Write writes the entry to the stored Cores, returns any errors, and returns
+// the CheckedEntry reference to a pool for immediate re-use. Finally, it
+// executes any required CheckWriteAction.
+func (ce *CheckedEntry) Write(fields ...Field) {
+	if ce == nil {
+		return
+	}
+
+	if ce.dirty {
+		if ce.ErrorOutput != nil {
+			// Make a best effort to detect unsafe re-use of this CheckedEntry.
+			// If the entry is dirty, log an internal error; because the
+			// CheckedEntry is being used after it was returned to the pool,
+			// the message may be an amalgamation from multiple call sites.
+			fmt.Fprintf(ce.ErrorOutput, "%v Unsafe CheckedEntry re-use near Entry %+v.\n", time.Now(), ce.Entry)
+			ce.ErrorOutput.Sync()
+		}
+		return
+	}
+	ce.dirty = true
+
+	var err error
+	for i := range ce.cores {
+		err = multierr.Append(err, ce.cores[i].Write(ce.Entry, fields))
+	}
+	if ce.ErrorOutput != nil {
+		if err != nil {
+			fmt.Fprintf(ce.ErrorOutput, "%v write error: %v\n", time.Now(), err)
+			ce.ErrorOutput.Sync()
+		}
+	}
+
+	should, msg := ce.should, ce.Message
+	putCheckedEntry(ce)
+
+	switch should {
+	case WriteThenPanic:
+		panic(msg)
+	case WriteThenFatal:
+		exit.Exit()
+	}
+}
+
+// AddCore adds a Core that has agreed to log this CheckedEntry. It's intended to be
+// used by Core.Check implementations, and is safe to call on nil CheckedEntry
+// references.
+func (ce *CheckedEntry) AddCore(ent Entry, core Core) *CheckedEntry {
+	if ce == nil {
+		ce = getCheckedEntry()
+		ce.Entry = ent
+	}
+	ce.cores = append(ce.cores, core)
+	return ce
+}
+
+// Should sets this CheckedEntry's CheckWriteAction, which controls whether a
+// Core will panic or fatal after writing this log entry. Like AddCore, it's
+// safe to call on nil CheckedEntry references.
+func (ce *CheckedEntry) Should(ent Entry, should CheckWriteAction) *CheckedEntry {
+	if ce == nil {
+		ce = getCheckedEntry()
+		ce.Entry = ent
+	}
+	ce.should = should
+	return ce
+}

vendor/go.uber.org/zap/zapcore/error.go

@@ -0,0 +1,120 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"fmt"
+	"sync"
+)
+
+// Encodes the given error into fields of an object. A field with the given
+// name is added for the error message.
+//
+// If the error implements fmt.Formatter, a field with the name ${key}Verbose
+// is also added with the full verbose error message.
+//
+// Finally, if the error implements errorGroup (from go.uber.org/multierr) or
+// causer (from github.com/pkg/errors), a ${key}Causes field is added with an
+// array of objects containing the errors this error was comprised of.
+//
+//  {
+//    "error": err.Error(),
+//    "errorVerbose": fmt.Sprintf("%+v", err),
+//    "errorCauses": [
+//      ...
+//    ],
+//  }
+func encodeError(key string, err error, enc ObjectEncoder) error {
+	basic := err.Error()
+	enc.AddString(key, basic)
+
+	switch e := err.(type) {
+	case errorGroup:
+		return enc.AddArray(key+"Causes", errArray(e.Errors()))
+	case fmt.Formatter:
+		verbose := fmt.Sprintf("%+v", e)
+		if verbose != basic {
+			// This is a rich error type, like those produced by
+			// github.com/pkg/errors.
+			enc.AddString(key+"Verbose", verbose)
+		}
+	}
+	return nil
+}
+
+type errorGroup interface {
+	// Provides read-only access to the underlying list of errors, preferably
+	// without causing any allocs.
+	Errors() []error
+}
+
+type causer interface {
+	// Provides access to the error that caused this error.
+	Cause() error
+}
+
+// Note that errArry and errArrayElem are very similar to the version
+// implemented in the top-level error.go file. We can't re-use this because
+// that would require exporting errArray as part of the zapcore API.
+
+// Encodes a list of errors using the standard error encoding logic.
+type errArray []error
+
+func (errs errArray) MarshalLogArray(arr ArrayEncoder) error {
+	for i := range errs {
+		if errs[i] == nil {
+			continue
+		}
+
+		el := newErrArrayElem(errs[i])
+		arr.AppendObject(el)
+		el.Free()
+	}
+	return nil
+}
+
+var _errArrayElemPool = sync.Pool{New: func() interface{} {
+	return &errArrayElem{}
+}}
+
+// Encodes any error into a {"error": ...} re-using the same errors logic.
+//
+// May be passed in place of an array to build a single-element array.
+type errArrayElem struct{ err error }
+
+func newErrArrayElem(err error) *errArrayElem {
+	e := _errArrayElemPool.Get().(*errArrayElem)
+	e.err = err
+	return e
+}
+
+func (e *errArrayElem) MarshalLogArray(arr ArrayEncoder) error {
+	return arr.AppendObject(e)
+}
+
+func (e *errArrayElem) MarshalLogObject(enc ObjectEncoder) error {
+	return encodeError("error", e.err, enc)
+}
+
+func (e *errArrayElem) Free() {
+	e.err = nil
+	_errArrayElemPool.Put(e)
+}

