| /* |
| * 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.samza.coordinator; |
| |
| import com.google.common.base.Preconditions; |
| import java.io.UnsupportedEncodingException; |
| import java.time.Duration; |
| import java.util.Optional; |
| import java.util.UUID; |
| import org.apache.samza.SamzaException; |
| import org.apache.samza.metadatastore.MetadataStore; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| |
| /** |
| * Generates RunId for Standalone use case |
| * If there is only one processor in the quorum (registered with ClusterMembership) then create new runid and add to store |
| * Else read runid from the store |
| * |
| * Steps to generate: |
| * 1. acquire lock |
| * 2. add self to quorum (register itself with ClusterMembership) |
| * 3. get number of processors in quorum |
| * 4. if qurorum size is 1 (only self) then create new runid and write to store |
| * 5. if quorum size if greater than 1 then read runid from store |
| * 6. unlock |
| */ |
| public class RunIdGenerator { |
| private static final Logger LOG = LoggerFactory.getLogger(RunIdGenerator.class); |
| |
| private final CoordinationUtils coordinationUtils; |
| private final MetadataStore metadataStore; |
| private final ClusterMembership clusterMembership; |
| private String processorId = null; |
| private volatile boolean closed = false; |
| |
| public RunIdGenerator(CoordinationUtils coordinationUtils, MetadataStore metadataStore) { |
| Preconditions.checkNotNull(coordinationUtils, "CoordinationUtils cannot be null"); |
| Preconditions.checkNotNull(metadataStore, "MetadataStore cannot be null"); |
| this.coordinationUtils = coordinationUtils; |
| this.metadataStore = metadataStore; |
| this.clusterMembership = coordinationUtils.getClusterMembership(); |
| Preconditions.checkNotNull(this.clusterMembership, "Failed to create utils for run id generation"); |
| } |
| |
| public Optional<String> getRunId() { |
| DistributedLock runIdLock; |
| String runId = null; |
| |
| runIdLock = coordinationUtils.getLock(CoordinationConstants.RUNID_LOCK_ID); |
| if (runIdLock == null) { |
| throw new SamzaException("Failed to create utils for run id generation"); |
| } |
| |
| try { |
| // acquire lock to write or read run.id |
| if (runIdLock.lock(Duration.ofMillis(CoordinationConstants.LOCK_TIMEOUT_MS))) { |
| LOG.info("lock acquired for run.id generation by this processor"); |
| processorId = clusterMembership.registerProcessor(); |
| int numberOfActiveProcessors = clusterMembership.getNumberOfProcessors(); |
| if (numberOfActiveProcessors == 0) { |
| String msg = String.format("Processor failed to fetch number of processors for run.id generation"); |
| throw new SamzaException(msg); |
| } |
| if (numberOfActiveProcessors == 1) { |
| runId = |
| String.valueOf(System.currentTimeMillis()) + "-" + UUID.randomUUID().toString().substring(0, 8); |
| LOG.info("Writing the run id for this run as {}", runId); |
| metadataStore.put(CoordinationConstants.RUNID_STORE_KEY, runId.getBytes("UTF-8")); |
| metadataStore.flush(); |
| } else { |
| runId = new String(metadataStore.get(CoordinationConstants.RUNID_STORE_KEY)); |
| LOG.info("Read the run id for this run as {}", runId); |
| } |
| runIdLock.unlock(); |
| } else { |
| throw new SamzaException("Processor timed out waiting to acquire lock for run.id generation"); |
| } |
| } catch (UnsupportedEncodingException e) { |
| throw new SamzaException("Processor could not serialize/deserialize string for run.id generation", e); |
| } |
| return Optional.ofNullable(runId); |
| } |
| |
| /** |
| * might be called several times and hence should be idempotent |
| */ |
| public void close() { |
| if (!closed && processorId != null) { |
| closed = true; |
| clusterMembership.unregisterProcessor(processorId); |
| } |
| } |
| } |