Fix: Allow MaxBreadcrumb 0 / Expose MaxBreadcrumb metadata. (#3836)

* expose max-breadcrumbs on meta data and implement disabled queue when maxbreadcrumbs sets to 0
* missing queue class and test
* update changelog

---------

Co-authored-by: Lucas <luca-zimerman1@hotmail.com>
Co-authored-by: Stefano <stefano.siano91@gmail.com>

CHANGELOG.md

@@ -4,10 +4,12 @@
 
 ### Features
 
+- Add meta option to set the maximum amount of breadcrumbs to be logged. ([#3836](https://github.com/getsentry/sentry-java/pull/3836))
 - Use a separate `Random` instance per thread to improve SDK performance ([#3835](https://github.com/getsentry/sentry-java/pull/3835))
 
 ### Fixes
 
+- Using MaxBreadcrumb with value 0 no longer crashes. ([#3836](https://github.com/getsentry/sentry-java/pull/3836))
 - Accept manifest integer values when requiring floating values ([#3823](https://github.com/getsentry/sentry-java/pull/3823))
 
 ## 7.16.0

sentry-android-core/src/main/java/io/sentry/android/core/ManifestMetadataReader.java

@@ -104,6 +104,8 @@ final class ManifestMetadataReader {
 
   static final String ENABLE_METRICS = "io.sentry.enable-metrics";
 
+  static final String MAX_BREADCRUMBS = "io.sentry.max-breadcrumbs";
+
   static final String REPLAYS_SESSION_SAMPLE_RATE = "io.sentry.session-replay.session-sample-rate";
 
   static final String REPLAYS_ERROR_SAMPLE_RATE = "io.sentry.session-replay.on-error-sample-rate";
@@ -213,6 +215,9 @@ static void applyMetadata(
                 SESSION_TRACKING_TIMEOUT_INTERVAL_MILLIS,
                 options.getSessionTrackingIntervalMillis()));
 
+        options.setMaxBreadcrumbs(
+            (int) readLong(metadata, logger, MAX_BREADCRUMBS, options.getMaxBreadcrumbs()));
+
         options.setEnableActivityLifecycleBreadcrumbs(
             readBool(
                 metadata,

sentry-android-core/src/test/java/io/sentry/android/core/ManifestMetadataReaderTest.kt

@@ -1516,6 +1516,31 @@ class ManifestMetadataReaderTest {
         assertTrue(fixture.options.experimental.sessionReplay.maskViewClasses.contains(SentryReplayOptions.TEXT_VIEW_CLASS_NAME))
     }
 
+    @Test
+    fun `applyMetadata reads maxBreadcrumbs to options and sets the value if found`() {
+        // Arrange
+        val bundle = bundleOf(ManifestMetadataReader.MAX_BREADCRUMBS to 1)
+        val context = fixture.getContext(metaData = bundle)
+
+        // Act
+        ManifestMetadataReader.applyMetadata(context, fixture.options, fixture.buildInfoProvider)
+
+        // Assert
+        assertEquals(1, fixture.options.maxBreadcrumbs)
+    }
+
+    @Test
+    fun `applyMetadata reads maxBreadcrumbs to options and keeps default if not found`() {
+        // Arrange
+        val context = fixture.getContext()
+
+        // Act
+        ManifestMetadataReader.applyMetadata(context, fixture.options, fixture.buildInfoProvider)
+
+        // Assert
+        assertEquals(100, fixture.options.maxBreadcrumbs)
+    }
+
     @Test
     fun `applyMetadata reads integers even when expecting floats`() {
         // Arrange

sentry-samples/sentry-samples-android/src/main/AndroidManifest.xml

@@ -152,6 +152,9 @@
         <!--    how to enable the attach screenshot feature-->
         <meta-data android:name="io.sentry.attach-screenshot" android:value="true" />
 
+        <!--    how many breadcrumbs will be stored-->
+        <meta-data android:name="io.sentry.max-breadcrumbs" android:value="100"/>
+
         <!--    how to enable the attach view hierarchy feature-->
         <meta-data android:name="io.sentry.attach-view-hierarchy" android:value="true" />
 

