| // 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 "content/browser/loader/resource_scheduler.h" |
| |
| #include <stdint.h> |
| #include <set> |
| #include <string> |
| #include <utility> |
| #include <vector> |
| |
| #include "base/macros.h" |
| #include "base/metrics/field_trial.h" |
| #include "base/metrics/histogram_macros.h" |
| #include "base/stl_util.h" |
| #include "base/strings/string_number_conversions.h" |
| #include "base/strings/string_piece.h" |
| #include "base/supports_user_data.h" |
| #include "content/common/resource_messages.h" |
| #include "content/public/browser/resource_controller.h" |
| #include "content/public/browser/resource_request_info.h" |
| #include "content/public/browser/resource_throttle.h" |
| #include "net/base/host_port_pair.h" |
| #include "net/base/load_flags.h" |
| #include "net/base/request_priority.h" |
| #include "net/http/http_server_properties.h" |
| #include "net/url_request/url_request.h" |
| #include "net/url_request/url_request_context.h" |
| #include "url/scheme_host_port.h" |
| |
| namespace content { |
| |
| namespace { |
| |
| enum StartMode { |
| START_SYNC, |
| START_ASYNC |
| }; |
| |
| // Field trial constants |
| const char kRequestLimitFieldTrial[] = "OutstandingRequestLimiting"; |
| const char kRequestLimitFieldTrialGroupPrefix[] = "Limit"; |
| |
| // Flags identifying various attributes of the request that are used |
| // when making scheduling decisions. |
| using RequestAttributes = uint8_t; |
| const RequestAttributes kAttributeNone = 0x00; |
| const RequestAttributes kAttributeInFlight = 0x01; |
| const RequestAttributes kAttributeDelayable = 0x02; |
| const RequestAttributes kAttributeLayoutBlocking = 0x04; |
| |
| } // namespace |
| |
| // The maximum number of delayable requests to allow to be in-flight at any |
| // point in time (across all hosts). |
| static const size_t kMaxNumDelayableRequestsPerClient = 10; |
| |
| // The maximum number of requests to allow be in-flight at any point in time per |
| // host. |
| static const size_t kMaxNumDelayableRequestsPerHostPerClient = 6; |
| |
| // The maximum number of delayable requests to allow to be in-flight at any |
| // point in time while in the layout-blocking phase of loading. |
| static const size_t kMaxNumDelayableWhileLayoutBlockingPerClient = 1; |
| |
| // The priority level above which resources are considered layout-blocking if |
| // the html_body has not started. |
| static const net::RequestPriority |
| kLayoutBlockingPriorityThreshold = net::MEDIUM; |
| |
| // The priority level below which resources are considered to be delayable. |
| static const net::RequestPriority |
| kDelayablePriorityThreshold = net::MEDIUM; |
| |
| // The number of in-flight layout-blocking requests above which all delayable |
| // requests should be blocked. |
| static const size_t kInFlightNonDelayableRequestCountPerClientThreshold = 1; |
| |
| struct ResourceScheduler::RequestPriorityParams { |
| RequestPriorityParams() |
| : priority(net::DEFAULT_PRIORITY), |
| intra_priority(0) { |
| } |
| |
| RequestPriorityParams(net::RequestPriority priority, int intra_priority) |
| : priority(priority), |
| intra_priority(intra_priority) { |
| } |
| |
| bool operator==(const RequestPriorityParams& other) const { |
| return (priority == other.priority) && |
| (intra_priority == other.intra_priority); |
| } |
| |
| bool operator!=(const RequestPriorityParams& other) const { |
| return !(*this == other); |
| } |
| |
| bool GreaterThan(const RequestPriorityParams& other) const { |
| if (priority != other.priority) |
| return priority > other.priority; |
| return intra_priority > other.intra_priority; |
| } |
| |
| net::RequestPriority priority; |
| int intra_priority; |
| }; |
| |
| class ResourceScheduler::RequestQueue { |
| public: |
| typedef std::multiset<ScheduledResourceRequest*, ScheduledResourceSorter> |
| NetQueue; |
| |
| RequestQueue() : fifo_ordering_ids_(0) {} |
| ~RequestQueue() {} |
| |
| // Adds |request| to the queue with given |priority|. |
| void Insert(ScheduledResourceRequest* request); |
| |
