Bug 939318 - Find and close HTTP connections without traffic after ne…

…twork change. r=mcmanus

SPDY/http2 connections get a ping and be allowed N seconds to respond.

Active HTTP connections will be allowed N seconds to get traffic, if they
don't afer N seconds they get closed to avoid risking stalled transfers.

N is 5 by default: pref is "network.http.network-changed.timeout"

modules/libpref/init/all.js

@@ -1198,6 +1198,11 @@ pref("network.http.connection-retry-timeout", 250);
 // to give up if the OS does not give up first
 pref("network.http.connection-timeout", 90);
 
+// The number of seconds to allow active connections to prove that they have
+// traffic before considered stalled, after a network change has been detected
+// and signalled.
+pref("network.http.network-changed.timeout", 5);
+
 // The maximum number of current global half open sockets allowable
 // when starting a new speculative connection.
 pref("network.http.speculative-parallel-limit", 6);

netwerk/protocol/http/ASpdySession.h

@@ -39,6 +39,8 @@ class ASpdySession : public nsAHttpTransaction
     return true;
   }
 
+  virtual void SendPing() = 0;
+
   const static uint32_t kSendingChunkSize = 4095;
   const static uint32_t kTCPSendBufferSize = 131072;
 

netwerk/protocol/http/Http2Session.cpp

@@ -98,6 +98,7 @@ Http2Session::Http2Session(nsISocketTransport *aSocketTransport)
   , mOutputQueueSent(0)
   , mLastReadEpoch(PR_IntervalNow())
   , mPingSentEpoch(0)
+  , mPreviousUsed(false)
   , mWaitingForSettingsAck(false)
   , mGoAwayOnPush(false)
 {
@@ -295,8 +296,14 @@ Http2Session::ReadTimeoutTick(PRIntervalTime now)
 
   if ((now - mLastReadEpoch) < mPingThreshold) {
     // recent activity means ping is not an issue
-    if (mPingSentEpoch)
+    if (mPingSentEpoch) {
       mPingSentEpoch = 0;
+      if (mPreviousUsed) {
+        // restore the former value
+        mPingThreshold = mPreviousPingThreshold;
+        mPreviousUsed = false;
+      }
+    }
 
     return PR_IntervalToSeconds(mPingThreshold) -
       PR_IntervalToSeconds(now - mLastReadEpoch);
@@ -316,8 +323,9 @@ Http2Session::ReadTimeoutTick(PRIntervalTime now)
   LOG3(("Http2Session::ReadTimeoutTick %p generating ping\n", this));
 
   mPingSentEpoch = PR_IntervalNow();
-  if (!mPingSentEpoch)
+  if (!mPingSentEpoch) {
     mPingSentEpoch = 1; // avoid the 0 sentinel value
+  }
   GeneratePing(false);
   ResumeRecv(); // read the ping reply
 
@@ -3303,5 +3311,29 @@ Http2Session::PushBack(const char *buf, uint32_t len)
   return mConnection->PushBack(buf, len);
 }
 
+void
+Http2Session::SendPing()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  if (mPreviousUsed) {
+    // alredy in progress, get out
+    return;
+  }
+
+  mPingSentEpoch = PR_IntervalNow();
+  if (!mPingSentEpoch) {
+    mPingSentEpoch = 1; // avoid the 0 sentinel value
+  }
+  if (!mPingThreshold ||
+      (mPingThreshold > gHttpHandler->NetworkChangedTimeout())) {
+    mPreviousPingThreshold = mPingThreshold;
+    mPreviousUsed = true;
+    mPingThreshold = gHttpHandler->NetworkChangedTimeout();
+  }
+  GeneratePing(false);
+  ResumeRecv();
+}
+
 } // namespace mozilla::net
 } // namespace mozilla

netwerk/protocol/http/Http2Session.h

@@ -213,6 +213,8 @@ class Http2Session MOZ_FINAL : public ASpdySession
   void DecrementServerSessionWindow (uint32_t bytes) { mServerSessionWindow -= bytes; }
   void GetNegotiatedToken(nsACString &s) { s.Assign(mNegotiatedToken); }
 
+  void SendPing() MOZ_OVERRIDE;
+
 private:
 
   // These internal states do not correspond to the states of the HTTP/2 specification
@@ -442,6 +444,9 @@ class Http2Session MOZ_FINAL : public ASpdySession
   PRIntervalTime       mLastDataReadEpoch; // used for IdleTime()
   PRIntervalTime       mPingSentEpoch;
 
