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/*
* Copyright (C) 2015 The Android Open Source Project
*
* 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.android.messaging.util;
import android.annotation.TargetApi;
import android.os.Build;
/**
* Helper class for systrace (see http://developer.android.com/tools/help/systrace.html).<p>
* To enable, set log.tag.Bugle_Trace (defined by {@link #TAG} to VERBOSE before
* the process starts.<p>
* Note that this will run only on JBMR2 or later; on earlier platforms or if the log
* tag isn't set, calls to {@link #beginSection(String)} or {@link #endSection()} are no-ops. <p>
* Internally, calls dispatch to either a class that actually does work or a class that doesn't.
* This avoids Dalvik complaining when it loads the class on earlier platforms that the
* opcodes aren't available, and, according to the Dalvik team, using vtable dispatching for
* something like this should be faster than if (OsUtil.isAtLeast...()) on each call.
*/
public final class Trace {
private static final String TAG = "Bugle_Trace";
private abstract static class AbstractTrace {
abstract void beginSection(String sectionName);
abstract void endSection();
}
private static final AbstractTrace sTrace;
// Static initializer to pick the correct trace class to handle tracing.
static {
// Use android.util.Log instead of LogUtil here to avoid pulling in Gservices
// too early in app startup.
if (OsUtil.isAtLeastJB_MR2() &&
android.util.Log.isLoggable(TAG, android.util.Log.VERBOSE)) {
sTrace = new TraceJBMR2();
} else {
sTrace = new TraceShim();
}
}
/**
* Writes a trace message to indicate that a given section of code has begun. This call must
* be followed by a corresponding call to {@link #endSection()} on the same thread.
*
* <p class="note"> At this time the vertical bar character '|', newline character '\n', and
* null character '\0' are used internally by the tracing mechanism. If sectionName contains
* these characters they will be replaced with a space character in the trace.
*
* @param sectionName The name of the code section to appear in the trace. This may be at
* most 127 Unicode code units long.
*/
public static void beginSection(String sectionName) {
if (LogUtil.isLoggable(TAG, LogUtil.VERBOSE)) {
LogUtil.v(TAG, "beginSection() " + sectionName);
}
sTrace.beginSection(sectionName);
}
/**
* Writes a trace message to indicate that a given section of code has ended. This call must
* be preceeded by a corresponding call to {@link #beginSection(String)}. Calling this method
* will mark the end of the most recently begun section of code, so care must be taken to
* ensure that beginSection / endSection pairs are properly nested and called from the same
* thread.
*/
public static void endSection() {
sTrace.endSection();
if (LogUtil.isLoggable(TAG, LogUtil.VERBOSE)) {
LogUtil.v(TAG, "endSection()");
}
}
/**
* Internal class that we use if we really did enable tracing.
*/
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
private static final class TraceJBMR2 extends AbstractTrace {
@Override
void beginSection(String sectionName) {
android.os.Trace.beginSection(sectionName);
}
@Override
void endSection() {
android.os.Trace.endSection();
}
}
/**
* Dummy class that we use if we aren't really tracing.
*/
private static final class TraceShim extends AbstractTrace {
@Override
void beginSection(String sectionName) {
}
@Override
void endSection() {
}
}
}
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