| // Removes |request| from the queue. |
| void Erase(ScheduledResourceRequest* request) { |
| PointerMap::iterator it = pointers_.find(request); |
| CHECK(it != pointers_.end()); |
| queue_.erase(it->second); |
| pointers_.erase(it); |
| } |
| |
| NetQueue::iterator GetNextHighestIterator() { |
| return queue_.begin(); |
| } |
| |
| NetQueue::iterator End() { |
| return queue_.end(); |
| } |
| |
| // Returns true if |request| is queued. |
| bool IsQueued(ScheduledResourceRequest* request) const { |
| return base::ContainsKey(pointers_, request); |
| } |
| |
| // Returns true if no requests are queued. |
| bool IsEmpty() const { return queue_.size() == 0; } |
| |
| private: |
| typedef std::map<ScheduledResourceRequest*, NetQueue::iterator> PointerMap; |
| |
| uint32_t MakeFifoOrderingId() { |
| fifo_ordering_ids_ += 1; |
| return fifo_ordering_ids_; |
| } |
| |
| // Used to create an ordering ID for scheduled resources so that resources |
| // with same priority/intra_priority stay in fifo order. |
| uint32_t fifo_ordering_ids_; |
| |
| NetQueue queue_; |
| PointerMap pointers_; |
| }; |
| |
| // This is the handle we return to the ResourceDispatcherHostImpl so it can |
| // interact with the request. |
| class ResourceScheduler::ScheduledResourceRequest : public ResourceThrottle { |
| public: |
| ScheduledResourceRequest(const ClientId& client_id, |
| net::URLRequest* request, |
| ResourceScheduler* scheduler, |
| const RequestPriorityParams& priority, |
| bool is_async) |
| : client_id_(client_id), |
| request_(request), |
| ready_(false), |
| deferred_(false), |
| is_async_(is_async), |
| attributes_(kAttributeNone), |
| scheduler_(scheduler), |
| priority_(priority), |
| fifo_ordering_(0), |
| weak_ptr_factory_(this) { |
| DCHECK(!request_->GetUserData(kUserDataKey)); |
| request_->SetUserData(kUserDataKey, new UnownedPointer(this)); |
| } |
| |
| ~ScheduledResourceRequest() override { |
| request_->RemoveUserData(kUserDataKey); |
| scheduler_->RemoveRequest(this); |
| } |
| |
| static ScheduledResourceRequest* ForRequest(net::URLRequest* request) { |
| return static_cast<UnownedPointer*>(request->GetUserData(kUserDataKey)) |
| ->get(); |
| } |
| |
| // Starts the request. If |start_mode| is START_ASYNC, the request will not |
| // be started immediately. |
| void Start(StartMode start_mode) { |
| DCHECK(!ready_); |
| |
| // If the request was cancelled, do nothing. |
| if (!request_->status().is_success()) |
| return; |
| |
| // If the request was deferred, need to start it. Otherwise, will just not |
| // defer starting it in the first place, and the value of |start_mode| |
| // makes no difference. |
| if (deferred_) { |
| // If can't start the request synchronously, post a task to start the |
| // request. |
| if (start_mode == START_ASYNC) { |
| base::ThreadTaskRunnerHandle::Get()->PostTask( |
| FROM_HERE, |
| base::Bind(&ScheduledResourceRequest::Start, |
| weak_ptr_factory_.GetWeakPtr(), |
| START_SYNC)); |
| return; |
| } |
| deferred_ = false; |
| controller()->Resume(); |
| } |
| |
| ready_ = true; |
| } |
| |
| void set_request_priority_params(const RequestPriorityParams& priority) { |
| priority_ = priority; |
| } |
| const RequestPriorityParams& get_request_priority_params() const { |
| return priority_; |
| } |
| const ClientId& client_id() const { return client_id_; } |
| net::URLRequest* url_request() { return request_; } |
| const net::URLRequest* url_request() const { return request_; } |
| bool is_async() const { return is_async_; } |
| uint32_t fifo_ordering() const { return fifo_ordering_; } |
| void set_fifo_ordering(uint32_t fifo_ordering) { |
| fifo_ordering_ = fifo_ordering; |
| } |
| RequestAttributes attributes() const { |
| return attributes_; |
| } |
| void set_attributes(RequestAttributes attributes) { |
| attributes_ = attributes; |
| } |
| |
| private: |
| class UnownedPointer : public base::SupportsUserData::Data { |
| public: |
| explicit UnownedPointer(ScheduledResourceRequest* pointer) |
| : pointer_(pointer) {} |
| |
| ScheduledResourceRequest* get() const { return pointer_; } |
