| /* |
| * 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.beam.runners.core; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.List; |
| import java.util.Map; |
| import org.apache.beam.sdk.state.BagState; |
| import org.apache.beam.sdk.state.CombiningState; |
| import org.apache.beam.sdk.state.GroupingState; |
| import org.apache.beam.sdk.state.ReadableState; |
| import org.apache.beam.sdk.state.SetState; |
| import org.apache.beam.sdk.state.State; |
| import org.apache.beam.sdk.transforms.windowing.BoundedWindow; |
| |
| /** Helpers for merging state. */ |
| public class StateMerging { |
| /** |
| * Clear all state in {@code address} in all windows under merge (even result windows) in {@code |
| * context}. |
| */ |
| public static <K, StateT extends State, W extends BoundedWindow> void clear( |
| MergingStateAccessor<K, W> context, StateTag<StateT> address) { |
| for (StateT state : context.accessInEachMergingWindow(address).values()) { |
| state.clear(); |
| } |
| } |
| |
| /** |
| * Prefetch all bag state in {@code address} across all windows under merge in {@code context}, |
| * except for the bag state in the final state address window which we can blindly append to. |
| */ |
| public static <K, T, W extends BoundedWindow> void prefetchBags( |
| MergingStateAccessor<K, W> context, StateTag<BagState<T>> address) { |
| Map<W, BagState<T>> map = context.accessInEachMergingWindow(address); |
| if (map.isEmpty()) { |
| // Nothing to prefetch. |
| return; |
| } |
| BagState<T> result = context.access(address); |
| // Prefetch everything except what's already in result. |
| for (BagState<T> source : map.values()) { |
| if (!source.equals(result)) { |
| prefetchRead(source); |
| } |
| } |
| } |
| |
| /** Merge all bag state in {@code address} across all windows under merge. */ |
| public static <K, T, W extends BoundedWindow> void mergeBags( |
| MergingStateAccessor<K, W> context, StateTag<BagState<T>> address) { |
| mergeBags(context.accessInEachMergingWindow(address).values(), context.access(address)); |
| } |
| |
| /** |
| * Merge all bag state in {@code sources} (which may include {@code result}) into {@code result}. |
| */ |
| public static <T, W extends BoundedWindow> void mergeBags( |
| Collection<BagState<T>> sources, BagState<T> result) { |
| if (sources.isEmpty()) { |
| // Nothing to merge. |
| return; |
| } |
| // Prefetch everything except what's already in result. |
| List<ReadableState<Iterable<T>>> futures = new ArrayList<>(sources.size()); |
| for (BagState<T> source : sources) { |
| if (!source.equals(result)) { |
| prefetchRead(source); |
| futures.add(source); |
| } |
| } |
| if (futures.isEmpty()) { |
| // Result already holds all the values. |
| return; |
| } |
| // Transfer from sources to result. |
| for (ReadableState<Iterable<T>> future : futures) { |
| for (T element : future.read()) { |
| result.add(element); |
| } |
| } |
| // Clear sources except for result. |
| for (BagState<T> source : sources) { |
| if (!source.equals(result)) { |
| source.clear(); |
| } |
| } |
| } |
| |
| /** Merge all set state in {@code address} across all windows under merge. */ |
| public static <K, T, W extends BoundedWindow> void mergeSets( |
| MergingStateAccessor<K, W> context, StateTag<SetState<T>> address) { |
| mergeSets(context.accessInEachMergingWindow(address).values(), context.access(address)); |
| } |
| |
| /** |
| * Merge all set state in {@code sources} (which may include {@code result}) into {@code result}. |
| */ |
| public static <T, W extends BoundedWindow> void mergeSets( |
| Collection<SetState<T>> sources, SetState<T> result) { |
| if (sources.isEmpty()) { |
| // Nothing to merge. |
| return; |
| } |
| // Prefetch everything except what's already in result. |
| List<ReadableState<Iterable<T>>> futures = new ArrayList<>(sources.size()); |
| for (SetState<T> source : sources) { |
| if (!source.equals(result)) { |
| prefetchRead(source); |
| futures.add(source); |
| } |
| } |
| if (futures.isEmpty()) { |
| // Result already holds all the values. |
| return; |
| } |
| // Transfer from sources to result. |
| for (ReadableState<Iterable<T>> future : futures) { |
| for (T element : future.read()) { |
| result.add(element); |
| } |
| } |
| // Clear sources except for result. |
| for (SetState<T> source : sources) { |
| if (!source.equals(result)) { |
| source.clear(); |
| } |
| } |
| } |
| |
| /** |
| * Prefetch all combining value state for {@code address} across all merging windows in {@code |
| * context}. |
| */ |
| public static <K, StateT extends GroupingState<?, ?>, W extends BoundedWindow> |
| void prefetchCombiningValues(MergingStateAccessor<K, W> context, StateTag<StateT> address) { |
| for (StateT state : context.accessInEachMergingWindow(address).values()) { |
| prefetchRead(state); |
| } |
| } |
| |
| /** Merge all value state in {@code address} across all merging windows in {@code context}. */ |
| public static <K, InputT, AccumT, OutputT, W extends BoundedWindow> void mergeCombiningValues( |
| MergingStateAccessor<K, W> context, |
| StateTag<CombiningState<InputT, AccumT, OutputT>> address) { |
| mergeCombiningValues( |
| context.accessInEachMergingWindow(address).values(), context.access(address)); |
| } |
| |
| /** |
| * Merge all value state from {@code sources} (which may include {@code result}) into {@code |
| * result}. |
| */ |
| public static <InputT, AccumT, OutputT, W extends BoundedWindow> void mergeCombiningValues( |
| Collection<CombiningState<InputT, AccumT, OutputT>> sources, |
| CombiningState<InputT, AccumT, OutputT> result) { |
| if (sources.isEmpty()) { |
| // Nothing to merge. |
| return; |
| } |
| if (sources.size() == 1 && sources.contains(result)) { |
| // Result already holds combined value. |
| return; |
| } |
| // Prefetch. |
| List<ReadableState<AccumT>> futures = new ArrayList<>(sources.size()); |
| for (CombiningState<InputT, AccumT, OutputT> source : sources) { |
| prefetchRead(source); |
| } |
| // Read. |
| List<AccumT> accumulators = new ArrayList<>(futures.size()); |
| for (CombiningState<InputT, AccumT, OutputT> source : sources) { |
| accumulators.add(source.getAccum()); |
| } |
| // Merge (possibly update and return one of the existing accumulators). |
| AccumT merged = result.mergeAccumulators(accumulators); |
| // Clear sources. |
| for (CombiningState<InputT, AccumT, OutputT> source : sources) { |
| source.clear(); |
| } |
| // Update result. |
| result.addAccum(merged); |
| } |
| |
| private static void prefetchRead(ReadableState<?> source) { |
| source.readLater(); |
| } |
| } |