| /** |
| * 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.oozie.util; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| |
| import java.io.BufferedReader; |
| import java.io.IOException; |
| import java.io.InputStreamReader; |
| import java.nio.charset.StandardCharsets; |
| |
| public class BufferDrainer { |
| |
| private final XLog LOG = XLog.getLog(getClass()); |
| private static final int DRAIN_BUFFER_SLEEP_TIME_MS = 500; |
| private final Process process; |
| private final int maxLength; |
| private boolean drainBuffersFinished; |
| private final StringBuffer inputBuffer; |
| private final StringBuffer errorBuffer; |
| |
| /** |
| * @param process The Process instance. |
| * @param maxLength The maximum data length to be stored in these buffers. This is an indicative value, and the |
| * store content may exceed this length. |
| */ |
| public BufferDrainer(Process process, int maxLength) { |
| this.process = process; |
| this.maxLength = maxLength; |
| drainBuffersFinished = false; |
| inputBuffer = new StringBuffer(); |
| errorBuffer = new StringBuffer(); |
| } |
| |
| /** |
| * Drains the inputStream and errorStream of the Process being executed. The contents of the streams are stored if a |
| * buffer is provided for the stream. |
| * |
| * @return the exit value of the processSettings. |
| * @throws IOException if IO related issue occurs |
| */ |
| public int drainBuffers() throws IOException { |
| if (drainBuffersFinished) { |
| throw new IllegalStateException("Buffer draining has already been finished"); |
| } |
| LOG.trace("drainBuffers() start"); |
| |
| int exitValue = -1; |
| |
| int inBytesRead = 0; |
| int errBytesRead = 0; |
| |
| boolean processEnded = false; |
| |
| try (final BufferedReader ir = |
| new BufferedReader(new InputStreamReader(process.getInputStream(), StandardCharsets.UTF_8)); |
| final BufferedReader er = |
| new BufferedReader(new InputStreamReader(process.getErrorStream(), StandardCharsets.UTF_8))) { |
| // Here we do some kind of busy waiting, checking whether the process has finished by calling Process#exitValue(). |
| // If not yet finished, an IllegalThreadStateException is thrown and ignored, the progress on stdout and stderr read, |
| // and retried until the process has ended. |
| // Note that Process#waitFor() may block sometimes, that's why we do a polling mechanism using Process#exitValue() |
| // instead. Until we extend unit and integration test coverage for SSH action, and we can introduce a more |
| // sophisticated error handling based on the extended coverage, this solution should stay in place. |
| while (!processEnded) { |
| try { |
| // Doesn't block but throws IllegalThreadStateException if the process hasn't finished yet |
| exitValue = process.exitValue(); |
| processEnded = true; |
| } |
| catch (final IllegalThreadStateException itse) { |
| // Continue to drain |
| } |
| |
| // Drain input and error streams |
| inBytesRead += drainBuffer(ir, inputBuffer, maxLength, inBytesRead, processEnded); |
| errBytesRead += drainBuffer(er, errorBuffer, maxLength, errBytesRead, processEnded); |
| |
| // Necessary evil: sleep and retry |
| if (!processEnded) { |
| try { |
| LOG.trace("Sleeping {}ms during buffer draining", DRAIN_BUFFER_SLEEP_TIME_MS); |
| Thread.sleep(DRAIN_BUFFER_SLEEP_TIME_MS); |
| } |
| catch (final InterruptedException ie) { |
| // Sleep a little, then check again |
| } |
| } |
| } |
| } |
| |
| LOG.trace("drainBuffers() end [exitValue={0}]", exitValue); |
| drainBuffersFinished = true; |
| return exitValue; |
| } |
| |
| public StringBuffer getInputBuffer() { |
| if (drainBuffersFinished) { |
| return inputBuffer; |
| } |
| else { |
| throw new IllegalStateException("Buffer draining has not been finished yet"); |
| } |
| } |
| |
| public StringBuffer getErrorBuffer() { |
| if (drainBuffersFinished) { |
| return errorBuffer; |
| } |
| else { |
| throw new IllegalStateException("Buffer draining has not been finished yet"); |
| } |
| } |
| |
| /** |
| * Reads the contents of a stream and stores them into the provided buffer. |
| * |
| * @param br The stream to be read. |
| * @param storageBuf The buffer into which the contents of the stream are to be stored. |
| * @param maxLength The maximum number of bytes to be stored in the buffer. An indicative value and may be |
| * exceeded. |
| * @param bytesRead The number of bytes read from this stream to date. |
| * @param readAll If true, the stream is drained while their is data available in it. Otherwise, only a single chunk |
| * of data is read, irrespective of how much is available. |
| * @return bReadSession returns drainBuffer for stream of contents |
| * @throws IOException |
| */ |
| @VisibleForTesting |
| static int drainBuffer(BufferedReader br, StringBuffer storageBuf, int maxLength, int bytesRead, boolean readAll) |
| throws IOException { |
| int bReadSession = 0; |
| int chunkSize = 1024; |
| if (br.ready()) { |
| char[] buf = new char[1024]; |
| int bReadCurrent; |
| boolean wantsToReadFurther; |
| do { |
| bReadCurrent = br.read(buf, 0, chunkSize); |
| if (storageBuf != null && bytesRead < maxLength && bReadCurrent != -1) { |
| storageBuf.append(buf, 0, bReadCurrent); |
| } |
| if (bReadCurrent != -1) { |
| bReadSession += bReadCurrent; |
| } |
| wantsToReadFurther = bReadCurrent != -1 && (readAll || bReadCurrent == chunkSize); |
| } while (br.ready() && wantsToReadFurther); |
| } |
| return bReadSession; |
| } |
| } |