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Diffstat (limited to 'vendor/github.com/docker/distribution/context/trace.go')
-rw-r--r-- | vendor/github.com/docker/distribution/context/trace.go | 104 |
1 files changed, 0 insertions, 104 deletions
diff --git a/vendor/github.com/docker/distribution/context/trace.go b/vendor/github.com/docker/distribution/context/trace.go deleted file mode 100644 index 721964a84..000000000 --- a/vendor/github.com/docker/distribution/context/trace.go +++ /dev/null @@ -1,104 +0,0 @@ -package context - -import ( - "runtime" - "time" - - "github.com/docker/distribution/uuid" -) - -// WithTrace allocates a traced timing span in a new context. This allows a -// caller to track the time between calling WithTrace and the returned done -// function. When the done function is called, a log message is emitted with a -// "trace.duration" field, corresponding to the elapsed time and a -// "trace.func" field, corresponding to the function that called WithTrace. -// -// The logging keys "trace.id" and "trace.parent.id" are provided to implement -// dapper-like tracing. This function should be complemented with a WithSpan -// method that could be used for tracing distributed RPC calls. -// -// The main benefit of this function is to post-process log messages or -// intercept them in a hook to provide timing data. Trace ids and parent ids -// can also be linked to provide call tracing, if so required. -// -// Here is an example of the usage: -// -// func timedOperation(ctx Context) { -// ctx, done := WithTrace(ctx) -// defer done("this will be the log message") -// // ... function body ... -// } -// -// If the function ran for roughly 1s, such a usage would emit a log message -// as follows: -// -// INFO[0001] this will be the log message trace.duration=1.004575763s trace.func=github.com/docker/distribution/context.traceOperation trace.id=<id> ... -// -// Notice that the function name is automatically resolved, along with the -// package and a trace id is emitted that can be linked with parent ids. -func WithTrace(ctx Context) (Context, func(format string, a ...interface{})) { - if ctx == nil { - ctx = Background() - } - - pc, file, line, _ := runtime.Caller(1) - f := runtime.FuncForPC(pc) - ctx = &traced{ - Context: ctx, - id: uuid.Generate().String(), - start: time.Now(), - parent: GetStringValue(ctx, "trace.id"), - fnname: f.Name(), - file: file, - line: line, - } - - return ctx, func(format string, a ...interface{}) { - GetLogger(ctx, - "trace.duration", - "trace.id", - "trace.parent.id", - "trace.func", - "trace.file", - "trace.line"). - Debugf(format, a...) - } -} - -// traced represents a context that is traced for function call timing. It -// also provides fast lookup for the various attributes that are available on -// the trace. -type traced struct { - Context - id string - parent string - start time.Time - fnname string - file string - line int -} - -func (ts *traced) Value(key interface{}) interface{} { - switch key { - case "trace.start": - return ts.start - case "trace.duration": - return time.Since(ts.start) - case "trace.id": - return ts.id - case "trace.parent.id": - if ts.parent == "" { - return nil // must return nil to signal no parent. - } - - return ts.parent - case "trace.func": - return ts.fnname - case "trace.file": - return ts.file - case "trace.line": - return ts.line - } - - return ts.Context.Value(key) -} |