ServerStats.java

/*
 * 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 org.apache.bookkeeper.proto;

public class ServerStats {
    private static ServerStats instance = new ServerStats();
    private long packetsSent;
    private long packetsReceived;
    private long maxLatency;
    private long minLatency = Long.MAX_VALUE;
    private long totalLatency = 0;
    private long count = 0;

    public interface Provider {
        public long getOutstandingRequests();

        public long getLastProcessedZxid();
    }

    private Provider provider = null;
    private Object mutex = new Object();

    static public ServerStats getInstance() {
        return instance;
    }

    static public void registerAsConcrete() {
        setInstance(new ServerStats());
    }

    static synchronized public void unregister() {
        instance = null;
    }

    static synchronized protected void setInstance(ServerStats newInstance) {
        assert instance == null;
        instance = newInstance;
    }

    protected ServerStats() {
    }

    // getters
    synchronized public long getMinLatency() {
        return (minLatency == Long.MAX_VALUE) ? 0 : minLatency;
    }

    synchronized public long getAvgLatency() {
        if (count != 0)
            return totalLatency / count;
        return 0;
    }

    synchronized public long getMaxLatency() {
        return maxLatency;
    }

    public long getOutstandingRequests() {
        synchronized (mutex) {
            return (provider != null) ? provider.getOutstandingRequests() : -1;
        }
    }

    public long getLastProcessedZxid() {
        synchronized (mutex) {
            return (provider != null) ? provider.getLastProcessedZxid() : -1;
        }
    }

    synchronized public long getPacketsReceived() {
        return packetsReceived;
    }

    synchronized public long getPacketsSent() {
        return packetsSent;
    }

    public String getServerState() {
        return "standalone";
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("Latency min/avg/max: " + getMinLatency() + "/" + getAvgLatency() + "/" + getMaxLatency() + "\n");
        sb.append("Received: " + getPacketsReceived() + "\n");
        sb.append("Sent: " + getPacketsSent() + "\n");
        if (provider != null) {
            sb.append("Outstanding: " + getOutstandingRequests() + "\n");
            sb.append("Zxid: 0x" + Long.toHexString(getLastProcessedZxid()) + "\n");
        }
        sb.append("Mode: " + getServerState() + "\n");
        return sb.toString();
    }

    // mutators
    public void setStatsProvider(Provider zk) {
        synchronized (mutex) {
            provider = zk;
        }
    }

    synchronized void updateLatency(long requestCreateTime) {
        long latency = System.currentTimeMillis() - requestCreateTime;
        totalLatency += latency;
        count++;
        if (latency < minLatency) {
            minLatency = latency;
        }
        if (latency > maxLatency) {
            maxLatency = latency;
        }
    }

    synchronized public void resetLatency() {
        totalLatency = count = maxLatency = 0;
        minLatency = Long.MAX_VALUE;
    }

    synchronized public void resetMaxLatency() {
        maxLatency = getMinLatency();
    }

    synchronized public void incrementPacketsReceived() {
        packetsReceived++;
    }

    synchronized public void incrementPacketsSent() {
        packetsSent++;
    }

    synchronized public void resetRequestCounters() {
        packetsReceived = packetsSent = 0;
    }

}