Optimize when maxBreadcrumb is 0 (#4504)

* breadcumbs queue is now a simple DisabledQueue when maxBreadcrumb is 0
* if breadcumbs is a DisabledQueue, no more processing is done (beforeBreadcrumb or scopeObservers)

Author: stefanosiano

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Fixes
 
+- Optimize scope when maxBreadcrumb is 0 ([#4504](https://github.com/getsentry/sentry-java/pull/4504))
 - Fix javadoc on TransportResult ([#4528](https://github.com/getsentry/sentry-java/pull/4528))
 
 ### Internal

sentry/src/main/java/io/sentry/Scope.java

@@ -466,7 +466,7 @@ public Queue<Breadcrumb> getBreadcrumbs() {
    */
   @Override
   public void addBreadcrumb(@NotNull Breadcrumb breadcrumb, @Nullable Hint hint) {
-    if (breadcrumb == null) {
+    if (breadcrumb == null || breadcrumbs instanceof DisabledQueue) {
       return;
     }
     if (hint == null) {
@@ -862,7 +862,7 @@ public void clearAttachments() {
   static @NotNull Queue<Breadcrumb> createBreadcrumbsList(final int maxBreadcrumb) {
     return maxBreadcrumb > 0
         ? SynchronizedQueue.synchronizedQueue(new CircularFifoQueue<>(maxBreadcrumb))
-        : SynchronizedQueue.synchronizedQueue(new DisabledQueue<>());
+        : new DisabledQueue<>();
   }
 
   /**

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

@@ -14,13 +14,15 @@ import kotlin.test.assertNotSame
 import kotlin.test.assertNull
 import kotlin.test.assertTrue
 import org.junit.Assert.assertArrayEquals
+import org.mockito.kotlin.any
 import org.mockito.kotlin.argThat
 import org.mockito.kotlin.check
 import org.mockito.kotlin.eq
 import org.mockito.kotlin.mock
 import org.mockito.kotlin.never
 import org.mockito.kotlin.times
 import org.mockito.kotlin.verify
+import org.mockito.kotlin.verifyNoInteractions
 import org.mockito.kotlin.whenever
 
 class ScopeTest {
@@ -331,6 +333,69 @@ class ScopeTest {
     assertEquals(1, scope.breadcrumbs.count())
   }
 
+  @Test
+  fun `when adding breadcrumb and maxBreadcrumb is 0, beforeBreadcrumb is not executed`() {
+    var called = false
+    val options =
+      SentryOptions().apply {
+        maxBreadcrumbs = 0
+        beforeBreadcrumb =
+          SentryOptions.BeforeBreadcrumbCallback { breadcrumb, _ ->
+            called = true
+            breadcrumb
+          }
+      }
+
+    val scope = Scope(options)
+    scope.addBreadcrumb(Breadcrumb())
+    assertEquals(0, scope.breadcrumbs.count())
+    assertFalse(called)
+  }
+
+  @Test
+  fun `when adding breadcrumb and maxBreadcrumb is not 0, beforeBreadcrumb is executed`() {
+    var called = false
+    val options =
+      SentryOptions().apply {
+        beforeBreadcrumb =
+          SentryOptions.BeforeBreadcrumbCallback { breadcrumb, _ ->
+            called = true
+            breadcrumb
+          }
+      }
+
+    val scope = Scope(options)
+    scope.addBreadcrumb(Breadcrumb())
+    assertEquals(1, scope.breadcrumbs.count())
+    assertTrue(called)
+  }
+
+  @Test
+  fun `when adding breadcrumb and maxBreadcrumb is 0, scopesObservers are not called`() {
+    val observer = mock<IScopeObserver>()
+    val options =
+      SentryOptions().apply {
+        maxBreadcrumbs = 0
+        addScopeObserver(observer)
+      }
+
+    val scope = Scope(options)
+    scope.addBreadcrumb(Breadcrumb())
+    assertEquals(0, scope.breadcrumbs.count())
+    verifyNoInteractions(observer)
+  }
+
+  @Test
+  fun `when adding breadcrumb and maxBreadcrumb is not 0, scopesObservers are called`() {
+    val observer = mock<IScopeObserver>()
+    val options = SentryOptions().apply { addScopeObserver(observer) }
+
+    val scope = Scope(options)
+    scope.addBreadcrumb(Breadcrumb())
+    assertEquals(1, scope.breadcrumbs.count())
+    verify(observer).addBreadcrumb(any())
+  }
+
   @Test
   fun `when adding eventProcessor, eventProcessor should be in the list`() {
     val processor = CustomEventProcessor()