Issue #1695 - Add clamping to websocket polling timeouts.

3 files changed, 30 insertions, 3 deletions

diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 314beac37..1e60c97c5 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1663,6 +1663,11 @@ pref("network.websocket.timeout.open", 20);
 // close message
 pref("network.websocket.timeout.close", 20);
 
+// Setting this to true will clamp the websocket timeout value to a minimum
+// regardless if there are pending events on the thread.
+// This is a workaround for runaway polling, see issue #1695
+pref("network.websocket.timeout.clamped", false);
+
 // the number of seconds of idle read activity to sustain before sending a
 // ping probe. 0 to disable.
 pref("network.websocket.timeout.ping.request", 0);
diff --git a/netwerk/base/nsSocketTransportService2.cpp b/netwerk/base/nsSocketTransportService2.cpp
index 6631db655..956332953 100644
--- a/netwerk/base/nsSocketTransportService2.cpp
+++ b/netwerk/base/nsSocketTransportService2.cpp
@@ -42,6 +42,7 @@ Atomic<PRThread*, Relaxed> gSocketThread;
 #define KEEPALIVE_PROBE_COUNT_PREF "network.tcp.keepalive.probe_count"
 #define SOCKET_LIMIT_TARGET 1000U
 #define SOCKET_LIMIT_MIN      50U
+#define SOCKET_CLAMP_PREF "network.websocket.timeout.clamped"
 #define BLIP_INTERVAL_PREF "network.activity.blipIntervalMilliseconds"
 #define MAX_TIME_BETWEEN_TWO_POLLS "network.sts.max_time_for_events_between_two_polls"
 #define MAX_TIME_FOR_PR_CLOSE_DURING_SHUTDOWN "network.sts.max_time_for_pr_close_during_shutdown"
@@ -120,6 +121,7 @@ nsSocketTransportService::nsSocketTransportService()
     , mKeepaliveEnabledPref(false)
     , mServingPendingQueue(false)
     , mMaxTimePerPollIter(100)
+    , mClampSocketTimeout(false)
     , mMaxTimeForPrClosePref(PR_SecondsToInterval(5))
     , mProbedMaxCount(false)
 #if defined(XP_WIN)
@@ -485,7 +487,11 @@ nsSocketTransportService::Poll(PRIntervalTime ts)
         mPollList[0].out_flags = 0;
         pollList = mPollList;
         pollCount = mActiveCount + 1;
-        pollTimeout = pendingEvents ? PR_INTERVAL_NO_WAIT : PollTimeout(ts);
+        pollTimeout = IsSocketTimeoutClamped() ?
+                        PR_MillisecondsToInterval(100) :
+                        pendingEvents ?
+                          PR_INTERVAL_NO_WAIT :
+                          PollTimeout(ts);
     }
     else {
         // no pollable event, so busy wait...
@@ -494,8 +500,11 @@ nsSocketTransportService::Poll(PRIntervalTime ts)
             pollList = &mPollList[1];
         else
             pollList = nullptr;
-        pollTimeout =
-            pendingEvents ? PR_INTERVAL_NO_WAIT : PR_MillisecondsToInterval(25);
+        pollTimeout = IsSocketTimeoutClamped() ?
+                        PR_MillisecondsToInterval(25) :
+                        pendingEvents ? 
+                          PR_INTERVAL_NO_WAIT :
+                          PR_MillisecondsToInterval(25);
     }
 
     SOCKET_LOG(("    timeout = %i milliseconds\n",
@@ -554,6 +563,7 @@ nsSocketTransportService::Init()
         tmpPrefService->AddObserver(KEEPALIVE_RETRY_INTERVAL_PREF, this, false);
         tmpPrefService->AddObserver(KEEPALIVE_PROBE_COUNT_PREF, this, false);
         tmpPrefService->AddObserver(MAX_TIME_BETWEEN_TWO_POLLS, this, false);
+        tmpPrefService->AddObserver(SOCKET_CLAMP_PREF, this, false);
         tmpPrefService->AddObserver(MAX_TIME_FOR_PR_CLOSE_DURING_SHUTDOWN, this, false);
     }
     UpdatePrefs();
@@ -1150,6 +1160,13 @@ nsSocketTransportService::UpdatePrefs()
         if (NS_SUCCEEDED(rv) && maxTimePref >= 0) {
             mMaxTimePerPollIter = maxTimePref;
         }
+        
+        bool socketTimeoutClamped = false;
+        rv = tmpPrefService->GetBoolPref(SOCKET_CLAMP_PREF,
+                                         &socketTimeoutClamped);
+        if (NS_SUCCEEDED(rv)) {
+            mClampSocketTimeout = socketTimeoutClamped;
+        }      
 
         int32_t maxTimeForPrClosePref;
         rv = tmpPrefService->GetIntPref(MAX_TIME_FOR_PR_CLOSE_DURING_SHUTDOWN,
diff --git a/netwerk/base/nsSocketTransportService2.h b/netwerk/base/nsSocketTransportService2.h
index 31efec1d9..9360dd905 100644
--- a/netwerk/base/nsSocketTransportService2.h
+++ b/netwerk/base/nsSocketTransportService2.h
@@ -116,6 +116,9 @@ public:
 
     // Returns true if keepalives are enabled in prefs.
     bool IsKeepaliveEnabled() { return mKeepaliveEnabledPref; }
+    
+    // Returns true if socket timeout clamping is enabled in prefs.
+    bool IsSocketTimeoutClamped() { return mClampSocketTimeout; }
 
     PRIntervalTime MaxTimeForPrClosePref() {return mMaxTimeForPrClosePref; }
 protected:
@@ -253,6 +256,8 @@ private:
     int32_t     mKeepaliveProbeCount;
     // True if TCP keepalive is enabled globally.
     bool        mKeepaliveEnabledPref;
+    // True if socket polling should be clamped.
+    bool        mClampSocketTimeout;
 
     Atomic<bool>                    mServingPendingQueue;
     Atomic<int32_t, Relaxed>        mMaxTimePerPollIter;