/*
* Copyright 2013 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.ex.camera2.utils;
import android.util.Log;
/**
* Writes trace events to the system trace buffer. These trace events can be
* collected and visualized using the Systrace tool.
*
* <p>
* This tracing mechanism is independent of the method tracing mechanism
* offered by {@link Debug#startMethodTracing}. In particular, it enables
* tracing of events that occur across multiple processes.
* </p>
*
* <p>
* All traces are written using the <pre>APP</pre> tag.
* </p>
*/
public final class SysTrace {
private static final String TAG = "SysTrace";
private static final boolean VERBOSE = Log.isLoggable(TAG, Log.VERBOSE);
private static int sNestingLevel = 0;
/**
* Writes trace message to indicate the value of a given counter.
*
* @param counterName The counter name to appear in the trace.
* @param counterValue The counter value.
*
*/
public static void traceCounter(String counterName, int counterValue) {
if (VERBOSE) {
Log.v(TAG, "traceCounter " + counterName + " " + counterValue);
}
}
/**
* 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 (VERBOSE) {
Log.v(TAG, String.format("beginSection[%d] %s", sNestingLevel, sectionName));
sNestingLevel++;
}
}
/**
* Writes a trace message to indicate that a given section of code has
* ended.
* <p>
* This call must be preceded 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.
* </p>
*/
public static void endSection() {
if (VERBOSE) {
sNestingLevel--;
Log.v(TAG, String.format("endSection[%d]", sNestingLevel));
}
}
/**
* Writes a trace message to indicate that a given section of code has
* begun.
*
* <p>Must be followed by a call to {@link #endSectionAsync} using the same
* tag. Unlike {@link #beginSection} and {@link #endSection},
* asynchronous events do not need to be nested. The name and cookie used to
* begin an event must be used to end it.</p>
*
* @param methodName The method name to appear in the trace.
* @param cookie Unique identifier for distinguishing simultaneous events
*/
public static void beginSectionAsync(String methodName, int cookie) {
if (VERBOSE) {
Log.v(TAG, "beginSectionAsync " + methodName + " " + cookie);
}
}
/**
* Writes a trace message to indicate that the current method has ended.
* Must be called exactly once for each call to {@link #beginSectionAsync}
* using the same tag, name and cookie.
*
* @param methodName The method name to appear in the trace.
* @param cookie Unique identifier for distinguishing simultaneous events
*/
public static void endSectionAsync(String methodName, int cookie) {
if (VERBOSE) {
Log.v(TAG, "endSectionAsync " + methodName + " " + cookie);
}
}
}