// Copyright 2018 The Fuchsia 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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// Can't compile this for Zircon userspace yet since libstdc++ isn't available.
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#ifndef FIT_NO_STD_FOR_ZIRCON_USERSPACE
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#include <lib/fit/scheduler.h>
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#include <map>
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#include <queue>
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#include <utility>
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namespace fit {
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namespace subtle {
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scheduler::scheduler() = default;
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scheduler::~scheduler() = default;
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void scheduler::schedule_task(pending_task task) {
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assert(task);
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runnable_tasks_.push(std::move(task));
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}
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suspended_task::ticket scheduler::obtain_ticket(uint32_t initial_refs) {
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suspended_task::ticket ticket = next_ticket_++;
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tickets_.emplace(ticket, ticket_record(initial_refs));
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return ticket;
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}
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void scheduler::finalize_ticket(suspended_task::ticket ticket,
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pending_task* task) {
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auto it = tickets_.find(ticket);
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assert(it != tickets_.end());
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assert(!it->second.task);
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assert(it->second.ref_count > 0);
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assert(task);
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it->second.ref_count--;
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if (!*task) {
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// task already finished
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} else if (it->second.was_resumed) {
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// task immediately became runnable
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runnable_tasks_.push(std::move(*task));
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} else if (it->second.ref_count > 0) {
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// task remains suspended
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it->second.task = std::move(*task);
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suspended_task_count_++;
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} // else, task was abandoned and caller retains ownership of it
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if (it->second.ref_count == 0) {
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tickets_.erase(it);
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}
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}
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void scheduler::duplicate_ticket(suspended_task::ticket ticket) {
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auto it = tickets_.find(ticket);
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assert(it != tickets_.end());
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assert(it->second.ref_count > 0);
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it->second.ref_count++;
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assert(it->second.ref_count != 0); // did we really make 4 billion refs?!
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}
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pending_task scheduler::release_ticket(suspended_task::ticket ticket) {
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auto it = tickets_.find(ticket);
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assert(it != tickets_.end());
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assert(it->second.ref_count > 0);
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it->second.ref_count--;
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if (it->second.ref_count == 0) {
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pending_task task = std::move(it->second.task);
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if (task) {
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assert(suspended_task_count_ > 0);
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suspended_task_count_--;
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}
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tickets_.erase(it);
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return task;
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}
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return pending_task();
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}
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bool scheduler::resume_task_with_ticket(suspended_task::ticket ticket) {
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auto it = tickets_.find(ticket);
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assert(it != tickets_.end());
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assert(it->second.ref_count > 0);
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bool did_resume = false;
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it->second.ref_count--;
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if (!it->second.was_resumed) {
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it->second.was_resumed = true;
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if (it->second.task) {
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did_resume = true;
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assert(suspended_task_count_ > 0);
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suspended_task_count_--;
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runnable_tasks_.push(std::move(it->second.task));
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}
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}
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if (it->second.ref_count == 0) {
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tickets_.erase(it);
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}
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return did_resume;
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}
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void scheduler::take_runnable_tasks(task_queue* tasks) {
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assert(tasks && tasks->empty());
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runnable_tasks_.swap(*tasks);
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}
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void scheduler::take_all_tasks(task_queue* tasks) {
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assert(tasks && tasks->empty());
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runnable_tasks_.swap(*tasks);
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if (suspended_task_count_ > 0) {
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for (auto& item : tickets_) {
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if (item.second.task) {
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assert(suspended_task_count_ > 0);
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suspended_task_count_--;
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tasks->push(std::move(item.second.task));
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}
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}
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}
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}
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} // namespace subtle
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} // namespace fit
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#endif // FIT_NO_STD_FOR_ZIRCON_USERSPACE
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