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 #include "base/macros.h" 10 #include "build/build_config.h" 11 12 #if defined(OS_IOS) 13 #include "base/bind.h" 14 #include "base/ios/scoped_critical_action.h" 15 #endif 16 17 namespace base { 18 19 namespace internal { 20 21 #if defined(OS_IOS) 22 // Returns true if multi-tasking is supported on this iOS device. 23 bool IsMultiTaskingSupported(); 24 25 // This class wraps a closure so it can continue to run for a period of time 26 // when the application goes to the background by using 27 // |ios::ScopedCriticalAction|. 28 template <typename R> 29 class CriticalClosure { 30 public: CriticalClosure(const Callback<R (void)> & closure)31 explicit CriticalClosure(const Callback<R(void)>& closure) 32 : closure_(closure) {} 33 ~CriticalClosure()34 ~CriticalClosure() {} 35 Run()36 R Run() { 37 return closure_.Run(); 38 } 39 40 private: 41 ios::ScopedCriticalAction critical_action_; 42 Callback<R(void)> closure_; 43 44 DISALLOW_COPY_AND_ASSIGN(CriticalClosure); 45 }; 46 #endif // defined(OS_IOS) 47 48 } // namespace internal 49 50 // Returns a closure (which may return a result, but must not require any extra 51 // arguments) that will continue to run for a period of time when the 52 // application goes to the background if possible on platforms where 53 // applications don't execute while backgrounded, otherwise the original task is 54 // returned. 55 // 56 // Example: 57 // file_task_runner_->PostTask( 58 // FROM_HERE, 59 // MakeCriticalClosure(base::Bind(&WriteToDiskTask, path_, data))); 60 // 61 // Note new closures might be posted in this closure. If the new closures need 62 // background running time, |MakeCriticalClosure| should be applied on them 63 // before posting. 64 #if defined(OS_IOS) 65 template <typename R> MakeCriticalClosure(const Callback<R (void)> & closure)66Callback<R(void)> MakeCriticalClosure(const Callback<R(void)>& closure) { 67 DCHECK(internal::IsMultiTaskingSupported()); 68 return base::Bind(&internal::CriticalClosure<R>::Run, 69 Owned(new internal::CriticalClosure<R>(closure))); 70 } 71 #else // defined(OS_IOS) 72 template <typename R> MakeCriticalClosure(const Callback<R (void)> & closure)73inline Callback<R(void)> MakeCriticalClosure(const Callback<R(void)>& closure) { 74 // No-op for platforms where the application does not need to acquire 75 // background time for closures to finish when it goes into the background. 76 return closure; 77 } 78 #endif // defined(OS_IOS) 79 80 } // namespace base 81 82 #endif // BASE_CRITICAL_CLOSURE_H_ 83