vendor/go.uber.org/zap/zapcore/field.go

@@ -0,0 +1,201 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"reflect"
+	"time"
+)
+
+// A FieldType indicates which member of the Field union struct should be used
+// and how it should be serialized.
+type FieldType uint8
+
+const (
+	// UnknownType is the default field type. Attempting to add it to an encoder will panic.
+	UnknownType FieldType = iota
+	// ArrayMarshalerType indicates that the field carries an ArrayMarshaler.
+	ArrayMarshalerType
+	// ObjectMarshalerType indicates that the field carries an ObjectMarshaler.
+	ObjectMarshalerType
+	// BinaryType indicates that the field carries an opaque binary blob.
+	BinaryType
+	// BoolType indicates that the field carries a bool.
+	BoolType
+	// ByteStringType indicates that the field carries UTF-8 encoded bytes.
+	ByteStringType
+	// Complex128Type indicates that the field carries a complex128.
+	Complex128Type
+	// Complex64Type indicates that the field carries a complex128.
+	Complex64Type
+	// DurationType indicates that the field carries a time.Duration.
+	DurationType
+	// Float64Type indicates that the field carries a float64.
+	Float64Type
+	// Float32Type indicates that the field carries a float32.
+	Float32Type
+	// Int64Type indicates that the field carries an int64.
+	Int64Type
+	// Int32Type indicates that the field carries an int32.
+	Int32Type
+	// Int16Type indicates that the field carries an int16.
+	Int16Type
+	// Int8Type indicates that the field carries an int8.
+	Int8Type
+	// StringType indicates that the field carries a string.
+	StringType
+	// TimeType indicates that the field carries a time.Time.
+	TimeType
+	// Uint64Type indicates that the field carries a uint64.
+	Uint64Type
+	// Uint32Type indicates that the field carries a uint32.
+	Uint32Type
+	// Uint16Type indicates that the field carries a uint16.
+	Uint16Type
+	// Uint8Type indicates that the field carries a uint8.
+	Uint8Type
+	// UintptrType indicates that the field carries a uintptr.
+	UintptrType
+	// ReflectType indicates that the field carries an interface{}, which should
+	// be serialized using reflection.
+	ReflectType
+	// NamespaceType signals the beginning of an isolated namespace. All
+	// subsequent fields should be added to the new namespace.
+	NamespaceType
+	// StringerType indicates that the field carries a fmt.Stringer.
+	StringerType
+	// ErrorType indicates that the field carries an error.
+	ErrorType
+	// SkipType indicates that the field is a no-op.
+	SkipType
+)
+
+// A Field is a marshaling operation used to add a key-value pair to a logger's
+// context. Most fields are lazily marshaled, so it's inexpensive to add fields
+// to disabled debug-level log statements.
+type Field struct {
+	Key       string
+	Type      FieldType
+	Integer   int64
+	String    string
+	Interface interface{}
+}
+
+// AddTo exports a field through the ObjectEncoder interface. It's primarily
+// useful to library authors, and shouldn't be necessary in most applications.
+func (f Field) AddTo(enc ObjectEncoder) {
+	var err error
+
+	switch f.Type {
+	case ArrayMarshalerType:
+		err = enc.AddArray(f.Key, f.Interface.(ArrayMarshaler))
+	case ObjectMarshalerType:
+		err = enc.AddObject(f.Key, f.Interface.(ObjectMarshaler))
+	case BinaryType:
+		enc.AddBinary(f.Key, f.Interface.([]byte))
+	case BoolType:
+		enc.AddBool(f.Key, f.Integer == 1)
+	case ByteStringType:
+		enc.AddByteString(f.Key, f.Interface.([]byte))
+	case Complex128Type:
+		enc.AddComplex128(f.Key, f.Interface.(complex128))
+	case Complex64Type:
+		enc.AddComplex64(f.Key, f.Interface.(complex64))
+	case DurationType:
+		enc.AddDuration(f.Key, time.Duration(f.Integer))
+	case Float64Type:
+		enc.AddFloat64(f.Key, math.Float64frombits(uint64(f.Integer)))
+	case Float32Type:
+		enc.AddFloat32(f.Key, math.Float32frombits(uint32(f.Integer)))
+	case Int64Type:
+		enc.AddInt64(f.Key, f.Integer)
+	case Int32Type:
+		enc.AddInt32(f.Key, int32(f.Integer))
+	case Int16Type:
+		enc.AddInt16(f.Key, int16(f.Integer))
+	case Int8Type:
+		enc.AddInt8(f.Key, int8(f.Integer))
+	case StringType:
+		enc.AddString(f.Key, f.String)
+	case TimeType:
+		if f.Interface != nil {
+			enc.AddTime(f.Key, time.Unix(0, f.Integer).In(f.Interface.(*time.Location)))
+		} else {
+			// Fall back to UTC if location is nil.
+			enc.AddTime(f.Key, time.Unix(0, f.Integer))
+		}
+	case Uint64Type:
+		enc.AddUint64(f.Key, uint64(f.Integer))
+	case Uint32Type:
+		enc.AddUint32(f.Key, uint32(f.Integer))
+	case Uint16Type:
+		enc.AddUint16(f.Key, uint16(f.Integer))
+	case Uint8Type:
+		enc.AddUint8(f.Key, uint8(f.Integer))
+	case UintptrType:
+		enc.AddUintptr(f.Key, uintptr(f.Integer))
+	case ReflectType:
+		err = enc.AddReflected(f.Key, f.Interface)
+	case NamespaceType:
+		enc.OpenNamespace(f.Key)
+	case StringerType:
+		enc.AddString(f.Key, f.Interface.(fmt.Stringer).String())
+	case ErrorType:
+		encodeError(f.Key, f.Interface.(error), enc)
+	case SkipType:
+		break
+	default:
+		panic(fmt.Sprintf("unknown field type: %v", f))
+	}
+
+	if err != nil {
+		enc.AddString(fmt.Sprintf("%sError", f.Key), err.Error())
+	}
+}
+
+// Equals returns whether two fields are equal. For non-primitive types such as
+// errors, marshalers, or reflect types, it uses reflect.DeepEqual.
+func (f Field) Equals(other Field) bool {
+	if f.Type != other.Type {
+		return false
+	}
+	if f.Key != other.Key {
+		return false
+	}
+
+	switch f.Type {
+	case BinaryType, ByteStringType:
+		return bytes.Equal(f.Interface.([]byte), other.Interface.([]byte))
+	case ArrayMarshalerType, ObjectMarshalerType, ErrorType, ReflectType:
+		return reflect.DeepEqual(f.Interface, other.Interface)
+	default:
+		return f == other
+	}
+}
+
+func addFields(enc ObjectEncoder, fields []Field) {
+	for i := range fields {
+		fields[i].AddTo(enc)
+	}
+}

