Per-renderer WebSocket throttling

content/browser/renderer_host/websocket_dispatcher_host.cc

 // Copyright 2013 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/renderer_host/websocket_dispatcher_host.h"
 
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/logging.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/rand_util.h"
 #include "base/stl_util.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/renderer_host/websocket_host.h"
 #include "content/common/websocket_messages.h"
 
 namespace content {
 
 namespace {
 
 // Many methods defined in this file return a WebSocketHostState enum
 // value. Make WebSocketHostState visible at file scope so it doesn't have to be
 // fully-qualified every time.
 typedef WebSocketDispatcherHost::WebSocketHostState WebSocketHostState;
 
+// Max number of pending connections per WebSocketDispatcherHost
+// used for per-renderer WebSocket throttling.
+const int kMaxPendingWebSocketConnections = 255;
+
 }  // namespace
 
 WebSocketDispatcherHost::WebSocketDispatcherHost(
     int process_id,
     const GetRequestContextCallback& get_context_callback)
     : BrowserMessageFilter(WebSocketMsgStart),
       process_id_(process_id),
       get_context_callback_(get_context_callback),
       websocket_host_factory_(
           base::Bind(&WebSocketDispatcherHost::CreateWebSocketHost,
-                     base::Unretained(this))) {}
+                     base::Unretained(this))),
+      num_pending_connections_(0),
+      num_current_succeeded_connections_(0),
+      num_previous_succeeded_connections_(0),
+      num_current_failed_connections_(0),
+      num_previous_failed_connections_(0) {}
 
 WebSocketDispatcherHost::WebSocketDispatcherHost(
     int process_id,
     const GetRequestContextCallback& get_context_callback,
     const WebSocketHostFactory& websocket_host_factory)
     : BrowserMessageFilter(WebSocketMsgStart),
       process_id_(process_id),
       get_context_callback_(get_context_callback),
-      websocket_host_factory_(websocket_host_factory) {}
+      websocket_host_factory_(websocket_host_factory),
+      num_pending_connections_(0),
+      num_current_succeeded_connections_(0),
+      num_previous_succeeded_connections_(0),
+      num_current_failed_connections_(0),
+      num_previous_failed_connections_(0) {}
 
-WebSocketHost* WebSocketDispatcherHost::CreateWebSocketHost(int routing_id) {
-  return new WebSocketHost(routing_id, this, get_context_callback_.Run());
+WebSocketHost* WebSocketDispatcherHost::CreateWebSocketHost(
+    int routing_id,
+    base::TimeDelta delay) {
+  return new WebSocketHost(
+      routing_id, this, get_context_callback_.Run(), delay);
 }
 
 bool WebSocketDispatcherHost::OnMessageReceived(const IPC::Message& message) {
   switch (message.type()) {
     case WebSocketHostMsg_AddChannelRequest::ID:
     case WebSocketMsg_SendFrame::ID:
     case WebSocketMsg_FlowControl::ID:
     case WebSocketMsg_DropChannel::ID:
       break;
 
     default:
       // Every message that has not been handled by a previous filter passes
       // through here, so it is good to pass them on as efficiently as possible.
       return false;
   }
 
   int routing_id = message.routing_id();
   WebSocketHost* host = GetHost(routing_id);
   if (message.type() == WebSocketHostMsg_AddChannelRequest::ID) {
     if (host) {
       DVLOG(1) << "routing_id=" << routing_id << " already in use.";
       // The websocket multiplexing spec says to should drop the physical
       // connection in this case, but there isn't a real physical connection
       // to the renderer, and killing the renderer for this would seem to be a
       // little extreme. So for now just ignore the bogus request.
       return true;  // We handled the message (by ignoring it).
     }
-    host = websocket_host_factory_.Run(routing_id);
+    if (num_pending_connections_ >= kMaxPendingWebSocketConnections) {
+      if(!Send(new WebSocketMsg_NotifyFailure(routing_id,
+          "Error in connection establishment: net::ERR_INSUFFICIENT_RESOURCES"
+          ))) {
+        DVLOG(1) << "Sending of message type "
+                 << "WebSocketMsg_NotifyFailure failed.";
+      }
+      return true;
+    }
+    host = websocket_host_factory_.Run(routing_id, CalculateDelay());
     hosts_.insert(WebSocketHostTable::value_type(routing_id, host));
+    ++num_pending_connections_;
+    if (!throttling_period_timer_.IsRunning())
+      throttling_period_timer_.Start(
+          FROM_HERE,
+          base::TimeDelta::FromMinutes(2),
+          this,
+          &WebSocketDispatcherHost::ThrottlingPeriodTimerCallback);
   }
   if (!host) {
     DVLOG(1) << "Received invalid routing ID " << routing_id
              << " from renderer.";
     return true;  // We handled the message (by ignoring it).
   }
   return host->OnMessageReceived(message);
 }
 
