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- // Copyright (c) 2012 The Chromium 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 "net/base/prioritized_dispatcher.h"
- #include <ostream>
- #include "base/check_op.h"
- namespace net {
- PrioritizedDispatcher::Limits::Limits(Priority num_priorities,
- size_t total_jobs)
- : total_jobs(total_jobs), reserved_slots(num_priorities) {}
- PrioritizedDispatcher::Limits::Limits(const Limits& other) = default;
- PrioritizedDispatcher::Limits::~Limits() = default;
- PrioritizedDispatcher::PrioritizedDispatcher(const Limits& limits)
- : queue_(limits.reserved_slots.size()),
- max_running_jobs_(limits.reserved_slots.size()) {
- SetLimits(limits);
- }
- PrioritizedDispatcher::~PrioritizedDispatcher() = default;
- PrioritizedDispatcher::Handle PrioritizedDispatcher::Add(
- Job* job, Priority priority) {
- DCHECK(job);
- DCHECK_LT(priority, num_priorities());
- if (num_running_jobs_ < max_running_jobs_[priority]) {
- ++num_running_jobs_;
- job->Start();
- return Handle();
- }
- return queue_.Insert(job, priority);
- }
- PrioritizedDispatcher::Handle PrioritizedDispatcher::AddAtHead(
- Job* job, Priority priority) {
- DCHECK(job);
- DCHECK_LT(priority, num_priorities());
- if (num_running_jobs_ < max_running_jobs_[priority]) {
- ++num_running_jobs_;
- job->Start();
- return Handle();
- }
- return queue_.InsertAtFront(job, priority);
- }
- void PrioritizedDispatcher::Cancel(const Handle& handle) {
- queue_.Erase(handle);
- }
- PrioritizedDispatcher::Job* PrioritizedDispatcher::EvictOldestLowest() {
- Handle handle = queue_.FirstMin();
- if (handle.is_null())
- return nullptr;
- Job* job = handle.value();
- Cancel(handle);
- return job;
- }
- PrioritizedDispatcher::Handle PrioritizedDispatcher::ChangePriority(
- const Handle& handle, Priority priority) {
- DCHECK(!handle.is_null());
- DCHECK_LT(priority, num_priorities());
- DCHECK_GE(num_running_jobs_, max_running_jobs_[handle.priority()]) <<
- "Job should not be in queue when limits permit it to start.";
- if (handle.priority() == priority)
- return handle;
- if (MaybeDispatchJob(handle, priority))
- return Handle();
- Job* job = handle.value();
- queue_.Erase(handle);
- return queue_.Insert(job, priority);
- }
- void PrioritizedDispatcher::OnJobFinished() {
- DCHECK_GT(num_running_jobs_, 0u);
- --num_running_jobs_;
- MaybeDispatchNextJob();
- }
- PrioritizedDispatcher::Limits PrioritizedDispatcher::GetLimits() const {
- size_t num_priorities = max_running_jobs_.size();
- Limits limits(num_priorities, max_running_jobs_.back());
- // Calculate the number of jobs reserved for each priority and higher. Leave
- // the number of jobs reserved for the lowest priority or higher as 0.
- for (size_t i = 1; i < num_priorities; ++i) {
- limits.reserved_slots[i] = max_running_jobs_[i] - max_running_jobs_[i - 1];
- }
- return limits;
- }
- void PrioritizedDispatcher::SetLimits(const Limits& limits) {
- DCHECK_EQ(queue_.num_priorities(), limits.reserved_slots.size());
- size_t total = 0;
- for (size_t i = 0; i < limits.reserved_slots.size(); ++i) {
- total += limits.reserved_slots[i];
- max_running_jobs_[i] = total;
- }
- // Unreserved slots are available for all priorities.
- DCHECK_LE(total, limits.total_jobs) << "sum(reserved_slots) <= total_jobs";
- size_t spare = limits.total_jobs - total;
- for (size_t i = limits.reserved_slots.size(); i > 0; --i) {
- max_running_jobs_[i - 1] += spare;
- }
- // Start pending jobs, if limits permit.
- while (true) {
- if (!MaybeDispatchNextJob())
- break;
- }
- }
- void PrioritizedDispatcher::SetLimitsToZero() {
- SetLimits(Limits(queue_.num_priorities(), 0));
- }
- bool PrioritizedDispatcher::MaybeDispatchJob(const Handle& handle,
- Priority job_priority) {
- DCHECK_LT(job_priority, num_priorities());
- if (num_running_jobs_ >= max_running_jobs_[job_priority])
- return false;
- Job* job = handle.value();
- queue_.Erase(handle);
- ++num_running_jobs_;
- job->Start();
- return true;
- }
- bool PrioritizedDispatcher::MaybeDispatchNextJob() {
- Handle handle = queue_.FirstMax();
- if (handle.is_null()) {
- DCHECK_EQ(0u, queue_.size());
- return false;
- }
- return MaybeDispatchJob(handle, handle.priority());
- }
- } // namespace net
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