Update mattermost library (#2152)

* Update mattermost library

* Fix linting

vendor/github.com/hashicorp/go-hclog/stacktrace.go

@@ -0,0 +1,109 @@
+// 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 hclog
+
+import (
+	"bytes"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+var (
+	_stacktraceIgnorePrefixes = []string{
+		"runtime.goexit",
+		"runtime.main",
+	}
+	_stacktracePool = sync.Pool{
+		New: func() interface{} {
+			return newProgramCounters(64)
+		},
+	}
+)
+
+// CapturedStacktrace represents a stacktrace captured by a previous call
+// to log.Stacktrace. If passed to a logging function, the stacktrace
+// will be appended.
+type CapturedStacktrace string
+
+// Stacktrace captures a stacktrace of the current goroutine and returns
+// it to be passed to a logging function.
+func Stacktrace() CapturedStacktrace {
+	return CapturedStacktrace(takeStacktrace())
+}
+
+func takeStacktrace() string {
+	programCounters := _stacktracePool.Get().(*programCounters)
+	defer _stacktracePool.Put(programCounters)
+
+	var buffer bytes.Buffer
+
+	for {
+		// Skip the call to runtime.Counters and takeStacktrace so that the
+		// program counters start at the caller of takeStacktrace.
+		n := runtime.Callers(2, programCounters.pcs)
+		if n < cap(programCounters.pcs) {
+			programCounters.pcs = programCounters.pcs[:n]
+			break
+		}
+		// Don't put the too-short counter slice back into the pool; this lets
+		// the pool adjust if we consistently take deep stacktraces.
+		programCounters = newProgramCounters(len(programCounters.pcs) * 2)
+	}
+
+	i := 0
+	frames := runtime.CallersFrames(programCounters.pcs)
+	for frame, more := frames.Next(); more; frame, more = frames.Next() {
+		if shouldIgnoreStacktraceFunction(frame.Function) {
+			continue
+		}
+		if i != 0 {
+			buffer.WriteByte('\n')
+		}
+		i++
+		buffer.WriteString(frame.Function)
+		buffer.WriteByte('\n')
+		buffer.WriteByte('\t')
+		buffer.WriteString(frame.File)
+		buffer.WriteByte(':')
+		buffer.WriteString(strconv.Itoa(int(frame.Line)))
+	}
+
+	return buffer.String()
+}
+
+func shouldIgnoreStacktraceFunction(function string) bool {
+	for _, prefix := range _stacktraceIgnorePrefixes {
+		if strings.HasPrefix(function, prefix) {
+			return true
+		}
+	}
+	return false
+}
+
+type programCounters struct {
+	pcs []uintptr
+}
+
+func newProgramCounters(size int) *programCounters {
+	return &programCounters{make([]uintptr, size)}
+}