org.apache.pig.tools.parameters.PreprocessorContext Maven / Gradle / Ivy
/*
* 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.
*/
/**
* This is helper class for parameter substitution
*/
package org.apache.pig.tools.parameters;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.log4j.Logger;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.util.Hashtable;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class PreprocessorContext {
private Hashtable param_val ;
private final Log log = LogFactory.getLog(getClass());
/**
* @param limit - max number of parameters. Passing
* smaller number only impacts performance
*/
public PreprocessorContext(int limit){
param_val = new Hashtable (limit);
}
/*
public void processLiteral(String key, String val) {
processLiteral(key, val, true);
} */
/**
* This method generates parameter value by running specified command
*
* @param key - parameter name
* @param val - string containing command to be executed
*/
public void processShellCmd(String key, String val) {
processShellCmd(key, val, true);
}
/**
* This method generates value for the specified key by
* performing substitution if needed within the value first.
*
* @param key - parameter name
* @param val - value supplied for the key
*/
public void processOrdLine(String key, String val) {
processOrdLine(key, val, true);
}
/*
public void processLiteral(String key, String val, Boolean overwrite) {
if (param_val.containsKey(key)) {
if (overwrite) {
log.warn("Warning : Multiple values found for " + key + ". Using value " + val);
} else {
return;
}
}
String sub_val = substitute(val);
param_val.put(key, sub_val);
} */
/**
* This method generates parameter value by running specified command
*
* @param key - parameter name
* @param val - string containing command to be executed
*/
public void processShellCmd(String key, String val, Boolean overwrite) {
if (param_val.containsKey(key)) {
if (overwrite) {
log.warn("Warning : Multiple values found for " + key + ". Using value " + val);
} else {
return;
}
}
val=val.substring(1, val.length()-1); //to remove the backticks
String sub_val = substitute(val);
sub_val = executeShellCommand(sub_val);
param_val.put(key, sub_val);
}
/**
* This method generates value for the specified key by
* performing substitution if needed within the value first.
*
* @param key - parameter name
* @param val - value supplied for the key
* @param overwrite - specifies whether the value should be replaced if it already exists
*/
public void processOrdLine(String key, String val, Boolean overwrite) {
if (param_val.containsKey(key)) {
if (overwrite) {
log.warn("Warning : Multiple values found for " + key + ". Using value " + val);
} else {
return;
}
}
String sub_val = substitute(val);
param_val.put(key, sub_val);
}
/*
* executes the 'cmd' in shell and returns result
*/
private String executeShellCommand (String cmd)
{
Process p;
String streamData="";
String streamError="";
try {
log.info("Executing command : " + cmd);
// we can't use exec directly since it does not handle
// case like foo -c "bar bar" correctly. It splits on white spaces even in presents of quotes
String[] cmdArgs = new String[3];
cmdArgs[0] = "bash";
cmdArgs[1] = "-c";
StringBuffer sb = new StringBuffer("exec ");
sb.append(cmd);
cmdArgs[2] = sb.toString();
p = Runtime.getRuntime().exec(cmdArgs);
} catch (IOException e) {
RuntimeException rte = new RuntimeException("IO Exception while executing shell command : "+e.getMessage() , e);
throw rte;
}
int exitVal;
try {
exitVal = p.waitFor();
} catch (InterruptedException e) {
RuntimeException rte = new RuntimeException("Interrupted Thread Exception while waiting for command to get over"+e.getMessage() , e);
throw rte;
}
if (exitVal != 0) {
RuntimeException rte = new RuntimeException("Error executing shell command: " + cmd + ". Command exit with exit code of " + exitVal );
throw rte;
}
BufferedReader br = null;
try{
InputStreamReader isr = new InputStreamReader(p.getInputStream());
br = new BufferedReader(isr);
String line=null;
StringBuilder sb = new StringBuilder();
while ( (line = br.readLine()) != null){
sb.append(line);
sb.append("\n");
}
streamData = sb.toString();
} catch (IOException e){
RuntimeException rte = new RuntimeException("IO Exception while executing shell command : "+e.getMessage() , e);
throw rte;
} finally {
if (br != null) try {br.close();} catch(Exception e) {}
}
try {
InputStreamReader isr = new InputStreamReader(p.getErrorStream());
br = new BufferedReader(isr);
String line=null;
StringBuilder sb = new StringBuilder();
while ( (line = br.readLine()) != null ) {
sb.append(line);
sb.append("\n");
}
streamError = sb.toString();
log.debug("Error stream while executing shell command : " + streamError);
} catch (Exception e) {
RuntimeException rte = new RuntimeException("IO Exception while executing shell command : "+e.getMessage() , e);
throw rte;
} finally {
if (br != null) try {br.close();} catch(Exception e) {}
}
return streamData.trim();
}
private Pattern id_pattern = Pattern.compile("\\$[_]*[a-zA-Z][a-zA-Z_0-9]*");
public String substitute(String line) {
int index = line.indexOf('$');
if (index == -1) return line;
String replaced_line = line;
Matcher keyMatcher = id_pattern.matcher( line );
String key="";
String val="";
while (keyMatcher.find()) {
// make sure that we don't perform parameter substitution
// for escaped vars of the form \$
if ( (keyMatcher.start() == 0) || (line.charAt( keyMatcher.start() - 1)) != '\\' ) {
key = keyMatcher.group().substring(1); //skip the '$'
if (!(param_val.containsKey(key))) {
throw new RuntimeException("Undefined parameter : "+key);
}
val = param_val.get(key);
//String litVal = Matcher.quoteReplacement(val);
replaced_line = replaced_line.replaceFirst("\\$"+key, val);
}
}
// unescape $
replaced_line = replaced_line.replaceAll("\\\\\\$","\\$");
return replaced_line;
}
}
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