mirror of
https://github.com/cwinfo/yggdrasil-go.git
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95 lines
2.2 KiB
Go
95 lines
2.2 KiB
Go
package util
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// These are misc. utility functions that didn't really fit anywhere else
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import "runtime"
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import "time"
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// A wrapper around runtime.Gosched() so it doesn't need to be imported elsewhere.
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func Yield() {
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runtime.Gosched()
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}
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// A wrapper around runtime.LockOSThread() so it doesn't need to be imported elsewhere.
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func LockThread() {
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runtime.LockOSThread()
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}
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// A wrapper around runtime.UnlockOSThread() so it doesn't need to be imported elsewhere.
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func UnlockThread() {
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runtime.UnlockOSThread()
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}
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// This is used to buffer recently used slices of bytes, to prevent allocations in the hot loops.
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// It's used like a sync.Pool, but with a fixed size and typechecked without type casts to/from interface{} (which were making the profiles look ugly).
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var byteStore chan []byte
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func init() {
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byteStore = make(chan []byte, 32)
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}
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// Gets an empty slice from the byte store, if one is available, or else returns a new nil slice.
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func GetBytes() []byte {
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select {
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case bs := <-byteStore:
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return bs[:0]
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default:
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return nil
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}
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}
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// Puts a slice in the store, if there's room, or else returns and lets the slice get collected.
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func PutBytes(bs []byte) {
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select {
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case byteStore <- bs:
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default:
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}
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}
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// This is a workaround to go's broken timer implementation
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func TimerStop(t *time.Timer) bool {
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stopped := t.Stop()
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select {
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case <-t.C:
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default:
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}
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return stopped
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}
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// Run a blocking function with a timeout.
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// Returns true if the function returns.
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// Returns false if the timer fires.
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// The blocked function remains blocked--the caller is responsible for somehow killing it.
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func FuncTimeout(f func(), timeout time.Duration) bool {
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success := make(chan struct{})
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go func() {
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defer close(success)
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f()
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}()
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timer := time.NewTimer(timeout)
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defer TimerStop(timer)
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select {
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case <-success:
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return true
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case <-timer.C:
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return false
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}
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}
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// This calculates the difference between two arrays and returns items
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// that appear in A but not in B - useful somewhat when reconfiguring
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// and working out what configuration items changed
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func Difference(a, b []string) []string {
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ab := []string{}
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mb := map[string]bool{}
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for _, x := range b {
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mb[x] = true
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}
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for _, x := range a {
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if !mb[x] {
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ab = append(ab, x)
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}
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}
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return ab
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}
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