content: /*
   * Copyright (C) 2014 The Android Open Source Project
   *
   * 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.android.ex.camera2.portability;
  
  import android.os.SystemClock;
  
  import com.android.ex.camera2.portability.debug.Log;
  
  public abstract class CameraStateHolder {
      private static final Log.Tag TAG = new Log.Tag("CamStateHolder");
  
      private int mState;
      private boolean mInvalid;
  
      /**
       * Construct a new instance of @{link CameraStateHolder} with an initial state.
       *
       * @param state The initial state.
       */
      public CameraStateHolder(int state) {
          setState(state);
          mInvalid = false;
      }
  
      /**
       * Change to a new state.
       *
       * @param state The new state.
       */
      public synchronized void setState(int state) {
          if (mState != state) {
              Log.v(TAG, "setState - state = " + Integer.toBinaryString(state));
          }
          mState = state;
          this.notifyAll();
      }
  
      /**
       * Obtain the current state.
       *
       * @return The current state.
       */
      public synchronized int getState() {
          return mState;
      }
  
      /**
       * Change the state to be invalid. Once invalidated, the state will be invalid forever.
       */
      public synchronized void invalidate() {
          mInvalid = true;
      }
  
      /**
       * Whether the state is invalid.
       *
       * @return True if the state is invalid.
       */
      public synchronized boolean isInvalid() {
          return mInvalid;
      }
  
      private static interface ConditionChecker {
          /**
           * @return Whether the condition holds.
           */
          boolean success();
      }
  
      /**
       * A helper method used by {@link #waitToAvoidStates(int)} and
       * {@link #waitForStates(int)}. This method will wait until the
       * condition is successful.
       *
       * @param stateChecker The state checker to be used.
       * @param timeoutMs The timeout limit in milliseconds.
       * @return {@code false} if the wait is interrupted or timeout limit is
       *         reached.
       */
      private boolean waitForCondition(ConditionChecker stateChecker,
              long timeoutMs) {
          long timeBound = SystemClock.uptimeMillis() + timeoutMs;
          synchronized (this) {
              while (!stateChecker.success()) {
                  try {
                      this.wait(timeoutMs);
                  } catch (InterruptedException ex) {
                      if (SystemClock.uptimeMillis() > timeBound) {
                          // Timeout.
                          Log.w(TAG, "Timeout waiting.");
                      }
                      return false;
                  }
              }
          }
          return true;
      }
  
      /**
       * Block the current thread until the state becomes one of the
       * specified.
       *
       * @param states Expected states.
       * @return {@code false} if the wait is interrupted or timeout limit is
       *         reached.
       */
      public boolean waitForStates(final int states) {
          Log.v(TAG, "waitForStates - states = " + Integer.toBinaryString(states));
          return waitForCondition(new ConditionChecker() {
              @Override
              public boolean success() {
                  return (states | getState()) == states;
              }
          }, CameraAgent.CAMERA_OPERATION_TIMEOUT_MS);
      }
  
      /**
       * Block the current thread until the state becomes NOT one of the
       * specified.
       *
       * @param states States to avoid.
       * @return {@code false} if the wait is interrupted or timeout limit is
       *         reached.
       */
      public boolean waitToAvoidStates(final int states) {
          Log.v(TAG, "waitToAvoidStates - states = " + Integer.toBinaryString(states));
          return waitForCondition(new ConditionChecker() {
              @Override
              public boolean success() {
                  return (states & getState()) == 0;
              }
          }, CameraAgent.CAMERA_OPERATION_TIMEOUT_MS);
      }
  }
  