[GitHub] [geode] DonalEvans commented on a change in pull request #7437: GEODE-10010: Refine per-second Redis stats

[GitBox <gi...@apache.org>]

DonalEvans commented on a change in pull request #7437:
URL: https://github.com/apache/geode/pull/7437#discussion_r825166041



##########
File path: geode-for-redis/src/main/java/org/apache/geode/redis/internal/statistics/RedisStats.java
##########
@@ -193,43 +198,57 @@ public void changeUniquePatternSubscriptions(long delta) {
 
   public void close() {
     geodeRedisStats.close();
-    stopPerSecondUpdater();
+    stopRollingAverageUpdater();
   }
 
-  private ScheduledExecutorService startPerSecondUpdater() {
-    int INTERVAL = 1;
+  private ScheduledExecutorService startRollingAverageUpdater() {
+    long microsPerSecond = 1_000_000;
+    final long delayMicros = microsPerSecond / ROLLING_AVERAGE_SAMPLES_PER_SECOND;
 
-    ScheduledExecutorService perSecondExecutor =
-        newSingleThreadScheduledExecutor("GemFireRedis-PerSecondUpdater-");
+    ScheduledExecutorService rollingAverageExecutor =
+        newSingleThreadScheduledExecutor("GemFireRedis-RollingAverageStatUpdater-");
 
-    perSecondExecutor.scheduleWithFixedDelay(
-        this::doPerSecondUpdates,
-        INTERVAL,
-        INTERVAL,
-        SECONDS);
+    rollingAverageExecutor.scheduleWithFixedDelay(this::doRollingAverageUpdates, delayMicros,
+        delayMicros, MICROSECONDS);
 
-    return perSecondExecutor;
+    return rollingAverageExecutor;
   }
 
-  private void stopPerSecondUpdater() {
-    perSecondExecutor.shutdownNow();
+  private void stopRollingAverageUpdater() {
+    rollingAverageExecutor.shutdownNow();
   }
 
-  private void doPerSecondUpdates() {
-    updateNetworkKilobytesReadLastSecond();
-    updateOpsPerformedOverLastSecond();
+  private void doRollingAverageUpdates() {
+    networkKiloBytesReadOverLastSecond = networkBytesReadRollingAverageStat.calculate() / 1024.0;
+    opsPerformedOverLastSecond = opsPerformedRollingAverageStat.calculate();
   }
 
-  private void updateNetworkKilobytesReadLastSecond() {
-    final long totalNetworkBytesRead = getTotalNetworkBytesRead();
-    long deltaNetworkBytesRead = totalNetworkBytesRead - previousNetworkBytesRead;
-    networkKiloBytesReadOverLastSecond = deltaNetworkBytesRead / 1024.0;
-    previousNetworkBytesRead = totalNetworkBytesRead;
-  }
+  private static class RollingAverageStat {
+    private int tickNumber = 0;
+    private long valueReadLastTick;
+    private final long[] valuesReadOverLastNSamples;
+    private final Callable<Long> statCallable;
+
+    private RollingAverageStat(int samplesPerSecond, Callable<Long> getCurrentValue) {
+      valuesReadOverLastNSamples = new long[samplesPerSecond];
+      statCallable = getCurrentValue;
+    }
 
-  private void updateOpsPerformedOverLastSecond() {
-    final long totalOpsPerformed = getCommandsProcessed();
-    opsPerformedOverLastSecond = totalOpsPerformed - opsPerformedLastTick;
-    opsPerformedLastTick = totalOpsPerformed;
+    private long calculate() {
+      long currentValue;
+      try {
+        currentValue = statCallable.call();
+      } catch (Exception e) {
+        throw new RedisException("Error while calculating RollingAverage stats", e);
+      }
+      long delta = currentValue - valueReadLastTick;
+      valueReadLastTick = currentValue;
+      valuesReadOverLastNSamples[tickNumber] = delta;
+      tickNumber++;
+      if (tickNumber >= valuesReadOverLastNSamples.length) {
+        tickNumber = 0;
+      }
+      return Arrays.stream(valuesReadOverLastNSamples).sum();
+    }

Review comment:
       Faster is better!




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