README
¶
Trace
This package provides an interface for recording the latency of operations and logging details about all operations where the latency exceeds a limit.
Usage
To create a trace:
func doSomething() {
opTrace := trace.New("operation", Field{Key: "fieldKey1", Value: "fieldValue1"})
defer opTrace.LogIfLong(100 * time.Millisecond)
// do something
}
To split an trace into multiple steps:
func doSomething() {
opTrace := trace.New("operation")
defer opTrace.LogIfLong(100 * time.Millisecond)
// do step 1
opTrace.Step("step1", Field{Key: "stepFieldKey1", Value: "stepFieldValue1"})
// do step 2
opTrace.Step("step2")
}
To nest traces:
func doSomething() {
rootTrace := trace.New("rootOperation")
defer rootTrace.LogIfLong(100 * time.Millisecond)
func() {
nestedTrace := rootTrace.Nest("nested", Field{Key: "nestedFieldKey1", Value: "nestedFieldValue1"})
defer nestedTrace.LogIfLong(50 * time.Millisecond)
// do nested operation
}()
}
Traces can also be logged unconditionally or introspected:
opTrace.TotalTime() // Duration since the Trace was created
opTrace.Log() // unconditionally log the trace
Using context.Context to nest traces
context.Context can be used to manage nested traces. Create traces by calling trace.GetTraceFromContext(ctx).Nest.
This is safe even if there is no parent trace already in the context because (*(Trace)nil).Nest() returns
a top level trace.
func doSomething(ctx context.Context) {
opTrace := trace.FromContext(ctx).Nest("operation") // create a trace, possibly nested
ctx = trace.ContextWithTrace(ctx, opTrace) // make this trace the parent trace of the context
defer opTrace.LogIfLong(50 * time.Millisecond)
doSomethingElse(ctx)
}
Documentation
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Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type ContextTraceKey ¶
type ContextTraceKey struct{}
ContextTraceKey provides a common key for traces in context.Context values.
type Field ¶
type Field struct {
Key string
Value interface{}
}
Field is a key value pair that provides additional details about the trace.
type Trace ¶
type Trace struct {
// contains filtered or unexported fields
}
Trace keeps track of a set of "steps" and allows us to log a specific step if it took longer than its share of the total allowed time
func FromContext ¶
FromContext returns the trace keyed by ContextTraceKey in the context values, if one is present, or nil If there is no trace in the Context. It is safe to call Nest() on the returned value even if it is nil because ((*Trace)nil).Nest returns a top level trace.
func New ¶
New creates a Trace with the specified name. The name identifies the operation to be traced. The Fields add key value pairs to provide additional details about the trace, such as operation inputs.
func (*Trace) Log ¶
func (t *Trace) Log()
Log is used to dump all the steps in the Trace. It also logs the nested trace messages using indentation. If the Trace is nested it is not immediately logged. Instead, it is logged when the trace it is nested within is logged.
func (*Trace) LogIfLong ¶
LogIfLong only logs the trace if the duration of the trace exceeds the threshold. Only steps that took longer than their share or the given threshold are logged. If klog is at verbosity level 4 or higher and the trace took longer than the threshold, all substeps and subtraces are logged. Otherwise, only those which took longer than their own threshold. If the Trace is nested it is not immediately logged. Instead, it is logged when the trace it is nested within is logged.
func (*Trace) Nest ¶
Nest adds a nested trace with the given message and fields and returns it. As a convenience, if the receiver is nil, returns a top level trace. This allows one to call FromContext(ctx).Nest without having to check if the trace in the context is nil.
func (*Trace) Step ¶
Step adds a new step with a specific message. Call this at the end of an execution step to record how long it took. The Fields add key value pairs to provide additional details about the trace step.
Example ¶
t := New("frobber")
time.Sleep(5 * time.Millisecond)
t.Step("reticulated splines") // took 5ms
time.Sleep(10 * time.Millisecond)
t.Step("sequenced particles") // took 10ms
klog.SetOutput(os.Stdout) // change output from stderr to stdout
t.Log()
Output:
Source Files