/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.twitter.distributedlog;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import com.google.common.base.Preconditions;
import com.twitter.distributedlog.exceptions.InvalidEnvelopedEntryException;
import org.apache.bookkeeper.stats.Counter;
import org.apache.bookkeeper.stats.OpStatsLogger;
import org.apache.bookkeeper.stats.StatsLogger;
import com.twitter.distributedlog.annotations.DistributedLogAnnotations.Compression;
import com.twitter.distributedlog.io.CompressionCodec;
import com.twitter.distributedlog.io.CompressionUtils;
import com.twitter.distributedlog.util.BitMaskUtils;
/**
* An enveloped entry written to BookKeeper.
*
* Data type in brackets. Interpretation should be on the basis of data types and not individual
* bytes to honor Endianness.
*
* Entry Structure:
* ---------------
* Bytes 0 : Version (Byte)
* Bytes 1 - (DATA = 1+Header.length-1) : Header (Integer)
* Bytes DATA - DATA+3 : Payload Length (Integer)
* BYTES DATA+4 - DATA+4+payload.length-1 : Payload (Byte[])
*
* V1 Header Structure: // Offsets relative to the start of the header.
* -------------------
* Bytes 0 - 3 : Flags (Integer)
* Bytes 4 - 7 : Original payload size before compression (Integer)
*
* Flags: // 32 Bits
* -----
* 0 ... 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
* |_|
* |
* Compression Type
*
* Compression Type: // 2 Bits (Least significant)
* ----------------
* 00 : No Compression
* 01 : LZ4 Compression
* 10 : Unused
* 11 : Unused
*/
public class EnvelopedEntry {
public static final int VERSION_LENGTH = 1; // One byte long
public static final byte VERSION_ONE = 1;
public static final byte LOWEST_SUPPORTED_VERSION = VERSION_ONE;
public static final byte HIGHEST_SUPPORTED_VERSION = VERSION_ONE;
public static final byte CURRENT_VERSION = VERSION_ONE;
private final OpStatsLogger compressionStat;
private final OpStatsLogger decompressionStat;
private final Counter compressedEntryBytes;
private final Counter decompressedEntryBytes;
private final byte version;
private Header header = new Header();
private Payload payloadCompressed = new Payload();
private Payload payloadDecompressed = new Payload();
public EnvelopedEntry(byte version,
StatsLogger statsLogger) throws InvalidEnvelopedEntryException {
Preconditions.checkNotNull(statsLogger);
if (version < LOWEST_SUPPORTED_VERSION || version > HIGHEST_SUPPORTED_VERSION) {
throw new InvalidEnvelopedEntryException("Invalid enveloped entry version " + version + ", expected to be in [ "
+ LOWEST_SUPPORTED_VERSION + " ~ " + HIGHEST_SUPPORTED_VERSION + " ]");
}
this.version = version;
this.compressionStat = statsLogger.getOpStatsLogger("compression_time");
this.decompressionStat = statsLogger.getOpStatsLogger("decompression_time");
this.compressedEntryBytes = statsLogger.getCounter("compressed_bytes");
this.decompressedEntryBytes = statsLogger.getCounter("decompressed_bytes");
}
/**
* @param statsLogger
* Used for getting stats for (de)compression time
* @param compressionType
* The compression type to use
* @param decompressed
* The decompressed payload
* NOTE: The size of the byte array passed as the decompressed payload can be larger
* than the actual contents to be compressed.
*/
public EnvelopedEntry(byte version,
CompressionCodec.Type compressionType,
byte[] decompressed,
int length,
StatsLogger statsLogger)
throws InvalidEnvelopedEntryException {
this(version, statsLogger);
Preconditions.checkNotNull(compressionType);
Preconditions.checkNotNull(decompressed);
Preconditions.checkArgument(length >= 0, "Invalid bytes length " + length);
this.header = new Header(compressionType, length);
this.payloadDecompressed = new Payload(length, decompressed);
}
private boolean isReady() {
return (header.ready && payloadDecompressed.ready);
}
@Compression
public void writeFully(DataOutputStream out) throws IOException {
Preconditions.checkNotNull(out);
if (!isReady()) {
throw new IOException("Entry not writable");
}
// Version
out.writeByte(version);
// Header
header.write(out);
// Compress
CompressionCodec codec = CompressionUtils.getCompressionCodec(header.compressionType);
byte[] compressed = codec.compress(
payloadDecompressed.payload,
0,
payloadDecompressed.length,
compressionStat);
this.payloadCompressed = new Payload(compressed.length, compressed);
this.compressedEntryBytes.add(payloadCompressed.length);
this.decompressedEntryBytes.add(payloadDecompressed.length);
payloadCompressed.write(out);
}
@Compression
public void readFully(DataInputStream in) throws IOException {
Preconditions.checkNotNull(in);
// Make sure we're reading the right versioned entry.
