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 * as indicated by the @author tags.
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 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
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 *     http://www.apache.org/licenses/LICENSE-2.0
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package io.undertow.server.handlers.accesslog;

import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.io.Writer;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.Deque;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;

import io.undertow.UndertowLogger;

Log Receiver that stores logs in a directory under the specified file name, and rotates them after midnight.

Web threads do not touch the log file, but simply queue messages to be written later by a worker thread. A lightweight CAS based locking mechanism is used to ensure than only 1 thread is active writing messages at any given time
Author:Stuart Douglas
/** * Log Receiver that stores logs in a directory under the specified file name, and rotates them after * midnight. * <p/> * Web threads do not touch the log file, but simply queue messages to be written later by a worker thread. * A lightweight CAS based locking mechanism is used to ensure than only 1 thread is active writing messages at * any given time * * @author Stuart Douglas */
public class DefaultAccessLogReceiver implements AccessLogReceiver, Runnable, Closeable { private static final String DEFAULT_LOG_SUFFIX = "log"; private final Executor logWriteExecutor; private final Deque<String> pendingMessages; //0 = not running //1 = queued //2 = running @SuppressWarnings("unused") private volatile int state = 0; private static final AtomicIntegerFieldUpdater<DefaultAccessLogReceiver> stateUpdater = AtomicIntegerFieldUpdater.newUpdater(DefaultAccessLogReceiver.class, "state"); private long changeOverPoint; private String currentDateString; private boolean forceLogRotation; private final Path outputDirectory; private final Path defaultLogFile; private final String logBaseName; private final String logNameSuffix; private Writer writer = null; private volatile boolean closed = false; private boolean initialRun = true; private final boolean rotate; private final LogFileHeaderGenerator fileHeaderGenerator; public DefaultAccessLogReceiver(final Executor logWriteExecutor, final File outputDirectory, final String logBaseName) { this(logWriteExecutor, outputDirectory.toPath(), logBaseName, null); } public DefaultAccessLogReceiver(final Executor logWriteExecutor, final File outputDirectory, final String logBaseName, final String logNameSuffix) { this(logWriteExecutor, outputDirectory.toPath(), logBaseName, logNameSuffix, true); } public DefaultAccessLogReceiver(final Executor logWriteExecutor, final File outputDirectory, final String logBaseName, final String logNameSuffix, boolean rotate) { this(logWriteExecutor, outputDirectory.toPath(), logBaseName, logNameSuffix, rotate); } public DefaultAccessLogReceiver(final Executor logWriteExecutor, final Path outputDirectory, final String logBaseName) { this(logWriteExecutor, outputDirectory, logBaseName, null); } public DefaultAccessLogReceiver(final Executor logWriteExecutor, final Path outputDirectory, final String logBaseName, final String logNameSuffix) { this(logWriteExecutor, outputDirectory, logBaseName, logNameSuffix, true); } public DefaultAccessLogReceiver(final Executor logWriteExecutor, final Path outputDirectory, final String logBaseName, final String logNameSuffix, boolean rotate) { this(logWriteExecutor, outputDirectory, logBaseName, logNameSuffix, rotate, null); } private DefaultAccessLogReceiver(final Executor logWriteExecutor, final Path outputDirectory, final String logBaseName, final String logNameSuffix, boolean rotate, LogFileHeaderGenerator fileHeader) { this.logWriteExecutor = logWriteExecutor; this.outputDirectory = outputDirectory; this.logBaseName = logBaseName; this.rotate = rotate; this.fileHeaderGenerator = fileHeader; this.logNameSuffix = (logNameSuffix != null) ? logNameSuffix : DEFAULT_LOG_SUFFIX; this.pendingMessages = new ConcurrentLinkedDeque<>(); this.defaultLogFile = outputDirectory.resolve(logBaseName + this.logNameSuffix); calculateChangeOverPoint(); } private void calculateChangeOverPoint() { Calendar calendar = Calendar.getInstance(); calendar.set(Calendar.SECOND, 0); calendar.set(Calendar.MINUTE, 0); calendar.set(Calendar.HOUR_OF_DAY, 0); calendar.add(Calendar.DATE, 1); SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd", Locale.US); currentDateString = df.format(new Date()); // if there is an existing default log file, use the date last modified instead of the current date if (Files.exists(defaultLogFile)) { try { currentDateString = df.format(new Date(Files.getLastModifiedTime(defaultLogFile).toMillis())); } catch(IOException e){ // ignore. use the current date if exception happens. } } changeOverPoint = calendar.getTimeInMillis(); } @Override public void logMessage(final String message) { this.pendingMessages.add(message); int state = stateUpdater.get(this); if (state == 0) { if (stateUpdater.compareAndSet(this, 0, 1)) { logWriteExecutor.execute(this); } } }
processes all queued log messages
/** * processes all queued log messages */
@Override public void run() { if (!stateUpdater.compareAndSet(this, 1, 2)) { return; } if (forceLogRotation) { doRotate(); } else if (initialRun && Files.exists(defaultLogFile)) { //if there is an existing log file check if it should be rotated long lm = 0; try { lm = Files.getLastModifiedTime(defaultLogFile).toMillis(); } catch (IOException e) { UndertowLogger.ROOT_LOGGER.errorRotatingAccessLog(e); } Calendar c = Calendar.getInstance(); c.setTimeInMillis(changeOverPoint); c.add(Calendar.DATE, -1); if (lm <= c.getTimeInMillis()) { doRotate(); } } initialRun = false; List<String> messages = new ArrayList<>(); String msg; //only grab at most 1000 messages at a time for (int i = 0; i < 1000; ++i) { msg = pendingMessages.poll(); if (msg == null) { break; } messages.add(msg); } try { if (!messages.isEmpty()) { writeMessage(messages); } } finally { stateUpdater.set(this, 0); //check to see if there is still more messages //if so then run this again if (!pendingMessages.isEmpty() || forceLogRotation) { if (stateUpdater.compareAndSet(this, 0, 1)) { logWriteExecutor.execute(this); } } else if (closed) { try { if(writer != null) { writer.flush(); writer.close(); writer = null; } } catch (IOException e) { UndertowLogger.ROOT_LOGGER.errorWritingAccessLog(e); } } } }
For tests only. Blocks the current thread until all messages are written Just does a busy wait.

