Problem: ZMQ_TCP_RECV_BUFFER/SEND_BUFFER are redundant

These options are confusing and redundant. Their names suggest
they apply to the tcp:// transport, yet they are used for all
stream protocols. The methods zmq::set_tcp_receive_buffer and
zmq::set_tcp_send_buffer don't use these values at all, they use
ZMQ_SNDBUF and ZMQ_RCVBUF.

Solution: merge these new options into ZMQ_SNDBUF and ZMQ_RCVBUF.

This means defaulting these two options to 8192, and removing the
new options. We now have ZMQ_SNDBUF and ZMQ_RCVBUF being used both
for TCP socket control, and for input/output buffering.

Note: the default for SNDBUF and RCVBUF are otherwise 4096.

doc/zmq_getsockopt.txt

@@ -498,6 +498,7 @@ documentation for the 'SO_RCVBUF' socket option.
 [horizontal]
 Option value type:: int
 Option value unit:: bytes
+Default value:: 8192
 Applicable socket types:: all
 
 
@@ -612,6 +613,7 @@ documentation for the 'SO_SNDBUF' socket option.
 [horizontal]
 Option value type:: int
 Option value unit:: bytes
+Default value:: 8192
 Applicable socket types:: all
 
 
@@ -763,31 +765,6 @@ Option value unit:: N/A
 Default value:: not set
 Applicable socket types:: all, when using TCP transport
 
-ZMQ_TCP_RECV_BUFFER: Size of the TCP receive buffer
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'ZMQ_TCP_RECV_BUFFER' specifies the maximum number of bytes which can
-be received by an individual syscall to receive data from the TCP socket.
-The default value is 8192.
-
-
-[horizontal]
-Option value type:: int
-Option value unit:: >0
-Default value:: 8192
-Applicable socket types:: all, when using TCP transport
-
-ZMQ_TCP_SEND_BUFFER: Size of the TCP receive buffer
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'ZMQ_TCP_SEND_BUFFER' specifies the maximum number of bytes which can
-be sent by an individual syscall to transmit data to the TCP socket.
-The default value is 8192.
-
-
-[horizontal]
-Option value type:: int
-Option value unit:: >0
-Default value:: 8192
-Applicable socket types:: all, when using TCP transport
 
 ZMQ_VMCI_BUFFER_SIZE: Retrieve buffer size of the VMCI socket
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

doc/zmq_setsockopt.txt

@@ -1102,31 +1102,6 @@ Option value unit:: boolean
 Default value:: 1 (true)
 Applicable socket types:: all, when using TCP transports.
 
-ZMQ_TCP_RECV_BUFFER: Size of the TCP receive buffer
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'ZMQ_TCP_RECV_BUFFER' specifies the maximum number of bytes which can
-be received by an individual syscall to receive data from the TCP socket.
-The default value is 8192.
-
-
-[horizontal]
-Option value type:: int
-Option value unit:: >0
-Default value:: 8192
-Applicable socket types:: all, when using TCP transport
-
-ZMQ_TCP_SEND_BUFFER: Size of the TCP receive buffer
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'ZMQ_TCP_SEND_BUFFER' specifies the maximum number of bytes which can
-be sent by an individual syscall to transmit data to the TCP socket.
-The default value is 8192.
-
-
-[horizontal]
-Option value type:: int
-Option value unit:: >0
-Default value:: 8192
-Applicable socket types:: all, when using TCP transport
 
 ZMQ_VMCI_BUFFER_SIZE: Set buffer size of the VMCI socket
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

include/zmq.h

@@ -339,8 +339,6 @@ ZMQ_EXPORT const char *zmq_msg_group (zmq_msg_t *msg);
 #define ZMQ_CONNECT_TIMEOUT 79
 #define ZMQ_TCP_MAXRT 80
 #define ZMQ_THREAD_SAFE 81
-#define ZMQ_TCP_RECV_BUFFER 82
-#define ZMQ_TCP_SEND_BUFFER 83
 #define ZMQ_MULTICAST_MAXTPDU 84
 #define ZMQ_VMCI_BUFFER_SIZE 85
 #define ZMQ_VMCI_BUFFER_MIN_SIZE 86

src/options.cpp

@@ -42,8 +42,8 @@ zmq::options_t::options_t () :
     recovery_ivl (10000),
     multicast_hops (1),
     multicast_maxtpdu (1500),
-    sndbuf (-1),
+    sndbuf (8192),
-    rcvbuf (-1),
+    rcvbuf (8192),
     tos (0),
     type (-1),
     linger (-1),
@@ -66,8 +66,6 @@ zmq::options_t::options_t () :
     tcp_keepalive_cnt (-1),
     tcp_keepalive_idle (-1),
     tcp_keepalive_intvl (-1),
-    tcp_recv_buffer_size (8192),
-    tcp_send_buffer_size (8192),
     mechanism (ZMQ_NULL),
     as_server (0),
     gss_plaintext (false),
@@ -298,20 +296,6 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
             }
             break;
 
