Documentation updates (API reference)

Signed-off-by: Martin Lucina <martin@lucina.net>

9 files changed, 132 insertions, 73 deletions

diff --git a/doc/xs.txt b/doc/xs.txt
index c582d34..8320dbd 100644
--- a/doc/xs.txt
+++ b/doc/xs.txt
@@ -48,18 +48,25 @@ Initialise Crossroads context::
 Terminate Crossroads context::
     linkxs:xs_term[3]
 
+Set Crossroads context options::
+    linkxs:xs_setctxopt[3]
+
 
 Thread safety
 ^^^^^^^^^^^^^
 A 'context' is thread safe and may be shared among as many application
-threads as necessary, without any additional locking required on the part of
-the caller.
-
-Individual Crossroads 'sockets' are _not_ thread safe except in the case where
-full memory barriers are issued when migrating a socket from one thread to
-another. In practice this means applications can create a socket in one thread
-with _xs_socket()_ and then pass it to a _newly created_ thread as part of
-thread initialization, for example via a structure passed as an argument to
+threads as necessary, without any additional locking required on the part
+of the caller.
+
+The individual 'sockets' within a 'context' are _not_ thread safe --
+applications may _not_ use a single 'socket' concurrently from multiple
+threads.
+
+A 'socket' _may_ be _migrated_ from one thread to another, by issuing a
+full memory barrier between individual calls on the 'socket'.  For example,
+this means applications can create a socket in one thread with
+_xs_socket()_ and then pass it to a _newly created_ thread as part of
+thread initialization via a structure passed as an argument to
 _pthread_create()_.
 
 
@@ -68,18 +75,28 @@ Multiple contexts
 Multiple 'contexts' may coexist within a single application. Thus, an
 application can use Crossroads directly and at the same time make use of any
 number of additional libraries or components which themselves make use of
-Crossroads as long as the above guidelines regarding thread safety are adhered
-to.
+Crossroads.
 
 
 Messages
 ~~~~~~~~
-A Crossroads message is a discrete unit of data passed between applications or
-components of the same application. Crossroads messages have no internal
+A Crossroads message is a discrete unit of data passed between applications
+or components of the same application. Crossroads messages have no internal
 structure and from the point of view of Crossroads themselves they are
 considered to be opaque binary data.
 
-The following functions are provided to work with messages:
+Applications using the Crossroads library send and receive messages
+directly from/to buffers provided by the application, using the Crossroads
+functions _xs_send()_ and _xs_recv()_.
+
+Alternatively, applications desiring zero-copy messaging and/or reference
+counted allocation of messages can use the message handling functions
+described in this section, and send and receive messages using
+_xs_sendmsg()_ and _xs_recvmsg()_ respectively.  These two approaches are
+interchangeable.
+
+The following functions are provided to work with messages using zero-copy
+and/or reference-counted allocation of messages:
 
 Initialise a message::
     linkxs:xs_msg_init[3]
@@ -97,6 +114,9 @@ Message manipulation::
     linkxs:xs_msg_copy[3]
     linkxs:xs_msg_move[3]
 
+Retrieve message option::
+    linkxs:xs_getmsgopt[3]
+
 
 Sockets
 ~~~~~~~
@@ -124,8 +144,12 @@ Sending and receiving messages::
     linkxs:xs_send[3]
     linkxs:xs_recv[3]
 
+Sending and receiving messages (zero-copy)::
+    linkxs:xs_sendmsg[3]
+    linkxs:xs_recvmsg[3]
+
 .Input/output multiplexing
-Crossroads provide a mechanism for applications to multiplex input/output events
+Crossroads provides a mechanism for applications to multiplex input/output events
 over a set containing both Crossroads sockets and standard sockets. This
 mechanism mirrors the standard _poll()_ system call, and is described in detail
 in linkxs:xs_poll[3].
@@ -151,6 +175,7 @@ Local inter-process communication transport::
 Local in-process (inter-thread) communication transport::
     linkxs:xs_inproc[7]
 
+
 ERROR HANDLING
 --------------
 The Crossroads library functions handle errors using the standard conventions
@@ -199,6 +224,10 @@ and Martin Lucina <martin@lucina.net>.
 
 COPYING
 -------
-Free use of Crossroads library is granted under the terms of the GNU Lesser
-General Public License (LGPL). For details see the files `COPYING` and
-`COPYING.LESSER` included with the Crossroads distribution.
+Free use of the Crossroads library software is granted under the terms of
+the GNU Lesser General Public License (LGPL). For details see the files
+`COPYING` and `COPYING.LESSER` included with the libxs distribution.
+
+As a special exception, the copyright holders of libxs grant you the right
+to link the library statically with your software. Refer to the end of
+the `COPYING.LESSER` file included with the libxs distribution for details.
diff --git a/doc/xs_init.txt b/doc/xs_init.txt
index 373822a..40a64bf 100644
--- a/doc/xs_init.txt
+++ b/doc/xs_init.txt
@@ -21,6 +21,28 @@ A 'context' is thread safe and may be shared among as many application
 threads as necessary, without any additional locking required on the part of
 the caller.
 
