Java tutorial
// 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.lib.skyframe; import com.google.common.base.Preconditions; import com.google.common.collect.ImmutableList; import com.google.devtools.build.lib.vfs.RootedPath; import com.google.devtools.build.skyframe.SkyFunctionName; import com.google.devtools.build.skyframe.SkyKey; import com.google.devtools.build.skyframe.SkyValue; /** * A value for ensuring that a file symlink error is reported exactly once. This is achieved by * forcing the same value key for two logically equivalent errors and letting Skyframe do its * magic. */ class AbstractFileSymlinkExceptionUniquenessValue implements SkyValue { protected static SkyKey key(SkyFunctionName functionName, ImmutableList<RootedPath> chain) { Preconditions.checkState(!chain.isEmpty()); return new SkyKey(functionName, canonicalize(chain)); } private static ImmutableList<RootedPath> canonicalize(ImmutableList<RootedPath> cycle) { int minPos = 0; String minString = cycle.get(0).toString(); for (int i = 1; i < cycle.size(); i++) { String candidateString = cycle.get(i).toString(); if (candidateString.compareTo(minString) < 0) { minPos = i; minString = candidateString; } } ImmutableList.Builder<RootedPath> builder = ImmutableList.builder(); for (int i = 0; i < cycle.size(); i++) { int pos = (minPos + i) % cycle.size(); builder.add(cycle.get(pos)); } return builder.build(); } }