 bool WebSocketDispatcherHost::CanReadRawCookies() const {
@@ skipping 17 matching lines @@
     DeleteWebSocketHost(message_routing_id);
     return WEBSOCKET_HOST_DELETED;
   }
   return WEBSOCKET_HOST_ALIVE;
 }
 
 WebSocketHostState WebSocketDispatcherHost::SendAddChannelResponse(
     int routing_id,
     const std::string& selected_protocol,
     const std::string& extensions) {
+  // Update throttling counters (success).
+  WebSocketHost* host = GetHost(routing_id);
+  DCHECK(host);
+  host->OnHandshakeSucceeded();
+  --num_pending_connections_;
+  DCHECK_GE(num_pending_connections_, 0);
+  ++num_current_succeeded_connections_;
+
   return SendOrDrop(new WebSocketMsg_AddChannelResponse(
       routing_id, selected_protocol, extensions));
 }
 
 WebSocketHostState WebSocketDispatcherHost::SendFrame(
     int routing_id,
     bool fin,
     WebSocketMessageType type,
     const std::vector<char>& data) {
   return SendOrDrop(new WebSocketMsg_SendFrame(routing_id, fin, type, data));
@@ skipping 60 matching lines @@
     hosts[i]->GoAway();
     hosts[i] = NULL;
   }
 
   STLDeleteContainerPairSecondPointers(hosts_.begin(), hosts_.end());
 }
 
 void WebSocketDispatcherHost::DeleteWebSocketHost(int routing_id) {
   WebSocketHostTable::iterator it = hosts_.find(routing_id);
   DCHECK(it != hosts_.end());
+  DCHECK(it->second);
+  if (!it->second->handshake_succeeded()) {
+    // Update throttling counters (failure).
+    --num_pending_connections_;
+    DCHECK_GE(num_pending_connections_, 0);
+    ++num_current_failed_connections_;
+  }
+
   delete it->second;
   hosts_.erase(it);
+
+  DCHECK_LE(base::checked_cast<size_t>(num_pending_connections_),
+            hosts_.size());
+}
+
+int64_t WebSocketDispatcherHost::num_failed_connections() const {
+  return num_previous_failed_connections_ +
+         num_current_failed_connections_;
+}
+
+int64_t WebSocketDispatcherHost::num_succeeded_connections() const {
+  return num_previous_succeeded_connections_ +
+         num_current_succeeded_connections_;
+}
+
+// Calculate delay as described in
+// the per-renderer WebSocket throttling design doc:
+// https://docs.google.com/document/d/1aw2oN5PKfk-1gLnBrlv1OwLA8K3-ykM2ckwX2lubTg4/edit?usp=sharing
+base::TimeDelta WebSocketDispatcherHost::CalculateDelay() const {
+  int64_t f = num_failed_connections();
+  int64_t s = num_succeeded_connections();
+  int p = num_pending_connections();
+  return base::TimeDelta::FromMilliseconds(
+      base::RandInt(1000, 5000) *
+      (1 << std::min(p + f / (s + 1), INT64_C(16))) / 65536);
+}
+
+void WebSocketDispatcherHost::ThrottlingPeriodTimerCallback() {
+  num_previous_failed_connections_ = num_current_failed_connections_;
+  num_current_failed_connections_ = 0;
+
+  num_previous_succeeded_connections_ = num_current_succeeded_connections_;
+  num_current_succeeded_connections_ = 0;
+
+  if (num_pending_connections_ == 0 &&
+      num_previous_failed_connections_ == 0 &&
+      num_previous_succeeded_connections_ == 0) {
+    throttling_period_timer_.Stop();
+  }
 }
 
 }  // namespace content