75 lines
2.0 KiB
Go
75 lines
2.0 KiB
Go
// Server: the HTTP listener and the background lease reaper, both shut down
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// cleanly on a signal.
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package infra
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import (
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"context"
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"errors"
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"log/slog"
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"net/http"
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"time"
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)
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const shutdownGrace = 15 * time.Second
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// Run serves handler until ctx is cancelled, then drains in-flight requests.
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func RunServer(ctx context.Context, log *slog.Logger, addr string, handler http.Handler) error {
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srv := &http.Server{
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Addr: addr,
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Handler: handler,
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ReadHeaderTimeout: 5 * time.Second,
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}
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// Buffered so this goroutine can exit even when nobody reads the channel
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// (the ctx.Done branch below) — an unbuffered send would leak it forever.
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errCh := make(chan error, 1)
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go func() {
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log.Info("userservice listening", "addr", addr)
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if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
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errCh <- err
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}
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}()
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select {
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case err := <-errCh:
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return err
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case <-ctx.Done():
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log.Info("shutdown signal received")
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}
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// A fresh context: ctx is already cancelled, and reusing it would abort the
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// very requests we are trying to let finish.
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shutdownCtx, cancel := context.WithTimeout(context.Background(), shutdownGrace)
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defer cancel()
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return srv.Shutdown(shutdownCtx)
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}
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// RunReaper periodically reclaims tasks whose lease elapsed, so a worker that
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// died without a heartbeat cannot strand its task in 'leased' forever.
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// RunPeriodic invokes fn on an interval until ctx is done, logging how many rows
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// each tick affected. It backs the background reapers (expired leases, offline
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// workers) — each is a set-based UPDATE that is safe to run repeatedly and
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// concurrently across coordinators.
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func RunPeriodic(ctx context.Context, log *slog.Logger, name string, interval time.Duration,
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fn func(context.Context) (int64, error)) {
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t := time.NewTicker(interval)
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defer t.Stop()
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for {
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select {
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case <-ctx.Done():
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return
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case <-t.C:
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n, err := fn(ctx)
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if err != nil {
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log.Debug(name+" skipped", "err", err)
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continue
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}
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if n > 0 {
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log.Info(name, "count", n)
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}
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}
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}
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}
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