http:Sessions are not reused in practice

so we could drop the support for that and enable simplifying

e.g. always do asyncShutdown automatically and remove the need for
callers to do that.

Signed-off-by: Caolán McNamara <caolan.mcnamara@collabora.com>
Change-Id: Ic1c66efce5f6e68e3c375ce30e0440eb24e0e01e

Author: caolanm

net/HttpRequest.hpp

@@ -71,9 +71,7 @@
 //
 // http::Session is the primary class that is
 // used for all requests. It is created for a
-// specific host. Because http::Session is
-// designed to be reusable, the connection itself
-// can also be reused, improving efficiency.
+// specific host.
 //
 // An http::Session takes an http::Request and,
 // only after initiating a new request, access
@@ -1314,28 +1312,17 @@ class Session final : public ProtocolHandlerInterface
     }
 
     /// Start an asynchronous request on the given SocketPoll.
-    /// Return true when it dispatches the socket to the SocketPoll.
-    /// Note: when reusing this Session, it is assumed that the socket
-    /// is already added to the SocketPoll on a previous call (do not
-    /// use multiple SocketPoll instances on the same Session).
+    /// Note: Sessions are not reusable, create a new one per request.
     void asyncRequest(const Request& req, const std::shared_ptr<SocketPoll>& poll)
     {
         LOG_TRC("new asyncRequest: " << req.getVerb() << ' ' << host() << ':' << port() << ' '
                                      << req.getUrl());
 
         newRequest(req);
 
-        if (!isConnected())
-        {
-            asyncConnect(poll);
-        }
-        else
-        {
-            // Technically, there is a race here. The socket can
-            // get disconnected and removed right after isConnected.
-            // In that case, we will timeout and no request will be sent.
-            poll->wakeup();
-        }
+        assert(!isConnected() && _socket.expired());
+
+        asyncConnect(poll);
 
         LOG_DBG("starting asyncRequest: " << req.getVerb() << ' ' << host() << ':' << port() << ' '
                                           << req.getUrl());
@@ -1441,7 +1428,8 @@ class Session final : public ProtocolHandlerInterface
 
         assert(!!_response && "Response must be set!");
 
-        if (!isConnected())
+        assert(!isConnected() && _socket.expired());
+
         {
             std::shared_ptr<StreamSocket> socket = connect();
             if (!socket)
@@ -1722,7 +1710,7 @@ class Session final : public ProtocolHandlerInterface
 
     void asyncConnectFailed(net::AsyncConnectResult result)
     {
-        assert(!_socket.use_count());
+        assert(_socket.expired());
         _result = result;
 
         LOG_ERR("Failed to connect to " << _host << ':' << _port);
@@ -1743,7 +1731,7 @@ class Session final : public ProtocolHandlerInterface
 
     void asyncConnect(const std::weak_ptr<SocketPoll>& poll)
     {
-        _socket.reset(); // Reset to make sure we are disconnected.
+        assert(_socket.expired());
 
         auto pushConnectCompleteToPoll =
             [this, poll](std::shared_ptr<StreamSocket> socket, net::AsyncConnectResult result)