| |
| private: |
| ScheduledResourceRequest* const pointer_; |
| |
| DISALLOW_COPY_AND_ASSIGN(UnownedPointer); |
| }; |
| |
| static const void* const kUserDataKey; |
| |
| // ResourceThrottle interface: |
| void WillStartRequest(bool* defer) override { |
| deferred_ = *defer = !ready_; |
| } |
| |
| const char* GetNameForLogging() const override { return "ResourceScheduler"; } |
| |
| const ClientId client_id_; |
| net::URLRequest* request_; |
| bool ready_; |
| bool deferred_; |
| bool is_async_; |
| RequestAttributes attributes_; |
| ResourceScheduler* scheduler_; |
| RequestPriorityParams priority_; |
| uint32_t fifo_ordering_; |
| |
| base::WeakPtrFactory<ResourceScheduler::ScheduledResourceRequest> |
| weak_ptr_factory_; |
| |
| DISALLOW_COPY_AND_ASSIGN(ScheduledResourceRequest); |
| }; |
| |
| const void* const ResourceScheduler::ScheduledResourceRequest::kUserDataKey = |
| &ResourceScheduler::ScheduledResourceRequest::kUserDataKey; |
| |
| bool ResourceScheduler::ScheduledResourceSorter::operator()( |
| const ScheduledResourceRequest* a, |
| const ScheduledResourceRequest* b) const { |
| // Want the set to be ordered first by decreasing priority, then by |
| // decreasing intra_priority. |
| // ie. with (priority, intra_priority) |
| // [(1, 0), (1, 0), (0, 100), (0, 0)] |
| if (a->get_request_priority_params() != b->get_request_priority_params()) |
| return a->get_request_priority_params().GreaterThan( |
| b->get_request_priority_params()); |
| |
| // If priority/intra_priority is the same, fall back to fifo ordering. |
| // std::multiset doesn't guarantee this until c++11. |
| return a->fifo_ordering() < b->fifo_ordering(); |
| } |
| |
| void ResourceScheduler::RequestQueue::Insert( |
| ScheduledResourceRequest* request) { |
| DCHECK(!base::ContainsKey(pointers_, request)); |
| request->set_fifo_ordering(MakeFifoOrderingId()); |
| pointers_[request] = queue_.insert(request); |
| } |
| |
| // Each client represents a tab. |
| class ResourceScheduler::Client { |
| public: |
| explicit Client(ResourceScheduler* scheduler) |
| : is_loaded_(false), |
| has_html_body_(false), |
| using_spdy_proxy_(false), |
| scheduler_(scheduler), |
| in_flight_delayable_count_(0), |
| total_layout_blocking_count_(0) {} |
| |
| ~Client() {} |
| |
| void ScheduleRequest(net::URLRequest* url_request, |
| ScheduledResourceRequest* request) { |
| SetRequestAttributes(request, DetermineRequestAttributes(request)); |
| if (ShouldStartRequest(request) == START_REQUEST) { |
| // New requests can be started synchronously without issue. |
| StartRequest(request, START_SYNC); |
| } else { |
| pending_requests_.Insert(request); |
| } |
| } |
| |
| void RemoveRequest(ScheduledResourceRequest* request) { |
| if (pending_requests_.IsQueued(request)) { |
| pending_requests_.Erase(request); |
| DCHECK(!base::ContainsKey(in_flight_requests_, request)); |
| } else { |
| EraseInFlightRequest(request); |
| |
| // Removing this request may have freed up another to load. |
| LoadAnyStartablePendingRequests(); |
| } |
| } |
| |
| RequestSet StartAndRemoveAllRequests() { |
| // First start any pending requests so that they will be moved into |
| // in_flight_requests_. This may exceed the limits |
| // kDefaultMaxNumDelayableRequestsPerClient and |
| // kMaxNumDelayableRequestsPerHostPerClient, so this method must not do |
| // anything that depends on those limits before calling |
| // ClearInFlightRequests() below. |
| while (!pending_requests_.IsEmpty()) { |
| ScheduledResourceRequest* request = |
| *pending_requests_.GetNextHighestIterator(); |
| pending_requests_.Erase(request); |
| // Starting requests asynchronously ensures no side effects, and avoids |
| // starting a bunch of requests that may be about to be deleted. |
| StartRequest(request, START_ASYNC); |
| } |
| RequestSet unowned_requests; |
| for (RequestSet::iterator it = in_flight_requests_.begin(); |
| it != in_flight_requests_.end(); ++it) { |
| unowned_requests.insert(*it); |
| (*it)->set_attributes(kAttributeNone); |
| } |
| ClearInFlightRequests(); |
| return unowned_requests; |
