Flush logs on crash

CHANGELOG.md

@@ -13,6 +13,10 @@
 - Replace `UUIDGenerator` implementation with Apache licensed code ([#4662](https://github.com/getsentry/sentry-java/pull/4662))
 - Replace `Random` implementation with MIT licensed code ([#4664](https://github.com/getsentry/sentry-java/pull/4664))
 
+### Fixes
+
+- Flush logs on crash ([#4684](https://github.com/getsentry/sentry-java/pull/4684))
+
 ## 8.20.0
 
 ### Fixes

sentry/src/main/java/io/sentry/SentryClient.java

@@ -36,6 +36,8 @@
 public final class SentryClient implements ISentryClient {
   static final String SENTRY_PROTOCOL_VERSION = "7";
 
+  private static final int LOG_FLUSH_ON_CRASH_TIMEOUT_MILLIS = 500;
+
   private boolean enabled;
 
   private final @NotNull SentryOptions options;
@@ -244,6 +246,11 @@ private boolean shouldApplyScopeData(final @NotNull CheckIn event, final @NotNul
     if (scope != null) {
       finalizeTransaction(scope, hint);
     }
+    // if event is backfillable or cached, it's an event from the past.
+    // Otherwise, we want to flush logs, as we encountered a crash.
+    if (event != null && !isBackfillable && !isCached && event.isCrashed()) {
+      loggerBatchProcessor.flush(LOG_FLUSH_ON_CRASH_TIMEOUT_MILLIS);
+    }
 
     return sentryId;
   }

sentry/src/test/java/io/sentry/SentryClientTest.kt

@@ -3023,6 +3023,25 @@ class SentryClientTest {
     assertTrue(terminated == true)
   }
 
+  @Test
+  fun `flush logs for crash events`() {
+    val sut = fixture.getSut()
+    val batchProcessor = mock<ILoggerBatchProcessor>()
+    sut.injectForField("loggerBatchProcessor", batchProcessor)
+    sut.captureLog(
+      SentryLogEvent(SentryId(), SentryNanotimeDate(), "message", SentryLogLevel.WARN),
+      fixture.scopes.scope,
+    )
+
+    sut.captureEvent(
+      SentryEvent().apply {
+        exceptions =
+          listOf(SentryException().apply { mechanism = Mechanism().apply { isHandled = false } })
+      }
+    )
+    verify(batchProcessor).flush(eq(500))
+  }
+
   @Test
   fun `cleans up replay folder for Backfillable replay events`() {
     val dir = File(tmpDir.newFolder().absolutePath)