[guava concurrent] Removed the executeFirst() method from SequentialE…

…xecutor, and its test case. Switched the internal representation of the task queue back to Queue from Deque.

The method was never public, and is no longer used in the depot.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=170244464

android/guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java

@@ -179,30 +179,6 @@ public void run() {
     assertEquals(ImmutableList.of(0, 1, 2), callOrder);
   }
 
-  public void testPrependContinuation() {
-    final List<Integer> callOrder = Lists.newArrayList();
-
-    class FakeOp implements Runnable {
-      final int op;
-
-      FakeOp(int op) {
-        this.op = op;
-      }
-
-      @Override
-      public void run() {
-        callOrder.add(op);
-      }
-    }
-
-    e.execute(new FakeOp(1));
-    e.execute(new FakeOp(2));
-    e.executeFirst(new FakeOp(0));
-    fakePool.runAll();
-
-    assertEquals(ImmutableList.of(0, 1, 2), callOrder);
-  }
-
   public void testRuntimeException_doesNotStopExecution() {
 
     final AtomicInteger numCalls = new AtomicInteger();

android/guava/src/com/google/common/util/concurrent/SequentialExecutor.java

@@ -19,7 +19,7 @@
 import com.google.errorprone.annotations.DoNotMock;
 import com.google.j2objc.annotations.WeakOuter;
 import java.util.ArrayDeque;
-import java.util.Deque;
+import java.util.Queue;
 import java.util.concurrent.Executor;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -53,7 +53,7 @@ class SequentialExecutor implements Executor {
   private final Executor executor;
 
   @GuardedBy("queue")
-  private final Deque<Runnable> queue = new ArrayDeque<>();
+  private final Queue<Runnable> queue = new ArrayDeque<>();
 
   @GuardedBy("queue")
   private boolean isWorkerRunning = false;
@@ -78,22 +78,7 @@ class SequentialExecutor implements Executor {
   @Override
   public void execute(Runnable task) {
     synchronized (queue) {
-      queue.addLast(task);
-      if (isWorkerRunning || suspensions > 0) {
-        return;
-      }
-      isWorkerRunning = true;
-    }
-    startQueueWorker();
-  }
-
-  /**
-   * Prepends a task to the front of the queue and makes sure a worker thread is running, unless the
-   * queue has been suspended.
-   */
-  public void executeFirst(Runnable task) {
-    synchronized (queue) {
-      queue.addFirst(task);
+      queue.add(task);
       if (isWorkerRunning || suspensions > 0) {
         return;
       }
@@ -122,8 +107,8 @@ public void suspend() {
    * if the suspension counter is zero.
    *
    * <p>If this method throws, e.g. a {@code RejectedExecutionException} from the delegate executor,
-   * execution of tasks will stop until a call to this method or to {@link #execute(Runnable)} or
-   * {@link #executeFirst(Runnable)} is made.
+   * execution of tasks will stop until a call to this method or to {@link #execute(Runnable)} is
+   * made.
    *
    * @throws java.lang.IllegalStateException if this executor is not suspended.
    */
@@ -191,7 +176,7 @@ private void workOnQueue() {
         synchronized (queue) {
           // TODO(user): How should we handle interrupts and shutdowns?
           if (suspensions == 0) {
-            task = queue.pollFirst();
+            task = queue.poll();
           }
           if (task == null) {
             isWorkerRunning = false;

guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java

@@ -179,30 +179,6 @@ public void run() {
     assertEquals(ImmutableList.of(0, 1, 2), callOrder);
   }
 
-  public void testPrependContinuation() {
-    final List<Integer> callOrder = Lists.newArrayList();
-
-    class FakeOp implements Runnable {
-      final int op;
-
-      FakeOp(int op) {
-        this.op = op;
-      }
-
-      @Override
-      public void run() {
-        callOrder.add(op);
-      }
-    }
-
-    e.execute(new FakeOp(1));
-    e.execute(new FakeOp(2));
-    e.executeFirst(new FakeOp(0));
-    fakePool.runAll();
-
-    assertEquals(ImmutableList.of(0, 1, 2), callOrder);
-  }
-
   public void testRuntimeException_doesNotStopExecution() {
 
     final AtomicInteger numCalls = new AtomicInteger();

guava/src/com/google/common/util/concurrent/SequentialExecutor.java

@@ -19,7 +19,7 @@
 import com.google.errorprone.annotations.DoNotMock;
 import com.google.j2objc.annotations.WeakOuter;
 import java.util.ArrayDeque;
-import java.util.Deque;
+import java.util.Queue;
 import java.util.concurrent.Executor;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -53,7 +53,7 @@ class SequentialExecutor implements Executor {
   private final Executor executor;
 
   @GuardedBy("queue")
-  private final Deque<Runnable> queue = new ArrayDeque<>();
+  private final Queue<Runnable> queue = new ArrayDeque<>();
 
   @GuardedBy("queue")
   private boolean isWorkerRunning = false;
@@ -78,22 +78,7 @@ class SequentialExecutor implements Executor {
   @Override
   public void execute(Runnable task) {
     synchronized (queue) {
-      queue.addLast(task);
-      if (isWorkerRunning || suspensions > 0) {
-        return;
-      }
-      isWorkerRunning = true;
-    }
-    startQueueWorker();
-  }
-
-  /**
-   * Prepends a task to the front of the queue and makes sure a worker thread is running, unless the
-   * queue has been suspended.
-   */
-  public void executeFirst(Runnable task) {
-    synchronized (queue) {
-      queue.addFirst(task);
+      queue.add(task);
       if (isWorkerRunning || suspensions > 0) {
         return;
       }
@@ -122,8 +107,8 @@ public void suspend() {
    * if the suspension counter is zero.
    *
    * <p>If this method throws, e.g. a {@code RejectedExecutionException} from the delegate executor,
-   * execution of tasks will stop until a call to this method or to {@link #execute(Runnable)} or
-   * {@link #executeFirst(Runnable)} is made.
+   * execution of tasks will stop until a call to this method or to {@link #execute(Runnable)} is
+   * made.
    *
    * @throws java.lang.IllegalStateException if this executor is not suspended.
    */
@@ -191,7 +176,7 @@ private void workOnQueue() {
         synchronized (queue) {
           // TODO(user): How should we handle interrupts and shutdowns?
           if (suspensions == 0) {
-            task = queue.pollFirst();
+            task = queue.poll();
           }
           if (task == null) {
             isWorkerRunning = false;