| } |
| |
| bool is_loaded() const { return is_loaded_; } |
| |
| void OnLoadingStateChanged(bool is_loaded) { |
| is_loaded_ = is_loaded; |
| } |
| |
| void OnNavigate() { |
| has_html_body_ = false; |
| is_loaded_ = false; |
| } |
| |
| void OnWillInsertBody() { |
| has_html_body_ = true; |
| LoadAnyStartablePendingRequests(); |
| } |
| |
| void OnReceivedSpdyProxiedHttpResponse() { |
| if (!using_spdy_proxy_) { |
| using_spdy_proxy_ = true; |
| LoadAnyStartablePendingRequests(); |
| } |
| } |
| |
| void ReprioritizeRequest(ScheduledResourceRequest* request, |
| RequestPriorityParams old_priority_params, |
| RequestPriorityParams new_priority_params) { |
| request->url_request()->SetPriority(new_priority_params.priority); |
| request->set_request_priority_params(new_priority_params); |
| SetRequestAttributes(request, DetermineRequestAttributes(request)); |
| if (!pending_requests_.IsQueued(request)) { |
| DCHECK(base::ContainsKey(in_flight_requests_, request)); |
| // Request has already started. |
| return; |
| } |
| |
| pending_requests_.Erase(request); |
| pending_requests_.Insert(request); |
| |
| if (new_priority_params.priority > old_priority_params.priority) { |
| // Check if this request is now able to load at its new priority. |
| LoadAnyStartablePendingRequests(); |
| } |
| } |
| |
| private: |
| enum ShouldStartReqResult { |
| DO_NOT_START_REQUEST_AND_STOP_SEARCHING, |
| DO_NOT_START_REQUEST_AND_KEEP_SEARCHING, |
| START_REQUEST, |
| }; |
| |
| void InsertInFlightRequest(ScheduledResourceRequest* request) { |
| in_flight_requests_.insert(request); |
| SetRequestAttributes(request, DetermineRequestAttributes(request)); |
| } |
| |
| void EraseInFlightRequest(ScheduledResourceRequest* request) { |
| size_t erased = in_flight_requests_.erase(request); |
| DCHECK_EQ(1u, erased); |
| // Clear any special state that we were tracking for this request. |
| SetRequestAttributes(request, kAttributeNone); |
| } |
| |
| void ClearInFlightRequests() { |
| in_flight_requests_.clear(); |
| in_flight_delayable_count_ = 0; |
| total_layout_blocking_count_ = 0; |
| } |
| |
| size_t CountRequestsWithAttributes( |
| const RequestAttributes attributes, |
| ScheduledResourceRequest* current_request) { |
| size_t matching_request_count = 0; |
| for (RequestSet::const_iterator it = in_flight_requests_.begin(); |
| it != in_flight_requests_.end(); ++it) { |
| if (RequestAttributesAreSet((*it)->attributes(), attributes)) |
| matching_request_count++; |
| } |
| if (!RequestAttributesAreSet(attributes, kAttributeInFlight)) { |
| bool current_request_is_pending = false; |
| for (RequestQueue::NetQueue::const_iterator |
| it = pending_requests_.GetNextHighestIterator(); |
| it != pending_requests_.End(); ++it) { |
| if (RequestAttributesAreSet((*it)->attributes(), attributes)) |
| matching_request_count++; |
| if (*it == current_request) |
| current_request_is_pending = true; |
| } |
| // Account for the current request if it is not in one of the lists yet. |
| if (current_request && |
| !base::ContainsKey(in_flight_requests_, current_request) && |
| !current_request_is_pending) { |
| if (RequestAttributesAreSet(current_request->attributes(), attributes)) |
| matching_request_count++; |
| } |
| } |
| return matching_request_count; |
| } |
| |
| bool RequestAttributesAreSet(RequestAttributes request_attributes, |
| RequestAttributes matching_attributes) const { |
| return (request_attributes & matching_attributes) == matching_attributes; |
| } |
| |
| void SetRequestAttributes(ScheduledResourceRequest* request, |
| RequestAttributes attributes) { |
| RequestAttributes old_attributes = request->attributes(); |
| if (old_attributes == attributes) |
| return; |
| |
| if (RequestAttributesAreSet(old_attributes, |
| kAttributeInFlight | kAttributeDelayable)) { |
| in_flight_delayable_count_--; |
| } |
| if (RequestAttributesAreSet(old_attributes, kAttributeLayoutBlocking)) |
| total_layout_blocking_count_--; |
| |
| if (RequestAttributesAreSet(attributes, |
| kAttributeInFlight | kAttributeDelayable)) { |
| in_flight_delayable_count_++; |
