Home | History | Annotate | Download | only in base 
      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 <utility>
      9 
     10 #include "base/callback.h"
     11 #include "base/macros.h"
     12 #include "build/build_config.h"
     13 
     14 #if defined(OS_IOS)
     15 #include "base/bind.h"
     16 #include "base/ios/scoped_critical_action.h"
     17 #endif
     18 
     19 namespace base {
     20 
     21 namespace internal {
     22 
     23 #if defined(OS_IOS)
     24 // Returns true if multi-tasking is supported on this iOS device.
     25 bool IsMultiTaskingSupported();
     26 
     27 // This class wraps a closure so it can continue to run for a period of time
     28 // when the application goes to the background by using
     29 // |ios::ScopedCriticalAction|.
     30 class CriticalClosure {
     31  public:
     32   explicit CriticalClosure(OnceClosure closure);
     33   ~CriticalClosure();
     34   void Run();
     35 
     36  private:
     37   ios::ScopedCriticalAction critical_action_;
     38   OnceClosure closure_;
     39 
     40   DISALLOW_COPY_AND_ASSIGN(CriticalClosure);
     41 };
     42 #endif  // defined(OS_IOS)
     43 
     44 }  // namespace internal
     45 
     46 // Returns a closure that will continue to run for a period of time when the
     47 // application goes to the background if possible on platforms where
     48 // applications don't execute while backgrounded, otherwise the original task is
     49 // returned.
     50 //
     51 // Example:
     52 //   file_task_runner_->PostTask(
     53 //       FROM_HERE,
     54 //       MakeCriticalClosure(base::Bind(&WriteToDiskTask, path_, data)));
     55 //
     56 // Note new closures might be posted in this closure. If the new closures need
     57 // background running time, |MakeCriticalClosure| should be applied on them
     58 // before posting.
     59 #if defined(OS_IOS)
     60 inline OnceClosure MakeCriticalClosure(OnceClosure closure) {
     61   DCHECK(internal::IsMultiTaskingSupported());
     62   return base::BindOnce(
     63       &internal::CriticalClosure::Run,
     64       Owned(new internal::CriticalClosure(std::move(closure))));
     65 }
     66 #else  // defined(OS_IOS)
     67 inline OnceClosure MakeCriticalClosure(OnceClosure closure) {
     68   // No-op for platforms where the application does not need to acquire
     69   // background time for closures to finish when it goes into the background.
     70   return closure;
     71 }
     72 #endif  // defined(OS_IOS)
     73 
     74 }  // namespace base
     75 
     76 #endif  // BASE_CRITICAL_CLOSURE_H_
     77