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/**
* 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.streaming.mapreduce;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.io.DataOutputBuffer;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;
import org.apache.hadoop.streaming.StreamUtil;
/**
* A way to interpret XML fragments as Mapper input records. Values are XML
* subtrees delimited by configurable tags. Keys could be the value of a certain
* attribute in the XML subtree, but this is left to the stream processor
* application.
*
* The name-value properties that StreamXmlRecordReader understands are: String
* begin (chars marking beginning of record) String end (chars marking end of
* record) int maxrec (maximum record size) int lookahead(maximum lookahead to
* sync CDATA) boolean slowmatch
*/
public class StreamXmlRecordReader extends StreamBaseRecordReader {
private Text key;
private Text value;
public StreamXmlRecordReader(FSDataInputStream in, FileSplit split,
TaskAttemptContext context, Configuration conf, FileSystem fs)
throws IOException {
super(in, split, context, conf, fs);
beginMark_ = checkJobGet(CONF_NS + "begin");
endMark_ = checkJobGet(CONF_NS + "end");
maxRecSize_ = conf_.getInt(CONF_NS + "maxrec", 50 * 1000);
lookAhead_ = conf_.getInt(CONF_NS + "lookahead", 2 * maxRecSize_);
synched_ = false;
slowMatch_ = conf_.getBoolean(CONF_NS + "slowmatch", false);
if (slowMatch_) {
beginPat_ = makePatternCDataOrMark(beginMark_);
endPat_ = makePatternCDataOrMark(endMark_);
}
init();
}
public final void init() throws IOException {
LOG.info("StreamBaseRecordReader.init: " + " start_=" + start_ + " end_="
+ end_ + " length_=" + length_ + " start_ > in_.getPos() ="
+ (start_ > in_.getPos()) + " " + start_ + " > " + in_.getPos());
if (start_ > in_.getPos()) {
in_.seek(start_);
}
pos_ = start_;
bin_ = new BufferedInputStream(in_);
seekNextRecordBoundary();
}
int numNext = 0;
public synchronized boolean next(Text key, Text value) throws IOException {
numNext++;
if (pos_ >= end_) {
return false;
}
DataOutputBuffer buf = new DataOutputBuffer();
if (!readUntilMatchBegin()) {
return false;
}
if (pos_ >= end_ || !readUntilMatchEnd(buf)) {
return false;
}
// There is only one elem..key/value splitting is not done here.
byte[] record = new byte[buf.getLength()];
System.arraycopy(buf.getData(), 0, record, 0, record.length);
numRecStats(record, 0, record.length);
key.set(record);
value.set("");
return true;
}
public void seekNextRecordBoundary() throws IOException {
readUntilMatchBegin();
}
boolean readUntilMatchBegin() throws IOException {
if (slowMatch_) {
return slowReadUntilMatch(beginPat_, false, null);
} else {
return fastReadUntilMatch(beginMark_, false, null);
}
}
private boolean readUntilMatchEnd(DataOutputBuffer buf) throws IOException {
if (slowMatch_) {
return slowReadUntilMatch(endPat_, true, buf);
} else {
return fastReadUntilMatch(endMark_, true, buf);
}
}
private boolean slowReadUntilMatch(Pattern markPattern, boolean includePat,
DataOutputBuffer outBufOrNull) throws IOException {
byte[] buf = new byte[Math.max(lookAhead_, maxRecSize_)];
int read = 0;
bin_.mark(Math.max(lookAhead_, maxRecSize_) + 2); // mark to invalidate if
// we read more
read = bin_.read(buf);
if (read == -1)
return false;
String sbuf = new String(buf, 0, read, "UTF-8");
Matcher match = markPattern.matcher(sbuf);
firstMatchStart_ = NA;
firstMatchEnd_ = NA;
int bufPos = 0;
int state = synched_ ? CDATA_OUT : CDATA_UNK;
int s = 0;
while (match.find(bufPos)) {
int input;
if (match.group(1) != null) {
input = CDATA_BEGIN;
} else if (match.group(2) != null) {
input = CDATA_END;
firstMatchStart_ = NA; // | ]]> should keep it
} else {
input = RECORD_MAYBE;
}
if (input == RECORD_MAYBE) {
if (firstMatchStart_ == NA) {
firstMatchStart_ = match.start();
firstMatchEnd_ = match.end();
}
}
state = nextState(state, input, match.start());