| } |
| if (RequestAttributesAreSet(attributes, kAttributeLayoutBlocking)) |
| total_layout_blocking_count_++; |
| |
| request->set_attributes(attributes); |
| DCHECK_EQ(CountRequestsWithAttributes( |
| kAttributeInFlight | kAttributeDelayable, request), |
| in_flight_delayable_count_); |
| DCHECK_EQ(CountRequestsWithAttributes(kAttributeLayoutBlocking, request), |
| total_layout_blocking_count_); |
| } |
| |
| RequestAttributes DetermineRequestAttributes( |
| ScheduledResourceRequest* request) { |
| RequestAttributes attributes = kAttributeNone; |
| |
| if (base::ContainsKey(in_flight_requests_, request)) |
| attributes |= kAttributeInFlight; |
| |
| if (RequestAttributesAreSet(request->attributes(), |
| kAttributeLayoutBlocking)) { |
| // If a request is already marked as layout-blocking make sure to keep the |
| // attribute across redirects. |
| attributes |= kAttributeLayoutBlocking; |
| } else if (!has_html_body_ && |
| request->url_request()->priority() > |
| kLayoutBlockingPriorityThreshold) { |
| // Requests that are above the non_delayable threshold before the HTML |
| // body has been parsed are inferred to be layout-blocking. |
| attributes |= kAttributeLayoutBlocking; |
| } else if (request->url_request()->priority() < |
| kDelayablePriorityThreshold) { |
| // Resources below the delayable priority threshold that are being |
| // requested from a server that does not support native prioritization are |
| // considered delayable. |
| url::SchemeHostPort scheme_host_port(request->url_request()->url()); |
| net::HttpServerProperties& http_server_properties = |
| *request->url_request()->context()->http_server_properties(); |
| if (!http_server_properties.SupportsRequestPriority(scheme_host_port)) |
| attributes |= kAttributeDelayable; |
| } |
| |
| return attributes; |
| } |
| |
| bool ShouldKeepSearching( |
| const net::HostPortPair& active_request_host) const { |
| size_t same_host_count = 0; |
| for (RequestSet::const_iterator it = in_flight_requests_.begin(); |
| it != in_flight_requests_.end(); ++it) { |
| net::HostPortPair host_port_pair = |
| net::HostPortPair::FromURL((*it)->url_request()->url()); |
| if (active_request_host.Equals(host_port_pair)) { |
| same_host_count++; |
| if (same_host_count >= kMaxNumDelayableRequestsPerHostPerClient) |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| void StartRequest(ScheduledResourceRequest* request, |
| StartMode start_mode) { |
| InsertInFlightRequest(request); |
| request->Start(start_mode); |
| } |
| |
| // ShouldStartRequest is the main scheduling algorithm. |
| // |
| // Requests are evaluated on five attributes: |
| // |
| // 1. Non-delayable requests: |
| // * Synchronous requests. |
| // * Non-HTTP[S] requests. |
| // |
| // 2. Requests to request-priority-capable origin servers. |
| // |
| // 3. High-priority requests: |
| // * Higher priority requests (>= net::LOW). |
| // |
| // 4. Layout-blocking requests: |
| // * High-priority requests (> net::LOW) initiated before the renderer has |
| // a <body>. |
| // |
| // 5. Low priority requests |
| // |
| // The following rules are followed: |
| // |
| // All types of requests: |
| // * If an outstanding request limit is in place, only that number |
| // of requests may be in flight for a single client at the same time. |
| // * Non-delayable, High-priority and request-priority capable requests are |
| // issued immediately. |
| // * Low priority requests are delayable. |
| // * While kInFlightNonDelayableRequestCountPerClientThreshold |
| // layout-blocking requests are loading or the body tag has not yet been |
| // parsed, limit the number of delayable requests that may be in flight |
| // (to kMaxNumDelayableWhileLayoutBlockingPerClient by default, or to zero |
| // if there's an outstanding request limit in place). |
| // * If no high priority or layout-blocking requests are in flight, start |
| // loading delayable requests. |
| // * Never exceed 10 delayable requests in flight per client. |
| // * Never exceed 6 delayable requests for a given host. |
| |