vendor/go.uber.org/zap/zapcore/hook.go

@@ -0,0 +1,68 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import "go.uber.org/multierr"
+
+type hooked struct {
+	Core
+	funcs []func(Entry) error
+}
+
+// RegisterHooks wraps a Core and runs a collection of user-defined callback
+// hooks each time a message is logged. Execution of the callbacks is blocking.
+//
+// This offers users an easy way to register simple callbacks (e.g., metrics
+// collection) without implementing the full Core interface.
+func RegisterHooks(core Core, hooks ...func(Entry) error) Core {
+	funcs := append([]func(Entry) error{}, hooks...)
+	return &hooked{
+		Core:  core,
+		funcs: funcs,
+	}
+}
+
+func (h *hooked) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+	// Let the wrapped Core decide whether to log this message or not. This
+	// also gives the downstream a chance to register itself directly with the
+	// CheckedEntry.
+	if downstream := h.Core.Check(ent, ce); downstream != nil {
+		return downstream.AddCore(ent, h)
+	}
+	return ce
+}
+
+func (h *hooked) With(fields []Field) Core {
+	return &hooked{
+		Core:  h.Core.With(fields),
+		funcs: h.funcs,
+	}
+}
+
+func (h *hooked) Write(ent Entry, _ []Field) error {
+	// Since our downstream had a chance to register itself directly with the
+	// CheckedMessage, we don't need to call it here.
+	var err error
+	for i := range h.funcs {
+		err = multierr.Append(err, h.funcs[i](ent))
+	}
+	return err
+}