if (state == RECORD_ACCEPT) {
break;
}
bufPos = match.end();
s++;
}
if (state != CDATA_UNK) {
synched_ = true;
}
boolean matched = (firstMatchStart_ != NA)
&& (state == RECORD_ACCEPT || state == CDATA_UNK);
if (matched) {
int endPos = includePat ? firstMatchEnd_ : firstMatchStart_;
bin_.reset();
for (long skiplen = endPos; skiplen > 0;) {
skiplen -= bin_.skip(skiplen); // Skip succeeds as we have read this
// buffer
}
pos_ += endPos;
if (outBufOrNull != null) {
outBufOrNull.writeBytes(sbuf.substring(0, endPos));
}
}
return matched;
}
// states
private final static int CDATA_IN = 10;
private final static int CDATA_OUT = 11;
private final static int CDATA_UNK = 12;
private final static int RECORD_ACCEPT = 13;
// inputs
private final static int CDATA_BEGIN = 20;
private final static int CDATA_END = 21;
private final static int RECORD_MAYBE = 22;
/* also updates firstMatchStart_; */
int nextState(int state, int input, int bufPos) {
switch (state) {
case CDATA_UNK:
case CDATA_OUT:
switch (input) {
case CDATA_BEGIN:
return CDATA_IN;
case CDATA_END:
if (state == CDATA_OUT) {
// System.out.println("buggy XML " + bufPos);
}
return CDATA_OUT;
case RECORD_MAYBE:
return (state == CDATA_UNK) ? CDATA_UNK : RECORD_ACCEPT;
}
break;
case CDATA_IN:
return (input == CDATA_END) ? CDATA_OUT : CDATA_IN;
}
throw new IllegalStateException(state + " " + input + " " + bufPos + " "
+ splitName_);
}
Pattern makePatternCDataOrMark(String escapedMark) {
StringBuffer pat = new StringBuffer();
addGroup(pat, StreamUtil.regexpEscape("CDATA[")); // CDATA_BEGIN
addGroup(pat, StreamUtil.regexpEscape("]]>")); // CDATA_END
addGroup(pat, escapedMark); // RECORD_MAYBE
return Pattern.compile(pat.toString());
}
void addGroup(StringBuffer pat, String escapedGroup) {
if (pat.length() > 0) {
pat.append("|");
}
pat.append("(");
pat.append(escapedGroup);
pat.append(")");
}
boolean fastReadUntilMatch(String textPat, boolean includePat,
DataOutputBuffer outBufOrNull) throws IOException {
byte[] cpat = textPat.getBytes("UTF-8");
int m = 0;
boolean match = false;
int msup = cpat.length;
int LL = 120000 * 10;
bin_.mark(LL); // large number to invalidate mark
while (true) {
int b = bin_.read();
if (b == -1)
break;
byte c = (byte) b; // this assumes eight-bit matching. OK with UTF-8
if (c == cpat[m]) {
m++;
if (m == msup) {
match = true;
break;
}
} else {
bin_.mark(LL); // rest mark so we could jump back if we found a match
if (outBufOrNull != null) {
outBufOrNull.write(cpat, 0, m);
outBufOrNull.write(c);
}
pos_ += m + 1; // skip m chars, +1 for 'c'
m = 0;
}
}
if (!includePat && match) {
bin_.reset();
} else if (outBufOrNull != null) {
outBufOrNull.write(cpat);
pos_ += msup;
}
return match;
}
String checkJobGet(String prop) throws IOException {
String val = conf_.get(prop);
if (val == null) {
throw new IOException("JobConf: missing required property: " + prop);
}
return val;
}
String beginMark_;
String endMark_;
Pattern beginPat_;
Pattern endPat_;
boolean slowMatch_;
int lookAhead_; // bytes to read to try to synch CDATA/non-CDATA. Should be
// more than max record size
int maxRecSize_;
BufferedInputStream bin_; // Wrap FSDataInputStream for efficient backward
// seeks
long pos_; // Keep track on position with respect encapsulated
// FSDataInputStream
private final static int NA = -1;
int firstMatchStart_ = 0; // candidate record boundary. Might just be CDATA.
int firstMatchEnd_ = 0;
boolean synched_;
@Override
public Text getCurrentKey() throws IOException, InterruptedException {
return key;
}
@Override
public Text getCurrentValue() throws IOException, InterruptedException {
return value;
}
@Override
public void initialize(InputSplit arg0, TaskAttemptContext arg1)
throws IOException, InterruptedException {
}
@Override
public boolean nextKeyValue() throws IOException, InterruptedException {
key = createKey();
value = createValue();
return next(key, value);
}
}
