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// Copyright 2014 The Bazel Authors. 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.common.flogger.GoogleLogger;
import com.google.devtools.build.lib.bugreport.BugReport;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.events.ExtendedEventHandler;
/**
* An utility for custom reporting of errors from cycles in 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 {
private static final GoogleLogger logger = GoogleLogger.forEnclosingClass();
/**
* 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,
ExtendedEventHandler 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, ExtendedEventHandler eventHandler) {
Preconditions.checkNotNull(eventHandler, "topLevelKey: %s, Cycles %s", topLevelKey, cycles);
boolean suppressedCycles = false;
boolean firstCycle = true;
for (CycleInfo cycleInfo : cycles) {
// TODO(janakr): if this assertion is never hit, remove topLevelKey as an argument to method.
if (!cycleInfo.getTopKey().equals(topLevelKey)) {
BugReport.sendBugReport(
new IllegalStateException("Cycle " + cycleInfo + " did not start with " + topLevelKey));
}
suppressedCycles |= maybeReportCycle(cycleInfo, topLevelKey, firstCycle, eventHandler);
firstCycle = false;
}
if (suppressedCycles) {
logger.atInfo().log(
"Some cycles were omitted for %s because they were already reported", topLevelKey);
}
}
private boolean maybeReportCycle(
CycleInfo cycleInfo,
SkyKey topLevelKey,
boolean firstCycle,
ExtendedEventHandler eventHandler) {
boolean alreadyReported = cycleDeduper.alreadySeen(cycleInfo.getCycle());
if (!firstCycle && alreadyReported) {
// We've already reported this top-level key and this cycle, although maybe not together.
// Enumerating all combinations of top-level keys and cycles is too spammy for the user.
return false;
}
for (SingleCycleReporter cycleReporter : cycleReporters) {
if (cycleReporter.maybeReportCycle(topLevelKey, cycleInfo, alreadyReported, eventHandler)) {
return true;
}
}
// No proper cycle reporter could be found. Blaze bug! Not fatal, though.
String rawCycle = printArbitraryCycle(topLevelKey, cycleInfo, alreadyReported);
eventHandler.handle(
Event.error(
"Cycle detected but could not be properly displayed due to an internal problem. Please"
+ " file an issue. Raw display: "
+ rawCycle));
BugReport.sendBugReport(new IllegalStateException(rawCycle + "\n" + cycleReporters));
return true;
}
private static String printArbitraryCycle(
SkyKey topLevelKey, CycleInfo cycleInfo, boolean alreadyReported) {
StringBuilder cycleMessage =
new StringBuilder()
.append("topLevelKey: ")
.append(topLevelKey)
.append("\n")
.append("alreadyReported: ")
.append(alreadyReported)
.append("\n")
.append("path to cycle:\n");
for (SkyKey skyKey : cycleInfo.getPathToCycle()) {
cycleMessage.append(skyKey).append("\n");
}
cycleMessage.append("cycle:\n");
for (SkyKey skyKey : cycleInfo.getCycle()) {
cycleMessage.append(skyKey).append("\n");
}
return cycleMessage.toString();
}
}