vendor/go.uber.org/zap/zapcore/json_encoder.go

@@ -0,0 +1,502 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"math"
+	"sync"
+	"time"
+	"unicode/utf8"
+
+	"go.uber.org/zap/buffer"
+	"go.uber.org/zap/internal/bufferpool"
+)
+
+// For JSON-escaping; see jsonEncoder.safeAddString below.
+const _hex = "0123456789abcdef"
+
+var _jsonPool = sync.Pool{New: func() interface{} {
+	return &jsonEncoder{}
+}}
+
+func getJSONEncoder() *jsonEncoder {
+	return _jsonPool.Get().(*jsonEncoder)
+}
+
+func putJSONEncoder(enc *jsonEncoder) {
+	if enc.reflectBuf != nil {
+		enc.reflectBuf.Free()
+	}
+	enc.EncoderConfig = nil
+	enc.buf = nil
+	enc.spaced = false
+	enc.openNamespaces = 0
+	enc.reflectBuf = nil
+	enc.reflectEnc = nil
+	_jsonPool.Put(enc)
+}
+
+type jsonEncoder struct {
+	*EncoderConfig
+	buf            *buffer.Buffer
+	spaced         bool // include spaces after colons and commas
+	openNamespaces int
+
+	// for encoding generic values by reflection
+	reflectBuf *buffer.Buffer
+	reflectEnc *json.Encoder
+}
+
+// NewJSONEncoder creates a fast, low-allocation JSON encoder. The encoder
+// appropriately escapes all field keys and values.
+//
+// Note that the encoder doesn't deduplicate keys, so it's possible to produce
+// a message like
+//   {"foo":"bar","foo":"baz"}
+// This is permitted by the JSON specification, but not encouraged. Many
+// libraries will ignore duplicate key-value pairs (typically keeping the last
+// pair) when unmarshaling, but users should attempt to avoid adding duplicate
+// keys.
+func NewJSONEncoder(cfg EncoderConfig) Encoder {
+	return newJSONEncoder(cfg, false)
+}
+
+func newJSONEncoder(cfg EncoderConfig, spaced bool) *jsonEncoder {
+	return &jsonEncoder{
+		EncoderConfig: &cfg,
+		buf:           bufferpool.Get(),
+		spaced:        spaced,
+	}
+}
+
+func (enc *jsonEncoder) AddArray(key string, arr ArrayMarshaler) error {
+	enc.addKey(key)
+	return enc.AppendArray(arr)
+}
+
+func (enc *jsonEncoder) AddObject(key string, obj ObjectMarshaler) error {
+	enc.addKey(key)
+	return enc.AppendObject(obj)
+}
+
+func (enc *jsonEncoder) AddBinary(key string, val []byte) {
+	enc.AddString(key, base64.StdEncoding.EncodeToString(val))
+}
+
+func (enc *jsonEncoder) AddByteString(key string, val []byte) {
+	enc.addKey(key)
+	enc.AppendByteString(val)
+}
+
+func (enc *jsonEncoder) AddBool(key string, val bool) {
+	enc.addKey(key)
+	enc.AppendBool(val)
+}
+
+func (enc *jsonEncoder) AddComplex128(key string, val complex128) {
+	enc.addKey(key)
+	enc.AppendComplex128(val)
+}
+
+func (enc *jsonEncoder) AddDuration(key string, val time.Duration) {
+	enc.addKey(key)
+	enc.AppendDuration(val)
+}
+
+func (enc *jsonEncoder) AddFloat64(key string, val float64) {
+	enc.addKey(key)
+	enc.AppendFloat64(val)
+}
+
+func (enc *jsonEncoder) AddInt64(key string, val int64) {
+	enc.addKey(key)
+	enc.AppendInt64(val)
+}
+
+func (enc *jsonEncoder) resetReflectBuf() {
+	if enc.reflectBuf == nil {
+		enc.reflectBuf = bufferpool.Get()
+		enc.reflectEnc = json.NewEncoder(enc.reflectBuf)
+	} else {
+		enc.reflectBuf.Reset()
+	}
+}
+
+func (enc *jsonEncoder) AddReflected(key string, obj interface{}) error {
+	enc.resetReflectBuf()
+	err := enc.reflectEnc.Encode(obj)
+	if err != nil {
+		return err
+	}
+	enc.reflectBuf.TrimNewline()
+	enc.addKey(key)
+	_, err = enc.buf.Write(enc.reflectBuf.Bytes())
+	return err
+}
+
+func (enc *jsonEncoder) OpenNamespace(key string) {
+	enc.addKey(key)
+	enc.buf.AppendByte('{')
+	enc.openNamespaces++
+}
+
+func (enc *jsonEncoder) AddString(key, val string) {
+	enc.addKey(key)
+	enc.AppendString(val)
+}
+
+func (enc *jsonEncoder) AddTime(key string, val time.Time) {
+	enc.addKey(key)
+	enc.AppendTime(val)
+}
+
+func (enc *jsonEncoder) AddUint64(key string, val uint64) {
+	enc.addKey(key)
+	enc.AppendUint64(val)
+}
+
+func (enc *jsonEncoder) AppendArray(arr ArrayMarshaler) error {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('[')
+	err := arr.MarshalLogArray(enc)
+	enc.buf.AppendByte(']')
+	return err
+}
+
+func (enc *jsonEncoder) AppendObject(obj ObjectMarshaler) error {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('{')
+	err := obj.MarshalLogObject(enc)
+	enc.buf.AppendByte('}')
+	return err
+}
+
+func (enc *jsonEncoder) AppendBool(val bool) {
+	enc.addElementSeparator()
+	enc.buf.AppendBool(val)
+}
+
+func (enc *jsonEncoder) AppendByteString(val []byte) {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('"')
+	enc.safeAddByteString(val)
+	enc.buf.AppendByte('"')
+}
+
+func (enc *jsonEncoder) AppendComplex128(val complex128) {
+	enc.addElementSeparator()
+	// Cast to a platform-independent, fixed-size type.
+	r, i := float64(real(val)), float64(imag(val))
+	enc.buf.AppendByte('"')
+	// Because we're always in a quoted string, we can use strconv without
+	// special-casing NaN and +/-Inf.
+	enc.buf.AppendFloat(r, 64)
+	enc.buf.AppendByte('+')
+	enc.buf.AppendFloat(i, 64)
+	enc.buf.AppendByte('i')
+	enc.buf.AppendByte('"')
+}
+
+func (enc *jsonEncoder) AppendDuration(val time.Duration) {
+	cur := enc.buf.Len()
+	enc.EncodeDuration(val, enc)
+	if cur == enc.buf.Len() {
+		// User-supplied EncodeDuration is a no-op. Fall back to nanoseconds to keep
+		// JSON valid.
+		enc.AppendInt64(int64(val))
+	}
+}
+
+func (enc *jsonEncoder) AppendInt64(val int64) {
+	enc.addElementSeparator()
+	enc.buf.AppendInt(val)
+}
+
+func (enc *jsonEncoder) AppendReflected(val interface{}) error {
+	enc.resetReflectBuf()
+	err := enc.reflectEnc.Encode(val)
+	if err != nil {
+		return err
+	}
+	enc.reflectBuf.TrimNewline()
+	enc.addElementSeparator()
+	_, err = enc.buf.Write(enc.reflectBuf.Bytes())
+	return err
+}
+
+func (enc *jsonEncoder) AppendString(val string) {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('"')
+	enc.safeAddString(val)
+	enc.buf.AppendByte('"')
+}
+
+func (enc *jsonEncoder) AppendTime(val time.Time) {
+	cur := enc.buf.Len()
+	enc.EncodeTime(val, enc)
+	if cur == enc.buf.Len() {
+		// User-supplied EncodeTime is a no-op. Fall back to nanos since epoch to keep
+		// output JSON valid.
+		enc.AppendInt64(val.UnixNano())
+	}
+}
+
+func (enc *jsonEncoder) AppendUint64(val uint64) {
+	enc.addElementSeparator()
+	enc.buf.AppendUint(val)
+}
+
+func (enc *jsonEncoder) AddComplex64(k string, v complex64) { enc.AddComplex128(k, complex128(v)) }
+func (enc *jsonEncoder) AddFloat32(k string, v float32)     { enc.AddFloat64(k, float64(v)) }
+func (enc *jsonEncoder) AddInt(k string, v int)             { enc.AddInt64(k, int64(v)) }
+func (enc *jsonEncoder) AddInt32(k string, v int32)         { enc.AddInt64(k, int64(v)) }
+func (enc *jsonEncoder) AddInt16(k string, v int16)         { enc.AddInt64(k, int64(v)) }
+func (enc *jsonEncoder) AddInt8(k string, v int8)           { enc.AddInt64(k, int64(v)) }
