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Quick workaround for a performance regression in IME APIs.

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It turns out that the performance of
InputMethodManager#getCurrentInputMethodSubtype() is regressed from ~1ms
to ~20ms when
 - Settings.Secure.SELECTED_INPUT_METHOD_SUBTYPE == -1 and
 - The active IME supports many subtypes (~100)
because we try to find a fallback subtype based on the system locales
every time when IMM#getCurrentInputMethodSubtype() is called.

This could be contributing UI janks because spell checker clients
running in the UI thread indirectly depend on that method.

Fortunatelly the critical path is in
InputMethodUtils#getImplicitlyApplicableSubtypesLockedImpl(), which is
basically a state-less method. We can easily and safely cache its
result by using LocaleList and InputMethod as cache keys.

With this CL the performance basically recovers to the Android M level.

Bug: 28889203
Change-Id: I5ed16c7f14cc18052854f4fd6c9bae8550c332ee
This commit is contained in:
Yohei Yukawa
2016-06-13 22:16:52 -07:00
parent 82f2df6108
commit ccb024aa2b
1 changed files with 38 additions and 0 deletions
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38
core/java/com/android/internal/inputmethod/InputMethodUtils.java
View File

@@ -41,6 +41,7 @@ import android.view.inputmethod.InputMethodSubtype;
import android.view.textservice.SpellCheckerInfo;
import android.view.textservice.TextServicesManager;
import com.android.internal.annotations.GuardedBy;
import com.android.internal.annotations.VisibleForTesting;
import java.util.ArrayList;
@@ -83,6 +84,17 @@ public class InputMethodUtils {
Locale.UK, // "en_GB"
};
// A temporary workaround for the performance concerns in
// #getImplicitlyApplicableSubtypesLocked(Resources, InputMethodInfo).
// TODO: Optimize all the critical paths including this one.
private static final Object sCacheLock = new Object();
@GuardedBy("sCacheLock")
private static LocaleList sCachedSystemLocales;
@GuardedBy("sCacheLock")
private static InputMethodInfo sCachedInputMethodInfo;
@GuardedBy("sCacheLock")
private static ArrayList<InputMethodSubtype> sCachedResult;
private InputMethodUtils() {
// This utility class is not publicly instantiable.
}
@@ -498,6 +510,32 @@ public class InputMethodUtils {
@VisibleForTesting
public static ArrayList<InputMethodSubtype> getImplicitlyApplicableSubtypesLocked(
Resources res, InputMethodInfo imi) {
final LocaleList systemLocales = res.getConfiguration().getLocales();
synchronized (sCacheLock) {
// We intentionally do not use InputMethodInfo#equals(InputMethodInfo) here because
// it does not check if subtypes are also identical.
if (systemLocales.equals(sCachedSystemLocales) && sCachedInputMethodInfo == imi) {
return new ArrayList<>(sCachedResult);
}
}
// Note: Only resource info in "res" is used in getImplicitlyApplicableSubtypesLockedImpl().
// TODO: Refactor getImplicitlyApplicableSubtypesLockedImpl() so that it can receive
// LocaleList rather than Resource.
final ArrayList<InputMethodSubtype> result =
getImplicitlyApplicableSubtypesLockedImpl(res, imi);
synchronized (sCacheLock) {
// Both LocaleList and InputMethodInfo are immutable. No need to copy them here.
sCachedSystemLocales = systemLocales;
sCachedInputMethodInfo = imi;
sCachedResult = new ArrayList<>(result);
}
return result;
}
private static ArrayList<InputMethodSubtype> getImplicitlyApplicableSubtypesLockedImpl(
Resources res, InputMethodInfo imi) {
final List<InputMethodSubtype> subtypes = InputMethodUtils.getSubtypes(imi);
final LocaleList systemLocales = res.getConfiguration().getLocales();
final String systemLocale = systemLocales.get(0).toString();