1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_CRITICAL_CLOSURE_H_ 6 #define BASE_CRITICAL_CLOSURE_H_ 7 8 #include "base/callback.h" 9 10 #if defined(OS_IOS) 11 #include "base/bind.h" 12 #include "base/ios/scoped_critical_action.h" 13 #endif 14 15 namespace base { 16 17 namespace internal { 18 19 #if defined(OS_IOS) 20 // Returns true if multi-tasking is supported on this iOS device. 21 bool IsMultiTaskingSupported(); 22 23 // This class wraps a closure so it can continue to run for a period of time 24 // when the application goes to the background by using 25 // |ios::ScopedCriticalAction|. 26 template <typename R> 27 class CriticalClosure { 28 public: CriticalClosure(const Callback<R (void)> & closure)29 explicit CriticalClosure(const Callback<R(void)>& closure) 30 : closure_(closure) {} 31 ~CriticalClosure()32 ~CriticalClosure() {} 33 Run()34 R Run() { 35 return closure_.Run(); 36 } 37 38 private: 39 ios::ScopedCriticalAction critical_action_; 40 Callback<R(void)> closure_; 41 42 DISALLOW_COPY_AND_ASSIGN(CriticalClosure); 43 }; 44 #endif // defined(OS_IOS) 45 46 } // namespace internal 47 48 // Returns a closure (which may return a result, but must not require any extra 49 // arguments) that will continue to run for a period of time when the 50 // application goes to the background if possible on platforms where 51 // applications don't execute while backgrounded, otherwise the original task is 52 // returned. 53 // 54 // Example: 55 // file_message_loop_proxy_->PostTask( 56 // FROM_HERE, 57 // MakeCriticalClosure(base::Bind(&WriteToDiskTask, path_, data))); 58 // 59 // Note new closures might be posted in this closure. If the new closures need 60 // background running time, |MakeCriticalClosure| should be applied on them 61 // before posting. 62 #if defined(OS_IOS) 63 template <typename R> MakeCriticalClosure(const Callback<R (void)> & closure)64Callback<R(void)> MakeCriticalClosure(const Callback<R(void)>& closure) { 65 DCHECK(internal::IsMultiTaskingSupported()); 66 return base::Bind(&internal::CriticalClosure<R>::Run, 67 Owned(new internal::CriticalClosure<R>(closure))); 68 } 69 #else // defined(OS_IOS) 70 template <typename R> MakeCriticalClosure(const Callback<R (void)> & closure)71inline Callback<R(void)> MakeCriticalClosure(const Callback<R(void)>& closure) { 72 // No-op for platforms where the application does not need to acquire 73 // background time for closures to finish when it goes into the background. 74 return closure; 75 } 76 #endif // defined(OS_IOS) 77 78 } // namespace base 79 80 #endif // BASE_CRITICAL_CLOSURE_H_ 81