poc: add heartbeat functionality to native backend

[bitsandfoxes]

Resolves https://github.com/getsentry/team-gdx/issues/155

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WIP    🚧🔨⏳⛔

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## Unreleased

### Features

- add heartbeat functionality to native backend ([#1742](https://github.com/getsentry/sentry-native/pull/1742))

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Generated by 🚫 dangerJS against 1f2c69d

[sentry]

Bug: In capture_and_send_app_hang, an envelope allocated by sentry__envelope_from_path is leaked if options->transport is NULL, as the freeing logic is skipped.
_{Severity: MEDIUM}

Suggested Fix

Ensure the envelope is always freed, regardless of whether sentry__capture_envelope is called. This can be achieved by moving the sentry_envelope_free call to a location that executes in all paths, or by adding an else block to handle the case where the transport is unavailable and free the envelope there.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: src/backends/native/sentry_crash_daemon.c#L2748-L2750

Potential issue: In the `capture_and_send_app_hang` function, an envelope is allocated
from a file path using `sentry__envelope_from_path`. This envelope is intended to be
freed within `sentry__capture_envelope`. However, the call to `sentry__capture_envelope`
is conditional on `options->transport` being non-NULL. If transport initialization fails
and `options->transport` is `NULL`, the condition is false, the function is not called,
and the allocated envelope is never freed, resulting in a memory leak. Since the daemon
is a long-running process, this leak can accumulate over time.

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[cursor]

Cursor Bugbot has reviewed your changes and found 4 potential issues.

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^{Reviewed by Cursor Bugbot for commit 1f2c69d. Configure here.}

[cursor]

Timer failure disables hangs

Medium Severity

If the Windows app-hang timer fails to initialize, the daemon won't set up its polling mechanism. This prevents app-hang detection from running, even when the feature is enabled and the host continues to send heartbeats.

 

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[cursor]

Failed capture still cools down

Medium Severity

After SENTRY_APP_HANG_FIRE, the daemon always sets last_fired_hb to the current heartbeat even when capture_and_send_app_hang fails (for example OpenThread with a zero or invalid app_hang_target_tid). While the monitored thread stays frozen the heartbeat timestamp does not change, so later ticks hit the cooldown branch and no ApplicationNotResponding event is sent.

Additional Locations (1)

• src/backends/native/sentry_crash_daemon.c#L2643-L2653

 

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[cursor]

Heartbeat use after free

Medium Severity

sentry_app_hang_heartbeat copies g_app_hang_shmem into a local pointer, then writes shared heartbeat fields through it. During native_backend_shutdown, another thread can clear that global and unmap IPC between the load and the store, so a concurrent heartbeat can touch freed shared memory.

Additional Locations (1)

• src/backends/sentry_backend_native.c#L685-L691

 

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[cursor]

App hang upload not flushed

High Severity

After an app-hang envelope is queued via sentry__capture_envelope, the daemon keeps running and never flushes its HTTP transport. Normal sentry_close() then terminates the daemon with TerminateProcess, so background sends can be cut off and the ApplicationNotResponding event may never reach Sentry.

 

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