Throttle HttpStreamFactoryImpl::Job to HTTP/2-supported servers

net/spdy/chromium/spdy_session_pool.cc

 // 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/spdy/chromium/spdy_session_pool.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ skipping 420 matching lines @@
           direct || request->url().SchemeIs(url::kHttpsScheme);
       request->OnStreamReady(
           used_ssl_config, used_proxy_info,
           base::MakeUnique<SpdyHttpStream>(spdy_session, use_relative_url,
                                            source_dependency));
     }
   }
   // TODO(mbelshe): Alert other valid requests.
 }
 
+bool SpdySessionPool::StartRequest(const SpdySessionKey& spdy_session_key,
+                                   const base::Closure& callback) {
+  auto iter = spdy_session_pending_request_map_.find(spdy_session_key);
+  if (iter == spdy_session_pending_request_map_.end()) {
+    spdy_session_pending_request_map_.emplace(spdy_session_key,
+                                              std::list<base::Closure>{});
+    return true;
+  }
+  iter->second.push_back(callback);
+  return false;
+}
+
+void SpdySessionPool::ResumeAllPendingRequests(
+    const SpdySessionKey& spdy_session_key) {
+  auto iter = spdy_session_pending_request_map_.find(spdy_session_key);
+  if (iter != spdy_session_pending_request_map_.end()) {
+    for (auto callback : iter->second) {
+      base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, callback);
+    }
+    spdy_session_pending_request_map_.erase(iter);
+  }
+}
+
+void SpdySessionPool::ResumeNextPendingRequest(
+    const SpdySessionKey& spdy_session_key) {
+  auto iter = spdy_session_pending_request_map_.find(spdy_session_key);
+  if (iter != spdy_session_pending_request_map_.end()) {
+    base::Closure callback = iter->second.front();
+    if (iter->second.size() == 1)
+      spdy_session_pending_request_map_.erase(iter);
+    iter->second.pop_front();

[Bence, 2017/06/09 19:17:39]

Do not dereference |iter| after it's erased.  How about:

base::Closure callback = iter->second.front();
iter->second.pop_front();
if (iter->second.empty())
  spdy_session_pending_request_map_.erase(iter);

[xunjieli, 2017/06/13 15:23:11]

Done. Thanks!

+    base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, callback);
+  }
+}
+
 void SpdySessionPool::AddRequestToSpdySessionRequestMap(
     const SpdySessionKey& spdy_session_key,
     HttpStreamFactoryImpl::Request* request) {
   if (request->HasSpdySessionKey())
     return;
   RequestSet& request_set = spdy_session_request_map_[spdy_session_key];
   DCHECK(!base::ContainsKey(request_set, request));
   request_set.insert(request);
   request->SetSpdySessionKey(spdy_session_key);
 }
 
 void SpdySessionPool::RemoveRequestFromSpdySessionRequestMap(
     HttpStreamFactoryImpl::Request* request) {
   if (!request->HasSpdySessionKey())
     return;
   const SpdySessionKey& spdy_session_key = request->GetSpdySessionKey();
   auto iter = spdy_session_request_map_.find(spdy_session_key);
   DCHECK(iter != spdy_session_request_map_.end());
   RequestSet& request_set = iter->second;
   DCHECK(base::ContainsKey(request_set, request));
   request_set.erase(request);
   if (request_set.empty())
     spdy_session_request_map_.erase(spdy_session_key);
   request->ResetSpdySessionKey();
+  ResumeNextPendingRequest(spdy_session_key);
 }
 
 void SpdySessionPool::DumpMemoryStats(
     base::trace_event::ProcessMemoryDump* pmd,
     const SpdyString& parent_dump_absolute_name) const {
   if (sessions_.empty())
     return;
   size_t total_size = 0;
   size_t buffer_size = 0;
   size_t cert_count = 0;
@@ skipping 99 matching lines @@
 
     if (idle_only && (*it)->is_active())
       continue;
 
     (*it)->CloseSessionOnError(error, description);
     DCHECK(!IsSessionAvailable(*it));
   }
 }
 
 }  // namespace net