Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 1 | // Copyright 2016 the V8 project 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 V8_HEAP_PAGE_PARALLEL_JOB_ |
| 6 | #define V8_HEAP_PAGE_PARALLEL_JOB_ |
| 7 | |
| 8 | #include "src/allocation.h" |
| 9 | #include "src/cancelable-task.h" |
| 10 | #include "src/utils.h" |
| 11 | #include "src/v8.h" |
| 12 | |
| 13 | namespace v8 { |
| 14 | namespace internal { |
| 15 | |
| 16 | class Heap; |
| 17 | class Isolate; |
| 18 | |
| 19 | // This class manages background tasks that process set of pages in parallel. |
| 20 | // The JobTraits class needs to define: |
| 21 | // - PerPageData type - state associated with each page. |
| 22 | // - PerTaskData type - state associated with each task. |
| 23 | // - static bool ProcessPageInParallel(Heap* heap, |
| 24 | // PerTaskData task_data, |
| 25 | // MemoryChunk* page, |
| 26 | // PerPageData page_data) |
| 27 | // The function should return true iff processing succeeded. |
| 28 | // - static const bool NeedSequentialFinalization |
| 29 | // - static void FinalizePageSequentially(Heap* heap, |
| 30 | // bool processing_succeeded, |
| 31 | // MemoryChunk* page, |
| 32 | // PerPageData page_data) |
| 33 | template <typename JobTraits> |
| 34 | class PageParallelJob { |
| 35 | public: |
Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame^] | 36 | // PageParallelJob cannot dynamically create a semaphore because of a bug in |
| 37 | // glibc. See http://crbug.com/609249 and |
| 38 | // https://sourceware.org/bugzilla/show_bug.cgi?id=12674. |
| 39 | // The caller must provide a semaphore with value 0 and ensure that |
| 40 | // the lifetime of the semaphore is the same as the lifetime of the Isolate. |
| 41 | // It is guaranteed that the semaphore value will be 0 after Run() call. |
| 42 | PageParallelJob(Heap* heap, CancelableTaskManager* cancelable_task_manager, |
| 43 | base::Semaphore* semaphore) |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 44 | : heap_(heap), |
| 45 | cancelable_task_manager_(cancelable_task_manager), |
| 46 | items_(nullptr), |
| 47 | num_items_(0), |
| 48 | num_tasks_(0), |
Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame^] | 49 | pending_tasks_(semaphore) {} |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 50 | |
| 51 | ~PageParallelJob() { |
| 52 | Item* item = items_; |
| 53 | while (item != nullptr) { |
| 54 | Item* next = item->next; |
| 55 | delete item; |
| 56 | item = next; |
| 57 | } |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 58 | } |
| 59 | |
| 60 | void AddPage(MemoryChunk* chunk, typename JobTraits::PerPageData data) { |
| 61 | Item* item = new Item(chunk, data, items_); |
| 62 | items_ = item; |
| 63 | ++num_items_; |
| 64 | } |
| 65 | |
| 66 | int NumberOfPages() { return num_items_; } |
| 67 | |
| 68 | // Returns the number of tasks that were spawned when running the job. |
| 69 | int NumberOfTasks() { return num_tasks_; } |
| 70 | |
| 71 | // Runs the given number of tasks in parallel and processes the previously |
| 72 | // added pages. This function blocks until all tasks finish. |
| 73 | // The callback takes the index of a task and returns data for that task. |
| 74 | template <typename Callback> |
| 75 | void Run(int num_tasks, Callback per_task_data_callback) { |
| 76 | if (num_items_ == 0) return; |
| 77 | DCHECK_GE(num_tasks, 1); |
| 78 | uint32_t task_ids[kMaxNumberOfTasks]; |
| 79 | const int max_num_tasks = Min( |
| 80 | kMaxNumberOfTasks, |
| 81 | static_cast<int>( |
| 82 | V8::GetCurrentPlatform()->NumberOfAvailableBackgroundThreads())); |
| 83 | num_tasks_ = Max(1, Min(num_tasks, max_num_tasks)); |
| 84 | int items_per_task = (num_items_ + num_tasks_ - 1) / num_tasks_; |
| 85 | int start_index = 0; |
| 86 | Task* main_task = nullptr; |