DO NOT USE THIS OUTSIDE OF A TEST
/** * For tests only. Blocks the current thread until all messages are written * Just does a busy wait. * <p/> * DO NOT USE THIS OUTSIDE OF A TEST */
void awaitWrittenForTest() throws InterruptedException { while (!pendingMessages.isEmpty() || forceLogRotation) { Thread.sleep(10); } while (state != 0) { Thread.sleep(10); } } private void writeMessage(final List<String> messages) { if (System.currentTimeMillis() > changeOverPoint) { doRotate(); } try { if (writer == null) { boolean created = !Files.exists(defaultLogFile); writer = Files.newBufferedWriter(defaultLogFile, StandardCharsets.UTF_8, StandardOpenOption.APPEND, StandardOpenOption.CREATE); if(Files.size(defaultLogFile) == 0 && fileHeaderGenerator != null) { String header = fileHeaderGenerator.generateHeader(); if(header != null) { writer.write(header); writer.write("\n"); writer.flush(); } } } for (String message : messages) { writer.write(message); writer.write('\n'); } writer.flush(); } catch (IOException e) { UndertowLogger.ROOT_LOGGER.errorWritingAccessLog(e); } } private void doRotate() { forceLogRotation = false; if (!rotate) { return; } try { if (writer != null) { writer.flush(); writer.close(); writer = null; } if (!Files.exists(defaultLogFile)) { return; } Path newFile = outputDirectory.resolve(logBaseName + currentDateString + "." + logNameSuffix); int count = 0; while (Files.exists(newFile)) { ++count; newFile = outputDirectory.resolve(logBaseName + currentDateString + "-" + count + "." + logNameSuffix); } Files.move(defaultLogFile, newFile); } catch (IOException e) { UndertowLogger.ROOT_LOGGER.errorRotatingAccessLog(e); } finally { calculateChangeOverPoint(); } }
forces a log rotation. This rotation is performed in an async manner, you cannot rely on the rotation being performed immediately after this method returns.
/** * forces a log rotation. This rotation is performed in an async manner, you cannot rely on the rotation * being performed immediately after this method returns. */
public void rotate() { forceLogRotation = true; if (stateUpdater.compareAndSet(this, 0, 1)) { logWriteExecutor.execute(this); } } @Override public void close() throws IOException { closed = true; if (stateUpdater.compareAndSet(this, 0, 1)) { logWriteExecutor.execute(this); } } public static Builder builder() { return new Builder(); } public static class Builder { private Executor logWriteExecutor; private Path outputDirectory; private String logBaseName; private String logNameSuffix; private boolean rotate; private LogFileHeaderGenerator logFileHeaderGenerator; public Executor getLogWriteExecutor() { return logWriteExecutor; } public Builder setLogWriteExecutor(Executor logWriteExecutor) { this.logWriteExecutor = logWriteExecutor; return this; } public Path getOutputDirectory() { return outputDirectory; } public Builder setOutputDirectory(Path outputDirectory) { this.outputDirectory = outputDirectory; return this; } public String getLogBaseName() { return logBaseName; } public Builder setLogBaseName(String logBaseName) { this.logBaseName = logBaseName; return this; } public String getLogNameSuffix() { return logNameSuffix; } public Builder setLogNameSuffix(String logNameSuffix) { this.logNameSuffix = logNameSuffix; return this; } public boolean isRotate() { return rotate; } public Builder setRotate(boolean rotate) { this.rotate = rotate; return this; } public LogFileHeaderGenerator getLogFileHeaderGenerator() { return logFileHeaderGenerator; } public Builder setLogFileHeaderGenerator(LogFileHeaderGenerator logFileHeaderGenerator) { this.logFileHeaderGenerator = logFileHeaderGenerator; return this; } public DefaultAccessLogReceiver build() { return new DefaultAccessLogReceiver(logWriteExecutor, outputDirectory, logBaseName, logNameSuffix, rotate, logFileHeaderGenerator); } } }