bug 1094522 - claim conns with null transactions instead of starting new ones r=hurley

netwerk/protocol/http/NullHttpTransaction.cpp

@@ -97,6 +97,7 @@ NullHttpTransaction::NullHttpTransaction(nsHttpConnectionInfo *ci,
   , mCapsToClear(0)
   , mRequestHead(nullptr)
   , mIsDone(false)
+  , mClaimed(false)
   , mCallbacks(callbacks)
   , mConnectionInfo(ci)
 {
@@ -126,6 +127,16 @@ NullHttpTransaction::~NullHttpTransaction()
   delete mRequestHead;
 }
 
+bool
+NullHttpTransaction::Claim()
+{
+  if (mClaimed) {
+    return false;
+  }
+  mClaimed = true;
+  return true;
+}
+
 void
 NullHttpTransaction::SetConnection(nsAHttpConnection *conn)
 {

netwerk/protocol/http/NullHttpTransaction.h

@@ -38,8 +38,11 @@ public:
                       nsIInterfaceRequestor *callbacks,
                       uint32_t caps);
 
+  bool Claim();
+
   // Overload of nsAHttpTransaction methods
   bool IsNullTransaction() MOZ_OVERRIDE MOZ_FINAL { return true; }
+  NullHttpTransaction *QueryNullTransaction() MOZ_OVERRIDE MOZ_FINAL { return this; }
   bool ResponseTimeoutEnabled() const MOZ_OVERRIDE MOZ_FINAL {return true; }
   PRIntervalTime ResponseTimeout() MOZ_OVERRIDE MOZ_FINAL
   {
@@ -62,6 +65,7 @@ private:
   uint32_t mCapsToClear;
   nsHttpRequestHead *mRequestHead;
   bool mIsDone;
+  bool mClaimed;
 
 protected:
   nsRefPtr<nsAHttpConnection> mConnection;

netwerk/protocol/http/TunnelUtils.cpp

@@ -750,6 +750,15 @@ TLSFilterTransaction::IsNullTransaction()
   return mTransaction->IsNullTransaction();
 }
 
+NullHttpTransaction *
+TLSFilterTransaction::QueryNullTransaction()
+{
+  if (!mTransaction) {
+    return nullptr;
+  }
+  return mTransaction->QueryNullTransaction();
+}
+
 nsHttpTransaction *
 TLSFilterTransaction::QueryHttpTransaction()
 {

netwerk/protocol/http/TunnelUtils.h

@@ -85,6 +85,7 @@ struct PRSocketOptionData;
 namespace mozilla { namespace net {
 
 class nsHttpRequestHead;
+class NullHttpTransaction;
 class TLSFilterTransaction;
 
 class NudgeTunnelCallback : public nsISupports
@@ -127,6 +128,7 @@ public:
   // nsAHttpTransaction overloads
   nsHttpPipeline *QueryPipeline() MOZ_OVERRIDE;
   bool IsNullTransaction() MOZ_OVERRIDE;
+  NullHttpTransaction *QueryNullTransaction() MOZ_OVERRIDE;
   nsHttpTransaction *QueryHttpTransaction() MOZ_OVERRIDE;
   SpdyConnectTransaction *QuerySpdyConnectTransaction() MOZ_OVERRIDE;
 

netwerk/protocol/http/nsAHttpTransaction.h

@@ -23,6 +23,7 @@ class nsHttpTransaction;
 class nsHttpPipeline;
 class nsHttpRequestHead;
 class nsHttpConnectionInfo;
+class NullHttpTransaction;
 class SpdyConnectTransaction;
 
 //----------------------------------------------------------------------------
@@ -119,7 +120,7 @@ public:
 
     // Occasionally the abstract interface has to give way to base implementations
     // to respect differences between spdy, pipelines, etc..
-    // These Query* (and IsNUllTransaction()) functions provide a way to do
+    // These Query* (and IsNullTransaction()) functions provide a way to do
     // that without using xpcom or rtti. Any calling code that can't deal with
     // a null response from one of them probably shouldn't be using nsAHttpTransaction
 
@@ -132,6 +133,7 @@ public:
     // A null transaction is expected to return BASE_STREAM_CLOSED on all of
     // its IO functions all the time.
     virtual bool IsNullTransaction() { return false; }
+    virtual NullHttpTransaction *QueryNullTransaction() { return nullptr; }
 
     // If we used rtti this would be the result of doing
     // dynamic_cast<nsHttpTransaction *>(this).. i.e. it can be nullptr for

netwerk/protocol/http/nsHttpConnectionMgr.cpp

@@ -1500,6 +1500,18 @@ nsHttpConnectionMgr::MakeNewConnection(nsConnectionEntry *ent,
         }
     }
 
+    uint32_t activeLength = ent->mActiveConns.Length();
+    for (uint32_t i = 0; i < activeLength; i++) {
+        nsAHttpTransaction *activeTrans = ent->mActiveConns[i]->Transaction();
+        NullHttpTransaction *nullTrans = activeTrans ? activeTrans->QueryNullTransaction() : nullptr;
+        if (nullTrans && nullTrans->Claim()) {
+            LOG(("nsHttpConnectionMgr::MakeNewConnection [ci = %s] "
+                 "Claiming a null transaction for later use\n",
+                 ent->mConnInfo->HashKey().get()));
+            return NS_OK;
+        }
+    }
+
     // If this host is trying to negotiate a SPDY session right now,
     // don't create any new connections until the result of the
     // negotiation is known.