d92f6f754a
By opening a TraceContext it is now possible to set a logging tag that
will be automatically included into all subsequent log statements that
are done by the same thread. When the TraceContext is closed the tag is
unset.
A tag has a name and a value. Having multiple tags with the same name
but different values is possible.
Adding a tag with the same name and same value a second time is possible
but has no effect.
With this change open TraceContexts are not propagated to newly started
threads that do work in the background. Support for this will be
implemented by the follow-up change.
Example:
// Initially there are no tags
logger.atSevere().log("log without tag");
// a tag can be set by opening a TraceContext
try (TraceContext ctx = new TraceContext("tag1", "value1")) {
logger.atSevere().log("with tag1=value1");
// by opening another TraceContext a another tag can be added
try (TraceContext ctx2 = new TraceContext("tag2", "value2")) {
logger.atSevere().log("log with tag1=value1 and tag2=value2");
// it's possible to have same tag name with multiple values
try (TraceContext ctx3 = new TraceContext("tag2", "value2a")) {
logger.atSevere().log("log with tag1=value1, tag2=value2 and tag2=value2a");
// adding a tag with the same name and value of an existing tag has no effect
try (TraceContext ctx4 = new TraceContext("tag2", "value2a")) {
logger.atSevere().log("log with tag1=value1, tag2=value2 and tag2=value2a");
}
// closing ctx4 didn't remove tag2=value2a since it was set before opening ctx4
logger.atSevere().log("log with tag1=value1, tag2=value2 and tag2=value2a");
}
// closing ctx3 removed tag2=value2a
logger.atSevere().log("log with tag1=value1 and tag2=value2");
}
// closing ctx2 removed tag2=value2
logger.atSevere().log("with tag1=value1");
}
// closing ctx1 removed tag1=value1
logger.atSevere().log("log without tag");
To support logging tags we must register a LoggingContext in Flogger.
This is done by setting the 'flogger.logging_context' system property.
Change-Id: Ib01eb90b9ad832be0b2d794e14ce23bdef2f0fb6
Signed-off-by: Edwin Kempin <ekempin@google.com>
79 lines
2.5 KiB
Java
79 lines
2.5 KiB
Java
// Copyright (C) 2009 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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public final class Main {
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private static final String FLOGGER_BACKEND_PROPERTY = "flogger.backend_factory";
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private static final String FLOGGER_LOGGING_CONTEXT = "flogger.logging_context";
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// We don't do any real work here because we need to import
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// the archive lookup code and we cannot import a class in
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// the default package. So this is just a tiny springboard
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// to jump into the real main code.
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//
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public static void main(String[] argv) throws Exception {
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if (onSupportedJavaVersion()) {
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configureFloggerBackend();
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com.google.gerrit.launcher.GerritLauncher.main(argv);
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} else {
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System.exit(1);
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}
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}
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private static boolean onSupportedJavaVersion() {
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final String version = System.getProperty("java.specification.version");
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if (1.8 <= parse(version)) {
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return true;
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}
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System.err.println("fatal: Gerrit Code Review requires Java 8 or later");
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System.err.println(" (trying to run on Java " + version + ")");
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return false;
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}
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private static void configureFloggerBackend() {
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System.setProperty(
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FLOGGER_LOGGING_CONTEXT, "com.google.gerrit.server.logging.LoggingContext#getInstance");
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if (System.getProperty(FLOGGER_BACKEND_PROPERTY) != null) {
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// Flogger backend is already configured
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return;
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}
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// Configure log4j backend
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System.setProperty(
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FLOGGER_BACKEND_PROPERTY,
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"com.google.common.flogger.backend.log4j.Log4jBackendFactory#getInstance");
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}
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private static double parse(String version) {
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if (version == null || version.length() == 0) {
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return 0.0;
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}
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try {
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final int fd = version.indexOf('.');
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final int sd = version.indexOf('.', fd + 1);
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if (0 < sd) {
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version = version.substring(0, sd);
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}
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return Double.parseDouble(version);
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} catch (NumberFormatException e) {
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return 0.0;
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}
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}
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private Main() {}
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}
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