FEAT: Add Operation throughput and latency metrics by mbean.

src/main/java/net/spy/memcached/MemcachedConnection.java

@@ -50,6 +50,8 @@
 import net.spy.memcached.compat.SpyObject;
 import net.spy.memcached.compat.log.LoggerFactory;
 import net.spy.memcached.internal.ReconnDelay;
+import net.spy.memcached.metrics.OpLatencyMonitor;
+import net.spy.memcached.metrics.OpThroughputMonitor;
 import net.spy.memcached.ops.KeyedOperation;
 import net.spy.memcached.ops.MultiOperationCallback;
 import net.spy.memcached.ops.Operation;
@@ -990,6 +992,7 @@ private void handleReads(MemcachedNode qa)
           throw new IllegalStateException("No read operation.");
         }
         currentOp.readFromBuffer(rbuf);
+        OpLatencyMonitor.getInstance().recordLatency(currentOp.getStartTime());
         if (currentOp.getState() == OperationState.COMPLETE) {
           getLogger().debug("Completed read op: %s and giving the next %d bytes",
                   currentOp, rbuf.remaining());
@@ -1519,6 +1522,7 @@ public String toString() {
    * @param op
    */
   public static void opTimedOut(Operation op) {
+    OpThroughputMonitor.getInstance().addTimeOutedOpCount(1);
     MemcachedConnection.setTimeout(op, true);
   }
 
@@ -1528,6 +1532,7 @@ public static void opTimedOut(Operation op) {
    * @param ops
    */
   public static void opsTimedOut(Collection<Operation> ops) {
+    OpThroughputMonitor.getInstance().addTimeOutedOpCount(ops.size());
     Collection<String> timedOutNodes = new HashSet<>();
     for (Operation op : ops) {
       try {

src/main/java/net/spy/memcached/metrics/LatencyMetricsSnapShot.java

@@ -0,0 +1,55 @@
+package net.spy.memcached.metrics;
+
+class LatencyMetricsSnapShot {
+  private static final LatencyMetricsSnapShot EMPTY = new LatencyMetricsSnapShot(0, 0, 0, 0, 0, 0);
+
+  private final long avgLatency;
+  private final long minLatency;
+  private final long maxLatency;
+  private final long p25Latency;
+  private final long p50Latency;
+  private final long p75Latency;
+  private final long timestamp;  // 캐시 생성 시간
+
+  LatencyMetricsSnapShot(long avg, long min, long max, long p25, long p50, long p75) {
+    this.avgLatency = avg;
+    this.minLatency = min;
+    this.maxLatency = max;
+    this.p25Latency = p25;
+    this.p50Latency = p50;
+    this.p75Latency = p75;
+    this.timestamp = System.currentTimeMillis();
+  }
+
+  public static LatencyMetricsSnapShot empty() {
+    return EMPTY;
+  }
+
+  public long getAvgLatency() {
+    return avgLatency;
+  }
+
+  public long getMinLatency() {
+    return minLatency;
+  }
+
+  public long getMaxLatency() {
+    return maxLatency;
+  }
+
+  public long getP25Latency() {
+    return p25Latency;
+  }
+
+  public long getP50Latency() {
+    return p50Latency;
+  }
+
+  public long getP75Latency() {
+    return p75Latency;
+  }
+
+  public long getTimestamp() {
+    return timestamp;
+  }
+}