+func (enc *jsonEncoder) AddUint(k string, v uint)           { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AddUint32(k string, v uint32)       { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AddUint16(k string, v uint16)       { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AddUint8(k string, v uint8)         { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AddUintptr(k string, v uintptr)     { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AppendComplex64(v complex64)        { enc.AppendComplex128(complex128(v)) }
+func (enc *jsonEncoder) AppendFloat64(v float64)            { enc.appendFloat(v, 64) }
+func (enc *jsonEncoder) AppendFloat32(v float32)            { enc.appendFloat(float64(v), 32) }
+func (enc *jsonEncoder) AppendInt(v int)                    { enc.AppendInt64(int64(v)) }
+func (enc *jsonEncoder) AppendInt32(v int32)                { enc.AppendInt64(int64(v)) }
+func (enc *jsonEncoder) AppendInt16(v int16)                { enc.AppendInt64(int64(v)) }
+func (enc *jsonEncoder) AppendInt8(v int8)                  { enc.AppendInt64(int64(v)) }
+func (enc *jsonEncoder) AppendUint(v uint)                  { enc.AppendUint64(uint64(v)) }
+func (enc *jsonEncoder) AppendUint32(v uint32)              { enc.AppendUint64(uint64(v)) }
+func (enc *jsonEncoder) AppendUint16(v uint16)              { enc.AppendUint64(uint64(v)) }
+func (enc *jsonEncoder) AppendUint8(v uint8)                { enc.AppendUint64(uint64(v)) }
+func (enc *jsonEncoder) AppendUintptr(v uintptr)            { enc.AppendUint64(uint64(v)) }
+
+func (enc *jsonEncoder) Clone() Encoder {
+	clone := enc.clone()
+	clone.buf.Write(enc.buf.Bytes())
+	return clone
+}
+
+func (enc *jsonEncoder) clone() *jsonEncoder {
+	clone := getJSONEncoder()
+	clone.EncoderConfig = enc.EncoderConfig
+	clone.spaced = enc.spaced
+	clone.openNamespaces = enc.openNamespaces
+	clone.buf = bufferpool.Get()
+	return clone
+}
+
+func (enc *jsonEncoder) EncodeEntry(ent Entry, fields []Field) (*buffer.Buffer, error) {
+	final := enc.clone()
+	final.buf.AppendByte('{')
+
+	if final.LevelKey != "" {
+		final.addKey(final.LevelKey)
+		cur := final.buf.Len()
+		final.EncodeLevel(ent.Level, final)
+		if cur == final.buf.Len() {
+			// User-supplied EncodeLevel was a no-op. Fall back to strings to keep
+			// output JSON valid.
+			final.AppendString(ent.Level.String())
+		}
+	}
+	if final.TimeKey != "" {
+		final.AddTime(final.TimeKey, ent.Time)
+	}
+	if ent.LoggerName != "" && final.NameKey != "" {
+		final.addKey(final.NameKey)
+		cur := final.buf.Len()
+		nameEncoder := final.EncodeName
+
+		// if no name encoder provided, fall back to FullNameEncoder for backwards
+		// compatibility
+		if nameEncoder == nil {
+			nameEncoder = FullNameEncoder
+		}
+
+		nameEncoder(ent.LoggerName, final)
+		if cur == final.buf.Len() {
+			// User-supplied EncodeName was a no-op. Fall back to strings to
+			// keep output JSON valid.
+			final.AppendString(ent.LoggerName)
+		}
+	}
+	if ent.Caller.Defined && final.CallerKey != "" {
+		final.addKey(final.CallerKey)
+		cur := final.buf.Len()
+		final.EncodeCaller(ent.Caller, final)
+		if cur == final.buf.Len() {
+			// User-supplied EncodeCaller was a no-op. Fall back to strings to
+			// keep output JSON valid.
+			final.AppendString(ent.Caller.String())
+		}
+	}
+	if final.MessageKey != "" {
+		final.addKey(enc.MessageKey)
+		final.AppendString(ent.Message)
+	}
+	if enc.buf.Len() > 0 {
+		final.addElementSeparator()
+		final.buf.Write(enc.buf.Bytes())
+	}
+	addFields(final, fields)
+	final.closeOpenNamespaces()
+	if ent.Stack != "" && final.StacktraceKey != "" {
+		final.AddString(final.StacktraceKey, ent.Stack)
+	}
+	final.buf.AppendByte('}')
+	if final.LineEnding != "" {
+		final.buf.AppendString(final.LineEnding)
+	} else {
+		final.buf.AppendString(DefaultLineEnding)
+	}
+
+	ret := final.buf
+	putJSONEncoder(final)
+	return ret, nil
+}
+
+func (enc *jsonEncoder) truncate() {
+	enc.buf.Reset()
+}
+
+func (enc *jsonEncoder) closeOpenNamespaces() {
+	for i := 0; i < enc.openNamespaces; i++ {
+		enc.buf.AppendByte('}')
+	}
+}
+
+func (enc *jsonEncoder) addKey(key string) {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('"')
+	enc.safeAddString(key)
+	enc.buf.AppendByte('"')
+	enc.buf.AppendByte(':')
+	if enc.spaced {
+		enc.buf.AppendByte(' ')
+	}
+}
+
+func (enc *jsonEncoder) addElementSeparator() {
+	last := enc.buf.Len() - 1
+	if last < 0 {
+		return
+	}
+	switch enc.buf.Bytes()[last] {
+	case '{', '[', ':', ',', ' ':
+		return
+	default:
+		enc.buf.AppendByte(',')
+		if enc.spaced {
+			enc.buf.AppendByte(' ')
+		}
+	}
+}
+
+func (enc *jsonEncoder) appendFloat(val float64, bitSize int) {
+	enc.addElementSeparator()
+	switch {
+	case math.IsNaN(val):
+		enc.buf.AppendString(`"NaN"`)
+	case math.IsInf(val, 1):
+		enc.buf.AppendString(`"+Inf"`)
+	case math.IsInf(val, -1):
+		enc.buf.AppendString(`"-Inf"`)
+	default:
+		enc.buf.AppendFloat(val, bitSize)
+	}
+}
+
+// safeAddString JSON-escapes a string and appends it to the internal buffer.
+// Unlike the standard library's encoder, it doesn't attempt to protect the
+// user from browser vulnerabilities or JSONP-related problems.
+func (enc *jsonEncoder) safeAddString(s string) {
+	for i := 0; i < len(s); {
+		if enc.tryAddRuneSelf(s[i]) {
+			i++
+			continue
+		}
+		r, size := utf8.DecodeRuneInString(s[i:])
+		if enc.tryAddRuneError(r, size) {
+			i++
+			continue
+		}
+		enc.buf.AppendString(s[i : i+size])
+		i += size
+	}
+}
+
+// safeAddByteString is no-alloc equivalent of safeAddString(string(s)) for s []byte.
+func (enc *jsonEncoder) safeAddByteString(s []byte) {
+	for i := 0; i < len(s); {
+		if enc.tryAddRuneSelf(s[i]) {
+			i++
+			continue
+		}
+		r, size := utf8.DecodeRune(s[i:])
+		if enc.tryAddRuneError(r, size) {
+			i++
+			continue
+		}
+		enc.buf.Write(s[i : i+size])
+		i += size
+	}
+}
+
+// tryAddRuneSelf appends b if it is valid UTF-8 character represented in a single byte.
+func (enc *jsonEncoder) tryAddRuneSelf(b byte) bool {
+	if b >= utf8.RuneSelf {
+		return false
+	}
+	if 0x20 <= b && b != '\\' && b != '"' {
+		enc.buf.AppendByte(b)
+		return true
+	}
+	switch b {
+	case '\\', '"':
+		enc.buf.AppendByte('\\')
+		enc.buf.AppendByte(b)
+	case '\n':
+		enc.buf.AppendByte('\\')
+		enc.buf.AppendByte('n')
+	case '\r':
+		enc.buf.AppendByte('\\')
+		enc.buf.AppendByte('r')
+	case '\t':
+		enc.buf.AppendByte('\\')
+		enc.buf.AppendByte('t')
+	default:
+		// Encode bytes < 0x20, except for the escape sequences above.
+		enc.buf.AppendString(`\u00`)
+		enc.buf.AppendByte(_hex[b>>4])
+		enc.buf.AppendByte(_hex[b&0xF])
+	}
+	return true
+}
+
+func (enc *jsonEncoder) tryAddRuneError(r rune, size int) bool {
+	if r == utf8.RuneError && size == 1 {
+		enc.buf.AppendString(`\ufffd`)
+		return true
+	}
+	return false
+}

