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MarkLogic Connector for Hadoop MapReduce
/*
* Copyright 2003-2017 MarkLogic Corporation
*
* Licensed 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.marklogic.mapreduce;
import java.io.IOException;
import java.math.BigInteger;
import java.util.List;
import java.util.Collection;
import java.util.Iterator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.util.ReflectionUtils;
import com.marklogic.mapreduce.functions.LexiconFunction;
import com.marklogic.mapreduce.utilities.InternalUtilities;
import com.marklogic.mapreduce.utilities.ForestHost;
import com.marklogic.xcc.AdhocQuery;
import com.marklogic.xcc.ContentSource;
import com.marklogic.xcc.RequestOptions;
import com.marklogic.xcc.ResultItem;
import com.marklogic.xcc.ResultSequence;
import com.marklogic.xcc.Session;
import com.marklogic.xcc.exceptions.QueryException;
import com.marklogic.xcc.exceptions.RequestException;
import com.marklogic.xcc.exceptions.XccConfigException;
/**
* A RecordReader that fetches data from MarkLogic server and generates
* key value pairs.
*
* @author jchen
*
* @param
*/
public abstract class MarkLogicRecordReader
extends RecordReader
implements MarkLogicConstants {
public static final Log LOG =
LogFactory.getLog(MarkLogicRecordReader.class);
/**
* Input split for this record reader
*/
protected MarkLogicInputSplit mlSplit;
/**
* Count of records fetched
*/
protected long count;
/**
* Session to the MarkLogic server.
*/
protected Session session;
/**
* ResultSequence from the MarkLogic server.
*/
protected ResultSequence result;
/**
* Job configuration.
*/
protected Configuration conf;
/**
* Total expected count of the records in a split.
*/
protected float length;
/**
* Redaction rule collection names.
*/
protected String[] redactionRuleCol;
/**
* list of forests for failover
*/
protected List replicas;
/**
* Current Forest to connect for failover
*/
protected int curForest;
/**
* Hostnames from the input split
*/
protected String[] hostNames;
/**
* for failover retry
*/
protected int retry;
protected final int maxRetries = 15;
protected int sleepTime;
protected final int maxSleepTime = 30000;
public MarkLogicRecordReader(Configuration conf) {
this.conf = conf;
}
@Override
public void close() throws IOException {
if (result != null) {
result.close();
}
if (session != null) {
session.close();
}
}
public Configuration getConf() {
return conf;
}
@Override
public float getProgress() throws IOException, InterruptedException {
return count/length;
}
private void appendNamespace(Collection nsCol, StringBuilder buf) {
for (Iterator nsIt = nsCol.iterator();
nsIt.hasNext();) {
String ns = nsIt.next();
buf.append('"').append(ns).append('"');
if (nsIt.hasNext()) {
buf.append(',');
}
}
}
protected void buildSrcInDocExprQuery(String docExpr, String subExpr, StringBuilder buf) {
buf.append("fn:unordered(fn:unordered(");
buf.append(docExpr == null ? "fn:collection()" : docExpr);
buf.append(")[$mlmr:splitstart to $mlmr:splitend]");
buf.append(subExpr == null ? "" : subExpr);
buf.append(")");
}
protected void buildDocExprQuery(String docExpr, Collection nsCol,
String subExpr, StringBuilder buf) {
buf.append("xdmp:with-namespaces((");
if (nsCol != null) {
appendNamespace(nsCol, buf);
}
buf.append("),");
if (redactionRuleCol != null) {
buf.append("rdt:redact(");
buildSrcInDocExprQuery(docExpr, subExpr, buf);
buf.append(",((");
for (int i = 0; i < redactionRuleCol.length; i++) {
if (i != 0) {
buf.append(",");
}
buf.append("\"" + redactionRuleCol[i] + "\"");
}
buf.append(")))");
} else {
buildSrcInDocExprQuery(docExpr, subExpr, buf);
}
buf.append(")");
}
protected void buildSrcInSearchQuery(String docExpr, String ctsQuery, StringBuilder buf) {
