Java tutorial
/* * Copyright 2014-present Facebook, Inc. * * 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.facebook.buck.log; import com.facebook.buck.io.MorePaths; import com.facebook.buck.io.PathListing; import com.google.common.base.Charsets; import com.google.common.collect.ImmutableList; import com.google.common.collect.Iterators; import org.stringtemplate.v4.ST; import java.io.ByteArrayInputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.io.SequenceInputStream; import java.nio.file.Files; import java.nio.file.Path; import java.util.Arrays; import java.util.Optional; import java.util.logging.Handler; import java.util.logging.LogManager; import java.util.logging.Logger; // NOPMD /** * Constructed by java.util.logging.LogManager via the system property * java.util.logging.LogManager.config. * * Extends LogManager's support for a single logging.properties file * to support a three-level config. Each existent property file is * concatenated together and used as a single LogManager configuration, * with later entries overriding earlier ones. * * 1) $BUCK_DIRECTORY/config/logging.properties.st * 2) $PROJECT_ROOT/.bucklogging.properties * 3) $PROJECT_ROOT/.bucklogging.local.properties */ @SuppressWarnings("checkstyle:hideutilityclassconstructor") public class LogConfig { private static final byte[] NEWLINE = { '\n' }; /** * Default constructor, called by LogManager. */ public LogConfig() throws IOException { setupLogging(LogConfigSetup.builder().from(LogConfigSetup.DEFAULT_SETUP).setLogFilePrefix("launch-") .setCount(1).build()); } /** * Creates the log output directory and concatenates logging.properties * files together to configure or re-configure LogManager. */ public static synchronized void setupLogging(LogConfigSetup logConfigSetup) throws IOException { // Bug JDK-6244047: The default FileHandler does not handle the directory not existing, // so we have to create it before any log statements actually run. Files.createDirectories(logConfigSetup.getLogDir()); if (logConfigSetup.getRotateLog()) { try { deleteOldLogFiles(logConfigSetup); } catch (IOException e) { System.err.format("Error deleting old log files (ignored): %s\n", e.getMessage()); } } ImmutableList.Builder<InputStream> inputStreamsBuilder = ImmutableList.builder(); if (!LogConfigPaths.MAIN_PATH.isPresent()) { System.err.format( "Error: Couldn't read system property %s (it should be set by buck_common or buck.cmd)\n", LogConfigPaths.BUCK_CONFIG_STRING_TEMPLATE_FILE_PROPERTY); } else { if (!addInputStreamForTemplate(LogConfigPaths.MAIN_PATH.get(), logConfigSetup, inputStreamsBuilder)) { System.err.format("Error: Couldn't open logging properties file %s\n", LogConfigPaths.MAIN_PATH.get()); } } // We ignore the return value for these files; they don't need to exist. addInputStreamForPath(LogConfigPaths.PROJECT_PATH, inputStreamsBuilder); addInputStreamForPath(LogConfigPaths.LOCAL_PATH, inputStreamsBuilder); // Concatenate each of the files together and read them in as a single properties file // for log settings. try (InputStream is = new SequenceInputStream( Iterators.asEnumeration(inputStreamsBuilder.build().iterator()))) { LogManager.getLogManager().readConfiguration(is); } } public static void flushLogs() { Logger rootLogger = LogManager.getLogManager().getLogger(""); if (rootLogger == null) { return; } Handler[] handlers = rootLogger.getHandlers(); if (handlers == null) { return; } for (Handler h : Arrays.asList(handlers)) { h.flush(); } } private static boolean addInputStreamForTemplate(Path path, LogConfigSetup logConfigSetup, ImmutableList.Builder<InputStream> inputStreamsBuilder) throws IOException { try { String template = new String(Files.readAllBytes(path), Charsets.UTF_8); ST st = new ST(template); st.add("default_file_pattern", MorePaths.pathWithUnixSeparators(logConfigSetup.getLogFilePath()).toString()); st.add("default_count", logConfigSetup.getCount()); st.add("default_max_size_bytes", logConfigSetup.getMaxLogSizeBytes()); String result = st.render(); inputStreamsBuilder.add(new ByteArrayInputStream(result.getBytes(Charsets.UTF_8))); inputStreamsBuilder.add(new ByteArrayInputStream(NEWLINE)); return true; } catch (FileNotFoundException e) { return false; } } private static boolean addInputStreamForPath(Path path, ImmutableList.Builder<InputStream> inputStreamsBuilder) { try { inputStreamsBuilder.add(new FileInputStream(path.toString())); // Handle the case where a file doesn't end with a newline. inputStreamsBuilder.add(new ByteArrayInputStream(NEWLINE)); return true; } catch (FileNotFoundException e) { return false; } } private static void deleteOldLogFiles(LogConfigSetup logConfigSetup) throws IOException { for (Path path : PathListing.listMatchingPathsWithFilters(logConfigSetup.getLogDir(), logConfigSetup.getLogFilePrefix() + "*.log*", PathListing.GET_PATH_MODIFIED_TIME, PathListing.FilterMode.EXCLUDE, Optional.empty(), Optional.of(logConfigSetup.getMaxLogSizeBytes()))) { Files.deleteIfExists(path); } } }