vendor/go.uber.org/zap/zapcore/level.go

@@ -0,0 +1,175 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+)
+
+var errUnmarshalNilLevel = errors.New("can't unmarshal a nil *Level")
+
+// A Level is a logging priority. Higher levels are more important.
+type Level int8
+
+const (
+	// DebugLevel logs are typically voluminous, and are usually disabled in
+	// production.
+	DebugLevel Level = iota - 1
+	// InfoLevel is the default logging priority.
+	InfoLevel
+	// WarnLevel logs are more important than Info, but don't need individual
+	// human review.
+	WarnLevel
+	// ErrorLevel logs are high-priority. If an application is running smoothly,
+	// it shouldn't generate any error-level logs.
+	ErrorLevel
+	// DPanicLevel logs are particularly important errors. In development the
+	// logger panics after writing the message.
+	DPanicLevel
+	// PanicLevel logs a message, then panics.
+	PanicLevel
+	// FatalLevel logs a message, then calls os.Exit(1).
+	FatalLevel
+
+	_minLevel = DebugLevel
+	_maxLevel = FatalLevel
+)
+
+// String returns a lower-case ASCII representation of the log level.
+func (l Level) String() string {
+	switch l {
+	case DebugLevel:
+		return "debug"
+	case InfoLevel:
+		return "info"
+	case WarnLevel:
+		return "warn"
+	case ErrorLevel:
+		return "error"
+	case DPanicLevel:
+		return "dpanic"
+	case PanicLevel:
+		return "panic"
+	case FatalLevel:
+		return "fatal"
+	default:
+		return fmt.Sprintf("Level(%d)", l)
+	}
+}
+
+// CapitalString returns an all-caps ASCII representation of the log level.
+func (l Level) CapitalString() string {
+	// Printing levels in all-caps is common enough that we should export this
+	// functionality.
+	switch l {
+	case DebugLevel:
+		return "DEBUG"
+	case InfoLevel:
+		return "INFO"
+	case WarnLevel:
+		return "WARN"
+	case ErrorLevel:
+		return "ERROR"
+	case DPanicLevel:
+		return "DPANIC"
+	case PanicLevel:
+		return "PANIC"
+	case FatalLevel:
+		return "FATAL"
+	default:
+		return fmt.Sprintf("LEVEL(%d)", l)
+	}
+}
+
+// MarshalText marshals the Level to text. Note that the text representation
+// drops the -Level suffix (see example).
+func (l Level) MarshalText() ([]byte, error) {
+	return []byte(l.String()), nil
+}
+
+// UnmarshalText unmarshals text to a level. Like MarshalText, UnmarshalText
+// expects the text representation of a Level to drop the -Level suffix (see
+// example).
+//
+// In particular, this makes it easy to configure logging levels using YAML,
+// TOML, or JSON files.
+func (l *Level) UnmarshalText(text []byte) error {
+	if l == nil {
+		return errUnmarshalNilLevel
+	}
+	if !l.unmarshalText(text) && !l.unmarshalText(bytes.ToLower(text)) {
+		return fmt.Errorf("unrecognized level: %q", text)
+	}
+	return nil
+}
+
+func (l *Level) unmarshalText(text []byte) bool {
+	switch string(text) {
+	case "debug", "DEBUG":
+		*l = DebugLevel
+	case "info", "INFO", "": // make the zero value useful
+		*l = InfoLevel
+	case "warn", "WARN":
+		*l = WarnLevel
+	case "error", "ERROR":
+		*l = ErrorLevel
+	case "dpanic", "DPANIC":
+		*l = DPanicLevel
+	case "panic", "PANIC":
+		*l = PanicLevel
+	case "fatal", "FATAL":
+		*l = FatalLevel
+	default:
+		return false
+	}
+	return true
+}
+
+// Set sets the level for the flag.Value interface.
+func (l *Level) Set(s string) error {
+	return l.UnmarshalText([]byte(s))
+}
+
+// Get gets the level for the flag.Getter interface.
+func (l *Level) Get() interface{} {
+	return *l
+}
+
+// Enabled returns true if the given level is at or above this level.
+func (l Level) Enabled(lvl Level) bool {
+	return lvl >= l
+}
+
+// LevelEnabler decides whether a given logging level is enabled when logging a
+// message.
+//
+// Enablers are intended to be used to implement deterministic filters;
+// concerns like sampling are better implemented as a Core.
+//
+// Each concrete Level value implements a static LevelEnabler which returns
+// true for itself and all higher logging levels. For example WarnLevel.Enabled()
+// will return true for WarnLevel, ErrorLevel, DPanicLevel, PanicLevel, and
+// FatalLevel, but return false for InfoLevel and DebugLevel.
+type LevelEnabler interface {
+	Enabled(Level) bool
+}

vendor/go.uber.org/zap/zapcore/level_strings.go

@@ -0,0 +1,46 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import "go.uber.org/zap/internal/color"
+
+var (
+	_levelToColor = map[Level]color.Color{
+		DebugLevel:  color.Magenta,
+		InfoLevel:   color.Blue,
+		WarnLevel:   color.Yellow,
+		ErrorLevel:  color.Red,
+		DPanicLevel: color.Red,
+		PanicLevel:  color.Red,
+		FatalLevel:  color.Red,
+	}
+	_unknownLevelColor = color.Red
+
+	_levelToLowercaseColorString = make(map[Level]string, len(_levelToColor))
+	_levelToCapitalColorString   = make(map[Level]string, len(_levelToColor))
+)
+
+func init() {
+	for level, color := range _levelToColor {
+		_levelToLowercaseColorString[level] = color.Add(level.String())
+		_levelToCapitalColorString[level] = color.Add(level.CapitalString())
+	}
+}

vendor/go.uber.org/zap/zapcore/marshaler.go

@@ -0,0 +1,53 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+// ObjectMarshaler allows user-defined types to efficiently add themselves to the
+// logging context, and to selectively omit information which shouldn't be
+// included in logs (e.g., passwords).
+type ObjectMarshaler interface {
+	MarshalLogObject(ObjectEncoder) error
+}
+
+// ObjectMarshalerFunc is a type adapter that turns a function into an
+// ObjectMarshaler.
+type ObjectMarshalerFunc func(ObjectEncoder) error
+
+// MarshalLogObject calls the underlying function.
+func (f ObjectMarshalerFunc) MarshalLogObject(enc ObjectEncoder) error {
+	return f(enc)
+}
+
+// ArrayMarshaler allows user-defined types to efficiently add themselves to the
+// logging context, and to selectively omit information which shouldn't be
+// included in logs (e.g., passwords).
+type ArrayMarshaler interface {
+	MarshalLogArray(ArrayEncoder) error
+}
+
+// ArrayMarshalerFunc is a type adapter that turns a function into an
+// ArrayMarshaler.
+type ArrayMarshalerFunc func(ArrayEncoder) error
+
+// MarshalLogArray calls the underlying function.
+func (f ArrayMarshalerFunc) MarshalLogArray(enc ArrayEncoder) error {
+	return f(enc)
+}

