mirror of
https://github.com/zrepl/zrepl.git
synced 2024-12-01 21:04:59 +01:00
10a14a8c50
package trace:
- introduce the concept of tasks and spans, tracked as linked list within ctx
- see package-level docs for an overview of the concepts
- **main feature 1**: unique stack of task and span IDs
- makes it easy to follow a series of log entries in concurrent code
- **main feature 2**: ability to produce a chrome://tracing-compatible trace file
- either via an env variable or a `zrepl pprof` subcommand
- this is not a CPU profile, we already have go pprof for that
- but it is very useful to visually inspect where the
replication / snapshotter / pruner spends its time
( fixes #307 )
usage in package daemon/logging:
- goal: every log entry should have a trace field with the ID stack from package trace
- make `logging.GetLogger(ctx, Subsys)` the authoritative `logger.Logger` factory function
- the context carries a linked list of injected fields which
`logging.GetLogger` adds to the logger it returns
- `logging.GetLogger` also uses package `trace` to get the
task-and-span-stack and injects it into the returned logger's fields
55 lines
1.1 KiB
Go
55 lines
1.1 KiB
Go
package trace
|
|
|
|
import (
|
|
"context"
|
|
"time"
|
|
|
|
"github.com/zrepl/zrepl/util/chainlock"
|
|
)
|
|
|
|
type SpanInfo interface {
|
|
StartedAt() time.Time
|
|
EndedAt() time.Time
|
|
TaskAndSpanStack(kind *StackKind) string
|
|
}
|
|
|
|
type Callback struct {
|
|
OnBegin func(ctx context.Context)
|
|
OnEnd func(ctx context.Context, spanInfo SpanInfo)
|
|
}
|
|
|
|
var callbacks struct {
|
|
mtx chainlock.L
|
|
cs []Callback
|
|
}
|
|
|
|
func RegisterCallback(c Callback) {
|
|
callbacks.mtx.HoldWhile(func() {
|
|
callbacks.cs = append(callbacks.cs, c)
|
|
})
|
|
}
|
|
|
|
func callbackBeginSpan(ctx context.Context) func(SpanInfo) {
|
|
// capture the current state of callbacks into a local variable
|
|
// this is safe because the slice is append-only and immutable
|
|
|
|
// (it is important that a callback registered _after_ callbackBeginSpin is called does not get called on OnEnd)
|
|
|
|
var cbs []Callback
|
|
callbacks.mtx.HoldWhile(func() {
|
|
cbs = callbacks.cs
|
|
})
|
|
for _, cb := range cbs {
|
|
if cb.OnBegin != nil {
|
|
cb.OnBegin(ctx)
|
|
}
|
|
}
|
|
return func(spanInfo SpanInfo) {
|
|
for _, cb := range cbs {
|
|
if cb.OnEnd != nil {
|
|
cb.OnEnd(ctx, spanInfo)
|
|
}
|
|
}
|
|
}
|
|
}
|