byte version = in.readByte();
if (version != this.version) {
throw new IOException(String.format("Version mismatch while reading. Received: %d," +
" Required: %d", version, this.version));
}
header.read(in);
payloadCompressed.read(in);
// Decompress
CompressionCodec codec = CompressionUtils.getCompressionCodec(header.compressionType);
byte[] decompressed = codec.decompress(
payloadCompressed.payload,
0,
payloadCompressed.length,
header.decompressedSize,
decompressionStat);
this.payloadDecompressed = new Payload(decompressed.length, decompressed);
this.compressedEntryBytes.add(payloadCompressed.length);
this.decompressedEntryBytes.add(payloadDecompressed.length);
}
public byte[] getDecompressedPayload() throws IOException {
if (!isReady()) {
throw new IOException("Decompressed payload is not initialized");
}
return payloadDecompressed.payload;
}
public static class Header {
public static final int COMPRESSION_CODEC_MASK = 0x3;
public static final int COMPRESSION_CODEC_NONE = 0x0;
public static final int COMPRESSION_CODEC_LZ4 = 0x1;
private int flags = 0;
private int decompressedSize = 0;
private CompressionCodec.Type compressionType = CompressionCodec.Type.UNKNOWN;
// Whether this struct is ready for reading/writing.
private boolean ready = false;
// Used while reading.
public Header() {
}
public Header(CompressionCodec.Type compressionType,
int decompressedSize) {
this.compressionType = compressionType;
this.decompressedSize = decompressedSize;
this.flags = 0;
switch (compressionType) {
case NONE:
this.flags = (int) BitMaskUtils.set(flags, COMPRESSION_CODEC_MASK,
COMPRESSION_CODEC_NONE);
break;
case LZ4:
this.flags = (int) BitMaskUtils.set(flags, COMPRESSION_CODEC_MASK,
COMPRESSION_CODEC_LZ4);
break;
default:
throw new RuntimeException(String.format("Unknown Compression Type: %s",
compressionType));
}
// This can now be written.
this.ready = true;
}
private void write(DataOutputStream out) throws IOException {
out.writeInt(flags);
out.writeInt(decompressedSize);
}
private void read(DataInputStream in) throws IOException {
this.flags = in.readInt();
int compressionType = (int) BitMaskUtils.get(flags, COMPRESSION_CODEC_MASK);
if (compressionType == COMPRESSION_CODEC_NONE) {
this.compressionType = CompressionCodec.Type.NONE;
} else if (compressionType == COMPRESSION_CODEC_LZ4) {
this.compressionType = CompressionCodec.Type.LZ4;
} else {
throw new IOException(String.format("Unsupported Compression Type: %s",
compressionType));
}
this.decompressedSize = in.readInt();
// Values can now be read.
this.ready = true;
}
}
public static class Payload {
private int length = 0;
private byte[] payload = null;
// Whether this struct is ready for reading/writing.
private boolean ready = false;
// Used for reading
Payload() {
}
Payload(int length, byte[] payload) {
this.length = length;
this.payload = payload;
this.ready = true;
}
private void write(DataOutputStream out) throws IOException {
out.writeInt(length);
out.write(payload, 0, length);
}
private void read(DataInputStream in) throws IOException {
this.length = in.readInt();
this.payload = new byte[length];
in.readFully(payload);
this.ready = true;
}
}
/**
* Return an InputStream that reads from the provided InputStream, decompresses the data
* and returns a new InputStream wrapping the underlying payload.
*
* Note that src is modified by this call.
*
* @return
* New Input stream with the underlying payload.
* @throws Exception
*/
public static InputStream fromInputStream(InputStream src,
StatsLogger statsLogger) throws IOException {
src.mark(VERSION_LENGTH);
byte version = new DataInputStream(src).readByte();
src.reset();
EnvelopedEntry entry = new EnvelopedEntry(version, statsLogger);
entry.readFully(new DataInputStream(src));
return new ByteArrayInputStream(entry.getDecompressedPayload());
}
}