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/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.os;
import android.content.Context;
import android.util.Log;
/**
* Advisory wakelock-like mechanism by which processes that should not be interrupted for
* OTA/update purposes can so advise the OS. This is particularly relevant for headless
* or kiosk-like operation.
*
* @hide
*/
public class UpdateLock {
private static final boolean DEBUG = false;
private static final String TAG = "UpdateLock";
private static IUpdateLock sService;
private static void checkService() {
if (sService == null) {
sService = IUpdateLock.Stub.asInterface(
ServiceManager.getService(Context.UPDATE_LOCK_SERVICE));
}
}
IBinder mToken;
int mCount = 0;
boolean mRefCounted = true;
boolean mHeld = false;
final String mTag;
/**
* Broadcast Intent action sent when the global update lock state changes,
* i.e. when the first locker acquires an update lock, or when the last
* locker releases theirs. The broadcast is sticky but is sent only to
* registered receivers.
*/
public static final String UPDATE_LOCK_CHANGED = "android.os.UpdateLock.UPDATE_LOCK_CHANGED";
/**
* Boolean Intent extra on the UPDATE_LOCK_CHANGED sticky broadcast, indicating
* whether now is an appropriate time to interrupt device activity with an
* update operation. True means that updates are okay right now; false indicates
* that perhaps later would be a better time.
*/
public static final String NOW_IS_CONVENIENT = "nowisconvenient";
/**
* Long Intent extra on the UPDATE_LOCK_CHANGED sticky broadcast, marking the
* wall-clock time [in UTC] at which the broadcast was sent. Note that this is
* in the System.currentTimeMillis() time base, which may be non-monotonic especially
* around reboots.
*/
public static final String TIMESTAMP = "timestamp";
/**
* Construct an UpdateLock instance.
* @param tag An arbitrary string used to identify this lock instance in dump output.
*/
public UpdateLock(String tag) {
mTag = tag;
mToken = new Binder();
}
/**
* Change the refcount behavior of this update lock.
*/
public void setReferenceCounted(boolean isRefCounted) {
if (DEBUG) {
Log.v(TAG, "setting refcounted=" + isRefCounted + " : " + this);
}
mRefCounted = isRefCounted;
}
/**
* Is this lock currently held?
*/
public boolean isHeld() {
synchronized (mToken) {
return mHeld;
}
}
/**
* Acquire an update lock.
*/
public void acquire() {
if (DEBUG) {
Log.v(TAG, "acquire() : " + this, new RuntimeException("here"));
}
checkService();
synchronized (mToken) {
acquireLocked();
}
}
private void acquireLocked() {
if (!mRefCounted || mCount++ == 0) {
if (sService != null) {
try {
sService.acquireUpdateLock(mToken, mTag);
} catch (RemoteException e) {
Log.e(TAG, "Unable to contact service to acquire");
}
}
mHeld = true;
}
}
/**
* Release this update lock.
*/
public void release() {
if (DEBUG) Log.v(TAG, "release() : " + this, new RuntimeException("here"));
checkService();
synchronized (mToken) {
releaseLocked();
}
}
private void releaseLocked() {
if (!mRefCounted || --mCount == 0) {
if (sService != null) {
try {
sService.releaseUpdateLock(mToken);
} catch (RemoteException e) {
Log.e(TAG, "Unable to contact service to release");
}
}
mHeld = false;
}
if (mCount < 0) {
throw new RuntimeException("UpdateLock under-locked");
}
}
@Override
protected void finalize() throws Throwable {
synchronized (mToken) {
// if mHeld is true, sService must be non-null
if (mHeld) {
Log.wtf(TAG, "UpdateLock finalized while still held");
try {
sService.releaseUpdateLock(mToken);
} catch (RemoteException e) {
Log.e(TAG, "Unable to contact service to release");
}
}
}
}
}
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