/**
* 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 org.apache.hadoop.contrib.bkjournal;
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import org.apache.hadoop.hdfs.server.namenode.EditLogInputStream;
import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp;
import org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader;
import org.apache.bookkeeper.client.LedgerHandle;
import org.apache.bookkeeper.client.LedgerEntry;
import org.apache.bookkeeper.client.BKException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Input stream which reads from a BookKeeper ledger.
*/
class BookKeeperEditLogInputStream extends EditLogInputStream {
static final Log LOG = LogFactory.getLog(BookKeeperEditLogInputStream.class);
private final long firstTxId;
private final long lastTxId;
private final int logVersion;
private final boolean inProgress;
private final LedgerHandle lh;
private final FSEditLogOp.Reader reader;
private final FSEditLogLoader.PositionTrackingInputStream tracker;
/**
* Construct BookKeeper edit log input stream.
* Starts reading from the first entry of the ledger.
*/
BookKeeperEditLogInputStream(final LedgerHandle lh,
final EditLogLedgerMetadata metadata)
throws IOException {
this(lh, metadata, 0);
}
/**
* Construct BookKeeper edit log input stream.
* Starts reading from firstBookKeeperEntry. This allows the stream
* to take a shortcut during recovery, as it doesn't have to read
* every edit log transaction to find out what the last one is.
*/
BookKeeperEditLogInputStream(LedgerHandle lh, EditLogLedgerMetadata metadata,
long firstBookKeeperEntry)
throws IOException {
this.lh = lh;
this.firstTxId = metadata.getFirstTxId();
this.lastTxId = metadata.getLastTxId();
this.logVersion = metadata.getDataLayoutVersion();
this.inProgress = metadata.isInProgress();
if (firstBookKeeperEntry < 0
|| firstBookKeeperEntry > lh.getLastAddConfirmed()) {
throw new IOException("Invalid first bk entry to read: "
+ firstBookKeeperEntry + ", LAC: " + lh.getLastAddConfirmed());
}
BufferedInputStream bin = new BufferedInputStream(
new LedgerInputStream(lh, firstBookKeeperEntry));
tracker = new FSEditLogLoader.PositionTrackingInputStream(bin);
DataInputStream in = new DataInputStream(tracker);
reader = new FSEditLogOp.Reader(in, tracker, logVersion);
}
@Override
public long getFirstTxId() {
return firstTxId;
}
@Override
public long getLastTxId() {
return lastTxId;
}
@Override
public int getVersion() throws IOException {
return logVersion;
}
@Override
protected FSEditLogOp nextOp() throws IOException {
return reader.readOp(false);
}
@Override
public void close() throws IOException {
try {
lh.close();
} catch (BKException e) {
throw new IOException("Exception closing ledger", e);
} catch (InterruptedException e) {
throw new IOException("Interrupted closing ledger", e);
}
}
@Override
public long getPosition() {
return tracker.getPos();
}
@Override
public long length() throws IOException {
return lh.getLength();
}
@Override
public String getName() {
return String.format(
"BookKeeperLedger[ledgerId=%d,firstTxId=%d,lastTxId=%d]", lh.getId(),
firstTxId, lastTxId);
}
@Override
public boolean isInProgress() {
return inProgress;
}
/**
* Skip forward to specified transaction id.
* Currently we do this by just iterating forward.
* If this proves to be too expensive, this can be reimplemented
* with a binary search over bk entries
*/
public void skipTo(long txId) throws IOException {
long numToSkip = getFirstTxId() - txId;
FSEditLogOp op = null;
for (long i = 0; i < numToSkip; i++) {
op = readOp();
}
if (op != null && op.getTransactionId() != txId-1) {
throw new IOException("Corrupt stream, expected txid "
+ (txId-1) + ", got " + op.getTransactionId());
}
}
@Override
public String toString() {
return ("BookKeeperEditLogInputStream {" + this.getName() + "}");
}
@Override
public void setMaxOpSize(int maxOpSize) {
reader.setMaxOpSize(maxOpSize);
}
/**
* Input stream implementation which can be used by
* FSEditLogOp.Reader
*/
private static class LedgerInputStream extends InputStream {
private long readEntries;
private InputStream entryStream = null;
private final LedgerHandle lh;
private final long maxEntry;
/**
* Construct ledger input stream
* @param lh the ledger handle to read from
* @param firstBookKeeperEntry ledger entry to start reading from
*/
LedgerInputStream(LedgerHandle lh, long firstBookKeeperEntry)
throws IOException {
this.lh = lh;
readEntries = firstBookKeeperEntry;
maxEntry = lh.getLastAddConfirmed();
}
/**
* Get input stream representing next entry in the
* ledger.
* @return input stream, or null if no more entries
*/
private InputStream nextStream() throws IOException {
try {
if (readEntries > maxEntry) {
return null;
}
Enumeration<LedgerEntry> entries
= lh.readEntries(readEntries, readEntries);
readEntries++;
if (entries.hasMoreElements()) {
LedgerEntry e = entries.nextElement();
assert !entries.hasMoreElements();
return e.getEntryInputStream();
}
} catch (BKException e) {
throw new IOException("Error reading entries from bookkeeper", e);
} catch (InterruptedException e) {
throw new IOException("Interrupted reading entries from bookkeeper", e);
}
return null;
}
@Override
public int read() throws IOException {
byte[] b = new byte[1];
if (read(b, 0, 1) != 1) {
return -1;
} else {
return b[0];
}
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
try {
int read = 0;
if (entryStream == null) {
entryStream = nextStream();
if (entryStream == null) {
return read;
}
}
while (read < len) {
int thisread = entryStream.read(b, off+read, (len-read));
if (thisread == -1) {
entryStream = nextStream();
if (entryStream == null) {
return read;
}
} else {
read += thisread;
}
}
return read;
} catch (IOException e) {
throw e;
}
}
}
}