Do not write SharedPreferences to disk in the main thread #1635
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StrictMode is most commonly used to catch accidental disk or network access on the application's main thread, where UI operations are received and animations take place. Keeping disk and network operations off the main thread makes for much smoother, more responsive applications[1]. [1] https://developer.android.com/reference/android/os/StrictMode
SettingsStore used to call editor.commit() to apply the value of a setting and write it to disk. That should not be done in the main thread though as it's a blocking operation. It's better to use apply() which atomically modifies the SharedPreferences object in memory and then uses a background thread to write it to disk. It's safe to replace commit() by apply() as long as the return value is not used, which is the case. This fixes reports like: D StrictMode policy violation; ~duration=3 ms: android.os.strictmode.DiskWriteViolation at android.os.StrictMode$AndroidBlockGuardPolicy.onWriteToDisk(StrictMode.java:1615) at libcore.io.BlockGuardOs.write(BlockGuardOs.java:446) at libcore.io.ForwardingOs.write(ForwardingOs.java:951) at libcore.io.IoBridge.write(IoBridge.java:649) at java.io.FileOutputStream.write(FileOutputStream.java:401) at com.android.internal.util.FastXmlSerializer.flushBytes(FastXmlSerializer.java:253) at com.android.internal.util.FastXmlSerializer.flush(FastXmlSerializer.java:274) at com.android.internal.util.FastXmlSerializer.endDocument(FastXmlSerializer.java:219) at com.android.internal.util.XmlSerializerWrapper.endDocument(XmlSerializerWrapper.java:68) at com.android.internal.util.XmlUtils.writeMapXml(XmlUtils.java:408) at android.app.SharedPreferencesImpl.writeToFile(SharedPreferencesImpl.java:803) at android.app.SharedPreferencesImpl.access$900(SharedPreferencesImpl.java:59) at android.app.SharedPreferencesImpl$2.run(SharedPreferencesImpl.java:672) at android.app.SharedPreferencesImpl.enqueueDiskWrite(SharedPreferencesImpl.java:691) at android.app.SharedPreferencesImpl.access$100(SharedPreferencesImpl.java:59) at android.app.SharedPreferencesImpl$EditorImpl.commit(SharedPreferencesImpl.java:604) at com.igalia.wolvic.browser.SettingsStore.resetCrashRestartCount(SettingsStore.java:766) at com.igalia.wolvic.VRBrowserActivity.lambda$onCreate$0$com-igalia-wolvic-VRBrowserActivity(VRBrowserActivity.java:296) at com.igalia.wolvic.VRBrowserActivity$$ExternalSyntheticLambda3.run(D8$$SyntheticClass:0) at android.os.Handler.handleCallback(Handler.java:938) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loopOnce(Looper.java:214) at android.os.Looper.loop(Looper.java:304) at android.app.ActivityThread.main(ActivityThread.java:7918) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1010)
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Note that the first commit is actually #1632 |
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SettingsStore used to call editor.commit() to apply the value of
a setting and write it to disk. That should not be done in the main
thread though as it's a blocking operation. It's better to use
apply() which atomically modifies the SharedPreferences object in
memory and then uses a background thread to write it to disk.
It's safe to replace commit() by apply() as long as the return
value is not used, which is the case.
This fixes reports like:
D StrictMode policy violation; ~duration=3 ms: android.os.strictmode.DiskWriteViolation
at android.os.StrictMode$AndroidBlockGuardPolicy.onWriteToDisk(StrictMode.java:1615)
at libcore.io.BlockGuardOs.write(BlockGuardOs.java:446)
at libcore.io.ForwardingOs.write(ForwardingOs.java:951)
at libcore.io.IoBridge.write(IoBridge.java:649)
at java.io.FileOutputStream.write(FileOutputStream.java:401)
at com.android.internal.util.FastXmlSerializer.flushBytes(FastXmlSerializer.java:253)
at com.android.internal.util.FastXmlSerializer.flush(FastXmlSerializer.java:274)
at com.android.internal.util.FastXmlSerializer.endDocument(FastXmlSerializer.java:219)
at com.android.internal.util.XmlSerializerWrapper.endDocument(XmlSerializerWrapper.java:68)
at com.android.internal.util.XmlUtils.writeMapXml(XmlUtils.java:408)
at android.app.SharedPreferencesImpl.writeToFile(SharedPreferencesImpl.java:803)
at android.app.SharedPreferencesImpl.access$900(SharedPreferencesImpl.java:59)
at android.app.SharedPreferencesImpl$2.run(SharedPreferencesImpl.java:672)
at android.app.SharedPreferencesImpl.enqueueDiskWrite(SharedPreferencesImpl.java:691)
at android.app.SharedPreferencesImpl.access$100(SharedPreferencesImpl.java:59)
at android.app.SharedPreferencesImpl$EditorImpl.commit(SharedPreferencesImpl.java:604)
at com.igalia.wolvic.browser.SettingsStore.resetCrashRestartCount(SettingsStore.java:766)
at com.igalia.wolvic.VRBrowserActivity.lambda$onCreate$0$com-igalia-wolvic-VRBrowserActivity(VRBrowserActivity.java:296)
at com.igalia.wolvic.VRBrowserActivity$$ExternalSyntheticLambda3.run(D8$$SyntheticClass:0)
at android.os.Handler.handleCallback(Handler.java:938)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loopOnce(Looper.java:214)
at android.os.Looper.loop(Looper.java:304)
at android.app.ActivityThread.main(ActivityThread.java:7918)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1010)