Support reading all segments from a single ByteBuffer, with tests
Sometimes it is desirable to read all segments from a single ByteBuffer, e.g. if reading messages from a memory-mapped file. Here we add such support, and add a test to check that the ByteBuffer read behaves the same as the ReadableByteChannel read.
This commit is contained in:
Ben Challenor
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ba0c120c77
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2 changed files with 163 additions and 0 deletions
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@ -107,6 +107,46 @@ public final class Serialize {
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return new MessageReader(segmentSlices, options);
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return new MessageReader(segmentSlices, options);
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}
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}
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public static MessageReader read(ByteBuffer bb) throws IOException {
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return read(bb, ReaderOptions.DEFAULT_READER_OPTIONS);
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}
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public static MessageReader read(ByteBuffer bb, ReaderOptions options) throws IOException {
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bb.order(ByteOrder.LITTLE_ENDIAN);
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int segmentCount = 1 + bb.getInt();
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if (segmentCount > 512) {
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throw new IOException("too many segments");
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}
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ByteBuffer[] segmentSlices = new ByteBuffer[segmentCount];
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int segmentSizesBase = bb.position();
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int segmentSizesSize = segmentCount * 4;
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int align = Constants.BYTES_PER_WORD - 1;
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int segmentBase = (segmentSizesBase + segmentSizesSize + align) & ~align;
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int totalWords = 0;
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for (int ii = 0; ii < segmentCount; ++ii) {
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int segmentSize = bb.getInt(segmentSizesBase + ii * 4);
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bb.position(segmentBase + totalWords * Constants.BYTES_PER_WORD);
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segmentSlices[ii] = bb.slice();
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segmentSlices[ii].limit(segmentSize * Constants.BYTES_PER_WORD);
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segmentSlices[ii].order(ByteOrder.LITTLE_ENDIAN);
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totalWords += segmentSize;
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}
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if (totalWords > options.traversalLimitInWords) {
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throw new DecodeException("Message size exceeds traversal limit.");
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}
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return new MessageReader(segmentSlices, options);
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}
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public static void write(WritableByteChannel outputChannel,
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public static void write(WritableByteChannel outputChannel,
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MessageBuilder message) throws IOException {
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MessageBuilder message) throws IOException {
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ByteBuffer[] segments = message.getSegmentsForOutput();
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ByteBuffer[] segments = message.getSegmentsForOutput();
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123
runtime/src/test/scala/org/capnproto/SerializeSuite.scala
Normal file
123
runtime/src/test/scala/org/capnproto/SerializeSuite.scala
Normal file
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@ -0,0 +1,123 @@
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// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
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// Licensed under the MIT License:
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package org.capnproto
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import java.nio.ByteBuffer
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import org.scalatest.FunSuite
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import org.scalatest.Matchers._
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class SerializeSuite extends FunSuite {
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/**
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* @param exampleSegmentCount number of segments
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* @param exampleBytes byte array containing `segmentCount` segments; segment `i` contains `i` words each set to `i`
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*/
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def expectSerializesTo(exampleSegmentCount: Int, exampleBytes: Array[Byte]): Unit = {
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def checkSegmentContents(arena: ReaderArena): Unit = {
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arena.segments should have length exampleSegmentCount
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for (i <- 0 until exampleSegmentCount) {
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val segment = arena.segments.get(i)
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val segmentWords = segment.buffer.asLongBuffer()
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segmentWords.capacity should equal (i)
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segmentWords.rewind()
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while (segmentWords.hasRemaining) {
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segmentWords.get should equal (i)
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}
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}
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}
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// ----
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// read via ReadableByteChannel
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{
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val messageReader = Serialize.read(new ArrayInputStream(ByteBuffer.wrap(exampleBytes)))
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checkSegmentContents(messageReader.arena)
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}
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// ------
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// read via ByteBuffer
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{
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val messageReader = Serialize.read(ByteBuffer.wrap(exampleBytes))
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checkSegmentContents(messageReader.arena)
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}
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}
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test("SegmentReading") {
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// When transmitting over a stream, the following should be sent. All integers are unsigned and little-endian.
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// - (4 bytes) The number of segments, minus one (since there is always at least one segment).
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// - (N * 4 bytes) The size of each segment, in words.
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// - (0 or 4 bytes) Padding up to the next word boundary.
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// - The content of each segment, in order.
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expectSerializesTo(1, Array[Byte](
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0, 0, 0, 0, // 1 segment
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0, 0, 0, 0 // Segment 0 contains 0 bytes
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// No padding
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// Segment 0 (empty)
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))
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expectSerializesTo(2, Array[Byte](
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1, 0, 0, 0, // 2 segments
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0, 0, 0, 0, // Segment 0 contains 0 words
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1, 0, 0, 0, // Segment 1 contains 1 words
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// Padding
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0, 0, 0, 0,
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// Segment 0 (empty)
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// Segment 1
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1, 0, 0, 0, 0, 0, 0, 0
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))
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expectSerializesTo(3, Array[Byte](
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2, 0, 0, 0, // 3 segments
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0, 0, 0, 0, // Segment 0 contains 0 words
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1, 0, 0, 0, // Segment 1 contains 1 words
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2, 0, 0, 0, // Segment 2 contains 2 words
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// No padding
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// Segment 0 (empty)
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// Segment 1
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1, 0, 0, 0, 0, 0, 0, 0,
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// Segment 2
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2, 0, 0, 0, 0, 0, 0, 0,
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2, 0, 0, 0, 0, 0, 0, 0
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))
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expectSerializesTo(4, Array[Byte](
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3, 0, 0, 0, // 4 segments
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0, 0, 0, 0, // Segment 0 contains 0 words
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1, 0, 0, 0, // Segment 1 contains 1 words
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2, 0, 0, 0, // Segment 2 contains 2 words
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3, 0, 0, 0, // Segment 3 contains 3 words
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// Padding
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0, 0, 0, 0,
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// Segment 0 (empty)
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// Segment 1
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1, 0, 0, 0, 0, 0, 0, 0,
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// Segment 2
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2, 0, 0, 0, 0, 0, 0, 0,
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2, 0, 0, 0, 0, 0, 0, 0,
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// Segment 3
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3, 0, 0, 0, 0, 0, 0, 0,
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3, 0, 0, 0, 0, 0, 0, 0,
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3, 0, 0, 0, 0, 0, 0, 0
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))
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}
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}
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