buf.append("fn:unordered(cts:search(");
buf.append(docExpr);
buf.append(",cts:query(xdmp:unquote('");
buf.append(ctsQuery);
buf.append("')/*),(\"unfiltered\",\"score-zero\")))");
}
protected void buildSearchQuery(String docExpr, String ctsQuery,
Collection nsCol, StringBuilder buf) {
if (docExpr == null) {
docExpr = "fn:collection()";
}
buf.append("xdmp:with-namespaces((");
if (nsCol != null) {
appendNamespace(nsCol, buf);
}
buf.append("),");
if (redactionRuleCol != null) {
buf.append("rdt:redact(");
buildSrcInSearchQuery(docExpr, ctsQuery, buf);
buf.append(",((");
for (int i = 0; i < redactionRuleCol.length; i++) {
if (i != 0) {
buf.append(",");
}
buf.append("\"" + redactionRuleCol[i] + "\"");
}
buf.append(")))");
} else {
buildSrcInSearchQuery(docExpr, ctsQuery, buf);
}
buf.append(")");
buf.append("[$mlmr:splitstart to $mlmr:splitend]");
}
@Override
public void initialize(InputSplit split, TaskAttemptContext context)
throws IOException, InterruptedException {
mlSplit = (MarkLogicInputSplit)split;
count = 0;
context.getCounter(MarkLogicCounter.ESTIMATED_INPUT_RECORDS)
.increment(mlSplit.getLength());
// check hostnames
hostNames = mlSplit.getLocations();
if (hostNames == null || hostNames.length < 1) {
throw new IllegalStateException("Empty split locations.");
}
if (LOG.isDebugEnabled()) {
LOG.debug("split location: " + hostNames[0]);
}
replicas = mlSplit.getReplicas();
curForest = -1;
if (replicas != null) {
for (int i = 0; i < replicas.size(); i++) {
if (replicas.get(i).getHostName().equals(hostNames[0])) {
curForest = i;
break;
}
}
}
retry = 0;
sleepTime = 500;
init();
}
/* in case of failover, use init() instead of initialize() for retry */
private void init()
throws IOException, InterruptedException {
// get job config properties
boolean advancedMode =
conf.get(INPUT_MODE, BASIC_MODE).equals(ADVANCED_MODE);
redactionRuleCol = conf.getStrings(REDACTION_RULE_COLLECTION);
// initialize the total length
float recToFragRatio = conf.getFloat(RECORD_TO_FRAGMENT_RATIO,
getDefaultRatio());
length = mlSplit.getLength() * recToFragRatio;
// generate the query
String queryLanguage = null;
String queryText = null;
long start = mlSplit.getStart() + 1 + count;
long end = mlSplit.isLastSplit() ?
Long.MAX_VALUE : start + mlSplit.getLength() - count - 1;
if (!advancedMode) {
StringBuilder buf = new StringBuilder();
buf.append("xquery version \"1.0-ml\"; \n");
if (redactionRuleCol != null) {
buf.append(
"import module namespace rdt = \"http://marklogic.com/xdmp/redaction\" at \"/MarkLogic/redaction.xqy\";\n");
}
String indent = conf.get(INDENTED, "FALSE");
Indentation ind = Indentation.valueOf(indent);
buf.append(
"declare namespace mlmr=\"http://marklogic.com/hadoop\";\n");
buf.append(
"declare variable $mlmr:splitstart as xs:integer external;\n");
buf.append(
"declare variable $mlmr:splitend as xs:integer external;\n");
buf.append(ind.getStatement());
buf.append("\n");
String docExpr = conf.get(DOCUMENT_SELECTOR);
String ctsQuery = conf.get(QUERY_FILTER);
String subExpr = conf.get(SUBDOCUMENT_EXPRESSION);
Collection nsCol = docExpr != null || subExpr != null?
conf.getStringCollection(PATH_NAMESPACE) : null;
if (ctsQuery != null) {
buildSearchQuery(docExpr, ctsQuery, nsCol, buf);
queryText = buf.toString();
} else if (docExpr != null || subExpr != null) {
buildDocExprQuery(docExpr, nsCol, subExpr, buf);
queryText = buf.toString();
} else {
LexiconFunction function = null;
Class lexiconClass =
conf.getClass(INPUT_LEXICON_FUNCTION_CLASS, null,
LexiconFunction.class);
if (lexiconClass != null) {
function = ReflectionUtils.newInstance(lexiconClass,
conf);
if (nsCol == null) {
nsCol = conf.getStringCollection(PATH_NAMESPACE);
}
queryText = function.getInputQuery(nsCol, start,
mlSplit.isLastSplit() ?
