Problem: tcp_recv/send_buffer should be byte value instead of scale factor

Solution: change option behaviour and adopt documentation

doc/zmq_getsockopt.txt

@@ -738,10 +738,9 @@ Applicable socket types:: all, when using TCP transport
 
 ZMQ_TCP_RECV_BUFFER: Size of the TCP receive buffer
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'ZMQ_RECV_BUFFER' specifies the maximum number of bytes which can
-be received by an individual syscall to receive data from the TCP
-socket. The buffer size is specified as an integer number from 0 (very small)
-to 10 (very large). The default value is 3.
+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]
@@ -752,10 +751,9 @@ Applicable socket types:: all, when using TCP transport
 
 ZMQ_TCP_SEND_BUFFER: Size of the TCP receive buffer
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'ZMQ_SEND_BUFFER' specifies the maximum number of bytes which can
-be sent by an individual syscall to transmit data to the TCP
-socket. The buffer size is specified as an integer number from 0 (very small)
-to 10 (very large). The default value is 3.
+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]

doc/zmq_setsockopt.txt

@@ -1073,10 +1073,9 @@ Applicable socket types:: all, when using TCP transports.
 
 ZMQ_TCP_RECV_BUFFER: Size of the TCP receive buffer
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'ZMQ_RECV_BUFFER' specifies the maximum number of bytes which can
-be received by an individual syscall to receive data from the TCP
-socket. The buffer size is specified as an integer number from 0 (very small)
-to 10 (very large). The default value is 3.
+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]
@@ -1087,10 +1086,9 @@ Applicable socket types:: all, when using TCP transport
 
 ZMQ_TCP_SEND_BUFFER: Size of the TCP receive buffer
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'ZMQ_SEND_BUFFER' specifies the maximum number of bytes which can
-be sent by an individual syscall to transmit data to the TCP
-socket. The buffer size is specified as an integer number from 0 (very small)
-to 10 (very large). The default value is 3.
+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]

src/options.cpp

@@ -28,7 +28,6 @@
 */
 
 #include <string.h>
-#include <cmath>
 
 #include "options.hpp"
 #include "err.hpp"
@@ -66,8 +65,8 @@ zmq::options_t::options_t () :
     tcp_keepalive_cnt (-1),
     tcp_keepalive_idle (-1),
     tcp_keepalive_intvl (-1),
-    tcp_recv_buffer_size (3),
-    tcp_send_buffer_size (3),
+    tcp_recv_buffer_size (8192),
+    tcp_send_buffer_size (8192),
     mechanism (ZMQ_NULL),
     as_server (0),
     gss_plaintext (false),
@@ -284,14 +283,16 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
             break;
 
         case ZMQ_TCP_RECV_BUFFER:
-            if (is_int && (value >= 0 && value <= 10) ) {
-                tcp_recv_buffer_size = static_cast<unsigned int>(std::pow(2.0, value)) * 1024;
+            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 && value <= 10) ) {
-                tcp_send_buffer_size = static_cast<unsigned int>(std::pow(2.0, value)) * 1024;
+            if (is_int && (value > 0) ) {
+                tcp_send_buffer_size = static_cast<unsigned int>(value);
+                return 0;
             }
             break;