src/main/java/net/spy/memcached/metrics/OpLatencyMonitor.java

@@ -0,0 +1,149 @@
+package net.spy.memcached.metrics;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.atomic.AtomicReferenceArray;
+
+import net.spy.memcached.ArcusMBeanServer;
+
+public final class OpLatencyMonitor implements OpLatencyMonitorMBean {
+
+  private static final OpLatencyMonitor INSTANCE = new OpLatencyMonitor();
+  private static final long CACHE_DURATION = 2000; // 2초 캐시
+  private static final int WINDOW_SIZE = 10_000;
+
+  private final AtomicReferenceArray<Long> latencies = new AtomicReferenceArray<>(WINDOW_SIZE);
+  private final AtomicInteger currentIndex = new AtomicInteger(0);
+  private final AtomicInteger count = new AtomicInteger(0);
+  private final AtomicReference<LatencyMetricsSnapShot> cachedMetrics
+          = new AtomicReference<>(LatencyMetricsSnapShot.empty());
+  private final boolean enabled;
+
+  private OpLatencyMonitor() {
+    if (System.getProperty("arcus.mbean", "false").toLowerCase().equals("false")) {
+      enabled = false;
+      return;
+    }
+    enabled = true;
+    for (int i = 0; i < WINDOW_SIZE; i++) {
+      latencies.set(i, 0L);
+    }
+
+    try {
+      ArcusMBeanServer mbs = ArcusMBeanServer.getInstance();
+      mbs.registMBean(this, this.getClass().getPackage().getName()
+              + ":type=" + this.getClass().getSimpleName());
+    } catch (Exception e) {
+      throw new RuntimeException("Failed to register MBean", e);
+    }
+  }
+
+  public static OpLatencyMonitor getInstance() {
+    return INSTANCE;
+  }
+
+  public void recordLatency(long startNanos) {
+    if (!enabled) {
+      return;
+    }
+    long latencyMicros = TimeUnit.NANOSECONDS.toMicros(System.nanoTime() - startNanos);
+    int index = currentIndex.getAndUpdate(i -> (i + 1) % WINDOW_SIZE);
+    latencies.lazySet(index, latencyMicros);
+
+    if (count.get() < WINDOW_SIZE) {
+      count.incrementAndGet();
+    }
+  }
+
+  // 모든 메트릭을 한 번에 계산하고 캐시하는 메서드
+  private LatencyMetricsSnapShot computeMetrics() {
+    int currentCount = count.get();
+    if (currentCount == 0) {
+      return LatencyMetricsSnapShot.empty();
+    }
+
+    // 현재 데이터를 배열로 복사
+    List<Long> sortedLatencies = new ArrayList<>(currentCount);
+    int startIndex = currentIndex.get();
+
+    for (int i = 0; i < currentCount; i++) {
+      int idx = (startIndex - i + WINDOW_SIZE) % WINDOW_SIZE;
+      long value = latencies.get(idx);
+      if (value > 0) {
+        sortedLatencies.add(value);
+      }
+    }
+
+    if (sortedLatencies.isEmpty()) {
+      return LatencyMetricsSnapShot.empty();
+    }
+
+    sortedLatencies.sort(Long::compareTo);
+
+    // 모든 메트릭을 한 번에 계산
+    long avg = sortedLatencies.stream().mapToLong(Long::longValue).sum() / sortedLatencies.size();
+    long min = sortedLatencies.get(0);
+    long max = sortedLatencies.get(sortedLatencies.size() - 1);
+    long p25 = sortedLatencies.get((int) Math.ceil((sortedLatencies.size() * 25.0) / 100.0) - 1);
+    long p50 = sortedLatencies.get((int) Math.ceil((sortedLatencies.size() * 50.0) / 100.0) - 1);
+    long p75 = sortedLatencies.get((int) Math.ceil((sortedLatencies.size() * 75.0) / 100.0) - 1);
+
+    return new LatencyMetricsSnapShot(avg, min, max, p25, p50, p75);
+  }
+
+  // 캐시된 메트릭을 가져오거나 필요시 새로 계산
+  private LatencyMetricsSnapShot getMetricsSnapshot() {
+    LatencyMetricsSnapShot current = cachedMetrics.get();
+    long now = System.currentTimeMillis();
+
+    // 캐시가 유효한지 확인
+    if (now - current.getTimestamp() < CACHE_DURATION) {
+      return current;
+    }
+
+    // 새로운 메트릭 계산 및 캐시 업데이트
+    LatencyMetricsSnapShot newMetrics = computeMetrics();
+    cachedMetrics.set(newMetrics);
+    return newMetrics;
+  }
+
+  @Override
+  public long getAverageLatencyMicros() {
+    return getMetricsSnapshot().getAvgLatency();
+  }
+
+  @Override
+  public long getMinLatencyMicros() {
+    return getMetricsSnapshot().getMinLatency();
+  }
+
+  @Override
+  public long getMaxLatencyMicros() {
+    return getMetricsSnapshot().getMaxLatency();
+  }
+
+  @Override
+  public long get25thPercentileLatencyMicros() {
+    return getMetricsSnapshot().getP25Latency();
+  }
+
+  @Override
+  public long get50thPercentileLatencyMicros() {
+    return getMetricsSnapshot().getP50Latency();
+  }
+
+  @Override
+  public long get75thPercentileLatencyMicros() {
+    return getMetricsSnapshot().getP75Latency();
+  }
+
+  @Override
+  public void resetStatistics() {
+    count.set(0);
+    currentIndex.set(0);
+    cachedMetrics.set(LatencyMetricsSnapShot.empty());
+  }
+}

