Improve efficiency of using the DataSource abstraction.
This adds getByteBuffer and copyTo methods to the DataSource
abstraction. These methods enable the client to avoid unnecessary
copying of the data source's data.
Bug: 27461702
Change-Id: If4e9f902ea75c1ca5c7be0e20c0e7218faf9c504
diff --git a/tools/apksigner/core/src/com/android/apksigner/core/internal/apk/v2/V2SchemeSigner.java b/tools/apksigner/core/src/com/android/apksigner/core/internal/apk/v2/V2SchemeSigner.java
index e185346..103a0ec 100644
--- a/tools/apksigner/core/src/com/android/apksigner/core/internal/apk/v2/V2SchemeSigner.java
+++ b/tools/apksigner/core/src/com/android/apksigner/core/internal/apk/v2/V2SchemeSigner.java
@@ -16,7 +16,6 @@
package com.android.apksigner.core.internal.apk.v2;
-import com.android.apksigner.core.internal.util.ByteBufferSink;
import com.android.apksigner.core.internal.util.Pair;
import com.android.apksigner.core.internal.zip.ZipUtils;
import com.android.apksigner.core.util.DataSource;
@@ -191,8 +190,10 @@
// offset field is treated as pointing to the offset at which the APK Signing Block will
// start.
long centralDirOffsetForDigesting = beforeCentralDir.size();
- ByteBuffer eocdBuf = copyToByteBuffer(eocd);
+ ByteBuffer eocdBuf = ByteBuffer.allocate((int) eocd.size());
eocdBuf.order(ByteOrder.LITTLE_ENDIAN);
+ eocd.copyTo(0, (int) eocd.size(), eocdBuf);
+ eocdBuf.flip();
ZipUtils.setZipEocdCentralDirectoryOffset(eocdBuf, centralDirOffsetForDigesting);
// Compute digests of APK contents.
@@ -600,15 +601,4 @@
}
return result.array();
}
-
- private static ByteBuffer copyToByteBuffer(DataSource dataSource) throws IOException {
- long dataSourceSize = dataSource.size();
- if (dataSourceSize > Integer.MAX_VALUE) {
- throw new IllegalArgumentException("Data source too large: " + dataSourceSize);
- }
- ByteBuffer result = ByteBuffer.allocate((int) dataSourceSize);
- dataSource.feed(0, result.remaining(), new ByteBufferSink(result));
- result.position(0);
- return result;
- }
}
diff --git a/tools/apksigner/core/src/com/android/apksigner/core/internal/util/ByteBufferDataSource.java b/tools/apksigner/core/src/com/android/apksigner/core/internal/util/ByteBufferDataSource.java
index f12f02e..b2d9ca1 100644
--- a/tools/apksigner/core/src/com/android/apksigner/core/internal/util/ByteBufferDataSource.java
+++ b/tools/apksigner/core/src/com/android/apksigner/core/internal/util/ByteBufferDataSource.java
@@ -35,7 +35,15 @@
* buffer between the buffer's position and limit.
*/
public ByteBufferDataSource(ByteBuffer buffer) {
- mBuffer = buffer.slice();
+ this(buffer, true);
+ }
+
+ /**
+ * Constructs a new {@code ByteBufferDigestSource} based on the data contained in the provided
+ * buffer between the buffer's position and limit.
+ */
+ private ByteBufferDataSource(ByteBuffer buffer, boolean sliceRequired) {
+ mBuffer = (sliceRequired) ? buffer.slice() : buffer;
mSize = buffer.remaining();
}
@@ -45,15 +53,12 @@
}
@Override
- public ByteBufferDataSource slice(long offset, long size) {
- if ((offset == 0) && (size == mSize)) {
- return this;
- }
+ public ByteBuffer getByteBuffer(long offset, int size) {
checkChunkValid(offset, size);
- // checkChunkValid ensures that it's OK to cast offset and size to int.
+ // checkChunkValid ensures that it's OK to cast offset to int.
int chunkPosition = (int) offset;
- int chunkLimit = (int) (chunkPosition + size);
+ int chunkLimit = chunkPosition + size;
// Creating a slice of ByteBuffer modifies the state of the source ByteBuffer (position
// and limit fields, to be more specific). We thus use synchronization around these
// state-changing operations to make instances of this class thread-safe.
@@ -66,35 +71,35 @@
mBuffer.limit(chunkLimit);
mBuffer.position(chunkPosition);
- // Create a ByteBufferDataSource for the slice of the buffer between limit and position.
- return new ByteBufferDataSource(mBuffer);
+ return mBuffer.slice();
}
}
@Override
+ public void copyTo(long offset, int size, ByteBuffer dest) {
+ dest.put(getByteBuffer(offset, size));
+ }
+
+ @Override
public void feed(long offset, long size, DataSink sink) throws IOException {
- checkChunkValid(offset, size);
-
- // checkChunkValid ensures that it's OK to cast offset and size to int.