+The individual 'sockets' within a 'context' are _not_ thread safe --
+applications may _not_ use a single 'socket' concurrently from multiple
+threads.
+
+A 'socket' _may_ be _migrated_ from one thread to another, by issuing a
+full memory barrier between individual calls on the 'socket'.  For example,
+this means applications can create a socket in one thread with
+_xs_socket()_ and then pass it to a _newly created_ thread as part of
+thread initialization via a structure passed as an argument to
+_pthread_create()_.
+
+.Context options
+Context options may be set prior to creating the first socket within a
+'context', using the _xs_setctxopt()_ function. See linkxs:xs_setctxopt[3]
+for details on the available context options.
+
+.Multiple contexts
+Multiple 'contexts' may coexist within a single application. Thus, an
+application can use Crossroads directly and at the same time make use of any
+number of additional libraries or components which themselves make use of
+Crossroads.
+
 
 RETURN VALUE
 ------------
@@ -38,6 +60,7 @@ SEE ALSO
 --------
 linkxs:xs[7]
 linkxs:xs_term[3]
+linkxs:xs_setctxopt[3]
 
 
 AUTHORS
diff --git a/doc/xs_poll.txt b/doc/xs_poll.txt
index 37f7dc5..c809e28 100644
--- a/doc/xs_poll.txt
+++ b/doc/xs_poll.txt
@@ -10,7 +10,7 @@ xs_poll - input/output multiplexing
 SYNOPSIS
 --------
 
-*int xs_poll (xs_pollitem_t '*items', int 'nitems', long 'timeout');*
+*int xs_poll (xs_pollitem_t '*items', int 'nitems', int 'timeout');*
 
 
 DESCRIPTION
diff --git a/doc/xs_recv.txt b/doc/xs_recv.txt
index 26a6c54..5706432 100644
--- a/doc/xs_recv.txt
+++ b/doc/xs_recv.txt
@@ -29,22 +29,22 @@ function shall fail with 'errno' set to EAGAIN.
 
 Multi-part messages
 ~~~~~~~~~~~~~~~~~~~
-A Crossroads message is composed of 1 or more message parts. Each message
-part is an independent 'xs_msg_t' in its own right. Crossroads ensure atomic
-delivery of messages; peers shall receive either all _message parts_ of a
-message or none at all. The total number of message parts is unlimited except
-by available memory.
+A Crossroads message is composed of 1 or more message parts.  Crossroads
+ensures atomic delivery of messages; peers shall receive either all
+_message parts_ of a message or none at all. The total number of message
+parts is unlimited except by available memory.
 
 An application that processes multipart messages must use the _XS_RCVMORE_
-linkxs:xs_getsockopt[3] option after calling _xs_recv()_ to determine if
-there are further parts to receive.
+linkxs:xs_getsockopt[3] option on the 'socket' after calling _xs_recv()_ to
+determine if there are further parts to receive.
 
 RETURN VALUE
 ------------
-The _xs_recv()_ function shall return number of bytes in the message
-if successful. Note that the value can exceed the value of the 'len' parameter
-in case the message was truncated. If not successful the function shall return
-`-1` and set 'errno' to one of the values defined below.
+The _xs_recv()_ function shall return the number of bytes in the received
+message if successful. Note that the value can exceed the value of the
+'len' parameter, in this case the message was truncated. If not successful
+the function shall return `-1` and set 'errno' to one of the values defined
+below.
 
 
 ERRORS
@@ -79,8 +79,9 @@ assert (nbytes != -1);
 
 SEE ALSO
 --------
-linkxs:xs_recvmsg[3]
-linkxs:xs_send[3]
+Applications that wish to use zero-copy messaging must use
+linkxs:xs_recvmsg[3] instead of _xs_recv()_.
+
 linkxs:xs_sendmsg[3]
 linkxs:xs_getsockopt[3]
 linkxs:xs_socket[7]
@@ -89,6 +90,5 @@ linkxs:xs[7]
 
 AUTHORS
 -------
-+This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
-+Lucina <martin@lucina.net> and Pieter Hintjens <ph@imatix.com>.
-
+This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
+Lucina <martin@lucina.net> and Pieter Hintjens <ph@imatix.com>.
diff --git a/doc/xs_recvmsg.txt b/doc/xs_recvmsg.txt
index 735fed0..4a88177 100644
--- a/doc/xs_recvmsg.txt
+++ b/doc/xs_recvmsg.txt
@@ -4,7 +4,7 @@ xs_recvmsg(3)
 
 NAME
 ----
-xs_recvmsg - receive a message part from a socket
+xs_recvmsg - receive a message part from a socket (zero-copy)
 
 
 SYNOPSIS
@@ -30,7 +30,7 @@ function shall fail with 'errno' set to EAGAIN.
 Multi-part messages
 ~~~~~~~~~~~~~~~~~~~
 A Crossroads message is composed of 1 or more message parts. Each message
-part is an independent 'xs_msg_t' in its own right. Crossroads ensure atomic
+part is an independent 'xs_msg_t' in its own right. Crossroads ensures atomic
 delivery of messages; peers shall receive either all _message parts_ of a
 message or none at all. The total number of message parts is unlimited except
 by available memory.
@@ -42,9 +42,9 @@ there are further parts to receive.
 
