/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License"),
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.ex.camera2.portability;
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import android.os.SystemClock;
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import com.android.ex.camera2.portability.debug.Log;
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public abstract class CameraStateHolder {
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private static final Log.Tag TAG = new Log.Tag("CamStateHolder");
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private int mState;
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private boolean mInvalid;
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/**
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* Construct a new instance of @{link CameraStateHolder} with an initial state.
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*
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* @param state The initial state.
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*/
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public CameraStateHolder(int state) {
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setState(state);
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mInvalid = false;
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}
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/**
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* Change to a new state.
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*
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* @param state The new state.
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*/
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public synchronized void setState(int state) {
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if (mState != state) {
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Log.v(TAG, "setState - state = " + Integer.toBinaryString(state));
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}
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mState = state;
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this.notifyAll();
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}
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/**
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* Obtain the current state.
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*
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* @return The current state.
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*/
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public synchronized int getState() {
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return mState;
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}
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/**
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* Change the state to be invalid. Once invalidated, the state will be invalid forever.
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*/
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public synchronized void invalidate() {
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mInvalid = true;
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}
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/**
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* Whether the state is invalid.
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*
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* @return True if the state is invalid.
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*/
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public synchronized boolean isInvalid() {
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return mInvalid;
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}
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private static interface ConditionChecker {
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/**
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* @return Whether the condition holds.
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*/
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boolean success();
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}
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/**
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* A helper method used by {@link #waitToAvoidStates(int)} and
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* {@link #waitForStates(int)}. This method will wait until the
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* condition is successful.
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*
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* @param stateChecker The state checker to be used.
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* @param timeoutMs The timeout limit in milliseconds.
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* @return {@code false} if the wait is interrupted or timeout limit is
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* reached.
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*/
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private boolean waitForCondition(ConditionChecker stateChecker,
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long timeoutMs) {
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long timeBound = SystemClock.uptimeMillis() + timeoutMs;
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synchronized (this) {
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while (!stateChecker.success()) {
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try {
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this.wait(timeoutMs);
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} catch (InterruptedException ex) {
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if (SystemClock.uptimeMillis() > timeBound) {
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// Timeout.
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Log.w(TAG, "Timeout waiting.");
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}
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return false;
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}
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}
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}
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return true;
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}
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/**
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* Block the current thread until the state becomes one of the
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* specified.
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*
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* @param states Expected states.
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* @return {@code false} if the wait is interrupted or timeout limit is
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* reached.
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*/
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public boolean waitForStates(final int states) {
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Log.v(TAG, "waitForStates - states = " + Integer.toBinaryString(states));
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return waitForCondition(new ConditionChecker() {
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@Override
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public boolean success() {
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return (states | getState()) == states;
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}
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}, CameraAgent.CAMERA_OPERATION_TIMEOUT_MS);
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}
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/**
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* Block the current thread until the state becomes NOT one of the
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* specified.
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*
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* @param states States to avoid.
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* @return {@code false} if the wait is interrupted or timeout limit is
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* reached.
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*/
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public boolean waitToAvoidStates(final int states) {
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Log.v(TAG, "waitToAvoidStates - states = " + Integer.toBinaryString(states));
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return waitForCondition(new ConditionChecker() {
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@Override
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public boolean success() {
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return (states & getState()) == 0;
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}
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}, CameraAgent.CAMERA_OPERATION_TIMEOUT_MS);
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}
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}
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