| ShouldStartReqResult ShouldStartRequest( |
| ScheduledResourceRequest* request) const { |
| const net::URLRequest& url_request = *request->url_request(); |
| // Syncronous requests could block the entire render, which could impact |
| // user-observable Clients. |
| if (!request->is_async()) |
| return START_REQUEST; |
| |
| // TODO(simonjam): This may end up causing disk contention. We should |
| // experiment with throttling if that happens. |
| if (!url_request.url().SchemeIsHTTPOrHTTPS()) |
| return START_REQUEST; |
| |
| if (using_spdy_proxy_ && url_request.url().SchemeIs(url::kHttpScheme)) |
| return START_REQUEST; |
| |
| // Implementation of the kRequestLimitFieldTrial. |
| if (scheduler_->limit_outstanding_requests() && |
| in_flight_requests_.size() >= scheduler_->outstanding_request_limit()) { |
| return DO_NOT_START_REQUEST_AND_STOP_SEARCHING; |
| } |
| |
| net::HostPortPair host_port_pair = |
| net::HostPortPair::FromURL(url_request.url()); |
| url::SchemeHostPort scheme_host_port(url_request.url()); |
| net::HttpServerProperties& http_server_properties = |
| *url_request.context()->http_server_properties(); |
| |
| // TODO(willchan): We should really improve this algorithm as described in |
| // crbug.com/164101. Also, theoretically we should not count a |
| // request-priority capable request against the delayable requests limit. |
| if (http_server_properties.SupportsRequestPriority(scheme_host_port)) |
| return START_REQUEST; |
| |
| // Non-delayable requests. |
| if (!RequestAttributesAreSet(request->attributes(), kAttributeDelayable)) |
| return START_REQUEST; |
| |
| if (in_flight_delayable_count_ >= kMaxNumDelayableRequestsPerClient) |
| return DO_NOT_START_REQUEST_AND_STOP_SEARCHING; |
| |
| if (ShouldKeepSearching(host_port_pair)) { |
| // There may be other requests for other hosts that may be allowed, |
| // so keep checking. |
| return DO_NOT_START_REQUEST_AND_KEEP_SEARCHING; |
| } |
| |
| // The in-flight requests consist of layout-blocking requests, |
| // normal requests and delayable requests. Everything except for |
| // delayable requests is handled above here so this is deciding what to |
| // do with a delayable request while we are in the layout-blocking phase |
| // of loading. |
| if (!has_html_body_ || total_layout_blocking_count_ != 0) { |
| size_t non_delayable_requests_in_flight_count = |
| in_flight_requests_.size() - in_flight_delayable_count_; |
| if (non_delayable_requests_in_flight_count > |
| kInFlightNonDelayableRequestCountPerClientThreshold) { |
| // Too many higher priority in-flight requests to allow lower priority |
| // requests through. |
| return DO_NOT_START_REQUEST_AND_STOP_SEARCHING; |
| } |
| if (in_flight_requests_.size() > 0 && |
| (scheduler_->limit_outstanding_requests() || |
| in_flight_delayable_count_ >= |
| kMaxNumDelayableWhileLayoutBlockingPerClient)) { |
| // Block the request if at least one request is in flight and the |
| // number of in-flight delayable requests has hit the configured |
| // limit. |
| return DO_NOT_START_REQUEST_AND_STOP_SEARCHING; |
| } |
| } |
| |
| return START_REQUEST; |
| } |
| |
| void LoadAnyStartablePendingRequests() { |
| // We iterate through all the pending requests, starting with the highest |
| // priority one. For each entry, one of three things can happen: |
| // 1) We start the request, remove it from the list, and keep checking. |
| // 2) We do NOT start the request, but ShouldStartRequest() signals us that |
| // there may be room for other requests, so we keep checking and leave |
| // the previous request still in the list. |
| // 3) We do not start the request, same as above, but StartRequest() tells |
| // us there's no point in checking any further requests. |
| RequestQueue::NetQueue::iterator request_iter = |
| pending_requests_.GetNextHighestIterator(); |
| |
| while (request_iter != pending_requests_.End()) { |
| ScheduledResourceRequest* request = *request_iter; |
| ShouldStartReqResult query_result = ShouldStartRequest(request); |
| |
| if (query_result == START_REQUEST) { |
| pending_requests_.Erase(request); |
