Pull cacheinvalidations code directory into chromium repo.

third_party/cacheinvalidation/src/java/com/google/ipc/invalidation/ticl/RunState.java

+/*
+ * Copyright 2011 Google Inc.
+ *
+ * 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.ipc.invalidation.ticl;
+
+import com.google.ipc.invalidation.ticl.proto.Client.RunStateP;
+import com.google.ipc.invalidation.util.Marshallable;
+
+/**
+ * An abstraction that keeps track of whether the caller is started or stopped and only allows
+ * the following transitions NOT_STARTED -> STARTED -> STOPPED. This class is thread-safe.
+ *
+ */
+public class RunState implements Marshallable<RunStateP> {
+  /** Current run state ({@link RunStateP}). */
+  private Integer currentState;
+  private Object lock = new Object();
+
+  /** Constructs a new instance in the {@code NOT_STARTED} state. */
+  public RunState() {
+    currentState = RunStateP.State.NOT_STARTED;
+  }
+
+  /** Constructs a new instance with the state given in {@code runState}. */
+  RunState(RunStateP runState) {
+    this.currentState = runState.getState();
+  }
+
+  /**
+   * Marks the current state to be STARTED.
+   * <p>
+   * REQUIRES: Current state is NOT_STARTED.
+   */
+  public void start() {
+    synchronized (lock) {
+      if (currentState != RunStateP.State.NOT_STARTED) {
+        throw new IllegalStateException("Cannot start: " + currentState);
+      }
+      currentState = RunStateP.State.STARTED;
+    }
+  }
+
+  /**
+   * Marks the current state to be STOPPED.
+   * <p>
+   * REQUIRES: Current state is STARTED.
+   */
+  public void stop() {
+    synchronized (lock) {
+      if (currentState != RunStateP.State.STARTED) {
+        throw new IllegalStateException("Cannot stop: " + currentState);
+      }
+      currentState = RunStateP.State.STOPPED;
+    }
+  }
+
+  /**
+   * Returns true iff {@link #start} has been called on this but {@link #stop} has not been called.
+   */
+  public boolean isStarted() {
+    synchronized (lock) {
+      return currentState == RunStateP.State.STARTED;
+    }
+  }
+
+  /** Returns true iff {@link #start} and {@link #stop} have been called on this object. */
+  public boolean isStopped() {
+    synchronized (lock) {
+      return currentState == RunStateP.State.STOPPED;
+    }
+  }
+
+  @Override
+  public RunStateP marshal() {
+    return RunStateP.create(currentState);
+  }
+
+  @Override
+  public String toString() {
+    return "<RunState: " + currentState + ">";
+  }
+}