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 15namespace base { 16 17namespace internal { 18 19#if defined(OS_IOS) 20// Returns true if multi-tasking is supported on this iOS device. 21bool 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|. 26template <typename R> 27class CriticalClosure { 28 public: 29 explicit CriticalClosure(const Callback<R(void)>& closure) 30 : closure_(closure) {} 31 32 ~CriticalClosure() {} 33 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) 63template <typename R> 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) 70template <typename R> 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