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// Copyright 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#if !defined(NDEBUG)
#import "ios/chrome/app/UIApplication+ExitsOnSuspend.h"
#include "base/ios/block_types.h"
#include "base/logging.h"
#include "base/threading/thread_restrictions.h"
NSString* const kExitsOnSuspend = @"EnableExitsOnSuspend";
namespace {
int backgroundTasksCount = 0;
UIBackgroundTaskIdentifier countTaskIdentifier = UIBackgroundTaskInvalid;
// Perform a block on the main thread. Asynchronously if the thread is not the
// main thread, synchronously if the thread is the main thread.
void ExecuteBlockOnMainThread(ProceduralBlock block) {
if ([NSThread isMainThread])
block();
else
dispatch_async(dispatch_get_main_queue(), block);
}
} // namespace
// Category defining interposing methods. These methods keep a tally of the
// background tasks count.
@implementation UIApplication (BackgroundTasksCounter)
// Method to replace -beginBackgroundTaskWithExpirationHandler:. The original
// method is called within.
- (UIBackgroundTaskIdentifier)
cr_interpose_beginBackgroundTaskWithExpirationHandler:
(ProceduralBlock)handler {
UIBackgroundTaskIdentifier identifier =
[self cr_interpose_beginBackgroundTaskWithExpirationHandler:handler];
if (identifier != UIBackgroundTaskInvalid) {
ExecuteBlockOnMainThread(^{
backgroundTasksCount++;
});
}
return identifier;
}
// Method to replace -endBackgroundTask:. The original method is called within.
- (void)cr_interpose_endBackgroundTask:(UIBackgroundTaskIdentifier)identifier {
if (identifier != UIBackgroundTaskInvalid)
ExecuteBlockOnMainThread(^{
backgroundTasksCount--;
});
[self cr_interpose_endBackgroundTask:identifier];
}
@end
@interface UIApplication (ExitsOnSuspend_Private)
// Terminate the app immediately. exit(0) is used.
- (void)cr_terminateImmediately;
// Terminate the app via -cr_terminateImmediately when the background tasks
// count is one. The remaining task is the count observation task.
- (void)cr_terminateWhenCountIsOne;
@end
@implementation UIApplication (ExitsOnSuspend)
- (void)cr_terminateWhenDoneWithBackgroundTasks {
// Add a background task for the count observation.
DCHECK(countTaskIdentifier == UIBackgroundTaskInvalid);
countTaskIdentifier = [self beginBackgroundTaskWithExpirationHandler:^{
// If we get to the end of the 10 minutes, exit.
[self cr_terminateImmediately];
}];
[self cr_terminateWhenCountIsOne];
}
- (void)cr_cancelTermination {
[NSObject
cancelPreviousPerformRequestsWithTarget:self
selector:@selector(
cr_terminateWhenCountIsOne)
object:nil];
// Cancel the count observation background task.
[self endBackgroundTask:countTaskIdentifier];
countTaskIdentifier = UIBackgroundTaskInvalid;
}
#pragma mark - Private
- (void)cr_terminateImmediately {
DVLOG(1) << "App exited when suspended after running background tasks.";
// exit(0) will trigger at_exit handlers. Some need to be run on a IOAllowed
// thread, such as file_util::MemoryMappedFile::CloseHandles().
base::ThreadRestrictions::SetIOAllowed(true);
exit(0);
}
- (void)cr_terminateWhenCountIsOne {
if (backgroundTasksCount <= 1)
[self cr_terminateImmediately];
[self performSelector:_cmd withObject:nil afterDelay:1];
}
@end
#endif // !defined(NDEBUG)