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Allow DiskRead ThreadPolicy in LetterboxConfigurationPersister

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The LetterboxConfigurationDeviceConfig needs to access the
file with the current reachability position once when the
device boots. Because DisplayThread uses allowIo=false
accessing a file triggers a DiskReadViolation.
Here we use StrictMode to allow the current thread to read
the AtomicFile once in the current thread restoring the
original ThreadPolicy after that.

Fix: 286620565
Test: Run `atest WmTests:LetterboxConfigurationDeviceConfigTests`

Change-Id: Ia358de8c817eea987547c82df0ea8612591c0600
This commit is contained in:
Massimo Carli
2023-06-20 20:16:46 +00:00
parent 01158d6e17
commit 0aea1f3800
1 changed files with 19 additions and 1 deletions
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20
services/core/java/com/android/server/wm/LetterboxConfigurationPersister.java
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@@ -16,6 +16,8 @@
package com.android.server.wm;
import static android.os.StrictMode.setThreadPolicy;
import static com.android.server.wm.WindowManagerDebugConfig.TAG_WITH_CLASS_NAME;
import static com.android.server.wm.WindowManagerDebugConfig.TAG_WM;
@@ -23,6 +25,8 @@ import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.Context;
import android.os.Environment;
import android.os.StrictMode;
import android.os.StrictMode.ThreadPolicy;
import android.util.AtomicFile;
import android.util.Slog;
@@ -125,7 +129,7 @@ class LetterboxConfigurationPersister {
final File prefFiles = new File(configFolder, LETTERBOX_CONFIGURATION_FILENAME);
mConfigurationFile = new AtomicFile(prefFiles);
mPersisterQueue = persisterQueue;
readCurrentConfiguration();
runWithDiskReadsThreadPolicy(this::readCurrentConfiguration);
}
/**
@@ -275,6 +279,20 @@ class LetterboxConfigurationPersister {
}
}
// The LetterboxConfigurationDeviceConfig needs to access the
// file with the current reachability position once when the
// device boots. Because DisplayThread uses allowIo=false
// accessing a file triggers a DiskReadViolation.
// Here we use StrictMode to allow the current thread to read
// the AtomicFile once in the current thread restoring the
// original ThreadPolicy after that.
private void runWithDiskReadsThreadPolicy(Runnable runnable) {
final ThreadPolicy currentPolicy = StrictMode.getThreadPolicy();
setThreadPolicy(new ThreadPolicy.Builder().permitDiskReads().build());
runnable.run();
setThreadPolicy(currentPolicy);
}
private static class UpdateValuesCommand implements
PersisterQueue.WriteQueueItem<UpdateValuesCommand> {