LineageOS/android_packages_modules_Connectivity
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Frameworks/base: Make debug helper lazy in ConnectivityManager

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Place helper map for callback field names into a holder. This avoids
the reflective calls in static initialization of ConnectivityManager
in the common (non-debug) case, which means the class can be
compile-time initialized. Also saves the storage necessary (both
the storage array as well as the reflection metadata).

Follow-up to 7e28683228.

Bug: 27265238
Change-Id: Ib4bfaf27acd234a035a5d198458340099a156a4c
This commit is contained in:
Andreas Gampe
2016-04-20 14:33:51 -07:00
parent a616d96929
commit 9537278b82
1 changed files with 28 additions and 7 deletions
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35
core/java/android/net/ConnectivityManager.java
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@@ -81,13 +81,6 @@ import java.util.concurrent.atomic.AtomicInteger;
public class ConnectivityManager {
private static final String TAG = "ConnectivityManager";
private static final SparseArray<String> sMagicDecoderRing = MessageUtils.findMessageNames(
new Class[]{ConnectivityManager.class}, new String[]{"CALLBACK_"});
private static final String whatToString(int what) {
return sMagicDecoderRing.get(what, Integer.toString(what));
}
/**
* A change in network connectivity has occurred. A default connection has either
* been established or lost. The NetworkInfo for the affected network is
@@ -3360,4 +3353,32 @@ public class ConnectivityManager {
throw e.rethrowFromSystemServer();
}
}
/**
* A holder class for debug info (mapping CALLBACK values to field names). This is stored
* in a holder for two reasons:
* 1) The reflection necessary to establish the map can't be run at compile-time. Thus, this
* code will make the enclosing class not compile-time initializeable, deferring its
* initialization to zygote startup. This leads to dirty (but shared) memory.
* As this is debug info, use a holder that isn't initialized by default. This way the map
* will be created on demand, while ConnectivityManager can be compile-time initialized.
* 2) Static initialization is still preferred for its strong thread safety guarantees without
* requiring a lock.
*/
private static class NoPreloadHolder {
public static final SparseArray<String> sMagicDecoderRing = MessageUtils.findMessageNames(
new Class[]{ConnectivityManager.class}, new String[]{"CALLBACK_"});
}
static {
// When debug is enabled, aggressively initialize the holder by touching the field (which
// will guarantee static initialization).
if (CallbackHandler.DBG) {
Object dummy = NoPreloadHolder.sMagicDecoderRing;
}
}
private static final String whatToString(int what) {
return NoPreloadHolder.sMagicDecoderRing.get(what, Integer.toString(what));
}
}