| /* |
| * 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.container; |
| |
| import java.util.Set; |
| import org.apache.samza.checkpoint.OffsetManager; |
| import org.apache.samza.scheduler.EpochTimeScheduler; |
| import org.apache.samza.system.IncomingMessageEnvelope; |
| import org.apache.samza.system.SystemStreamPartition; |
| import org.apache.samza.task.ReadableCoordinator; |
| import org.apache.samza.task.TaskCallbackFactory; |
| |
| |
| /** |
| * The interface required for a task's execution to be managed within {@link RunLoop}. |
| * |
| * Some notes on thread safety and exclusivity between methods: |
| * |
| * TODO SAMZA-2531: isAsyncCommitEnabled is either an incomplete feature or misnamed |
| * RunLoop will ensure exclusivity between {@link #window}, {@link #commit}, {@link #scheduler}, and |
| * {@link #endOfStream}. |
| * |
| * There is an exception for {@link #process}, which may execute concurrently with {@link #commit} IF the encapsulating |
| * {@link RunLoop} has its isAsyncCommitEnabled set to true. In this case, the implementer of this interface should |
| * take care to ensure that any objects shared between commit and process are thread safe. |
| * |
| * Be aware that {@link #commit}, {@link #window} and {@link #scheduler} can be run in their own thread pool outside |
| * the main RunLoop thread (which executes {@link #process}) so may run concurrently between tasks. For example, one |
| * task may be executing a commit while another is executing window. For this reason, implementers of this class must |
| * ensure that objects shared between instances of RunLoopTask are thread safe. |
| */ |
| public interface RunLoopTask { |
| |
| /** |
| * The {@link TaskName} associated with this RunLoopTask. |
| * |
| * @return taskName |
| */ |
| TaskName taskName(); |
| |
| /** |
| * Process an incoming message envelope. |
| * |
| * @param envelope The envelope to be processed |
| * @param coordinator Manages execution of tasks |
| * @param callbackFactory Creates a callback to be used to indicate completion of or failure to process the |
| * envelope. {@link TaskCallbackFactory#createCallback()} should be called before processing |
| * begins. |
| */ |
| void process(IncomingMessageEnvelope envelope, ReadableCoordinator coordinator, TaskCallbackFactory callbackFactory); |
| |
| /** |
| * Performs a window for this task. If {@link #isWindowableTask()} is true, this method will be invoked periodically |
| * by {@link RunLoop} according to its windowMs. |
| * |
| * This method can be used to perform aggregations within a task. |
| * |
| * @param coordinator Manages execution of tasks |
| */ |
| void window(ReadableCoordinator coordinator); |
| |
| /** |
| * Used in conjunction with {@link #epochTimeScheduler()} to execute scheduled callbacks. See documentation of |
| * {@link EpochTimeScheduler} for more information. |
| * |
| * @param coordinator Manages execution of tasks. |
| */ |
| void scheduler(ReadableCoordinator coordinator); |
| |
| /** |
| * Performs a commit for this task. Operations for persisting checkpoint-related information for this task should |
| * be done here. |
| */ |
| void commit(); |
| |
| /** |
| * Called when all {@link SystemStreamPartition} processed by a task have reached end of stream. This is called only |
| * once per task. {@link RunLoop} will issue a shutdown request to the coordinator immediately following the |
| * invocation of this method. |
| * |
| * @param coordinator manages execution of tasks. |
| */ |
| void endOfStream(ReadableCoordinator coordinator); |
| |
| /** |
| * Indicates whether {@link #window} should be invoked on this task. If true, {@link RunLoop} |
| * will schedule window to execute periodically according to its windowMs. |
| * |
| * @return whether the task should perform window |
| */ |
| boolean isWindowableTask(); |
| |
| /** |
| * Whether this task has intermediate streams. Intermediate streams may be used to facilitate task processing |
| * before terminal output is produced. {@link RunLoop} uses this information to determine when the task has reached |
| * end of stream. |
| * |
| * @return whether the task uses intermediate streams |
| */ |
| Set<String> intermediateStreams(); |
| |
| /** |
| * The set of {@link SystemStreamPartition} this task consumes from. |
| * |
| * @return the set of SSPs |
| */ |
| Set<SystemStreamPartition> systemStreamPartitions(); |
| |
| /** |
| * An {@link OffsetManager}, if any, to use to track offsets for each input SSP. Offsets will be updated after successful |
| * completion of an envelope from an SSP. |
| * |
| * @return the offset manager, or null otherwise |
| */ |
| OffsetManager offsetManager(); |
| |
| /** |
| * The metrics instance {@link RunLoop} will use to emit metrics related to execution of this task. |
| * |
| * @return metrics instance for this task |
| */ |
| TaskInstanceMetrics metrics(); |
| |
| /** |
| * An {@link EpochTimeScheduler}, if any, used by the task to handle timer based callbacks. |
| * |
| * @return the scheduler, or null otherwise |
| */ |
| EpochTimeScheduler epochTimeScheduler(); |
| } |