1 files changed, 109 insertions, 0 deletions
diff --git a/generator/src/main/java/com/google/archivepatcher/generator/bsdiff/RandomAccessObjectFactory.java b/generator/src/main/java/com/google/archivepatcher/generator/bsdiff/RandomAccessObjectFactory.java
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+++ b/generator/src/main/java/com/google/archivepatcher/generator/bsdiff/RandomAccessObjectFactory.java
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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.bsdiff;
+
+import com.google.archivepatcher.generator.bsdiff.RandomAccessObject.RandomAccessByteArrayObject;
+import com.google.archivepatcher.generator.bsdiff.RandomAccessObject.RandomAccessFileObject;
+import com.google.archivepatcher.generator.bsdiff.RandomAccessObject.RandomAccessMmapObject;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+
+/**
+ * A factory for creating instances of {@link RandomAccessObject}. BsDiff needs to store some
+ * ancillary data of size proportional to the binary to be patched. This allows abstraction of the
+ * allocation so that BsDiff can run either entirely in-memory (faster) or with file-backed swap
+ * (handles bigger inputs without consuming inordinate amounts of memory).
+ */
+public interface RandomAccessObjectFactory {
+  public RandomAccessObject create(int size) throws IOException;
+
+  /**
+   * A factory that produces {@link RandomAccessFileObject} instances backed by temp files.
+   */
+  // TODO(hartmanng): rethink the handling of these temp files. It's confusing and shouldn't
+  // really be the responsibility of RandomAccessObject.
+  public static final class RandomAccessFileObjectFactory implements RandomAccessObjectFactory {
+    private static final String FILE_NAME_PREFIX = "wavsprafof";
+    private final String mMode;
+
+    /**
+     * Factory for a RandomAccessFileObject.
+     * @param mode the file mode string ("r", "w", "rw", etc - see documentation for
+     * {@link RandomAccessFile})
+     */
+    public RandomAccessFileObjectFactory(String mode) {
+      mMode = mode;
+    }
+
+    /**
+     * Creates a temp file, and returns a {@link RandomAccessFile} wrapped in a
+     * {@link RandomAccessFileObject} representing the new temp file. The temp file does not need to
+     * explicitly be managed (deleted) by the caller, as long as the caller ensures
+     * {@link RandomAccessObject#close()} is called when the object is no longer needed.
+     */
+    // TODO(hartmanng): rethink the handling of these temp files. It's confusing and shouldn't
+    // really be the responsibility of RandomAccessObject.
+    @Override
+    public RandomAccessObject create(int size) throws IOException {
+      return new RandomAccessObject.RandomAccessFileObject(
+          File.createTempFile(FILE_NAME_PREFIX, "temp"), mMode, true);
+    }
+  }
+
+  /**
+   * A factory that produces {@link RandomAccessByteArrayObject} instances backed by memory.
+   */
+  public static final class RandomAccessByteArrayObjectFactory
+      implements RandomAccessObjectFactory {
+    @Override
+    public RandomAccessObject create(int size) {
+      return new RandomAccessObject.RandomAccessByteArrayObject(size);
+    }
+  }
+
+  /**
+   * A factory that produces {@link RandomAccessMmapObject} instances backed by temp files..
+   */
+  // TODO(hartmanng): rethink the handling of these temp files. It's confusing and shouldn't
+  // really be the responsibility of RandomAccessObject.
+  public static final class RandomAccessMmapObjectFactory implements RandomAccessObjectFactory {
+    private static final String FILE_NAME_PREFIX = "wavsprafof";
+    private String mMode;
+
+    /**
+     * Factory for a RandomAccessMmapObject.
+     * @param mode the file mode string ("r", "w", "rw", etc - see documentation for
+     * {@link RandomAccessFile})
+     */
+    public RandomAccessMmapObjectFactory(String mode) {
+      mMode = mode;
+    }
+
+    /**
+     * Creates a temp file, and returns a {@link RandomAccessFile} wrapped in a
+     * {@link RandomAccessMmapObject} representing the new temp file. The temp file does not need to
+     * explicitly be managed (deleted) by the caller, as long as the caller ensures
+     * {@link RandomAccessObject#close()} is called when the object is no longer needed.
+     */
+    // TODO(hartmanng): rethink the handling of these temp files. It's confusing and shouldn't
+    // really be the responsibility of RandomAccessObject.
+    @Override
+    public RandomAccessObject create(int size) throws IOException {
+      return new RandomAccessObject.RandomAccessMmapObject(FILE_NAME_PREFIX, mMode, size);
+    }
+  }
+}