base/critical_closure.h

   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/location.h"
  12 #include "base/strings/string_piece.h"
  13 #include "build/build_config.h"
  14
  15 #if defined(OS_IOS)
  16 #include "base/bind.h"
  17 #include "base/ios/scoped_critical_action.h"
  18 #endif
  19
  20 namespace base {
  21
  22 namespace internal {
  23
  24 #if defined(OS_IOS)
  25 // Returns true if multi-tasking is supported on this iOS device.
  26 bool IsMultiTaskingSupported();
  27
  28 // This class wraps a closure so it can continue to run for a period of time
  29 // when the application goes to the background by using
  30 // |ios::ScopedCriticalAction|.
  31 class CriticalClosure {
  32  public:
  33   explicit CriticalClosure(StringPiece task_name, OnceClosure closure);
  34   CriticalClosure(const CriticalClosure&) = delete;
  35   CriticalClosure& operator=(const CriticalClosure&) = delete;
  36   ~CriticalClosure();
  37   void Run();
  38
  39  private:
  40   ios::ScopedCriticalAction critical_action_;
  41   OnceClosure closure_;
  42 };
  43 #endif  // defined(OS_IOS)
  44
  45 }  // namespace internal
  46
  47 // Returns a closure that will continue to run for a period of time when the
  48 // application goes to the background if possible on platforms where
  49 // applications don't execute while backgrounded, otherwise the original task is
  50 // returned.
  51 //
  52 // Example:
  53 //   file_task_runner_->PostTask(
  54 //       FROM_HERE,
  55 //       MakeCriticalClosure(task_name,
  56 //                           base::BindOnce(&WriteToDiskTask, path_, data)));
  57 //
  58 // Note new closures might be posted in this closure. If the new closures need
  59 // background running time, |MakeCriticalClosure| should be applied on them
  60 // before posting. |task_name| is used by the platform to identify any tasks
  61 // that do not complete in time for suspension.
  62 #if defined(OS_IOS)
  63 inline OnceClosure MakeCriticalClosure(StringPiece task_name,
  64                                        OnceClosure closure) {
  65   DCHECK(internal::IsMultiTaskingSupported());
  66   return base::BindOnce(
  67       &internal::CriticalClosure::Run,
  68       Owned(new internal::CriticalClosure(task_name, std::move(closure))));
  69 }
  70
  71 inline OnceClosure MakeCriticalClosure(const Location& posted_from,
  72                                        OnceClosure closure) {
  73   return MakeCriticalClosure(posted_from.ToString(), std::move(closure));
  74 }
  75
  76 #else  // defined(OS_IOS)
  77 inline OnceClosure MakeCriticalClosure(StringPiece task_name,
  78                                        OnceClosure closure) {
  79   // No-op for platforms where the application does not need to acquire
  80   // background time for closures to finish when it goes into the background.
  81   return closure;
  82 }
  83
  84 inline OnceClosure MakeCriticalClosure(const Location& posted_from,
  85                                        OnceClosure closure) {
  86   return closure;
  87 }
  88
  89 #endif  // defined(OS_IOS)
  90
  91 }  // namespace base
  92
  93 #endif  // BASE_CRITICAL_CLOSURE_H_