AndroidXTracer.java
/*
* Copyright (C) 2022 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 androidx.test.platform.tracing;
import static androidx.tracing.Trace.beginSection;
import static androidx.tracing.Trace.endSection;
import static androidx.tracing.Trace.forceEnableAppTracing;
import android.util.Log;
import androidx.annotation.NonNull;
import androidx.tracing.Trace;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.ArrayDeque;
/**
* AndroidX Tracing wrapper implementation of the Tracer API.
*
* <p>Registering this tracer does not guarantee trace collection as the underlying Android tracing
* feature has its own enabling logic. The Android tracing API depends on the runtime SDK API: <br>
* - Below API 18 (JB MR2), AndroidX Tracing is a no-op as the underlying feature did not exist.<br>
* - API 18 up to 28: Tracing is enabled by a call to {@link Trace#forceEnableAppTracing()}.<br>
* - API 29 or 30: Tracing can also be enabled via a manifest flag. <br>
* - API 31 and above: Tracing is enabled by default, unless it's disabled.
*
* <p>See details below in the AndroidX Tracing {@link Trace} documentation.
*
* <p>For API 18+, an instance of this wrapper is automatically created and registered in {@link
* Tracing}.
*
* @see <a
* href="https://developer.android.com/reference/androidx/tracing/Trace">androidx.tracing.Trace</a>
*/
class AndroidXTracer implements Tracer {
private static final String TAG = AndroidXTracer.class.getSimpleName();
/** android.os.Trace.beginSection() has a limit on name length. */
private static final int MAX_SECTION_NAME_LEN = 127;
/** Enables tracing to systrace for devices with API 18-28. */
@CanIgnoreReturnValue
public AndroidXTracer enableTracing() {
try {
forceEnableAppTracing();
} catch (RuntimeException e) {
// The AndroidX call can fail if reflection is not allowed.
// We want to log the error yet we should not break any test in this case.
Log.e(TAG, "enableTracing failed", e);
}
return this;
}
@NonNull
@Override
public Span beginSpan(@NonNull String name) {
beginSection(sanitizeSpanName(name));
return new AndroidXTracerSpan();
}
private static class AndroidXTracerSpan implements Span {
private final ArrayDeque<AndroidXTracerSpan> nestedSpans = new ArrayDeque<>();
@NonNull
@Override
public Span beginChildSpan(@NonNull String name) {
beginSection(sanitizeSpanName(name));
AndroidXTracerSpan span = new AndroidXTracerSpan();
nestedSpans.add(span);
return span;
}
@Override
public void close() {
AndroidXTracerSpan span;
while ((span = nestedSpans.pollLast()) != null) {
span.close();
}
endSection();
}
}
/**
* android.os.Trace.beginSection() has a hard limit on the name length and throws if the name is
* too long. We shorten here with a warning if needed.
*/
@NonNull
private static String sanitizeSpanName(@NonNull String name) {
if (name.length() > MAX_SECTION_NAME_LEN) {
Log.w(TAG, "Span name exceeds limits: " + name);
name = name.substring(0, MAX_SECTION_NAME_LEN);
}
return name;
}
}