anmolanmol1234 commented on code in PR #8137: URL: https://github.com/apache/hadoop/pull/8137#discussion_r2650700026
########## hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/MetricsBucket.java: ########## @@ -0,0 +1,196 @@ +/** + * 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.hadoop.fs.azurebfs.services; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; +import java.util.Set; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentLinkedQueue; +import java.util.concurrent.atomic.AtomicReference; + +import org.apache.hadoop.fs.azurebfs.utils.SimpleRateLimiter; + +/** + * MetricsBucket holds metrics for multiple AbfsClients and + * dispatches them in batches, respecting rate limits. + */ +final class MetricsBucket { + + // Rate limiter to control the rate of dispatching metrics. + private final SimpleRateLimiter rateLimiter; + + // Buffer to hold metrics before sending. + private final AtomicReference<ConcurrentLinkedQueue<String>> metricsBuffer = + new AtomicReference<>(new ConcurrentLinkedQueue<>()); + + // Set of registered AbfsClients. + private final Set<AbfsClient> clients = + ConcurrentHashMap.newKeySet(); + + // Maximum size of metrics header in characters. + private static final long MAX_HEADER_SIZE = 1024; + + // Constructor + MetricsBucket(SimpleRateLimiter rateLimiter) { + this.rateLimiter = rateLimiter; + } + + /** + * Register a new AbfsClient. + * @param client the AbfsClient to register + */ + public void registerClient(AbfsClient client) { + if (client != null) { + clients.add(client); + } + } + + /** + * Deregister an AbfsClient. If this is the last client, drain and send + * any remaining metrics. + * @param client the AbfsClient to deregister + * @return true if the client was deregistered, false otherwise + */ + public boolean deregisterClient(AbfsClient client) { + if (client == null) { + return false; + } + ConcurrentLinkedQueue<String> batchToSend = null; + boolean isLastClient = false; + + synchronized (this) { + if (!clients.contains(client)) { + return false; + } + + if (clients.size() == 1) { + // This client is the last one — drain metrics now + batchToSend = metricsBuffer.getAndSet(new ConcurrentLinkedQueue<>()); + isLastClient = true; + } + + clients.remove(client); + } + if (isLastClient) { + sendMetrics(client, batchToSend); + } + return true; + } + + /** + * Add a metric to the buffer. + * @param metric the metric to add + */ + void addRequest(String metric) { + if (metric != null) { + metricsBuffer.get().add(metric); + } + } + + /** + * Drain the metrics buffer and send if there are registered clients. + */ + public void drainAndSendIfReady() { + AbfsClient client; + + synchronized (this) { + if (clients.isEmpty()) { + return; + } + client = clients.iterator().next(); + } + + ConcurrentLinkedQueue<String> batch = metricsBuffer.getAndSet( + new ConcurrentLinkedQueue<>()); + if (batch.isEmpty()) { + return; + } + + sendMetrics(client, batch); + } + + // Send metrics outside synchronized block + private void sendMetrics(AbfsClient client, + ConcurrentLinkedQueue<String> batchToSend) { + // Send outside synchronized block + if (client != null && batchToSend != null && !batchToSend.isEmpty()) { + for (String chunk : splitListBySize(batchToSend, MAX_HEADER_SIZE)) { + rateLimiter.acquire(); // Rate limiting + try { + client.getMetricCall(chunk); + } catch (IOException ignored) {} + } + } + } + + // Check if there are no registered clients + public boolean isEmpty() { + return clients.isEmpty(); + } + + /** + * Split the list of metrics into chunks that fit within maxChars. + * Each metric is wrapped in square brackets and separated by colons. + */ + private static List<String> splitListBySize( + ConcurrentLinkedQueue<String> items, long maxChars) { + + if (items.isEmpty()) { + return Collections.emptyList(); + } + + List<String> result = new ArrayList<>(); + StringBuilder sb = new StringBuilder(); + + for (String s : new ArrayList<>(items)) { Review Comment: No need of copy here, you can directly iterate as for (String s: items) -- This is an automated message from the Apache Git Service. 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