Long.MAX_VALUE : (long)length);
}
}
if (queryText == null) {
buildDocExprQuery(docExpr, nsCol, subExpr, buf);
queryText = buf.toString();
}
} else {
queryText = conf.get(MarkLogicConstants.INPUT_QUERY);
queryLanguage = conf.get(MarkLogicConstants.INPUT_QUERY_LANGUAGE);
if (queryText == null) {
throw new IllegalStateException(
"Input query is required in advanced mode but not defined.");
}
}
if (LOG.isDebugEnabled()) {
LOG.debug(queryText);
}
// set up a connection to the server
while (retry < maxRetries) {
try {
if (retry == 1) {
LOG.info("Retrying connect");
}
String curForestName = "";
String curHostName = "";
if (curForest == -1) {
curForestName = mlSplit.getForestId().toString();
curHostName = hostNames[0];
} else {
curForestName = replicas.get(curForest).getForest();
curHostName = replicas.get(curForest).getHostName();
}
ContentSource cs = InternalUtilities.getInputContentSource(conf,
curHostName);
session = cs.newSession("#"+curForestName);
if (LOG.isDebugEnabled()) {
LOG.debug("Connect to forest "
+ curForestName + " on "
+ session.getConnectionUri().getHost());
}
AdhocQuery query = session.newAdhocQuery(queryText);
if (advancedMode) {
boolean bindSplitRange =
conf.getBoolean(BIND_SPLIT_RANGE, false);
if (bindSplitRange) {
query.setNewIntegerVariable(MR_NAMESPACE,
SPLIT_START_VARNAME, start);
query.setNewIntegerVariable(MR_NAMESPACE,
SPLIT_END_VARNAME, end);
} else {
query.setPosition(start);
if (LOG.isDebugEnabled()) {
LOG.debug("split start position: " + start);
}
query.setCount(mlSplit.isLastSplit() ?
Long.MAX_VALUE : mlSplit.getLength());
}
} else {
query.setNewIntegerVariable(MR_NAMESPACE,
SPLIT_START_VARNAME, start);
query.setNewIntegerVariable(MR_NAMESPACE,
SPLIT_END_VARNAME, end);
}
RequestOptions options = new RequestOptions();
options.setCacheResult(false);
if (queryLanguage != null) {
options.setQueryLanguage(queryLanguage);
}
String ts = conf.get(INPUT_QUERY_TIMESTAMP);
if (ts != null) {
options.setEffectivePointInTime(new BigInteger(ts));
if (LOG.isDebugEnabled()) {
LOG.debug("Query timestamp: " + ts);
}
}
if (LOG.isDebugEnabled()) {
LOG.debug("Input query: " + query.toString());
}
query.setOptions(options);
result = session.submitRequest(query);
} catch (XccConfigException e) {
LOG.error("XccConfigException:" + e);
throw new IOException(e);
} catch (QueryException e) {
LOG.error("QueryException:" + e);
throw new IOException(e);
} catch (RequestException e) {
LOG.error("RequestException:" + e.getMessage());
if (curForest != -1) {
if (++retry < maxRetries) {
// failover
try {
InternalUtilities.sleep(sleepTime);
} catch (Exception e2) {
}
sleepTime = Math.min(sleepTime * 2,maxSleepTime);
curForest = (curForest+1)%replicas.size();
continue;
}
LOG.info("Exceeded max retry");
}
LOG.info("Query: " + queryText);
if (LOG.isDebugEnabled()) {
LOG.debug("RequestException: " + e);
}
throw new IOException(e);
}
break;
} // retry
}
@Override
public boolean nextKeyValue() throws IOException, InterruptedException {
retry = 0;
sleepTime = 500;
while (retry < maxRetries) {
try {
if (result != null && result.hasNext()) {
ResultItem item = result.next();
boolean ret = nextResult(item);
// need to increment the count after nextResult is successful
count++;
return ret;
} else {
endOfResult();
return false;
}
} catch (RuntimeException e) {
LOG.error("RuntimeException:" + e.getMessage());
if (curForest != -1) {
if (++retry < maxRetries) {
try {
InternalUtilities.sleep(sleepTime);
} catch (Exception e2) {
}
sleepTime = Math.min(sleepTime * 2,maxSleepTime);
curForest = (curForest+1)%replicas.size();
init();
continue;
}
LOG.info("Exceeded max retry");
}
throw e;
}
}
endOfResult();
return false;
}
abstract protected void endOfResult();
abstract protected boolean nextResult(ResultItem result);
protected abstract float getDefaultRatio();
public long getCount() {
return count;
}
}