| 87 | for (int i = 0; i < num_tasks_; i++, start_index += items_per_task) { |
| 88 | if (start_index >= num_items_) { |
| 89 | start_index -= num_items_; |
| 90 | } |
| 91 | Task* task = new Task(heap_, items_, num_items_, start_index, |
| 92 | pending_tasks_, per_task_data_callback(i)); |
| 93 | task_ids[i] = task->id(); |
| 94 | if (i > 0) { |
| 95 | V8::GetCurrentPlatform()->CallOnBackgroundThread( |
| 96 | task, v8::Platform::kShortRunningTask); |
| 97 | } else { |
| 98 | main_task = task; |
| 99 | } |
| 100 | } |
| 101 | // Contribute on main thread. |
| 102 | main_task->Run(); |
| 103 | delete main_task; |
| 104 | // Wait for background tasks. |
| 105 | for (int i = 0; i < num_tasks_; i++) { |
| 106 | if (!cancelable_task_manager_->TryAbort(task_ids[i])) { |
| 107 | pending_tasks_->Wait(); |
| 108 | } |
| 109 | } |
| 110 | if (JobTraits::NeedSequentialFinalization) { |
| 111 | Item* item = items_; |
| 112 | while (item != nullptr) { |
| 113 | bool success = (item->state.Value() == kFinished); |
| 114 | JobTraits::FinalizePageSequentially(heap_, item->chunk, success, |
| 115 | item->data); |
| 116 | item = item->next; |
| 117 | } |
| 118 | } |
| 119 | } |
| 120 | |
| 121 | private: |
| 122 | static const int kMaxNumberOfTasks = 10; |
| 123 | |
| 124 | enum ProcessingState { kAvailable, kProcessing, kFinished, kFailed }; |
| 125 | |
| 126 | struct Item : public Malloced { |
| 127 | Item(MemoryChunk* chunk, typename JobTraits::PerPageData data, Item* next) |
| 128 | : chunk(chunk), state(kAvailable), data(data), next(next) {} |
| 129 | MemoryChunk* chunk; |
Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame^] | 130 | base::AtomicValue<ProcessingState> state; |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 131 | typename JobTraits::PerPageData data; |
| 132 | Item* next; |
| 133 | }; |
| 134 | |
| 135 | class Task : public CancelableTask { |
| 136 | public: |
| 137 | Task(Heap* heap, Item* items, int num_items, int start_index, |
| 138 | base::Semaphore* on_finish, typename JobTraits::PerTaskData data) |
| 139 | : CancelableTask(heap->isolate()), |
| 140 | heap_(heap), |
| 141 | items_(items), |
| 142 | num_items_(num_items), |
| 143 | start_index_(start_index), |
| 144 | on_finish_(on_finish), |
| 145 | data_(data) {} |
| 146 | |
| 147 | virtual ~Task() {} |
| 148 | |
| 149 | private: |
| 150 | // v8::internal::CancelableTask overrides. |
| 151 | void RunInternal() override { |
| 152 | // Each task starts at a different index to improve parallelization. |
| 153 | Item* current = items_; |
| 154 | int skip = start_index_; |
| 155 | while (skip-- > 0) { |
| 156 | current = current->next; |
| 157 | } |
| 158 | for (int i = 0; i < num_items_; i++) { |
| 159 | if (current->state.TrySetValue(kAvailable, kProcessing)) { |
| 160 | bool success = JobTraits::ProcessPageInParallel( |
| 161 | heap_, data_, current->chunk, current->data); |
| 162 | current->state.SetValue(success ? kFinished : kFailed); |
| 163 | } |
| 164 | current = current->next; |
| 165 | // Wrap around if needed. |
| 166 | if (current == nullptr) { |
| 167 | current = items_; |
| 168 | } |
| 169 | } |
| 170 | on_finish_->Signal(); |
| 171 | } |
| 172 | |
| 173 | Heap* heap_; |
| 174 | Item* items_; |
| 175 | int num_items_; |
| 176 | int start_index_; |
| 177 | base::Semaphore* on_finish_; |
| 178 | typename JobTraits::PerTaskData data_; |
| 179 | DISALLOW_COPY_AND_ASSIGN(Task); |
| 180 | }; |
| 181 | |
| 182 | Heap* heap_; |
| 183 | CancelableTaskManager* cancelable_task_manager_; |
| 184 | Item* items_; |
| 185 | int num_items_; |
| 186 | int num_tasks_; |
| 187 | base::Semaphore* pending_tasks_; |
| 188 | DISALLOW_COPY_AND_ASSIGN(PageParallelJob); |
| 189 | }; |
| 190 | |
| 191 | } // namespace internal |
| 192 | } // namespace v8 |
| 193 | |
| 194 | #endif // V8_HEAP_PAGE_PARALLEL_JOB_ |