Generalize the CrashlyticsWorker

Author: mrober

firebase-crashlytics/firebase-crashlytics.gradle

@@ -111,4 +111,6 @@ dependencies {
     androidTestImplementation(libs.androidx.test.junit)
     androidTestImplementation(libs.androidx.test.runner)
     androidTestImplementation(libs.truth)
+    androidTestImplementation(libs.playservices.tasks)
+    androidTestImplementation(project(":integ-testing"))
 }

firebase-crashlytics/src/androidTest/java/com/google/firebase/crashlytics/internal/CrashlyticsWorkerTest.java

@@ -0,0 +1,334 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.firebase.crashlytics.internal;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import com.google.android.gms.tasks.Task;
+import com.google.android.gms.tasks.Tasks;
+import com.google.firebase.concurrent.TestOnlyExecutors;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicBoolean;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+public class CrashlyticsWorkerTest {
+  private CrashlyticsWorker crashlyticsWorker;
+
+  @Before
+  public void setUp() {
+    crashlyticsWorker = new CrashlyticsWorker(TestOnlyExecutors.background());
+  }
+
+  @After
+  public void tearDown() throws Exception {
+    // Drain the worker, just in case any test cases would fail but didn't await.
+    crashlyticsWorker.await();
+  }
+
+  @Test
+  public void executesTasksOnThreadPool() throws Exception {
+    Set<String> threads = new HashSet<>();
+
+    // Find thread names by adding the names we touch to the set.
+    for (int i = 0; i < 100; i++) {
+      crashlyticsWorker.submit(() -> threads.add(Thread.currentThread().getName()));
+    }
+
+    crashlyticsWorker.await();
+
+    // Verify that we touched at lease some of the expected background threads.
+    assertThat(threads)
+        .containsAnyOf(
+            "Firebase Background Thread #0",
+            "Firebase Background Thread #1",
+            "Firebase Background Thread #2",
+            "Firebase Background Thread #3");
+  }
+
+  @Test
+  public void executesTasksInOrder() throws Exception {
+    List<Integer> list = new ArrayList<>();
+
+    // Add sequential numbers to the list to validate tasks execute in order.
+    for (int i = 0; i < 100; i++) {
+      int sequential = i;
+      crashlyticsWorker.submit(() -> list.add(sequential));
+    }
+
+    crashlyticsWorker.await();
+
+    // Verify that the tasks executed in order.
+    assertThat(list).isInOrder();
+  }
+
+  @Test
+  public void executesTasksSequentially() throws Exception {
+    List<Integer> list = new ArrayList<>();
+    AtomicBoolean reentrant = new AtomicBoolean(false);
+
+    for (int i = 0; i < 100; i++) {
+      int sequential = i;
+      crashlyticsWorker.submit(
+          () -> {
+            if (reentrant.get()) {
+              // Return early if two runnables ran at the same time.
+              return;
+            }
+
+            reentrant.set(true);
+            // Sleep a bit to simulate some work.
+            sleep(5);
+            list.add(sequential);
+            reentrant.set(false);
+          });
+    }
+
+    crashlyticsWorker.await();
+
+    // Verify that all the runnable tasks executed, one at a time, and in order.
+    assertThat(list).hasSize(100);
+    assertThat(list).isInOrder();
+  }
+
+  @Test
+  public void submitCallableThatReturns() throws Exception {
+    String ender = "Remember, the enemy's gate is down.";
+    Task<String> task = crashlyticsWorker.submit(() -> ender);
+
+    String result = Tasks.await(task);
+
+    assertThat(result).isEqualTo(ender);
+  }
+
+  @Test
+  public void submitCallableThatReturnsNull() throws Exception {
+    Task<String> task = crashlyticsWorker.submit(() -> null);
+
+    String result = Tasks.await(task);
+
+    assertThat(result).isNull();
+  }
+
+  @Test
+  public void submitCallableThatThrows() {
+    Task<Void> task =
+        crashlyticsWorker.submit(
+            () -> {
+              throw new Exception("I threw in the callable");
+            });
+
+    ExecutionException thrown = assertThrows(ExecutionException.class, () -> Tasks.await(task));
+
+    assertThat(thrown).hasCauseThat().hasMessageThat().isEqualTo("I threw in the callable");
+  }
+
+  @Test
+  public void submitRunnable() throws Exception {
+    Task<Void> task = crashlyticsWorker.submit(() -> {});
+
+    Void result = Tasks.await(task);
+
+    // A Runnable does not return, so the task evaluates to null.
+    assertThat(result).isNull();
+  }
+
+  @Test
+  public void submitRunnableThatThrows() {
+    Task<Void> task =
+        crashlyticsWorker.submit(
+            (Runnable)
+                () -> {
+                  throw new RuntimeException("I threw in the runnable");
+                });
+
+    ExecutionException thrown = assertThrows(ExecutionException.class, () -> Tasks.await(task));
+
+    assertThat(thrown).hasCauseThat().hasMessageThat().isEqualTo("I threw in the runnable");
+  }
+
+  @Test
+  public void submitTaskThatReturns() throws Exception {
+    String skippy = "Think of the problem as an enemy, and defeat them in detail.";
+    Task<String> task = crashlyticsWorker.submitTask(() -> Tasks.forResult(skippy));
+
+    String result = Tasks.await(task);
+
+    assertThat(result).isEqualTo(skippy);
+  }
+
+  @Test