vendor/go.uber.org/zap/zapcore/memory_encoder.go

@@ -0,0 +1,179 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import "time"
+
+// MapObjectEncoder is an ObjectEncoder backed by a simple
+// map[string]interface{}. It's not fast enough for production use, but it's
+// helpful in tests.
+type MapObjectEncoder struct {
+	// Fields contains the entire encoded log context.
+	Fields map[string]interface{}
+	// cur is a pointer to the namespace we're currently writing to.
+	cur map[string]interface{}
+}
+
+// NewMapObjectEncoder creates a new map-backed ObjectEncoder.
+func NewMapObjectEncoder() *MapObjectEncoder {
+	m := make(map[string]interface{})
+	return &MapObjectEncoder{
+		Fields: m,
+		cur:    m,
+	}
+}
+
+// AddArray implements ObjectEncoder.
+func (m *MapObjectEncoder) AddArray(key string, v ArrayMarshaler) error {
+	arr := &sliceArrayEncoder{elems: make([]interface{}, 0)}
+	err := v.MarshalLogArray(arr)
+	m.cur[key] = arr.elems
+	return err
+}
+
+// AddObject implements ObjectEncoder.
+func (m *MapObjectEncoder) AddObject(k string, v ObjectMarshaler) error {
+	newMap := NewMapObjectEncoder()
+	m.cur[k] = newMap.Fields
+	return v.MarshalLogObject(newMap)
+}
+
+// AddBinary implements ObjectEncoder.
+func (m *MapObjectEncoder) AddBinary(k string, v []byte) { m.cur[k] = v }
+
+// AddByteString implements ObjectEncoder.
+func (m *MapObjectEncoder) AddByteString(k string, v []byte) { m.cur[k] = string(v) }
+
+// AddBool implements ObjectEncoder.
+func (m *MapObjectEncoder) AddBool(k string, v bool) { m.cur[k] = v }
+
+// AddDuration implements ObjectEncoder.
+func (m MapObjectEncoder) AddDuration(k string, v time.Duration) { m.cur[k] = v }
+
+// AddComplex128 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddComplex128(k string, v complex128) { m.cur[k] = v }
+
+// AddComplex64 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddComplex64(k string, v complex64) { m.cur[k] = v }
+
+// AddFloat64 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddFloat64(k string, v float64) { m.cur[k] = v }
+
+// AddFloat32 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddFloat32(k string, v float32) { m.cur[k] = v }
+
+// AddInt implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt(k string, v int) { m.cur[k] = v }
+
+// AddInt64 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt64(k string, v int64) { m.cur[k] = v }
+
+// AddInt32 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt32(k string, v int32) { m.cur[k] = v }
+
+// AddInt16 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt16(k string, v int16) { m.cur[k] = v }
+
+// AddInt8 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt8(k string, v int8) { m.cur[k] = v }
+
+// AddString implements ObjectEncoder.
+func (m *MapObjectEncoder) AddString(k string, v string) { m.cur[k] = v }
+
+// AddTime implements ObjectEncoder.
+func (m MapObjectEncoder) AddTime(k string, v time.Time) { m.cur[k] = v }
+
+// AddUint implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint(k string, v uint) { m.cur[k] = v }
+
+// AddUint64 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint64(k string, v uint64) { m.cur[k] = v }
+
+// AddUint32 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint32(k string, v uint32) { m.cur[k] = v }
+
+// AddUint16 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint16(k string, v uint16) { m.cur[k] = v }
+
+// AddUint8 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint8(k string, v uint8) { m.cur[k] = v }
+
+// AddUintptr implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUintptr(k string, v uintptr) { m.cur[k] = v }
+
+// AddReflected implements ObjectEncoder.
+func (m *MapObjectEncoder) AddReflected(k string, v interface{}) error {
+	m.cur[k] = v
+	return nil
+}
+
+// OpenNamespace implements ObjectEncoder.
+func (m *MapObjectEncoder) OpenNamespace(k string) {
+	ns := make(map[string]interface{})
+	m.cur[k] = ns
+	m.cur = ns
+}
+
+// sliceArrayEncoder is an ArrayEncoder backed by a simple []interface{}. Like
+// the MapObjectEncoder, it's not designed for production use.
+type sliceArrayEncoder struct {
+	elems []interface{}
+}
+
+func (s *sliceArrayEncoder) AppendArray(v ArrayMarshaler) error {
+	enc := &sliceArrayEncoder{}
+	err := v.MarshalLogArray(enc)
+	s.elems = append(s.elems, enc.elems)
+	return err
+}
+
+func (s *sliceArrayEncoder) AppendObject(v ObjectMarshaler) error {
+	m := NewMapObjectEncoder()
+	err := v.MarshalLogObject(m)
+	s.elems = append(s.elems, m.Fields)
+	return err
+}
+
+func (s *sliceArrayEncoder) AppendReflected(v interface{}) error {
+	s.elems = append(s.elems, v)
+	return nil
+}
+
+func (s *sliceArrayEncoder) AppendBool(v bool)              { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendByteString(v []byte)      { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendComplex128(v complex128)  { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendComplex64(v complex64)    { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendDuration(v time.Duration) { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendFloat64(v float64)        { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendFloat32(v float32)        { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt(v int)                { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt64(v int64)            { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt32(v int32)            { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt16(v int16)            { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt8(v int8)              { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendString(v string)          { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendTime(v time.Time)         { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint(v uint)              { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint64(v uint64)          { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint32(v uint32)          { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint16(v uint16)          { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint8(v uint8)            { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUintptr(v uintptr)        { s.elems = append(s.elems, v) }