src/main/java/net/spy/memcached/metrics/OpLatencyMonitorMBean.java

@@ -0,0 +1,17 @@
+package net.spy.memcached.metrics;
+
+public interface OpLatencyMonitorMBean {
+  long getAverageLatencyMicros();
+
+  long getMaxLatencyMicros();
+
+  long getMinLatencyMicros();
+
+  long get25thPercentileLatencyMicros();
+
+  long get50thPercentileLatencyMicros();
+
+  long get75thPercentileLatencyMicros();
+
+  void resetStatistics();
+}

src/main/java/net/spy/memcached/metrics/OpThroughputMonitor.java

@@ -0,0 +1,90 @@
+package net.spy.memcached.metrics;
+
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.LongAdder;
+
+import net.spy.memcached.ArcusMBeanServer;
+
+public final class OpThroughputMonitor implements OpThroughputMonitorMBean {
+  private static final OpThroughputMonitor INSTANCE = new OpThroughputMonitor();
+
+  private final LongAdder completeOps = new LongAdder();
+  private final LongAdder cancelOps = new LongAdder();
+  private final LongAdder timeOutOps = new LongAdder();
+  private final AtomicLong lastResetTime = new AtomicLong(System.currentTimeMillis());
+  private final boolean enabled;
+
+  private OpThroughputMonitor() {
+    if (System.getProperty("arcus.mbean", "false").toLowerCase().equals("false")) {
+      enabled = false;
+      return;
+    }
+    enabled = true;
+    try {
+      ArcusMBeanServer mbs = ArcusMBeanServer.getInstance();
+      mbs.registMBean(this, this.getClass().getPackage().getName()
+              + ":type=" + this.getClass().getSimpleName());
+    } catch (Exception e) {
+      throw new RuntimeException("Failed to register Throughput MBean", e);
+    }
+  }
+
+  public static OpThroughputMonitor getInstance() {
+    return INSTANCE;
+  }
+
+  public void addCompletedOpCount() {
+    if (!enabled) {
+      return;
+    }
+    completeOps.increment();
+  }
+
+  public void addCanceledOpCount() {
+    if (!enabled) {
+      return;
+    }
+    cancelOps.increment();
+  }
+
+  public void addTimeOutedOpCount(int count) {
+    if (!enabled) {
+      return;
+    }
+    timeOutOps.add(count);
+  }
+
+  @Override
+  public long getCompletedOps() {
+    return getThroughput(completeOps);
+  }
+
+  @Override
+  public long getCanceledOps() {
+    return getThroughput(cancelOps);
+  }
+
+  @Override
+  public long getTimeoutOps() {
+    return getThroughput(timeOutOps);
+  }
+
+  @Override
+  public void resetStatistics() {
+    completeOps.reset();
+    cancelOps.reset();
+    timeOutOps.reset();
+    lastResetTime.set(System.currentTimeMillis());
+  }
+
+  private long getThroughput(LongAdder ops) {
+    long currentTime = System.currentTimeMillis();
+    long lastTime = lastResetTime.get();
+    long countValue = ops.sum();
+
+    // 경과 시간 계산 (초 단위)
+    long elapsedSeconds = (long) ((currentTime - lastTime) / 1000.0);
+
+    return countValue / elapsedSeconds;
+  }
+}

src/main/java/net/spy/memcached/metrics/OpThroughputMonitorMBean.java

@@ -0,0 +1,11 @@
+package net.spy.memcached.metrics;
+
+public interface OpThroughputMonitorMBean {
+  long getCompletedOps();
+
+  long getCanceledOps();
+
+  long getTimeoutOps();
+
+  void resetStatistics();
+}

src/main/java/net/spy/memcached/ops/Operation.java

@@ -134,4 +134,8 @@ public interface Operation {
   /* ENABLE_MIGRATION end */
 
   APIType getAPIType();
+
+  void setStartTime(long startTime);
+
+  long getStartTime();
 }