private void sumLock() {
    lock = redissonClient.getLock("sum-lock");
    
    boolean b = lock.tryLock();
    if (!b) {
        log.info("獲取不到鎖");
        return;
    }
    
    try {
        for (int j = 0; j < 20000; j++) {
            ++sum;
        }
    } finally {
        lock.unlock();
    }
    
}

public RLock getLock(String name) {
? ? // 實(shí)例化 RedissonLock，參數(shù)為指令執(zhí)行器和鎖名稱
? ? return new RedissonLock(this.connectionManager.getCommandExecutor(), name);
}

public RedissonLock(CommandAsyncExecutor commandExecutor, String name) {
? ? super(commandExecutor, name);
? ? // 命令執(zhí)行器，用于執(zhí)行l(wèi)ua腳本
? ? this.commandExecutor = commandExecutor;
? ? // 連接管理器的ID
? ? this.id = commandExecutor.getConnectionManager().getId();
? ? // 鎖續(xù)期時(shí)間（看門狗），鎖默認(rèn)續(xù)期時(shí)間是 30s。
? ? this.internalLockLeaseTime = commandExecutor.getConnectionManager().getCfg().getLockWatchdogTimeout();
? ? this.entryName = this.id + ":" + name;
? ? this.pubSub = commandExecutor.getConnectionManager().getSubscribeService().getLockPubSub();
}

@Override
public boolean tryLock() {
? ? return get(tryLockAsync());
}

@Override
public RFuture<Boolean> tryLockAsync() {
? ? return tryLockAsync(Thread.currentThread().getId());
}

@Override
public RFuture<Boolean> tryLockAsync(long threadId) {
? ? return tryAcquireOnceAsync(-1, -1, null, threadId);
}

private RFuture<Boolean> tryAcquireOnceAsync(long waitTime, long leaseTime, TimeUnit unit, long threadId) {
? ? // 由于我們調(diào)用tryLocak沒(méi)有傳遞任何參數(shù)，leaseTime默認(rèn)為-1，不走判斷
? ? if (leaseTime != -1) {
? ? ? ? return tryLockInnerAsync(waitTime, leaseTime, unit, threadId, RedisCommands.EVAL_NULL_BOOLEAN);
? ? }
? ??
? ? // 調(diào)用獲取鎖 枷鎖的主要邏輯在這里
? ? RFuture<Boolean> ttlRemainingFuture = tryLockInnerAsync(waitTime,
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? commandExecutor.getConnectionManager().getCfg().getLockWatchdogTimeout(),
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? TimeUnit.MILLISECONDS, threadId, RedisCommands.EVAL_NULL_BOOLEAN);
? ??
? ? ttlRemainingFuture.onComplete((ttlRemaining, e) -> {
? ? ? ? // 如果發(fā)生異常那么直接放回了
? ? ? ? if (e != null) {
? ? ? ? ? ? return;
? ? ? ? }

? ? ? ? // 鎖續(xù)期
? ? ? ? if (ttlRemaining) {
? ? ? ? ? ? scheduleExpirationRenewal(threadId);
? ? ? ? }
? ? });
? ? // 返回結(jié)果
? ? return ttlRemainingFuture;
}

<T> RFuture<T> tryLockInnerAsync(long waitTime, long leaseTime, TimeUnit unit, long threadId, RedisStrictCommand<T> command) {
    // 將時(shí)間轉(zhuǎn)化為毫秒
    internalLockLeaseTime = unit.toMillis(leaseTime);
    // 執(zhí)行腳本
    return evalWriteAsync(getName(), LongCodec.INSTANCE, command,
            "if (redis.call('exists', KEYS[1]) == 0) then " +
                    "redis.call('hincrby', KEYS[1], ARGV[2], 1); " +
                    "redis.call('pexpire', KEYS[1], ARGV[1]); " +
                    "return nil; " +
                    "end; " +
                    "if (redis.call('hexists', KEYS[1], ARGV[2]) == 1) then " +
                    "redis.call('hincrby', KEYS[1], ARGV[2], 1); " +
                    "redis.call('pexpire', KEYS[1], ARGV[1]); " +
                    "return nil; " +
                    "end; " +
                    "return redis.call('pttl', KEYS[1]);",
            Collections.singletonList(getName()), internalLockLeaseTime, getLockName(threadId));
}

@Override
public void unlock() {
? ? try {
? ? ? ? get(unlockAsync(Thread.currentThread().getId()));
? ? } catch (RedisException e) {
? ? ? ? if (e.getCause() instanceof IllegalMonitorStateException) {
? ? ? ? ? ? throw (IllegalMonitorStateException) e.getCause();
? ? ? ? } else {
? ? ? ? ? ? throw e;
? ? ? ? }
? ? }
}

@Override
public RFuture<Void> unlockAsync(long threadId) {
? ? RPromise<Void> result = new RedissonPromise<Void>();
? ? // 釋放鎖的邏輯主要這里
? ? RFuture<Boolean> future = unlockInnerAsync(threadId);

? ? future.onComplete((opStatus, e) -> {
? ? ? ? cancelExpirationRenewal(threadId);

? ? ? ? if (e != null) {
? ? ? ? ? ? result.tryFailure(e);
? ? ? ? ? ? return;
? ? ? ? }

? ? ? ? if (opStatus == null) {
? ? ? ? ? ? IllegalMonitorStateException cause = new IllegalMonitorStateException("attempt to unlock lock, not locked by current thread by node id: "
? ? ? ? ? ? ? ? ? ? + id + " thread-id: " + threadId);
? ? ? ? ? ? result.tryFailure(cause);
? ? ? ? ? ? return;
? ? ? ? }

? ? ? ? result.trySuccess(null);
? ? });

? ? return result;
}

protected RFuture<Boolean> unlockInnerAsync(long threadId) {
    return evalWriteAsync(getName(), LongCodec.INSTANCE, RedisCommands.EVAL_BOOLEAN,
            "if (redis.call('hexists', KEYS[1], ARGV[3]) == 0) then " +
                    "return nil;" +
                    "end; " +
                    "local counter = redis.call('hincrby', KEYS[1], ARGV[3], -1); " +
                    "if (counter > 0) then " +
                    "redis.call('pexpire', KEYS[1], ARGV[2]); " +
                    "return 0; " +
                    "else " +
                    "redis.call('del', KEYS[1]); " +
                    "redis.call('publish', KEYS[2], ARGV[1]); " +
                    "return 1; " +
                    "end; " +
                    "return nil;",
            Arrays.asList(getName(), getChannelName()), LockPubSub.UNLOCK_MESSAGE, internalLockLeaseTime, getLockName(threadId));
}