[GitHub] [kafka] junrao commented on a change in pull request #9114: KAFKA-10162; Use Token Bucket algorithm for controller mutation quota (KIP-599, Part III)

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junrao commented on a change in pull request #9114:
URL: https://github.com/apache/kafka/pull/9114#discussion_r464724281



##########
File path: clients/src/main/java/org/apache/kafka/common/metrics/stats/TokenBucket.java
##########
@@ -0,0 +1,83 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.kafka.common.metrics.stats;
+
+import java.util.concurrent.TimeUnit;
+import org.apache.kafka.common.metrics.MeasurableStat;
+import org.apache.kafka.common.metrics.MetricConfig;
+
+public class TokenBucket implements MeasurableStat {
+    private final TimeUnit unit;
+    private double credits;
+    private long lastUpdateMs;
+
+    public TokenBucket() {
+        this(TimeUnit.SECONDS);
+    }
+
+    public TokenBucket(TimeUnit unit) {
+        this.unit = unit;
+        this.credits = 0;
+        this.lastUpdateMs = 0;
+    }
+
+    @Override
+    public double measure(final MetricConfig config, final long timeMs) {
+        if (config.quota() == null)
+            return Long.MAX_VALUE;
+        final double quota = config.quota().bound();
+        final double burst = (config.samples() - 1) * convert(config.timeWindowMs()) * quota;
+        refill(quota, burst, timeMs);
+        return this.credits;
+    }
+
+    @Override
+    public void record(final MetricConfig config, final double value, final long timeMs) {
+        if (config.quota() == null)
+            return;
+        final double quota = config.quota().bound();
+        final double burst = (config.samples() - 1) * convert(config.timeWindowMs()) * quota;

Review comment:
       Should burst be computed from `#samples` or `#samples - 1` ?

##########
File path: clients/src/main/java/org/apache/kafka/common/metrics/stats/TokenBucket.java
##########
@@ -0,0 +1,83 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.kafka.common.metrics.stats;
+
+import java.util.concurrent.TimeUnit;
+import org.apache.kafka.common.metrics.MeasurableStat;
+import org.apache.kafka.common.metrics.MetricConfig;
+
+public class TokenBucket implements MeasurableStat {
+    private final TimeUnit unit;
+    private double credits;
+    private long lastUpdateMs;
+
+    public TokenBucket() {
+        this(TimeUnit.SECONDS);
+    }
+
+    public TokenBucket(TimeUnit unit) {
+        this.unit = unit;
+        this.credits = 0;

Review comment:
       Should we start with 0 credit or the full burst credits? The benefit of the latter is that during initialization, the requests won't be throttled as much due to a cold start.

##########
File path: core/src/main/scala/kafka/server/ControllerMutationQuotaManager.scala
##########
@@ -131,6 +133,16 @@ class PermissiveControllerMutationQuota(private val time: Time,
 
 object ControllerMutationQuotaManager {
   val QuotaControllerMutationDefault = Int.MaxValue.toDouble
+
+  def throttleTime(e: QuotaViolationException, timeMs: Long): Long = {
+    e.metric().measurable() match {
+      case _: TokenBucket => Math.round(-e.value() * e.bound())

Review comment:
       Hmm, assuming bound is the per sec rate, it seems that the throttleTimeMs should be `-e.value() / e.bound * 1000`?




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