com.google.idea.blaze.base.filecache.FileDiffer.java Source code

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Here is the source code for com.google.idea.blaze.base.filecache.FileDiffer.java

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/*
 * Copyright 2016 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.idea.blaze.base.filecache;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Sets;
import com.google.idea.blaze.base.io.ModifiedTimeScanner;
import com.intellij.openapi.diagnostic.Logger;
import java.io.File;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.jetbrains.annotations.Nullable;

/** Provides a diffing service for a collection of files. */
public final class FileDiffer {
    private static Logger LOG = Logger.getInstance(FileDiffer.class);

    private FileDiffer() {
    }

    @Nullable
    public static ImmutableMap<File, Long> updateFiles(@Nullable ImmutableMap<File, Long> oldState,
            Iterable<File> files, List<File> updatedFiles, List<File> removedFiles) {
        ImmutableMap<File, Long> newState = readFileState(files);
        if (newState == null) {
            return null;
        }
        diffState(oldState, newState, updatedFiles, removedFiles);
        return newState;
    }

    @Nullable
    public static ImmutableMap<File, Long> readFileState(Iterable<File> files) {
        try {
            return ModifiedTimeScanner.readTimestamps(files);
        } catch (Exception e) {
            LOG.error(e);
            return null;
        }
    }

    public static <K, V> void diffState(@Nullable Map<K, V> oldState, Map<K, V> newState, List<K> updated,
            List<K> removed) {
        oldState = oldState != null ? oldState : ImmutableMap.of();

        // Find changed/new
        for (Map.Entry<K, V> entry : newState.entrySet()) {
            K key = entry.getKey();
            V value = entry.getValue();
            V oldValue = oldState.get(key);

            final boolean isUpdated = oldValue == null || !value.equals(oldValue);
            if (isUpdated) {
                updated.add(key);
            }
        }

        // Find removed
        Set<K> removedSet = Sets.newHashSet();
        removedSet.addAll(oldState.keySet());
        removedSet.removeAll(newState.keySet());
        removed.addAll(removedSet);
    }
}