+  PRIntervalTime       mPreviousPingThreshold; // backup for the former value
+  bool                 mPreviousUsed;          // true when backup is used
+
   // used as a temporary buffer while enumerating the stream hash during GoAway
   nsDeque  mGoAwayStreamsToRestart;
 

netwerk/protocol/http/SpdySession3.cpp

@@ -73,6 +73,7 @@ SpdySession3::SpdySession3(nsISocketTransport *aSocketTransport)
   , mLastReadEpoch(PR_IntervalNow())
   , mPingSentEpoch(0)
   , mNextPingID(1)
+  , mPreviousUsed(false)
 {
   MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
 
@@ -224,8 +225,14 @@ SpdySession3::ReadTimeoutTick(PRIntervalTime now)
 
     if ((now - mLastReadEpoch) < mPingThreshold) {
       // recent activity means ping is not an issue
-      if (mPingSentEpoch)
+      if (mPingSentEpoch) {
         mPingSentEpoch = 0;
+        if (mPreviousUsed) {
+          // restore the former value
+          mPingThreshold = mPreviousPingThreshold;
+          mPreviousUsed = false;
+        }
+      }
 
       return PR_IntervalToSeconds(mPingThreshold) -
         PR_IntervalToSeconds(now - mLastReadEpoch);
@@ -2813,5 +2820,34 @@ SpdySession3::PushBack(const char *buf, uint32_t len)
   return mConnection->PushBack(buf, len);
 }
 
+void
+SpdySession3::SendPing()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  if (mPreviousUsed) {
+    // alredy in progress, get out
+    return;
+  }
+
+  mPingSentEpoch = PR_IntervalNow();
+  if (!mPingSentEpoch) {
+    mPingSentEpoch = 1; // avoid the 0 sentinel value
+  }
+  if (!mPingThreshold ||
+      (mPingThreshold > gHttpHandler->NetworkChangedTimeout())) {
+    mPreviousPingThreshold = mPingThreshold;
+    mPreviousUsed = true;
+    mPingThreshold = gHttpHandler->NetworkChangedTimeout();
+  }
+
+  GeneratePing(mNextPingID);
+  mNextPingID += 2;
+  ResumeRecv();
+
+  gHttpHandler->ConnMgr()->ActivateTimeoutTick();
+}
+
+
 } // namespace mozilla::net
 } // namespace mozilla

netwerk/protocol/http/SpdySession3.h

@@ -189,6 +189,8 @@ class SpdySession3 MOZ_FINAL : public ASpdySession
   z_stream *UpstreamZlib() { return &mUpstreamZlib; }
   nsISocketTransport *SocketTransport() { return mSocketTransport; }
 
+  void SendPing() MOZ_OVERRIDE;
+
 private:
 
   enum stateType {
@@ -378,6 +380,9 @@ class SpdySession3 MOZ_FINAL : public ASpdySession
   PRIntervalTime       mPingSentEpoch;
   uint32_t             mNextPingID;
 
+  PRIntervalTime       mPreviousPingThreshold; // backup for the former value
+  bool                 mPreviousUsed;          // true when backup is used
+
   // used as a temporary buffer while enumerating the stream hash during GoAway
   nsDeque  mGoAwayStreamsToRestart;
 

netwerk/protocol/http/SpdySession31.cpp

@@ -75,6 +75,7 @@ SpdySession31::SpdySession31(nsISocketTransport *aSocketTransport)
   , mLastReadEpoch(PR_IntervalNow())
   , mPingSentEpoch(0)
   , mNextPingID(1)
+  , mPreviousUsed(false)
 {
   MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
 
@@ -227,8 +228,14 @@ SpdySession31::ReadTimeoutTick(PRIntervalTime now)
 
   if ((now - mLastReadEpoch) < mPingThreshold) {
     // recent activity means ping is not an issue
-    if (mPingSentEpoch)
+    if (mPingSentEpoch) {
       mPingSentEpoch = 0;
+      if (mPreviousUsed) {
+        // restore the former value
+        mPingThreshold = mPreviousPingThreshold;
+        mPreviousUsed = false;
+      }
+    }
 
     return PR_IntervalToSeconds(mPingThreshold) -
       PR_IntervalToSeconds(now - mLastReadEpoch);
@@ -2957,5 +2964,33 @@ SpdySession31::PushBack(const char *buf, uint32_t len)
   return mConnection->PushBack(buf, len);
 }
 
