聊聊dubbo的ExecuteLimitFilter

public class ExecuteLimitFilter extends ListenableFilter {
​
    private static final String EXECUTELIMIT_FILTER_START_TIME = "execugtelimit_filter_start_time";
​
    public ExecuteLimitFilter() {
        super.listener = new ExecuteLimitListener();
    }
​
    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
        URL url = invoker.getUrl();
        String methodName = invocation.getMethodName();
        int max = url.getMethodParameter(methodName, EXECUTES_KEY, 0);
        if (!RpcStatus.beginCount(url, methodName, max)) {
            throw new RpcException("Failed to invoke method " + invocation.getMethodName() + " in provider " +
                    url + ", cause: The service using threads greater than <dubbo:service executes=\"" + max +
                    "\" /> limited.");
        }
​
        invocation.setAttachment(EXECUTELIMIT_FILTER_START_TIME, String.valueOf(System.currentTimeMillis()));
        try {
            return invoker.invoke(invocation);
        } catch (Throwable t) {
            if (t instanceof RuntimeException) {
                throw (RuntimeException) t;
            } else {
                throw new RpcException("unexpected exception when ExecuteLimitFilter", t);
            }
        }
    }
​
    static class ExecuteLimitListener implements Listener {
        @Override
        public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {
            RpcStatus.endCount(invoker.getUrl(), invocation.getMethodName(), getElapsed(invocation), true);
        }
​
        @Override
        public void onError(Throwable t, Invoker<?> invoker, Invocation invocation) {
            RpcStatus.endCount(invoker.getUrl(), invocation.getMethodName(), getElapsed(invocation), false);
        }
​
        private long getElapsed(Invocation invocation) {
            String beginTime = invocation.getAttachment(EXECUTELIMIT_FILTER_START_TIME);
            return StringUtils.isNotEmpty(beginTime) ? System.currentTimeMillis() - Long.parseLong(beginTime) : 0;
        }
    }
}

public class RpcStatus {
​
    private static final ConcurrentMap<String, RpcStatus> SERVICE_STATISTICS = new ConcurrentHashMap<String, RpcStatus>();
​
    private static final ConcurrentMap<String, ConcurrentMap<String, RpcStatus>> METHOD_STATISTICS = new ConcurrentHashMap<String, ConcurrentMap<String, RpcStatus>>();
    private final ConcurrentMap<String, Object> values = new ConcurrentHashMap<String, Object>();
    private final AtomicInteger active = new AtomicInteger();
    private final AtomicLong total = new AtomicLong();
    private final AtomicInteger failed = new AtomicInteger();
    private final AtomicLong totalElapsed = new AtomicLong();
    private final AtomicLong failedElapsed = new AtomicLong();
    private final AtomicLong maxElapsed = new AtomicLong();
    private final AtomicLong failedMaxElapsed = new AtomicLong();
    private final AtomicLong succeededMaxElapsed = new AtomicLong();
​
    //......
​
    public static void beginCount(URL url, String methodName) {
        beginCount(url, methodName, Integer.MAX_VALUE);
    }
​
    /**
     * @param url
     */
    public static boolean beginCount(URL url, String methodName, int max) {
        max = (max <= 0) ? Integer.MAX_VALUE : max;
        RpcStatus appStatus = getStatus(url);
        RpcStatus methodStatus = getStatus(url, methodName);
        if (methodStatus.active.incrementAndGet() > max) {
            methodStatus.active.decrementAndGet();
            return false;
        } else {
            appStatus.active.incrementAndGet();
            return true;
        }
    }
​
    /**
     * @param url
     * @param elapsed
     * @param succeeded
     */
    public static void endCount(URL url, String methodName, long elapsed, boolean succeeded) {
        endCount(getStatus(url), elapsed, succeeded);
        endCount(getStatus(url, methodName), elapsed, succeeded);
    }
​
    private static void endCount(RpcStatus status, long elapsed, boolean succeeded) {
        status.active.decrementAndGet();
        status.total.incrementAndGet();
        status.totalElapsed.addAndGet(elapsed);
        if (status.maxElapsed.get() < elapsed) {
            status.maxElapsed.set(elapsed);
        }
        if (succeeded) {
            if (status.succeededMaxElapsed.get() < elapsed) {
                status.succeededMaxElapsed.set(elapsed);
            }
        } else {
            status.failed.incrementAndGet();
            status.failedElapsed.addAndGet(elapsed);
            if (status.failedMaxElapsed.get() < elapsed) {
                status.failedMaxElapsed.set(elapsed);
            }
        }
    }
​
    //......
}