86 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Go
		
	
	
	
			
		
		
	
	
			86 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Go
		
	
	
	
// Copyright (c) 2016 Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package zap
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import (
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	"runtime"
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	"sync"
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	"go.uber.org/zap/internal/bufferpool"
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)
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var (
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	_stacktracePool = sync.Pool{
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		New: func() interface{} {
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			return newProgramCounters(64)
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		},
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	}
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)
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func takeStacktrace(skip int) string {
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	buffer := bufferpool.Get()
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	defer buffer.Free()
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	programCounters := _stacktracePool.Get().(*programCounters)
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	defer _stacktracePool.Put(programCounters)
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	var numFrames int
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	for {
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		// Skip the call to runtime.Callers and takeStacktrace so that the
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		// program counters start at the caller of takeStacktrace.
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		numFrames = runtime.Callers(skip+2, programCounters.pcs)
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		if numFrames < len(programCounters.pcs) {
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			break
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		}
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		// Don't put the too-short counter slice back into the pool; this lets
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		// the pool adjust if we consistently take deep stacktraces.
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		programCounters = newProgramCounters(len(programCounters.pcs) * 2)
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	}
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	i := 0
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	frames := runtime.CallersFrames(programCounters.pcs[:numFrames])
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	// Note: On the last iteration, frames.Next() returns false, with a valid
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	// frame, but we ignore this frame. The last frame is a a runtime frame which
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	// adds noise, since it's only either runtime.main or runtime.goexit.
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	for frame, more := frames.Next(); more; frame, more = frames.Next() {
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		if i != 0 {
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			buffer.AppendByte('\n')
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		}
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		i++
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		buffer.AppendString(frame.Function)
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		buffer.AppendByte('\n')
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		buffer.AppendByte('\t')
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		buffer.AppendString(frame.File)
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		buffer.AppendByte(':')
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		buffer.AppendInt(int64(frame.Line))
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	}
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	return buffer.String()
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}
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type programCounters struct {
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	pcs []uintptr
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}
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func newProgramCounters(size int) *programCounters {
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	return &programCounters{make([]uintptr, size)}
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}
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