+void
+SpdySession31::SendPing()
+{
+  MOZ_ASSERT(PR_GetCurrentThread() == gSocketThread);
+
+  if (mPreviousUsed) {
+    // alredy in progress, get out
+    return;
+  }
+
+  mPingSentEpoch = PR_IntervalNow();
+  if (!mPingSentEpoch) {
+    mPingSentEpoch = 1; // avoid the 0 sentinel value
+  }
+  if (!mPingThreshold ||
+      (mPingThreshold >  gHttpHandler->NetworkChangedTimeout())) {
+    mPreviousPingThreshold = mPingThreshold;
+    mPreviousUsed = true;
+    mPingThreshold = gHttpHandler->NetworkChangedTimeout();
+  }
+
+  GeneratePing(mNextPingID);
+  mNextPingID += 2;
+  ResumeRecv();
+
+  gHttpHandler->ConnMgr()->ActivateTimeoutTick();
+}
+
 } // namespace mozilla::net
 } // namespace mozilla

netwerk/protocol/http/SpdySession31.h

@@ -193,6 +193,8 @@ class SpdySession31 MOZ_FINAL : public ASpdySession
   int64_t RemoteSessionWindow() { return mRemoteSessionWindow; }
   void DecrementRemoteSessionWindow (uint32_t bytes) { mRemoteSessionWindow -= bytes; }
 
+  void SendPing() MOZ_OVERRIDE;
+
 private:
 
   enum stateType {
@@ -397,6 +399,9 @@ class SpdySession31 MOZ_FINAL : public ASpdySession
   PRIntervalTime       mPingSentEpoch;
   uint32_t             mNextPingID;
 
+  PRIntervalTime       mPreviousPingThreshold; // backup for the former value
+  bool                 mPreviousUsed;          // true when backup is used
+
   // used as a temporary buffer while enumerating the stream hash during GoAway
   nsDeque  mGoAwayStreamsToRestart;
 

netwerk/protocol/http/nsHttpConnection.cpp

@@ -69,6 +69,7 @@ nsHttpConnection::nsHttpConnection()
     , mExperienced(false)
     , mInSpdyTunnel(false)
     , mForcePlainText(false)
+    , mTrafficStamp(false)
     , mHttp1xTransactionCount(0)
     , mRemainingConnectionUses(0xffffffff)
     , mClassification(nsAHttpTransaction::CLASS_GENERAL)
@@ -2080,5 +2081,23 @@ nsHttpConnection::GetInterface(const nsIID &iid, void **result)
     return NS_ERROR_NO_INTERFACE;
 }
 
+void
+nsHttpConnection::CheckForTraffic(bool check)
+{
+    if (check) {
+        if (mSpdySession) {
+            // Send a ping to verify it is still alive
+            mSpdySession->SendPing();
+        } else {
+            // If not SPDY, Store snapshot amount of data right now
+            mTrafficCount = mTotalBytesWritten + mTotalBytesRead;
+            mTrafficStamp = true;
+        }
+    } else {
+        // mark it as not checked
+        mTrafficStamp = false;
+    }
+}
+
 } // namespace mozilla::net
 } // namespace mozilla

netwerk/protocol/http/nsHttpConnection.h

@@ -200,6 +200,18 @@ class nsHttpConnection MOZ_FINAL : public nsAHttpSegmentReader
     void    SetupSecondaryTLS();
     void    SetInSpdyTunnel(bool arg);
 
+    // Check active connections for traffic (or not). SPDY connections send a
+    // ping, ordinary HTTP connections get some time to get traffic to be
+    // considered alive.
+    void CheckForTraffic(bool check);
+
+    // NoTraffic() returns true if there's been no traffic on the (non-spdy)
+    // connection since CheckForTraffic() was called.
+    bool NoTraffic() {
+        return mTrafficStamp &&
+            (mTrafficCount == (mTotalBytesWritten + mTotalBytesRead));
+    }
+
 private:
     // Value (set in mTCPKeepaliveConfig) indicates which set of prefs to use.
     enum TCPKeepaliveConfig {
@@ -292,6 +304,10 @@ class nsHttpConnection MOZ_FINAL : public nsAHttpSegmentReader
     bool                            mInSpdyTunnel;
     bool                            mForcePlainText;
 
+    // A snapshot of current number of transfered bytes
+    int64_t                         mTrafficCount;
+    bool                            mTrafficStamp; // true then the above is set
+
     // The number of <= HTTP/1.1 transactions performed on this connection. This
     // excludes spdy transactions.
     uint32_t                        mHttp1xTransactionCount;