vendor/go.uber.org/zap/zapcore/sampler.go

@@ -0,0 +1,134 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"time"
+
+	"go.uber.org/atomic"
+)
+
+const (
+	_numLevels        = _maxLevel - _minLevel + 1
+	_countersPerLevel = 4096
+)
+
+type counter struct {
+	resetAt atomic.Int64
+	counter atomic.Uint64
+}
+
+type counters [_numLevels][_countersPerLevel]counter
+
+func newCounters() *counters {
+	return &counters{}
+}
+
+func (cs *counters) get(lvl Level, key string) *counter {
+	i := lvl - _minLevel
+	j := fnv32a(key) % _countersPerLevel
+	return &cs[i][j]
+}
+
+// fnv32a, adapted from "hash/fnv", but without a []byte(string) alloc
+func fnv32a(s string) uint32 {
+	const (
+		offset32 = 2166136261
+		prime32  = 16777619
+	)
+	hash := uint32(offset32)
+	for i := 0; i < len(s); i++ {
+		hash ^= uint32(s[i])
+		hash *= prime32
+	}
+	return hash
+}
+
+func (c *counter) IncCheckReset(t time.Time, tick time.Duration) uint64 {
+	tn := t.UnixNano()
+	resetAfter := c.resetAt.Load()
+	if resetAfter > tn {
+		return c.counter.Inc()
+	}
+
+	c.counter.Store(1)
+
+	newResetAfter := tn + tick.Nanoseconds()
+	if !c.resetAt.CAS(resetAfter, newResetAfter) {
+		// We raced with another goroutine trying to reset, and it also reset
+		// the counter to 1, so we need to reincrement the counter.
+		return c.counter.Inc()
+	}
+
+	return 1
+}
+
+type sampler struct {
+	Core
+
+	counts            *counters
+	tick              time.Duration
+	first, thereafter uint64
+}
+
+// NewSampler creates a Core that samples incoming entries, which caps the CPU
+// and I/O load of logging while attempting to preserve a representative subset
+// of your logs.
+//
+// Zap samples by logging the first N entries with a given level and message
+// each tick. If more Entries with the same level and message are seen during
+// the same interval, every Mth message is logged and the rest are dropped.
+//
+// Keep in mind that zap's sampling implementation is optimized for speed over
+// absolute precision; under load, each tick may be slightly over- or
+// under-sampled.
+func NewSampler(core Core, tick time.Duration, first, thereafter int) Core {
+	return &sampler{
+		Core:       core,
+		tick:       tick,
+		counts:     newCounters(),
+		first:      uint64(first),
+		thereafter: uint64(thereafter),
+	}
+}
+
+func (s *sampler) With(fields []Field) Core {
+	return &sampler{
+		Core:       s.Core.With(fields),
+		tick:       s.tick,
+		counts:     s.counts,
+		first:      s.first,
+		thereafter: s.thereafter,
+	}
+}
+
+func (s *sampler) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+	if !s.Enabled(ent.Level) {
+		return ce
+	}
+
+	counter := s.counts.get(ent.Level, ent.Message)
+	n := counter.IncCheckReset(ent.Time, s.tick)
+	if n > s.first && (n-s.first)%s.thereafter != 0 {
+		return ce
+	}
+	return s.Core.Check(ent, ce)
+}

vendor/go.uber.org/zap/zapcore/tee.go

@@ -0,0 +1,81 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import "go.uber.org/multierr"
+
+type multiCore []Core
+
+// NewTee creates a Core that duplicates log entries into two or more
+// underlying Cores.
+//
+// Calling it with a single Core returns the input unchanged, and calling
+// it with no input returns a no-op Core.
+func NewTee(cores ...Core) Core {
+	switch len(cores) {
+	case 0:
+		return NewNopCore()
+	case 1:
+		return cores[0]
+	default:
+		return multiCore(cores)
+	}
+}
+
+func (mc multiCore) With(fields []Field) Core {
+	clone := make(multiCore, len(mc))
+	for i := range mc {
+		clone[i] = mc[i].With(fields)
+	}
+	return clone
+}
+
+func (mc multiCore) Enabled(lvl Level) bool {
+	for i := range mc {
+		if mc[i].Enabled(lvl) {
+			return true
+		}
+	}
+	return false
+}
+
+func (mc multiCore) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+	for i := range mc {
+		ce = mc[i].Check(ent, ce)
+	}
+	return ce
+}
+
+func (mc multiCore) Write(ent Entry, fields []Field) error {
+	var err error
+	for i := range mc {
+		err = multierr.Append(err, mc[i].Write(ent, fields))
+	}
+	return err
+}
+
+func (mc multiCore) Sync() error {
+	var err error
+	for i := range mc {
+		err = multierr.Append(err, mc[i].Sync())
+	}
+	return err
+}

vendor/go.uber.org/zap/zapcore/write_syncer.go

@@ -0,0 +1,123 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"io"
+	"sync"
+
+	"go.uber.org/multierr"
+)
+
+// A WriteSyncer is an io.Writer that can also flush any buffered data. Note
+// that *os.File (and thus, os.Stderr and os.Stdout) implement WriteSyncer.
+type WriteSyncer interface {
+	io.Writer
+	Sync() error
+}
+
+// AddSync converts an io.Writer to a WriteSyncer. It attempts to be
+// intelligent: if the concrete type of the io.Writer implements WriteSyncer,
+// we'll use the existing Sync method. If it doesn't, we'll add a no-op Sync.
+func AddSync(w io.Writer) WriteSyncer {
+	switch w := w.(type) {
+	case WriteSyncer:
+		return w
+	default:
+		return writerWrapper{w}
+	}
+}
+
+type lockedWriteSyncer struct {
+	sync.Mutex
+	ws WriteSyncer
+}
+
+// Lock wraps a WriteSyncer in a mutex to make it safe for concurrent use. In
+// particular, *os.Files must be locked before use.
+func Lock(ws WriteSyncer) WriteSyncer {
+	if _, ok := ws.(*lockedWriteSyncer); ok {
+		// no need to layer on another lock
+		return ws
+	}
+	return &lockedWriteSyncer{ws: ws}
+}
+
+func (s *lockedWriteSyncer) Write(bs []byte) (int, error) {
+	s.Lock()
+	n, err := s.ws.Write(bs)
+	s.Unlock()
+	return n, err
+}
+
+func (s *lockedWriteSyncer) Sync() error {
+	s.Lock()
+	err := s.ws.Sync()
+	s.Unlock()
+	return err
+}
+
+type writerWrapper struct {
+	io.Writer
+}
+
+func (w writerWrapper) Sync() error {
+	return nil
+}
+
+type multiWriteSyncer []WriteSyncer
+
+// NewMultiWriteSyncer creates a WriteSyncer that duplicates its writes
+// and sync calls, much like io.MultiWriter.
+func NewMultiWriteSyncer(ws ...WriteSyncer) WriteSyncer {
+	if len(ws) == 1 {
+		return ws[0]
+	}
+	// Copy to protect against https://github.com/golang/go/issues/7809
+	return multiWriteSyncer(append([]WriteSyncer(nil), ws...))
+}
+
+// See https://golang.org/src/io/multi.go
+// When not all underlying syncers write the same number of bytes,
+// the smallest number is returned even though Write() is called on
+// all of them.
+func (ws multiWriteSyncer) Write(p []byte) (int, error) {
+	var writeErr error
+	nWritten := 0
+	for _, w := range ws {
+		n, err := w.Write(p)
+		writeErr = multierr.Append(writeErr, err)
+		if nWritten == 0 && n != 0 {
+			nWritten = n
+		} else if n < nWritten {
+			nWritten = n
+		}
+	}
+	return nWritten, writeErr
+}
+
+func (ws multiWriteSyncer) Sync() error {
+	var err error
+	for _, w := range ws {
+		err = multierr.Append(err, w.Sync())
+	}
+	return err
+}