 RETURN VALUE
 ------------
-The _xs_recvmsg()_ function shall return number of bytes in the message
-if successful. Otherwise it shall return `-1` and set 'errno' to one of the
-values defined below.
+The _xs_recvmsg()_ function shall return the number of bytes in the
+received message if successful. Otherwise it shall return `-1` and set
+'errno' to one of the values defined below.
 
 
 ERRORS
@@ -106,8 +106,9 @@ do {
 
 SEE ALSO
 --------
-linkxs:xs_recv[3]
-linkxs:xs_send[3]
+Applications that do not require zero-copy messaging can use the simpler
+linkxs:xs_recv[3] instead of _xs_recvmsg()_.
+
 linkxs:xs_sendmsg[3]
 linkxs:xs_getsockopt[3]
 linkxs:xs_socket[7]
@@ -118,4 +119,3 @@ AUTHORS
 -------
 This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
 Lucina <martin@lucina.net> and Pieter Hintjens <ph@imatix.com>.
-
diff --git a/doc/xs_send.txt b/doc/xs_send.txt
index f2d66e4..72bbf88 100644
--- a/doc/xs_send.txt
+++ b/doc/xs_send.txt
@@ -4,7 +4,7 @@ xs_send(3)
 
 NAME
 ----
-xs_send - send a message part  on a socket
+xs_send - send a message part on a socket
 
 
 SYNOPSIS
@@ -35,14 +35,13 @@ the 'socket' and Crossroads have assumed responsibility for the message.
 