| StartRequest(request, START_ASYNC); |
| |
| // StartRequest can modify the pending list, so we (re)start evaluation |
| // from the currently highest priority request. Avoid copying a singular |
| // iterator, which would trigger undefined behavior. |
| if (pending_requests_.GetNextHighestIterator() == |
| pending_requests_.End()) |
| break; |
| request_iter = pending_requests_.GetNextHighestIterator(); |
| } else if (query_result == DO_NOT_START_REQUEST_AND_KEEP_SEARCHING) { |
| ++request_iter; |
| continue; |
| } else { |
| DCHECK(query_result == DO_NOT_START_REQUEST_AND_STOP_SEARCHING); |
| break; |
| } |
| } |
| } |
| |
| bool is_loaded_; |
| // Tracks if the main HTML parser has reached the body which marks the end of |
| // layout-blocking resources. |
| bool has_html_body_; |
| bool using_spdy_proxy_; |
| RequestQueue pending_requests_; |
| RequestSet in_flight_requests_; |
| ResourceScheduler* scheduler_; |
| // The number of delayable in-flight requests. |
| size_t in_flight_delayable_count_; |
| // The number of layout-blocking in-flight requests. |
| size_t total_layout_blocking_count_; |
| }; |
| |
| ResourceScheduler::ResourceScheduler() |
| : limit_outstanding_requests_(false), |
| outstanding_request_limit_(0) { |
| std::string outstanding_limit_trial_group = |
| base::FieldTrialList::FindFullName(kRequestLimitFieldTrial); |
| std::vector<std::string> split_group( |
| base::SplitString(outstanding_limit_trial_group, "=", |
| base::KEEP_WHITESPACE, base::SPLIT_WANT_ALL)); |
| int outstanding_limit = 0; |
| if (split_group.size() == 2 && |
| split_group[0] == kRequestLimitFieldTrialGroupPrefix && |
| base::StringToInt(split_group[1], &outstanding_limit) && |
| outstanding_limit > 0) { |
| limit_outstanding_requests_ = true; |
| outstanding_request_limit_ = outstanding_limit; |
| } |
| } |
| |
| ResourceScheduler::~ResourceScheduler() { |
| DCHECK(unowned_requests_.empty()); |
| DCHECK(client_map_.empty()); |
| } |
| |
| std::unique_ptr<ResourceThrottle> ResourceScheduler::ScheduleRequest( |
| int child_id, |
| int route_id, |
| bool is_async, |
| net::URLRequest* url_request) { |
| DCHECK(CalledOnValidThread()); |
| ClientId client_id = MakeClientId(child_id, route_id); |
| std::unique_ptr<ScheduledResourceRequest> request( |
| new ScheduledResourceRequest( |
| client_id, url_request, this, |
| RequestPriorityParams(url_request->priority(), 0), is_async)); |
| |
| ClientMap::iterator it = client_map_.find(client_id); |
| if (it == client_map_.end()) { |
| // There are several ways this could happen: |
| // 1. <a ping> requests don't have a route_id. |
| // 2. Most unittests don't send the IPCs needed to register Clients. |
| // 3. The tab is closed while a RequestResource IPC is in flight. |
| unowned_requests_.insert(request.get()); |
| request->Start(START_SYNC); |
| return std::move(request); |
| } |
| |
| Client* client = it->second; |
| client->ScheduleRequest(url_request, request.get()); |
| return std::move(request); |
| } |
| |
| void ResourceScheduler::RemoveRequest(ScheduledResourceRequest* request) { |
| DCHECK(CalledOnValidThread()); |
| if (base::ContainsKey(unowned_requests_, request)) { |
| unowned_requests_.erase(request); |
| return; |
| } |
| |
| ClientMap::iterator client_it = client_map_.find(request->client_id()); |
| if (client_it == client_map_.end()) { |
| return; |
| } |
| |
| Client* client = client_it->second; |
| client->RemoveRequest(request); |
| } |
| |
| void ResourceScheduler::OnClientCreated(int child_id, |
| int route_id) { |
| DCHECK(CalledOnValidThread()); |
| ClientId client_id = MakeClientId(child_id, route_id); |
| DCHECK(!base::ContainsKey(client_map_, client_id)); |
| |
| Client* client = new Client(this); |
| client_map_[client_id] = client; |
| } |
| |
| void ResourceScheduler::OnClientDeleted(int child_id, int route_id) { |
| DCHECK(CalledOnValidThread()); |
| ClientId client_id = MakeClientId(child_id, route_id); |
| ClientMap::iterator it = client_map_.find(client_id); |
| DCHECK(it != client_map_.end()); |
| |
| Client* client = it->second; |
