Class ProcessLock

xutils/src/main/java/org/xutils/common/util/ProcessLock.java:24–234

进程间锁, 仅在同一个应用中有效.

 * 进程间锁, 仅在同一个应用中有效.
 */
public final class ProcessLock implements Closeable {

    private final String mLockName;
    private final FileLock mFileLock;
    private final File mFile;
    private final Closeable mStream;
    private final boolean mWriteMode;

    private final static String LOCK_FILE_DIR = "process_lock";
    /**
     * key1: lockName
     * key2: fileLock.hashCode()
     */
    private final static DoubleKeyValueMap<String, Integer, ProcessLock> LOCK_MAP = new DoubleKeyValueMap<String, Integer, ProcessLock>();

    static {
        File dir = x.app().getDir(LOCK_FILE_DIR, Context.MODE_PRIVATE);
        IOUtil.deleteFileOrDir(dir);
    }

    private ProcessLock(String lockName, File file, FileLock fileLock, Closeable stream, boolean writeMode) {
        mLockName = lockName;
        mFileLock = fileLock;
        mFile = file;
        mStream = stream;
        mWriteMode = writeMode;
    }

    /**
     * 获取进程锁
     *
     * @param lockName  锁的名称, 相同的名称被认为是同一个锁.
     * @param writeMode 是否写入模式(支持读并发).
     * @return null 或 进程锁, 如果锁已经被占用, 返回null.
     */
    public static ProcessLock tryLock(final String lockName, final boolean writeMode) {
        return tryLockInternal(lockName, customHash(lockName), writeMode);
    }

    /**
     * 获取进程锁
     *
     * @param lockName          锁的名称, 相同的名称被认为是同一个锁.
     * @param writeMode         是否写入模式(支持读并发).
     * @param maxWaitTimeMillis 最大值 1000 * 60
     * @return null 或 进程锁, 如果锁已经被占用, 则在超时时间内继续尝试获取该锁.
     */
    public static ProcessLock tryLock(final String lockName, final boolean writeMode, final long maxWaitTimeMillis) throws InterruptedException {
        ProcessLock lock = null;
        long expiryTime = System.currentTimeMillis() + maxWaitTimeMillis;
        String hash = customHash(lockName);
        synchronized (LOCK_MAP) {
            while (System.currentTimeMillis() < expiryTime) {
                lock = tryLockInternal(lockName, hash, writeMode);
                if (lock != null) {
                    break;
                } else {
                    try {