flutter_flutter/shell/platform/embedder/embedder_task_runner.cc
Chinmay Garde cb8eb801a4
Allow embedders to specify their own task runner interfaces. (#8273)
Currently, all Flutter threads are managed by the engine itself. This works for
all threads except the platform thread. On this thread, the engine cannot see
the underlying event multiplexing mechanism. Using the new task runner
interfaces, the engine can relinquish the task of setting up the event
multiplexing mechanism and instead have the embedder provide one for it during
setup.

This scheme is only wired up for the platform thread. But, the eventual goal
is to expose this message loop interoperability for all threads.
2019-03-27 16:16:59 -07:00

73 lines
1.9 KiB
C++

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "flutter/shell/platform/embedder/embedder_task_runner.h"
#include "flutter/fml/message_loop_impl.h"
namespace shell {
EmbedderTaskRunner::EmbedderTaskRunner(DispatchTable table)
: TaskRunner(nullptr /* loop implemenation*/),
dispatch_table_(std::move(table)) {
FML_DCHECK(dispatch_table_.post_task_callback);
FML_DCHECK(dispatch_table_.runs_task_on_current_thread_callback);
}
EmbedderTaskRunner::~EmbedderTaskRunner() = default;
void EmbedderTaskRunner::PostTask(fml::closure task) {
PostTaskForTime(task, fml::TimePoint::Now());
}
void EmbedderTaskRunner::PostTaskForTime(fml::closure task,
fml::TimePoint target_time) {
if (!task) {
return;
}
uint64_t baton = 0;
{
// Release the lock before the jump via the dispatch table.
std::lock_guard<std::mutex> lock(tasks_mutex_);
baton = ++last_baton_;
pending_tasks_[baton] = task;
}
dispatch_table_.post_task_callback(this, baton, target_time);
}
void EmbedderTaskRunner::PostDelayedTask(fml::closure task,
fml::TimeDelta delay) {
PostTaskForTime(task, fml::TimePoint::Now() + delay);
}
bool EmbedderTaskRunner::RunsTasksOnCurrentThread() {
return dispatch_table_.runs_task_on_current_thread_callback();
}
bool EmbedderTaskRunner::PostTask(uint64_t baton) {
fml::closure task;
{
std::lock_guard<std::mutex> lock(tasks_mutex_);
auto found = pending_tasks_.find(baton);
if (found == pending_tasks_.end()) {
FML_LOG(ERROR) << "Embedder attempted to post an unknown task.";
return false;
}
task = found->second;
pending_tasks_.erase(found);
// Let go of the tasks mutex befor executing the task.
}
FML_DCHECK(task);
task();
return true;
}
} // namespace shell