sentry/src/main/java/io/sentry/DisabledQueue.java

@@ -0,0 +1,115 @@
+package io.sentry;
+
+import java.io.Serializable;
+import java.util.AbstractCollection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.Queue;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+final class DisabledQueue<E> extends AbstractCollection<E> implements Queue<E>, Serializable {
+
+  /** Serialization version. */
+  private static final long serialVersionUID = -8423413834657610417L;
+
+  /** Constructor that creates a queue that does not accept any element. */
+  public DisabledQueue() {}
+
+  // -----------------------------------------------------------------------
+  /**
+   * Returns the number of elements stored in the queue.
+   *
+   * @return this queue's size
+   */
+  @Override
+  public int size() {
+    return 0;
+  }
+
+  /**
+   * Returns true if this queue is empty; false otherwise.
+   *
+   * @return false
+   */
+  @Override
+  public boolean isEmpty() {
+    return false;
+  }
+
+  /** Does nothing. */
+  @Override
+  public void clear() {}
+
+  /**
+   * Since the queue is disabled, the element will not be added.
+   *
+   * @param element the element to add
+   * @return false, always
+   */
+  @Override
+  public boolean add(final @NotNull E element) {
+    return false;
+  }
+
+  // -----------------------------------------------------------------------
+
+  /**
+   * Receives an element but do nothing with it.
+   *
+   * @param element the element to add
+   * @return false, always
+   */
+  @Override
+  public boolean offer(@NotNull E element) {
+    return false;
+  }
+
+  @Override
+  public @Nullable E poll() {
+    return null;
+  }
+
+  @Override
+  public @Nullable E element() {
+    return null;
+  }
+
+  @Override
+  public @Nullable E peek() {
+    return null;
+  }
+
+  @Override
+  public @NotNull E remove() {
+    throw new NoSuchElementException("queue is disabled");
+  }
+
+  // -----------------------------------------------------------------------
+
+  /**
+   * Returns an iterator over this queue's elements.
+   *
+   * @return an iterator over this queue's elements
+   */
+  @Override
+  public @NotNull Iterator<E> iterator() {
+    return new Iterator<E>() {
+
+      @Override
+      public boolean hasNext() {
+        return false;
+      }
+
+      @Override
+      public E next() {
+        throw new NoSuchElementException();
+      }
+
+      @Override
+      public void remove() {
+        throw new IllegalStateException();
+      }
+    };
+  }
+}

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

@@ -754,7 +754,9 @@ public void clearAttachments() {
    * @return the breadcrumbs queue
    */
   private @NotNull Queue<Breadcrumb> createBreadcrumbsList(final int maxBreadcrumb) {
-    return SynchronizedQueue.synchronizedQueue(new CircularFifoQueue<>(maxBreadcrumb));
+    return maxBreadcrumb > 0
+        ? SynchronizedQueue.synchronizedQueue(new CircularFifoQueue<>(maxBreadcrumb))
+        : SynchronizedQueue.synchronizedQueue(new DisabledQueue<>());
   }
 
   /**

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

@@ -0,0 +1,93 @@
+package io.sentry
+import org.junit.Assert.assertThrows
+import java.util.NoSuchElementException
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertNull
+
+class DisabledQueueTest {
+
+    @Test
+    fun `size starts empty`() {
+        val queue = DisabledQueue<Int>()
+        assertEquals(0, queue.size, "Size should always be zero.")
+    }
+
+    @Test
+    fun `add does not add elements`() {
+        val queue = DisabledQueue<Int>()
+        assertFalse(queue.add(1), "add should always return false.")
+        assertEquals(0, queue.size, "Size should still be zero after attempting to add an element.")
+    }
+
+    @Test
+    fun `isEmpty returns false when created`() {
+        val queue = DisabledQueue<Int>()
+        assertFalse(queue.isEmpty(), "isEmpty should always return false.")
+    }
+
+    @Test
+    fun `isEmpty always returns false if add function was called`() {
+        val queue = DisabledQueue<Int>()
+        queue.add(1)
+
+        assertFalse(queue.isEmpty(), "isEmpty should always return false.")
+    }
+
+    @Test
+    fun `offer does not add elements`() {
+        val queue = DisabledQueue<Int>()
+        assertFalse(queue.offer(1), "offer should always return false.")
+        assertEquals(0, queue.size, "Size should still be zero after attempting to offer an element.")
+    }
+
+    @Test
+    fun `poll returns null`() {
+        val queue = DisabledQueue<Int>()
+        queue.add(1)
+        assertNull(queue.poll(), "poll should always return null.")
+    }
+
+    @Test
+    fun `peek returns null`() {
+        val queue = DisabledQueue<Int>()
+        queue.add(1)
+
+        assertNull(queue.peek(), "peek should always return null.")
+    }
+
+    @Test
+    fun `element returns null`() {
+        val queue = DisabledQueue<Int>()
+        assertNull(queue.element(), "element should always return null.")
+    }
+
+    @Test
+    fun `remove throws NoSuchElementException`() {
+        val queue = DisabledQueue<Int>()
+        assertThrows(NoSuchElementException::class.java) { queue.remove() }
+    }
+
+    @Test
+    fun `clear does nothing`() {
+        val queue = DisabledQueue<Int>()
+        queue.clear() // Should not throw an exception
+        assertEquals(0, queue.size, "Size should remain zero after clear.")
+    }
+
+    @Test
+    fun `iterator has no elements`() {
+        val queue = DisabledQueue<Int>()
+        val iterator = queue.iterator()
+        assertFalse(iterator.hasNext(), "Iterator should have no elements.")
+        assertThrows(NoSuchElementException::class.java) { iterator.next() }
+    }
+
+    @Test
+    fun `iterator remove throws IllegalStateException`() {
+        val queue = DisabledQueue<Int>()
+        val iterator = queue.iterator()
+        assertThrows(IllegalStateException::class.java) { iterator.remove() }
+    }
+}

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

@@ -1029,6 +1029,17 @@ class ScopeTest {
         )
     }
 
+    @Test
+    fun `creating a new scope won't crash if max breadcrumbs is set to zero`() {
+        val options = SentryOptions().apply {
+            maxBreadcrumbs = 0
+        }
+        val scope = Scope(options)
+
+        // expect no exception to be thrown
+        // previously was crashing, see https://github.com/getsentry/sentry-java/issues/3313
+    }
+
     private fun eventProcessor(): EventProcessor {
         return object : EventProcessor {
             override fun process(event: SentryEvent, hint: Hint): SentryEvent? {