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package trace2hooks
import (
"context"
"encoding/json"
"fmt"
"gitlab.com/gitlab-org/gitaly/v16/internal/git/trace2"
"gitlab.com/gitlab-org/gitaly/v16/internal/log"
"golang.org/x/time/rate"
)
// NewLogExporter initializes LogExporter, which is a hook that uses the parsed
// trace2 events from the manager to export them to the Gitaly log. It's invocations are limited
// by the rateLimiter. The limiter allows maxBurstToken number of events to happen at once and then
// replenishes by maxEventPerSecond. It works on the token bucket algorithm where you have a number
// of tokens in the bucket to start and you can consume them in each call whilst the bucket gets
// refilled at the specified rate.
func NewLogExporter(rl *rate.Limiter, logger log.Logger) *LogExporter {
return &LogExporter{
rateLimiter: rl,
logger: logger,
}
}
// LogExporter is a trace2 hook that adds trace2 api event logs to Gitaly's logs.
type LogExporter struct {
logger log.Logger
rateLimiter *rate.Limiter
}
// Name returns the name of tracing exporter
func (t *LogExporter) Name() string {
return "log_exporter"
}
// Handle will log the trace in a readable json format in Gitaly's logs. Metadata is also collected
// and additional information is added to the log. It is also rate limited to protect it from overload
// when there are a lot of trace2 events triggered from git operations.
func (t *LogExporter) Handle(rootCtx context.Context, trace *trace2.Trace) error {
if !t.rateLimiter.Allow() {
// When the event is not allowed, return an error to the caller, this may cause traces to be skipped/dropped.
return fmt.Errorf("rate has exceeded current limit")
}
trace.Walk(rootCtx, func(ctx context.Context, t *trace2.Trace) context.Context {
t.SetMetadata("elapsed_ms", fmt.Sprintf("%d", t.FinishTime.Sub(t.StartTime).Milliseconds()))
return ctx
})
childrenJSON, err := json.Marshal(trace.Children)
if err != nil {
return fmt.Errorf("marshal json: %w", err)
}
escapedChildren := json.RawMessage(childrenJSON)
t.logger.WithFields(log.Fields{
"name": trace.Name,
"thread": trace.Thread,
"component": "trace2hooks." + t.Name(),
"start_time": trace.StartTime,
"finish_time": trace.FinishTime,
"metadata": trace.Metadata,
"children": escapedChildren,
}).Info("Git Trace2 API")
return nil
}
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