- int chunkPosition = (int) offset;
- int chunkLimit = (int) (chunkPosition + size);
- ByteBuffer chunk;
- // Creating a slice of ByteBuffer modifies the state of the source ByteBuffer (position
- // and limit fields, to be more specific). We thus use synchronization around these
- // state-changing operations to make instances of this class thread-safe.
- synchronized (mBuffer) {
- // ByteBuffer.limit(int) and .position(int) check that that the position >= limit
- // invariant is not broken. Thus, the only way to safely change position and limit
- // without caring about their current values is to first set position to 0 or set the
- // limit to capacity.
- mBuffer.position(0);
-
- mBuffer.limit(chunkLimit);
- mBuffer.position(chunkPosition);
- chunk = mBuffer.slice();
+ if ((size < 0) || (size > mSize)) {
+ throw new IllegalArgumentException("size: " + size + ", source size: " + mSize);
}
+ sink.consume(getByteBuffer(offset, (int) size));
+ }
- sink.consume(chunk);
+ @Override
+ public ByteBufferDataSource slice(long offset, long size) {
+ if ((offset == 0) && (size == mSize)) {
+ return this;
+ }
+ if ((size < 0) || (size > mSize)) {
+ throw new IllegalArgumentException("size: " + size + ", source size: " + mSize);
+ }
+ return new ByteBufferDataSource(
+ getByteBuffer(offset, (int) size),
+ false // no need to slice -- it's already a slice
+ );
}
private void checkChunkValid(long offset, long size) {
diff --git a/tools/apksigner/core/src/com/android/apksigner/core/util/DataSource.java b/tools/apksigner/core/src/com/android/apksigner/core/util/DataSource.java
index 27ff7a8..e268dd2 100644
--- a/tools/apksigner/core/src/com/android/apksigner/core/util/DataSource.java
+++ b/tools/apksigner/core/src/com/android/apksigner/core/util/DataSource.java
@@ -17,6 +17,7 @@
package com.android.apksigner.core.util;
import java.io.IOException;
+import java.nio.ByteBuffer;
/**
* Abstract representation of a source of data.
@@ -29,6 +30,25 @@
* may have worked as the unifying abstraction.</li>
* <li>Support sources which do not fit into logical memory as a contiguous region.</li>
* </ul>
+ *
+ * <p>There are following ways to obtain a chunk of data from the data source:
+ * <ul>
+ * <li>Stream the chunk's data into a {@link DataSink} using
+ * {@link #feed(long, long, DataSink) feed}. This is best suited for scenarios where there is no
+ * need to have the chunk's data accessible at the same time, for example, when computing the
+ * digest of the chunk. If you need to keep the chunk's data around after {@code feed}
+ * completes, you must create a copy during {@code feed}. However, in that case the following
+ * methods of obtaining the chunk's data may be more appropriate.</li>
+ * <li>Obtain a {@link ByteBuffer} containing the chunk's data using
+ * {@link #getByteBuffer(long, int) getByteBuffer}. Depending on the data source, the chunk's
+ * data may or may not be copied by this operation. This is best suited for scenarios where
+ * you need to access the chunk's data in arbitrary order, but don't need to modify the data and
+ * thus don't require a copy of the data.</li>
+ * <li>Copy the chunk's data to a {@link ByteBuffer} using
+ * {@link #copyTo(long, int, ByteBuffer) copyTo}. This is best suited for scenarios where
+ * you require a copy of the chunk's data, such as to when you need to modify the data.
+ * </li>
+ * </ul>
*/
public interface DataSource {
@@ -46,8 +66,33 @@
void feed(long offset, long size, DataSink sink) throws IOException;
/**
+ * Returns a buffer holding the contents of the specified chunk of data from this data source.
+ * Changes to the data source are not guaranteed to be reflected in the returned buffer.
+ * Similarly, changes in the buffer are not guaranteed to be reflected in the data source.
+ *
+ * <p>The returned buffer's position is {@code 0}, and the buffer's limit and capacity is
+ * {@code size}.
+ *
+ * @param offset index (in bytes) at which the chunk starts inside data source
+ * @param size size (in bytes) of the chunk
+ */
+ ByteBuffer getByteBuffer(long offset, int size) throws IOException;
+
+ /**
+ * Copies the specified chunk from this data source into the provided destination buffer,
+ * advancing the destination buffer's position by {@code size}.
+ *
+ * @param offset index (in bytes) at which the chunk starts inside data source
+ * @param size size (in bytes) of the chunk
+ */
+ void copyTo(long offset, int size, ByteBuffer dest) throws IOException;
+
+ /**
* Returns a data source representing the specified region of data of this data source. Changes
* to data represented by this data source will also be visible in the returned data source.
+ *
+ * @param offset index (in bytes) at which the region starts inside data source
+ * @param size size (in bytes) of the region
*/
DataSource slice(long offset, long size);
}
