Refactor responsibility of releasing failed messages

APISendMessageToConnection, _APISendMessageToConnection, and SNP_SendMessage
now expect the *caller* to release the message if it changes.  Since
there are many failure points but only a few call sites, this resulted
in a net reduction in lines of code and is imo simpler.  But more
importantly it sets us up so that we can continue this one level higher,
into the public API, so that we can allow the app to retain failed
messages.  For lots of app code, I anticipate that this will be useful
so that they can retry them later if they want.  The most important and
legitimate failure case here is if the send buffer is full.

Author: zpostfacto

src/steamnetworkingsockets/clientlib/csteamnetworkingmessages.cpp

@@ -518,6 +518,7 @@ EResult CSteamNetworkingMessages::SendMessageToUser( const SteamNetworkingIdenti
 	int64 nMsgNumberOrResult = pConn->_APISendMessageToConnection( pMsg, usecNow, nullptr );
 	if ( nMsgNumberOrResult > 0 )
 		return k_EResultOK;
+	pMsg->Release();
 	return EResult( -nMsgNumberOrResult );
 }
 

src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp

@@ -1364,6 +1364,8 @@ void CSteamNetworkingSockets::SendMessages( int nMessages, SteamNetworkingMessag
 			result = pConn->APISendMessageToConnection( pMsg, usecNow, &bThinkImmediately );
 			if ( bThinkImmediately )
 				bConnectionThinkImmediately = true;
+			if ( result <= 0 )
+				pMsg->Release();
 		}
 		else
 		{

src/steamnetworkingsockets/clientlib/steamnetworkingsockets_connections.cpp

@@ -2053,6 +2053,7 @@ EResult CSteamNetworkConnectionBase::APISendMessageToConnection( const void *pDa
 			*pOutMessageNumber = nMsgNumberOrResult;
 		return k_EResultOK;
 	}
+	pMsg->Release();
 	return EResult( -nMsgNumberOrResult );
 }
 
@@ -2069,24 +2070,19 @@ int64 CSteamNetworkConnectionBase::APISendMessageToConnection( CSteamNetworkingM
 		case k_ESteamNetworkingConnectionState_Dead:
 		default:
 			AssertMsg( false, "Why are making API calls on this connection?" );
-			pMsg->Release();
 			return -k_EResultInvalidState;
 
 		case k_ESteamNetworkingConnectionState_Connecting:
 		case k_ESteamNetworkingConnectionState_FindingRoute:
 			if ( pMsg->m_nFlags & k_nSteamNetworkingSend_NoDelay )
-			{
-				pMsg->Release();
 				return -k_EResultIgnored;
-			}
 			break;
 
 		case k_ESteamNetworkingConnectionState_Connected:
 			break;
 
 		case k_ESteamNetworkingConnectionState_ClosedByPeer:
 		case k_ESteamNetworkingConnectionState_ProblemDetectedLocally:
-			pMsg->Release();
 			return -k_EResultNoConnection;
 	}
 
@@ -2095,7 +2091,6 @@ int64 CSteamNetworkConnectionBase::APISendMessageToConnection( CSteamNetworkingM
 	if ( (unsigned)pMsg->m_cbSize > (unsigned)cbMaxMessageSizeSend )
 	{
 		SpewWarning( "Message size %u is too big.  Max is %d", pMsg->m_cbSize, cbMaxMessageSizeSend );
-		pMsg->Release();
 		return -k_EResultInvalidParam;
 	}
 
@@ -2112,7 +2107,6 @@ int64 CSteamNetworkConnectionBase::_APISendMessageToConnection( CSteamNetworking
 	if ( (unsigned)pMsg->m_cbSize > (unsigned)k_cbMaxSteamNetworkingSocketsMessageSizeSend_Internal )
 	{
 		AssertMsg2( false, "Message size %d is too big.  Max internal size is %d", pMsg->m_cbSize, k_cbMaxSteamNetworkingSocketsMessageSizeSend_Internal );
-		pMsg->Release();
 		return -k_EResultInvalidParam;
 	}
 
@@ -4069,13 +4063,11 @@ int64 CSteamNetworkConnectionPipe::_APISendMessageToConnection( CSteamNetworking
 	{
 		// Caller should have checked the connection at a higher level, so this is a bug
 		AssertMsg( false, "No partner pipe?" );
-		pMsg->Release();
 		return -k_EResultFail;
 	}
 
 	if ( (int)pMsg->m_idxLane >= len( m_senderState.m_vecLanes ) )
 	{
-		pMsg->Release();
 		return -k_EResultInvalidParam;
 	}
 	SSNPSenderState::Lane &lane = m_senderState.m_vecLanes[ pMsg->m_idxLane ];

src/steamnetworkingsockets/clientlib/steamnetworkingsockets_connections.h

@@ -368,7 +368,8 @@ class CSteamNetworkConnectionBase : public ILockableThinker< ConnectionLock >
 	/// Send a message
 	EResult APISendMessageToConnection( const void *pData, uint32 cbData, int nSendFlags, int64 *pOutMessageNumber );
 
-	/// Send a message.  Returns the assigned message number, or a negative EResult value
+	/// Send a message.  Returns the assigned message number, or a negative EResult value.
+	/// Does NOT Release the message on failure -- the caller is responsible for that.
 	int64 APISendMessageToConnection( CSteamNetworkingMessage *pMsg, SteamNetworkingMicroseconds usecNow, bool *pbThinkImmediately = nullptr );
 
 	/// Flush any messages queued for Nagle

src/steamnetworkingsockets/clientlib/steamnetworkingsockets_snp.cpp

@@ -312,7 +312,6 @@ int64 CSteamNetworkConnectionBase::SNP_SendMessage( CSteamNetworkingMessage *pSe
 	if ( (size_t)pSendMessage->m_idxLane >= m_senderState.m_vecLanes.size() )
 	{
 		SpewBug( "Invalid lane %d.  Only %d lanes configured\n", (int)pSendMessage->m_idxLane, (int)m_senderState.m_vecLanes.size() );
-		pSendMessage->Release();
 		return -k_EResultInvalidParam;
 	}
 	SSNPSenderState::Lane &lane = m_senderState.m_vecLanes[ pSendMessage->m_idxLane ];
@@ -321,7 +320,6 @@ int64 CSteamNetworkConnectionBase::SNP_SendMessage( CSteamNetworkingMessage *pSe
 	if ( m_senderState.PendingBytesTotal() + cbData > m_connectionConfig.SendBufferSize.Get() )
 	{
 		SpewWarningRateLimited( usecNow, "Connection already has %u bytes pending, cannot queue any more messages\n", m_senderState.PendingBytesTotal() );
-		pSendMessage->Release();
 		return -k_EResultLimitExceeded;
 	}