+  public void submitTaskThatReturnsNull() throws Exception {
+    Task<String> task = crashlyticsWorker.submitTask(() -> Tasks.forResult(null));
+
+    String result = Tasks.await(task);
+
+    assertThat(result).isNull();
+  }
+
+  @Test
+  public void submitTaskThatThrows() {
+    Task<String> task =
+        crashlyticsWorker.submitTask(
+            () -> Tasks.forException(new Exception("Thrown from a task.")));
+
+    ExecutionException thrown = assertThrows(ExecutionException.class, () -> Tasks.await(task));
+
+    assertThat(thrown).hasCauseThat().hasMessageThat().isEqualTo("Thrown from a task.");
+  }
+
+  @Test
+  public void submitTaskThatThrowsThenReturns() throws Exception {
+    crashlyticsWorker.submitTask(() -> Tasks.forException(new IllegalStateException()));
+    Task<String> task = crashlyticsWorker.submitTask(() -> Tasks.forResult("The Hail Mary"));
+
+    String result = Tasks.await(task);
+
+    assertThat(result).isEqualTo("The Hail Mary");
+  }
+
+  @Test
+  public void submitTaskThatCancels() {
+    Task<Void> task = crashlyticsWorker.submitTask(Tasks::forCanceled);
+
+    CancellationException thrown =
+        assertThrows(CancellationException.class, () -> Tasks.await(task));
+
+    assertThat(task.isCanceled()).isTrue();
+    assertThat(thrown).hasMessageThat().contains("Task is already canceled");
+  }
+
+  @Test
+  public void submitTaskThatCancelsThenReturns() throws Exception {
+    crashlyticsWorker.submitTask(Tasks::forCanceled);
+    Task<String> task = crashlyticsWorker.submitTask(() -> Tasks.forResult("Flying Dutchman"));
+
+    String result = Tasks.await(task);
+
+    assertThat(task.isCanceled()).isFalse();
+    assertThat(result).isEqualTo("Flying Dutchman");
+  }
+
+  @Test
+  public void submitTaskThatCancelsThenAwaitsThenReturns() throws Exception {
+    Task<?> cancelled = crashlyticsWorker.submitTask(Tasks::forCanceled);
+
+    // Await on the cancelled task to force the exception to propagate.
+    assertThrows(CancellationException.class, () -> Tasks.await(cancelled));
+
+    // Submit another task.
+    Task<String> task = crashlyticsWorker.submitTask(() -> Tasks.forResult("Valkyrie"));
+
+    String result = Tasks.await(task);
+
+    assertThat(cancelled.isCanceled()).isTrue();
+    assertThat(task.isCanceled()).isFalse();
+    assertThat(result).isEqualTo("Valkyrie");
+  }
+
+  @Test
+  public void submitTaskThatCancelsThenAwaitsThenRunnable() throws Exception {
+    Task<?> cancelled = crashlyticsWorker.submitTask(Tasks::forCanceled);
+
+    // Await on the cancelled task to force the exception to propagate.
+    assertThrows(CancellationException.class, () -> Tasks.await(cancelled));
+
+    // Submit an empty runnable.
+    Task<Void> task = crashlyticsWorker.submit(() -> {});
+
+    Void result = Tasks.await(task);
+
+    assertThat(cancelled.isCanceled()).isTrue();
+    assertThat(task.isCanceled()).isFalse();
+    assertThat(result).isNull();
+  }
+
+  @Test
+  public void submitTaskFromAnotherWorker() throws Exception {
+    Task<String> otherTask =
+        new CrashlyticsWorker(TestOnlyExecutors.blocking())
+            .submit(() -> "Dog's fine. Just sleeping.");
+
+    // This will not use a background thread while waiting for the task on blocking thread.
+    Task<String> task = crashlyticsWorker.submitTask(() -> otherTask);
+
+    String result = Tasks.await(task);
+    assertThat(result).isEqualTo("Dog's fine. Just sleeping.");
+  }
+
+  @Test
+  public void submitTaskFromAnotherWorkerDoesNotUseLocalThreads() throws Exception {
+    // Setup a "local" worker.
+    ThreadPoolExecutor localExecutor = (ThreadPoolExecutor) Executors.newFixedThreadPool(4);
+    CrashlyticsWorker localWorker = new CrashlyticsWorker(localExecutor);
+
+    // Use a task off crashlyticsWorker to represent an other task.
+    Task<Integer> otherTask =
+        crashlyticsWorker.submit(
+            () -> {
+              sleep(30);
+              return localExecutor.getActiveCount();
+            });
+
+    // No active threads yet.
+    assertThat(localExecutor.getActiveCount()).isEqualTo(0);
+
+    // 1 active thread when doing a local task.
+    assertThat(Tasks.await(localWorker.submit(localExecutor::getActiveCount))).isEqualTo(1);
+
+    // 0 active local threads when waiting for other task.
+    // Waiting for a task from another worker does not block a local thread.
+    assertThat(Tasks.await(localWorker.submitTask(() -> otherTask))).isEqualTo(0);
+
+    // 1 active thread when doing a task.
+    assertThat(Tasks.await(localWorker.submit(localExecutor::getActiveCount))).isEqualTo(1);
+
+    // No active threads after.
+    assertThat(localExecutor.getActiveCount()).isEqualTo(0);
+  }
+
+  @Test
+  public void submitTaskWhenThreadPoolFull() {
+    // Fill the backing executor thread pool.
+    for (int i = 0; i < 10; i++) {
+      crashlyticsWorker.getExecutor().execute(() -> sleep(1_000));
+    }
+
+    Task<Integer> task = crashlyticsWorker.submitTask(() -> Tasks.forResult(42));
+
+    assertThrows(TimeoutException.class, () -> Tasks.await(task, 300, TimeUnit.MILLISECONDS));
+  }
+
+  private static void sleep(long millis) {
+    try {
+      Thread.sleep(millis);
+    } catch (InterruptedException ex) {
+      Thread.currentThread().interrupt();
+    }
+  }
+}