feat(transport): add HTTP retry with exponential backoff by jpnurmi · Pull Request #1520 · getsentry/sentry-native

jpnurmi · 2026-02-13T15:44:54Z

Add HTTP retry with exponential backoff for network failures, modeled after Crashpad's upload retry behavior.

Note

Adds an explicit 15s connect timeout to both curl and WinHTTP, matching the value used by Crashpad. This reduces the time the transport worker is blocked on unreachable hosts, previously ~75s on curl (OS TCP SYN retry limit) and 60s on WinHTTP.

Failed envelopes are stored as <db>/cache/<ts>-<n>-<uuid>.envelope and retried on startup after a 100ms throttle, and then with exponential backoff (15min, 30min, 1h, 2h, 4h, 8h). When retries are exhausted, and offline caching is enabled, envelopes are stored as <db>/cache/<uuid>.envelope instead of being discarded.

flowchart TD
    startup --> sretry{retry?}
    sretry -->|yes| throttle
    throttle -. 100ms .-> send
    send -->|success| discard
    send -->|fail| retry{retry?}
    retry -->|no| cache{cache?}
    cache -->|no| discard
    cache -->|yes| cache-dump[&lt;db&gt;/cache/<br/>&lt;uuid&gt;.envelope]
    retry -->|yes| cache-retry[&lt;db&gt;/cache/<br/>&lt;ts&gt;-&lt;n&gt;-&lt;uuid&gt;.envelope]
    cache-retry --> backoff
    backoff -. 2ⁿ×15min .-> send

Builds upon:

See also:

github-actions · 2026-02-13T15:45:22Z

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📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

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jpnurmi · 2026-02-16T08:59:33Z

@sentry review

jpnurmi · 2026-02-16T08:59:39Z

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src/sentry_sync.c

src/transports/sentry_http_transport.c

src/sentry_retry.c

src/transports/sentry_http_transport_winhttp.c

src/sentry_retry.c

jpnurmi · 2026-02-16T15:21:30Z

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jpnurmi · 2026-02-16T15:21:38Z

@cursor review

src/transports/sentry_http_transport.c

src/sentry_retry.c

jpnurmi · 2026-02-16T16:09:06Z

@cursor review

src/sentry_sync.c

src/sentry_database.c

jpnurmi · 2026-02-16T16:41:48Z

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jpnurmi · 2026-02-16T19:42:40Z

@cursor review

src/sentry_retry.c

src/sentry_transport.c

jpnurmi · 2026-02-17T09:34:34Z

@cursor review

src/sentry_retry.c

src/sentry_sync.c

jpnurmi · 2026-02-17T10:27:24Z

@sentry review

jpnurmi · 2026-02-17T10:27:33Z

@cursor review

src/sentry_options.c

jpnurmi · 2026-02-17T11:22:11Z

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…nd_task The local `HINTERNET request = client->request` snapshot was only needed for the cancel_client approach. Since shutdown_client only fires at the timeout point, mid-function reads of client->request are safe. Keep only the InterlockedExchangePointer in the exit block to prevent double-close. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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src/sentry_sync.c

Move sentry__atomic_store(&bgw->running, 0) from before the on_timeout callback to the else branch (detach path). This lets the worker's shutdown_task set running=0 naturally after finishing in-flight work, making the dump_queue safety-net reachable if the callback fails to unblock the worker within another 250ms cycle. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/transports/sentry_http_transport.c

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src/sentry_retry.c

…iness Tests that directly call sentry__retry_send were racing with the transport's background retry worker polling the same cache directory. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/sentry_retry.c

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src/sentry_sync.c

src/sentry_retry.c

…e data loss After retry_enqueue writes an envelope and stores its address in sealed_envelope, the envelope is freed when the bgworker task completes. If a subsequent envelope is allocated at the same address and is still pending during shutdown, retry_dump_cb would incorrectly skip it, losing the envelope. Clear sealed_envelope after the first match so later iterations cannot false-match a reused address. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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src/sentry_sync.c

jpnurmi · 2026-02-27T09:07:21Z

5/5 consecutive CI runs passed 🎉

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Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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src/sentry_sync.c

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src/sentry_sync.c

src/sentry_retry.c

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src/sentry_retry.c

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src/sentry_retry.c

src/sentry_sync.c

Move cache_keep logic into http_send_task so envelopes are cached only when sending actually fails, rather than unconditionally in process_old_runs. For non-HTTP transports, process_old_runs still handles caching since there is no http_send_task. - Add cache_keep/run fields to http_transport_state_t - Cache in http_send_task when send fails and retry is unavailable - Simplify can_cache in process_old_runs to check transport capability - Fix NULL transport dereference in sentry__transport_flush - Update sentry_options_set_cache_keep/http_retry docs Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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src/transports/sentry_http_transport.c

Move envelope caching from process_old_runs (synchronous, before send) into http_send_task (on HTTP failure). This ensures envelopes are only cached when the send actually fails, rather than unconditionally. Add transport cleanup_func to submit cache cleanup as a FIFO task on the bg worker, guaranteeing it runs after pending send tasks from process_old_runs. Add explicit flush argument to sentry_example for deterministic test behavior across platforms with varying HTTP timeout characteristics. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Its only production use was the can_cache check in process_old_runs, which was removed in the previous commit. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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src/transports/sentry_http_transport.c

src/sentry_retry.c

When bgworker_shutdown_cb times out, the thread is detached and sentry_close frees options while the cleanup task may still be queued. Incref options when submitting and use sentry_options_free as the task cleanup function to ensure safe lifetime. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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src/sentry_sync.c

jpnurmi force-pushed the jpnurmi/feat/http-retry branch 2 times, most recently from b083a57 to a264f66 Compare February 13, 2026 17:47

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This was referenced Feb 16, 2026

ref: parse event_id from raw envelopes #1512

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feat(sync): add delayed task submission #1506

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WIP: feat(transport): TUS upload for large attachments #1545

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WIP: feat: client reports #1549

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ref: consolidate filename formatting into make_cache_path

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Adapt to sentry__session_new() change

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Clarify bgworker shutdown timeout comment

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Remove unused sentry__transport_can_retry

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