-        case ZMQ_TCP_RECV_BUFFER:
-            if (is_int && (value > 0) ) {
-                tcp_recv_buffer_size = static_cast<unsigned int>(value);
-                return 0;
-            }
-            break;
-
-        case ZMQ_TCP_SEND_BUFFER:
-            if (is_int && (value > 0) ) {
-                tcp_send_buffer_size = static_cast<unsigned int>(value);
-                return 0;
-            }
-            break;
-
         case ZMQ_IMMEDIATE:
             if (is_int && (value == 0 || value == 1)) {
                 immediate = value;
@@ -866,20 +850,6 @@ int zmq::options_t::getsockopt (int option_, void *optval_, size_t *optvallen_)
             }
             break;
 
-        case ZMQ_TCP_SEND_BUFFER:
-            if (is_int) {
-                *value = tcp_send_buffer_size;
-                return 0;
-            }
-            break;
-
-        case ZMQ_TCP_RECV_BUFFER:
-            if (is_int) {
-                *value = tcp_recv_buffer_size;
-                return 0;
-            }
-            break;
-
         case ZMQ_MECHANISM:
             if (is_int) {
                 *value = mechanism;

src/options.hpp

@@ -160,10 +160,6 @@ namespace zmq
         typedef std::vector <tcp_address_mask_t> tcp_accept_filters_t;
         tcp_accept_filters_t tcp_accept_filters;
 
-        // TCP buffer sizes
-        unsigned int tcp_recv_buffer_size;
-        unsigned int tcp_send_buffer_size;
-
         // IPC accept() filters
 #       if defined ZMQ_HAVE_SO_PEERCRED || defined ZMQ_HAVE_LOCAL_PEERCRED
         bool zap_ipc_creds;

src/stream_engine.cpp

@@ -203,10 +203,10 @@ void zmq::stream_engine_t::plug (io_thread_t *io_thread_,
 
     if (options.raw_socket) {
         // no handshaking for raw sock, instantiate raw encoder and decoders
-        encoder = new (std::nothrow) raw_encoder_t (options.tcp_send_buffer_size);
+        encoder = new (std::nothrow) raw_encoder_t (options.sndbuf);
         alloc_assert (encoder);
 
-        decoder = new (std::nothrow) raw_decoder_t (options.tcp_recv_buffer_size);
+        decoder = new (std::nothrow) raw_decoder_t (options.rcvbuf);
         alloc_assert (decoder);
 
         // disable handshaking for raw socket
@@ -385,12 +385,12 @@ void zmq::stream_engine_t::out_event ()
         outpos = NULL;
         outsize = encoder->encode (&outpos, 0);
 
-        while (outsize < options.tcp_send_buffer_size) {
+        while (outsize < (size_t) options.sndbuf) {
             if ((this->*next_msg) (&tx_msg) == -1)
                 break;
             encoder->load_msg (&tx_msg);
             unsigned char *bufptr = outpos + outsize;
-            size_t n = encoder->encode (&bufptr, options.tcp_send_buffer_size - outsize);
+            size_t n = encoder->encode (&bufptr, options.sndbuf - outsize);
             zmq_assert (n > 0);
             if (outpos == NULL)
                 outpos = bufptr;
@@ -587,10 +587,10 @@ bool zmq::stream_engine_t::handshake ()
            return false;
         }
 
-        encoder = new (std::nothrow) v1_encoder_t (options.tcp_send_buffer_size);
+        encoder = new (std::nothrow) v1_encoder_t (options.sndbuf);
         alloc_assert (encoder);
 
-        decoder = new (std::nothrow) v1_decoder_t (options.tcp_recv_buffer_size, options.maxmsgsize);
+        decoder = new (std::nothrow) v1_decoder_t (options.rcvbuf, options.maxmsgsize);
         alloc_assert (decoder);
 
         //  We have already sent the message header.
@@ -635,11 +635,11 @@ bool zmq::stream_engine_t::handshake ()
         }
 
         encoder = new (std::nothrow) v1_encoder_t (
-           options.tcp_send_buffer_size);
+           options.sndbuf);
         alloc_assert (encoder);
 
         decoder = new (std::nothrow) v1_decoder_t (
-            options.tcp_recv_buffer_size, options.maxmsgsize);
+            options.rcvbuf, options.maxmsgsize);
         alloc_assert (decoder);
     }
     else
@@ -650,19 +650,19 @@ bool zmq::stream_engine_t::handshake ()
            return false;
         }
 
-        encoder = new (std::nothrow) v2_encoder_t (options.tcp_send_buffer_size);
+        encoder = new (std::nothrow) v2_encoder_t (options.sndbuf);
         alloc_assert (encoder);
 
         decoder = new (std::nothrow) v2_decoder_t (
-            options.tcp_recv_buffer_size, options.maxmsgsize);
+            options.rcvbuf, options.maxmsgsize);
         alloc_assert (decoder);
     }
     else {
-        encoder = new (std::nothrow) v2_encoder_t (options.tcp_send_buffer_size);
+        encoder = new (std::nothrow) v2_encoder_t (options.sndbuf);
         alloc_assert (encoder);
 
         decoder = new (std::nothrow) v2_decoder_t (
-                options.tcp_recv_buffer_size, options.maxmsgsize);
+                options.rcvbuf, options.maxmsgsize);
         alloc_assert (decoder);
 
         if (options.mechanism == ZMQ_NULL