eu.stratosphere.nephele.executiongraph.ExecutionSignature Maven / Gradle / Ivy
/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* 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 eu.stratosphere.nephele.executiongraph;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import eu.stratosphere.nephele.execution.librarycache.LibraryCacheManager;
import eu.stratosphere.nephele.jobgraph.JobID;
import eu.stratosphere.nephele.template.AbstractInvokable;
/**
* An execution signature allows to uniquely identify a job vertex. The signature involves the name of the
* class to be invoked at runtime as well as a cryptographic hash of all the JAR files which are required to
* instantiate the class and run it. The execution is the basis for feedback learning as it enables the profiler
* to recognize particular parts of a job. Execution signature objects are immutable and, consequently, thread-safe.
*
* This class is thread-safe.
*
*/
public final class ExecutionSignature {
/**
* The log object used for debugging.
*/
private static final Log LOG = LogFactory.getLog(ExecutionSignature.class);
/**
* The name of the hashing algorithm to be used.
*/
private static final String HASHINGALGORITHM = "SHA-1";
/**
* The message digest object used to calculate the signature.
*/
private static MessageDigest messageDigest = null;
/**
* The buffer storing the signature.
*/
private final byte[] signature;
/**
* Constructs a new execution signature object and passes the signature buffer.
*
* @param signature
* the byte buffer containing the signature.
*/
private ExecutionSignature(final byte[] signature) {
this.signature = signature;
}
/**
* Calculates the execution signature from the given class name and job ID.
*
* @param invokableClass
* the name of the class to contain the task program
* @param jobID
* the ID of the job
* @return the cryptographic signature of this vertex
*/
public static synchronized ExecutionSignature createSignature(
final Class invokableClass, final JobID jobID) {
// First, try to load message digest algorithm, if necessary
if (messageDigest == null) {
try {
messageDigest = MessageDigest.getInstance(HASHINGALGORITHM);
} catch (NoSuchAlgorithmException e) {
LOG.error("Unable to load message digest algorithm " + HASHINGALGORITHM);
return null;
}
}
// Reset digest buffer and add the name of the invokable class to the message digest buffer
messageDigest.reset();
messageDigest.update(invokableClass.getName().getBytes());
String[] requiredJarFiles;
// Next, retrieve the JAR-files associated with this job
try {
requiredJarFiles = LibraryCacheManager.getRequiredJarFiles(jobID);
} catch (IOException ioe) {
// Output an error message and return
LOG.error("Cannot access library cache manager for job ID " + jobID);
return null;
}
// Now, sort the list of JAR-files in order to always calculate the signature in the same manner
Arrays.sort(requiredJarFiles);
// Finally, add the names of the JAR-files to the hash calculation
for (int i = 0; i < requiredJarFiles.length; i++) {
messageDigest.update(requiredJarFiles[i].getBytes());
}
return new ExecutionSignature(messageDigest.digest());
}
@Override
public boolean equals(final Object obj) {
if (obj instanceof ExecutionSignature) {
final ExecutionSignature executionSignature = (ExecutionSignature) obj;
return Arrays.equals(this.signature, executionSignature.signature);
}
return false;
}
@Override
public int hashCode() {
int hashCode = 0;
for (int i = 0; i < this.signature.length; i++) {
hashCode += this.signature[i];
}
return hashCode;
}
@Override
public String toString() {
final StringBuffer stringBuffer = new StringBuffer();
for (int i = 0; i < this.signature.length; i++) {
stringBuffer.append(Integer.toHexString(0xFF & this.signature[i]));
}
return stringBuffer.toString();
}
}