| // Copyright 2014 Google Inc. All rights reserved. |
| // |
| // Licensed 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 com.google.devtools.build.skyframe; |
| |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.ImmutableList; |
| import com.google.devtools.build.lib.events.EventHandler; |
| |
| /** |
| * An utility for custom reporting of errors from cycles in the the Skyframe graph. This class is |
| * stateful in order to differentiate between new cycles and cycles that have already been |
| * reported (do not reuse the instances or cache the results as it could end up printing |
| * inconsistent information or leak memory). It treats two cycles as the same if they contain the |
| * same {@link SkyKey}s in the same order, but perhaps with different starting points. See |
| * {@link CycleDeduper} for more information. |
| */ |
| public class CyclesReporter { |
| |
| /** |
| * Interface for reporting custom information about a single cycle. |
| */ |
| public interface SingleCycleReporter { |
| |
| /** |
| * Reports the given cycle and returns {@code true}, or return {@code false} if this |
| * {@link SingleCycleReporter} doesn't know how to report the cycle. |
| * |
| * @param topLevelKey the top level key that transitively depended on the cycle |
| * @param cycleInfo the cycle |
| * @param alreadyReported whether the cycle has already been reported to the |
| * {@link CyclesReporter}. |
| * @param eventHandler the eventHandler to which to report the error |
| */ |
| boolean maybeReportCycle(SkyKey topLevelKey, CycleInfo cycleInfo, boolean alreadyReported, |
| EventHandler eventHandler); |
| } |
| |
| private final ImmutableList<SingleCycleReporter> cycleReporters; |
| private final CycleDeduper<SkyKey> cycleDeduper = new CycleDeduper<>(); |
| |
| /** |
| * Constructs a {@link CyclesReporter} that delegates to the given {@link SingleCycleReporter}s, |
| * in the given order, to report custom information about cycles. |
| */ |
| public CyclesReporter(SingleCycleReporter... cycleReporters) { |
| this.cycleReporters = ImmutableList.copyOf(cycleReporters); |
| } |
| |
| /** |
| * Reports the given cycles, differentiating between cycles that have already been reported. |
| * |
| * @param cycles The {@code Iterable} of cycles. |
| * @param topLevelKey This key represents the top level value key that returned cycle errors. |
| * @param eventHandler the eventHandler to which to report the error |
| */ |
| public void reportCycles(Iterable<CycleInfo> cycles, SkyKey topLevelKey, |
| EventHandler eventHandler) { |
| Preconditions.checkNotNull(eventHandler); |
| for (CycleInfo cycleInfo : cycles) { |
| boolean alreadyReported = false; |
| if (!cycleDeduper.seen(cycleInfo.getCycle())) { |
| alreadyReported = true; |
| } |
| boolean successfullyReported = false; |
| for (SingleCycleReporter cycleReporter : cycleReporters) { |
| if (cycleReporter.maybeReportCycle(topLevelKey, cycleInfo, alreadyReported, eventHandler)) { |
| successfullyReported = true; |
| break; |
| } |
| } |
| Preconditions.checkState(successfullyReported, |
| printArbitraryCycle(topLevelKey, cycleInfo, alreadyReported)); |
| } |
| } |
| |
| private String printArbitraryCycle(SkyKey topLevelKey, CycleInfo cycleInfo, |
| boolean alreadyReported) { |
| StringBuilder cycleMessage = new StringBuilder() |
| .append("topLevelKey: " + topLevelKey + "\n") |
| .append("alreadyReported: " + alreadyReported + "\n") |
| .append("path to cycle:\n"); |
| for (SkyKey skyKey : cycleInfo.getPathToCycle()) { |
| cycleMessage.append(skyKey + "\n"); |
| } |
| cycleMessage.append("cycle:\n"); |
| for (SkyKey skyKey : cycleInfo.getCycle()) { |
| cycleMessage.append(skyKey + "\n"); |
| } |
| return cycleMessage.toString(); |
| } |
| } |