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gaaclarke
104 lines
3.9 KiB
C++
104 lines
3.9 KiB
C++
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef FLUTTER_SHELL_PLATFORM_EMBEDDER_EMBEDDER_TASK_RUNNER_H_
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#define FLUTTER_SHELL_PLATFORM_EMBEDDER_EMBEDDER_TASK_RUNNER_H_
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#include <mutex>
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#include <unordered_map>
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#include "flutter/fml/macros.h"
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#include "flutter/fml/task_runner.h"
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namespace flutter {
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//------------------------------------------------------------------------------
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/// A task runner which delegates responsibility of task execution to an
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/// embedder. This is done by managing a dispatch table to the embedder.
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///
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class EmbedderTaskRunner final : public fml::TaskRunner {
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public:
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//----------------------------------------------------------------------------
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/// @brief A
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///
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struct DispatchTable {
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//--------------------------------------------------------------------------
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/// Delegates responsibility of deferred task execution to the embedder.
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/// Once the embedder gets the task, it must call
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/// `EmbedderTaskRunner::PostTask` with the supplied `task_baton` on the
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/// correct thread after the tasks `target_time` point expires.
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///
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std::function<void(EmbedderTaskRunner* task_runner,
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uint64_t task_baton,
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fml::TimePoint target_time)>
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post_task_callback;
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//--------------------------------------------------------------------------
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/// Asks the embedder if tasks posted to it on this task task runner via the
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/// `post_task_callback` will be executed (after task expiry) on the calling
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/// thread.
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///
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std::function<bool(void)> runs_task_on_current_thread_callback;
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};
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//----------------------------------------------------------------------------
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/// @brief Create a task runner with a dispatch table for delegation of
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/// task runner responsibility to the embedder. When embedders
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/// specify task runner dispatch tables that service tasks on the
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/// same thread, they also must ensure that their
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/// `embedder_idetifier`s match. This allows the engine to
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/// determine task runner equality without actually posting tasks
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/// to the task runner.
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///
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/// @param[in] table The task runner dispatch table.
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/// @param[in] embedder_identifier The embedder identifier
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///
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EmbedderTaskRunner(DispatchTable table, size_t embedder_identifier);
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// |fml::TaskRunner|
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~EmbedderTaskRunner() override;
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//----------------------------------------------------------------------------
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/// @brief The unique identifier provided by the embedder for the task
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/// runner. Embedders whose dispatch tables service tasks on the
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/// same underlying OS thread must ensure that their identifiers
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/// match. This allows the engine to determine task runner
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/// equality without posting tasks on the thread.
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///
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/// @return The embedder identifier.
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///
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size_t GetEmbedderIdentifier() const;
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bool PostTask(uint64_t baton);
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private:
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const size_t embedder_identifier_;
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DispatchTable dispatch_table_;
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std::mutex tasks_mutex_;
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uint64_t last_baton_;
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std::unordered_map<uint64_t, fml::closure> pending_tasks_;
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fml::TaskQueueId placeholder_id_;
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// |fml::TaskRunner|
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void PostTask(const fml::closure& task) override;
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// |fml::TaskRunner|
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void PostTaskForTime(const fml::closure& task,
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fml::TimePoint target_time) override;
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// |fml::TaskRunner|
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void PostDelayedTask(const fml::closure& task, fml::TimeDelta delay) override;
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// |fml::TaskRunner|
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bool RunsTasksOnCurrentThread() override;
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// |fml::TaskRunner|
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fml::TaskQueueId GetTaskQueueId() override;
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FML_DISALLOW_COPY_AND_ASSIGN(EmbedderTaskRunner);
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};
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} // namespace flutter
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#endif // FLUTTER_SHELL_PLATFORM_EMBEDDER_EMBEDDER_TASK_RUNNER_H_
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