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1ae087bfcf
- 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
- introduce the concept of tasks and spans, also tracked as linked list within ctx
- [ ] TODO automatic logging of span begins and ends, with a unique
ID stack that makes it easy to follow a series of log entries in
concurrent code
- 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 )
42 lines
748 B
Go
42 lines
748 B
Go
package semaphore
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import (
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"context"
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wsemaphore "golang.org/x/sync/semaphore"
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"github.com/zrepl/zrepl/daemon/logging"
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)
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type S struct {
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ws *wsemaphore.Weighted
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}
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func New(max int64) *S {
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return &S{wsemaphore.NewWeighted(max)}
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}
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type AcquireGuard struct {
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s *S
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released bool
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}
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// The returned AcquireGuard is not goroutine-safe.
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func (s *S) Acquire(ctx context.Context) (*AcquireGuard, error) {
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defer logging.WithSpanFromStackUpdateCtx(&ctx)()
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if err := s.ws.Acquire(ctx, 1); err != nil {
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return nil, err
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} else if err := ctx.Err(); err != nil {
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return nil, err
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}
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return &AcquireGuard{s, false}, nil
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}
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func (g *AcquireGuard) Release() {
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if g == nil || g.released {
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return
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}
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g.released = true
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g.s.ws.Release(1)
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}
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