| // ResourceDispatcherHost cancels all requests except for cross-renderer |
| // navigations, async revalidations and detachable requests after |
| // OnClientDeleted() returns. |
| RequestSet client_unowned_requests = client->StartAndRemoveAllRequests(); |
| for (RequestSet::iterator it = client_unowned_requests.begin(); |
| it != client_unowned_requests.end(); ++it) { |
| unowned_requests_.insert(*it); |
| } |
| |
| delete client; |
| client_map_.erase(it); |
| } |
| |
| void ResourceScheduler::OnLoadingStateChanged(int child_id, |
| int route_id, |
| bool is_loaded) { |
| Client* client = GetClient(child_id, route_id); |
| DCHECK(client); |
| client->OnLoadingStateChanged(is_loaded); |
| } |
| |
| void ResourceScheduler::OnNavigate(int child_id, int route_id) { |
| DCHECK(CalledOnValidThread()); |
| ClientId client_id = MakeClientId(child_id, route_id); |
| |
| ClientMap::iterator it = client_map_.find(client_id); |
| if (it == client_map_.end()) { |
| // The client was likely deleted shortly before we received this IPC. |
| return; |
| } |
| |
| Client* client = it->second; |
| client->OnNavigate(); |
| } |
| |
| void ResourceScheduler::OnWillInsertBody(int child_id, int route_id) { |
| DCHECK(CalledOnValidThread()); |
| ClientId client_id = MakeClientId(child_id, route_id); |
| |
| ClientMap::iterator it = client_map_.find(client_id); |
| if (it == client_map_.end()) { |
| // The client was likely deleted shortly before we received this IPC. |
| return; |
| } |
| |
| Client* client = it->second; |
| client->OnWillInsertBody(); |
| } |
| |
| void ResourceScheduler::OnReceivedSpdyProxiedHttpResponse( |
| int child_id, |
| int route_id) { |
| DCHECK(CalledOnValidThread()); |
| ClientId client_id = MakeClientId(child_id, route_id); |
| |
| ClientMap::iterator client_it = client_map_.find(client_id); |
| if (client_it == client_map_.end()) { |
| return; |
| } |
| |
| Client* client = client_it->second; |
| client->OnReceivedSpdyProxiedHttpResponse(); |
| } |
| |
| bool ResourceScheduler::HasLoadingClients() const { |
| for (const auto& client : client_map_) { |
| if (!client.second->is_loaded()) |
| return true; |
| } |
| return false; |
| } |
| |
| ResourceScheduler::Client* ResourceScheduler::GetClient(int child_id, |
| int route_id) { |
| ClientId client_id = MakeClientId(child_id, route_id); |
| ClientMap::iterator client_it = client_map_.find(client_id); |
| if (client_it == client_map_.end()) { |
| return NULL; |
| } |
| return client_it->second; |
| } |
| |
| void ResourceScheduler::ReprioritizeRequest(net::URLRequest* request, |
| net::RequestPriority new_priority, |
| int new_intra_priority_value) { |
| if (request->load_flags() & net::LOAD_IGNORE_LIMITS) { |
| // Requests with the IGNORE_LIMITS flag must stay at MAXIMUM_PRIORITY. |
| return; |
| } |
| |
| auto* scheduled_resource_request = |
| ScheduledResourceRequest::ForRequest(request); |
| |
| // Downloads don't use the resource scheduler. |
| if (!scheduled_resource_request) { |
| request->SetPriority(new_priority); |
| return; |
| } |
| |
| RequestPriorityParams new_priority_params(new_priority, |
| new_intra_priority_value); |
| RequestPriorityParams old_priority_params = |
| scheduled_resource_request->get_request_priority_params(); |
| |
| if (old_priority_params == new_priority_params) |
| return; |
| |
| ClientMap::iterator client_it = |
| client_map_.find(scheduled_resource_request->client_id()); |
| if (client_it == client_map_.end()) { |
| // The client was likely deleted shortly before we received this IPC. |
| request->SetPriority(new_priority_params.priority); |
| scheduled_resource_request->set_request_priority_params( |
| new_priority_params); |
| return; |
| } |
| |
| Client* client = client_it->second; |
| client->ReprioritizeRequest(scheduled_resource_request, old_priority_params, |
| new_priority_params); |
| } |
| |
| ResourceScheduler::ClientId ResourceScheduler::MakeClientId( |
| int child_id, int route_id) { |
| return (static_cast<ResourceScheduler::ClientId>(child_id) << 32) | route_id; |
| } |
| |
| } // namespace content |