Auto merge of zcash#1847 - bitcartel:1680_rpckeepalive_deadlock, r=eb…

…full

Closes zcash#1680, temporary fix for rpc deadlock inherited from upstream.

qa/rpc-tests/httpbasics.py

@@ -38,13 +38,9 @@ def run_test(self):
         conn.request('POST', '/', '{"method": "getbestblockhash"}', headers)
         out1 = conn.getresponse().read();
         assert_equal('"error":null' in out1, True)
-        assert_equal(conn.sock!=None, True) #according to http/1.1 connection must still be open!
-
-        #send 2nd request without closing connection
-        conn.request('POST', '/', '{"method": "getchaintips"}', headers)
-        out2 = conn.getresponse().read();
-        assert_equal('"error":null' in out1, True) #must also response with a correct json-rpc message
-        assert_equal(conn.sock!=None, True) #according to http/1.1 connection must still be open!
+
+        # TODO #1856: Re-enable support for persistent connections.
+        assert_equal(conn.sock!=None, False)
         conn.close()
 
         #same should be if we add keep-alive because this should be the std. behaviour
@@ -55,13 +51,9 @@ def run_test(self):
         conn.request('POST', '/', '{"method": "getbestblockhash"}', headers)
         out1 = conn.getresponse().read();
         assert_equal('"error":null' in out1, True)
-        assert_equal(conn.sock!=None, True) #according to http/1.1 connection must still be open!
-
-        #send 2nd request without closing connection
-        conn.request('POST', '/', '{"method": "getchaintips"}', headers)
-        out2 = conn.getresponse().read();
-        assert_equal('"error":null' in out1, True) #must also response with a correct json-rpc message
-        assert_equal(conn.sock!=None, True) #according to http/1.1 connection must still be open!
+
+        # TODO #1856: Re-enable support for persistent connections.
+        assert_equal(conn.sock!=None, False)
         conn.close()
 
         #now do the same with "Connection: close"
@@ -96,7 +88,10 @@ def run_test(self):
         conn.request('POST', '/', '{"method": "getbestblockhash"}', headers)
         out1 = conn.getresponse().read();
         assert_equal('"error":null' in out1, True)
-        assert_equal(conn.sock!=None, True) #connection must be closed because bitcoind should use keep-alive by default
+
+        # TODO #1856: Re-enable support for persistent connections.
+        assert_equal(conn.sock!=None, False)
+        conn.close()
 
 if __name__ == '__main__':
     HTTPBasicsTest ().main ()

src/init.cpp

@@ -425,7 +425,10 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-rpcport=<port>", strprintf(_("Listen for JSON-RPC connections on <port> (default: %u or testnet: %u)"), 8232, 18232));
     strUsage += HelpMessageOpt("-rpcallowip=<ip>", _("Allow JSON-RPC connections from specified source. Valid for <ip> are a single IP (e.g. 1.2.3.4), a network/netmask (e.g. 1.2.3.4/255.255.255.0) or a network/CIDR (e.g. 1.2.3.4/24). This option can be specified multiple times"));
     strUsage += HelpMessageOpt("-rpcthreads=<n>", strprintf(_("Set the number of threads to service RPC calls (default: %d)"), 4));
-    strUsage += HelpMessageOpt("-rpckeepalive", strprintf(_("RPC support for HTTP persistent connections (default: %d)"), 1));
+
+    // TODO #1856: Re-enable support for persistent connections.
+    // Disabled to avoid rpc deadlock #1680, until we backport upstream changes which replace boost::asio with libevent, or another solution is implemented.
+    //strUsage += HelpMessageOpt("-rpckeepalive", strprintf(_("RPC support for HTTP persistent connections (default: %d)"), 1));
 
     // Disabled until we can lock notes and also tune performance of libsnark which by default uses multiple threads
     //strUsage += HelpMessageOpt("-rpcasyncthreads=<n>", strprintf(_("Set the number of threads to service Async RPC calls (default: %d)"), 1));

src/rpcserver.cpp

@@ -1025,9 +1025,15 @@ void ServiceConnection(AcceptedConnection *conn)
         // Read HTTP message headers and body
         ReadHTTPMessage(conn->stream(), mapHeaders, strRequest, nProto, MAX_SIZE);
 
+        // TODO #1856: Re-enable support for persistent connections.
+        // We have disabled support for HTTP Keep-Alive until resolution of #1680, upstream rpc deadlock.
+        // Close connection immediately.
+        fRun = false;
+        /*
         // HTTP Keep-Alive is false; close connection immediately
         if ((mapHeaders["connection"] == "close") || (!GetBoolArg("-rpckeepalive", true)))
             fRun = false;
+        */
 
         // Process via JSON-RPC API
         if (strURI == "/") {