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// Copyright 2016 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.archivepatcher.generator;
import com.google.archivepatcher.generator.bsdiff.BsDiffDeltaGenerator;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
/**
* Generates file-by-file patches.
*/
public class FileByFileV1DeltaGenerator implements DeltaGenerator {
/** Optional modifiers for planning and patch generation. */
private final List<RecommendationModifier> recommendationModifiers;
/**
* Constructs a new generator for File-by-File v1 patches, using the specified configuration.
*
* @param recommendationModifiers optionally, {@link RecommendationModifier}s to use for modifying
* the planning phase of patch generation. These can be used to, e.g., limit the total amount
* of recompression that a patch applier needs to do. Modifiers are applied in the order they
* are specified.
*/
public FileByFileV1DeltaGenerator(RecommendationModifier... recommendationModifiers) {
if (recommendationModifiers != null) {
this.recommendationModifiers =
Collections.unmodifiableList(Arrays.asList(recommendationModifiers));
} else {
this.recommendationModifiers = Collections.emptyList();
}
}
/**
* Generate a V1 patch for the specified input files and write the patch to the specified {@link
* OutputStream}. The written patch is <em>raw</em>, i.e. it has not been compressed. Compression
* should almost always be applied to the patch, either right in the specified {@link
* OutputStream} or in a post-processing step, prior to transmitting the patch to the patch
* applier.
*
* @param oldFile the original old file to read (will not be modified)
* @param newFile the original new file to read (will not be modified)
* @param patchOut the stream to write the patch to
* @throws IOException if unable to complete the operation due to an I/O error
* @throws InterruptedException if any thread has interrupted the current thread
*/
@Override
public void generateDelta(File oldFile, File newFile, OutputStream patchOut)
throws IOException, InterruptedException {
try (TempFileHolder deltaFriendlyOldFile = new TempFileHolder();
TempFileHolder deltaFriendlyNewFile = new TempFileHolder();
TempFileHolder deltaFile = new TempFileHolder();
FileOutputStream deltaFileOut = new FileOutputStream(deltaFile.file);
BufferedOutputStream bufferedDeltaOut = new BufferedOutputStream(deltaFileOut)) {
PreDiffExecutor.Builder builder =
new PreDiffExecutor.Builder()
.readingOriginalFiles(oldFile, newFile)
.writingDeltaFriendlyFiles(deltaFriendlyOldFile.file, deltaFriendlyNewFile.file);
for (RecommendationModifier modifier : recommendationModifiers) {
builder.withRecommendationModifier(modifier);
}
PreDiffExecutor executor = builder.build();
PreDiffPlan preDiffPlan = executor.prepareForDiffing();
DeltaGenerator deltaGenerator = getDeltaGenerator();
deltaGenerator.generateDelta(
deltaFriendlyOldFile.file, deltaFriendlyNewFile.file, bufferedDeltaOut);
bufferedDeltaOut.close();
PatchWriter patchWriter =
new PatchWriter(
preDiffPlan,
deltaFriendlyOldFile.file.length(),
deltaFriendlyNewFile.file.length(),
deltaFile.file);
patchWriter.writeV1Patch(patchOut);
}
}
/**
* Generate a V1 patch pre diffing plan.
*
* @param oldFile the original old file to read (will not be modified)
* @param newFile the original new file to read (will not be modified)
* @return the plan
* @throws IOException if unable to complete the operation due to an I/O error
* @throws InterruptedException if any thread has interrupted the current thread
*/
public PreDiffPlan generatePreDiffPlan(File oldFile, File newFile)
throws IOException, InterruptedException {
try (TempFileHolder deltaFriendlyOldFile = new TempFileHolder();
TempFileHolder deltaFriendlyNewFile = new TempFileHolder()) {
PreDiffExecutor.Builder builder =
new PreDiffExecutor.Builder()
.readingOriginalFiles(oldFile, newFile)
.writingDeltaFriendlyFiles(deltaFriendlyOldFile.file, deltaFriendlyNewFile.file);
for (RecommendationModifier modifier : recommendationModifiers) {
builder.withRecommendationModifier(modifier);
}
PreDiffExecutor executor = builder.build();
return executor.prepareForDiffing();
}
}
// Visible for testing only
protected DeltaGenerator getDeltaGenerator() {
return new BsDiffDeltaGenerator();
}
}
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