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→Usage for start up: add Android 11+ instructions
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(→Usage for start up: add Android 11+ instructions) |
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You can open <code>*.trace</code> files generated by the Debug API in the Firefox Profiler. Just go to https://profiler.firefox.com/ and click "Load a profile from a file". The profiler interface works nearly as well as profiles taken within the Firefox Profiler. | You can open <code>*.trace</code> files generated by the Debug API in the Firefox Profiler. Just go to https://profiler.firefox.com/ and click "Load a profile from a file". The profiler interface works nearly as well as profiles taken within the Firefox Profiler. | ||
== Usage for start up == | == Usage for start up: Android 11 and later == | ||
On Android 11 and later OS versions, we need to save the profile data to a file within our data directory, prompt the user to create a file for us, and copy the profile data into that file. | |||
First, you need to start tracing. Add the following to <code>FenixApplication.kt</code> to measure start up as early as possible: | |||
<syntaxhighlight lang="kotlin"> | |||
override fun attachBaseContext(base: Context) { | |||
if (base.isMainProcess()) { | |||
Debug.startMethodTracingSampling( | |||
base.filesDir.absolutePath + "/startup.trace", | |||
0, | |||
TimeUnit.MILLISECONDS.toMicros(1).toInt() | |||
) | |||
} | |||
super.attachBaseContext(base) | |||
} | |||
</syntaxhighlight> | |||
Then, we need to stop tracing by calling <code>Debug.stopMethodTracing()</code>: where you call this depends on what you're trying to profile. Immediately after we stop the profiler, we need to prompt the user for a file we can save the profile into. An easy place to put it all is at the end of <code>HomeActivity.onResume</code>. Here is a sample of code you can add to that method: | |||
<syntaxhighlight lang="kotlin"> | |||
Debug.stopMethodTracing() | |||
val intent = Intent(Intent.ACTION_CREATE_DOCUMENT).apply { | |||
addCategory(Intent.CATEGORY_OPENABLE) | |||
type = "application/octet-stream" | |||
putExtra(Intent.EXTRA_TITLE, "startup.trace") | |||
} | |||
@Suppress("DEPRECATION") | |||
startActivityForResult(intent, 1234) | |||
</syntaxhighlight> | |||
Then we need to add code to <code>onActivityResult</code> to get the file path the user selected and copy the profile data to that file: | |||
<syntaxhighlight lang="kotlin"> | |||
if (requestCode == 1234) { | |||
require(resultCode == Activity.RESULT_OK) | |||
data?.data?.also { uri -> | |||
// This is main thread IO: we should never do this in a production app. | |||
File(filesDir.absolutePath + "/startup.trace").inputStream().buffered().use { inputStream -> | |||
contentResolver.openOutputStream(uri)!!.buffered().use { outputStream -> | |||
val buffer = ByteArray(1024 * 8) | |||
while (true) { | |||
val bytesRead = inputStream.read(buffer, 0, 1024 * 8) | |||
if (bytesRead != -1) { | |||
outputStream.write(buffer, 0, bytesRead) | |||
} else { | |||
break | |||
} | |||
} | |||
} | |||
} | |||
} | |||
} | |||
</syntaxhighlight> | |||
Once the device has hit <code>stopMethodTracing</code> and you selected a save location, you can pull the profile from the device. For example, if you saved <code>startup.trace</code> to the downloads directory, you can probably run: | |||
<syntaxhighlight lang="sh"> | |||
adb pull /sdcard/Download/startup.trace | |||
</syntaxhighlight> | |||
This profile can then be [[#Firefox Profiler interface|opened by the Firefox Profiler]] (preferred) or the Android Studio profiler (with File -> Open). | |||
== Usage for start up: Android 10 and earlier == | |||
On Android 10 and earlier OS versions, we can use a simpler technique: we can write the profile data directly to external storage. | |||
First, you need to start tracing. Add the following to <code>FenixApplication.kt</code> to measure start up as early as possible: | First, you need to start tracing. Add the following to <code>FenixApplication.kt</code> to measure start up as early as possible: | ||