Make flush delay-aware so it waits for delayed tasks

The flush marker now uses the last task's deadline (capped at the flush
timeout) so it sorts after all current tasks including delayed ones.

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

Author: jpnurmi

src/sentry_sync.c

@@ -361,11 +361,23 @@ sentry__bgworker_flush(sentry_bgworker_t *bgw, uint64_t timeout)
     sentry__cond_init(&flush_task->signal);
     sentry__mutex_init(&flush_task->lock);
 
+    // flush potential delayed tasks up until the timeout
+    uint64_t delay_ms = 0;
+    uint64_t before = sentry__monotonic_time();
+    sentry__mutex_lock(&bgw->task_lock);
+    if (bgw->last_task && bgw->last_task->execute_after > before) {
+        delay_ms = bgw->last_task->execute_after - before;
+        if (delay_ms > timeout) {
+            delay_ms = timeout;
+        }
+    }
+    sentry__mutex_unlock(&bgw->task_lock);
+
     sentry__mutex_lock(&flush_task->lock);
 
     /* submit the task that triggers our condvar once it runs */
-    sentry__bgworker_submit(bgw, sentry__flush_task,
-        (void (*)(void *))sentry__flush_task_decref, flush_task);
+    sentry__bgworker_submit_delayed(bgw, sentry__flush_task,
+        (void (*)(void *))sentry__flush_task_decref, flush_task, delay_ms);
 
     uint64_t started = sentry__monotonic_time();
     bool was_flushed = false;

tests/unit/test_sync.c

@@ -215,13 +215,14 @@ SENTRY_TEST(bgworker_task_delay)
         bgw, record_order_task, NULL, (void *)1, 50);
 
     sentry__bgworker_start(bgw);
-    TEST_CHECK_INT_EQUAL(sentry__bgworker_shutdown(bgw, 500), 0);
+    TEST_CHECK_INT_EQUAL(sentry__bgworker_flush(bgw, 500), 0);
     uint64_t after = sentry__monotonic_time();
 
     TEST_CHECK_INT_EQUAL(os.count, 1);
     TEST_CHECK_INT_EQUAL(os.order[0], 1);
     TEST_CHECK(after - before >= 50);
 
+    sentry__bgworker_shutdown(bgw, 500);
     sentry__bgworker_decref(bgw);
 }
 
@@ -264,7 +265,7 @@ SENTRY_TEST(bgworker_delayed_tasks)
     sentry__bgworker_submit(bgw, record_order_task, NULL, (void *)10);
 
     sentry__bgworker_start(bgw);
-    TEST_CHECK_INT_EQUAL(sentry__bgworker_shutdown(bgw, 5000), 0);
+    TEST_CHECK_INT_EQUAL(sentry__bgworker_flush(bgw, 5000), 0);
 
     // all tasks execute: immediate first, then delayed in deadline order
     TEST_CHECK_INT_EQUAL(os.count, 10);
@@ -279,6 +280,7 @@ SENTRY_TEST(bgworker_delayed_tasks)
     TEST_CHECK_INT_EQUAL(os.order[8], 4);
     TEST_CHECK_INT_EQUAL(os.order[9], 5);
 
+    sentry__bgworker_shutdown(bgw, 500);
     sentry__bgworker_decref(bgw);
 }