 Multi-part messages
 ~~~~~~~~~~~~~~~~~~~
-A Crossroads message is composed of 1 or more message parts. Each message
-part is an independent 'xs_msg_t' in its own right. Crossroads ensure atomic
-delivery of messages; peers shall receive either all _message parts_ of a
-message or none at all. The total number of message parts is unlimited except
-by available memory.
+A Crossroads message is composed of 1 or more message parts. Crossroads
+ensures atomic delivery of messages; peers shall receive either all
+_message parts_ of a message or none at all. The total number of message
+parts is unlimited except by available memory.
 
 An application that sends multipart messages must use the _XS_SNDMORE_ flag
-when sending each data part except the final one.
+when sending each message part except the final one.
 
 
 RETURN VALUE
@@ -88,15 +87,15 @@ assert (rc == 2);
 
 SEE ALSO
 --------
-linkxs:xs_sendmsg[3]
+Applications that wish to use zero-copy messaging must use
+linkxs:xs_sendmsg[3] instead of _xs_send()_.
+
 linkxs:xs_recv[3]
-linkxs:xs_recvmsg[3]
 linkxs:xs_socket[7]
 linkxs:xs[7]
 
 
 AUTHORS
 -------
-+This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
-+Lucina <martin@lucina.net> and Pieter Hintjens <ph@imatix.com>.
-
+This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
+Lucina <martin@lucina.net> and Pieter Hintjens <ph@imatix.com>.
diff --git a/doc/xs_sendmsg.txt b/doc/xs_sendmsg.txt
index 9478b4a..7445f25 100644
--- a/doc/xs_sendmsg.txt
+++ b/doc/xs_sendmsg.txt
@@ -4,7 +4,7 @@ xs_sendmsg(3)
 
 NAME
 ----
-xs_sendmsg - send a message part on a socket
+xs_sendmsg - send a message part on a socket (zero-copy)
 
 
 SYNOPSIS
@@ -48,6 +48,7 @@ by available memory.
 An application that sends multipart messages must use the _XS_SNDMORE_ flag
 when sending each data part except the final one.
 
+
 RETURN VALUE
 ------------
 The _xs_sendmsg()_ function shall return number of bytes in the message
@@ -104,8 +105,9 @@ rc = xs_sendmsg (socket, &part3, 0);
 
 SEE ALSO
 --------
-linkxs:xs_recv[3]
-linkxs:xs_recv[3]
+Applications that do not require zero-copy messaging can use the simpler
+linkxs:xs_send[3] instead of _xs_sendmsg()_.
+
 linkxs:xs_recvmsg[3]
 linkxs:xs_socket[7]
 linkxs:xs[7]
@@ -113,6 +115,5 @@ linkxs:xs[7]
 
 AUTHORS
 -------
-+This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
-+Lucina <martin@lucina.net> and Pieter Hintjens <ph@imatix.com>.
-
+This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
+Lucina <martin@lucina.net> and Pieter Hintjens <ph@imatix.com>.
diff --git a/doc/xs_setctxopt.txt b/doc/xs_setctxopt.txt
index d26d319..ccdd2db 100644
--- a/doc/xs_setctxopt.txt
+++ b/doc/xs_setctxopt.txt
@@ -12,22 +12,24 @@ SYNOPSIS
 --------
 *int xs_setctxopt (void '*context', int 'option_name', const void '*option_value', size_t 'option_len');*
 
-Caution: All options take effect only if set prior to creating the first socket.
 
 DESCRIPTION
 -----------
 The _xs_setctxopt()_ function shall set the option specified by the
-'option_name' argument to the value pointed to by the 'option_value' argument
-for the Crossroads context pointed to by the 'context' argument.
+'option_name' argument to the value pointed to by the 'option_value'
+argument, for the Crossroads context pointed to by the 'context' argument.
 The 'option_len' argument is the size of the option value in bytes.
 
+CAUTION: Context options take effect only if set with _xs_setctxopt()_
+prior to creating the first socket in a given 'context' with _xs_socket()_.
+
 The following options can be set with the _xs_setctxopt()_ function:
 
 
 XS_MAX_SOCKETS: Set maximum number of sockets
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'XS_MAX_SOCKETS' option shall set specify the maximum nuber of sockets
-that can be open at the same time.
+The 'XS_MAX_SOCKETS' option shall set the maximum nuber of sockets that can
+be simultaneously active in the given 'context'.
 
 [horizontal]
 Option value type:: int
@@ -36,8 +38,9 @@ Default value:: 512
 
 XS_IO_THREADS: Set number of worker threads
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The 'XS_IO_THREADS' option shall set specify the size of the thread pool to
-handle I/O operations. The value should be at least 1.
+The 'XS_IO_THREADS' option shall set the size of the thread pool created by
+the given 'context' to handle I/O operations. The minimum value for this
+option is `1`.
 
 [horizontal]
 Option value type:: int
@@ -60,21 +63,23 @@ The provided 'context' was invalid.
 
 EXAMPLE
 -------
-.Setting maximal number of sockets to three.
+.Setting the number of I/O threads for a context to four.
 ----
-int val = 3;
-rc = xs_setctxopt (context, XS_CTX_MAX_SOCKETS, &val, sizeof (val));
+void *context = xs_init ();
+int io_threads = 4;
+rc = xs_setctxopt (context, XS_IO_THREADS, &io_threads, sizeof (io_threads));
 assert (rc == 0);
+/* The above call MUST be called before any socket is created in context */
+void *socket = xs_socket (context, XS_PUB);
 ----
 
 SEE ALSO
 --------
-linkxs:xs_getsockopt[3]
-linkxs:xs_setsockopt[3]
 linkxs:xs_init[3]
 linkxs:xs[7]
 
 
 AUTHORS
 -------
-This manual page was written by Martin Sustrik <sustrik@250bpm.com>.
+The Crossroads documentation was written by Martin Sustrik <sustrik@250bpm.com>
+and Martin Lucina <martin@lucina.net>.
diff --git a/doc/xs_zmq.txt b/doc/xs_zmq.txt
index 310ab64..570ef5e 100644
--- a/doc/xs_zmq.txt
+++ b/doc/xs_zmq.txt
@@ -72,6 +72,8 @@ Messages
 *int zmq_msg_init (zmq_msg_t '*msg');*
 *int zmq_msg_init_size (zmq_msg_t '*msg', size_t 'size');*
 *int zmq_msg_init_data (zmq_msg_t '*msg', void '*data', size_t 'size', zmq_free_fn '*ffn', void '*hint');*
+*size_t zmq_msg_size (zmq_msg_t '*msg');*
+*void *zmq_msg_data (zmq_msg_t '*msg');*
 *int zmq_msg_close (zmq_msg_t '*msg');*
 *int zmq_msg_copy (zmq_msg_t '*dest', zmq_msg_t '*src');*
 *int zmq_msg_move (zmq_msg_t '*dest', zmq_msg_t '*src');*