NN_SYMBOL_INFO(3) nanomsg manual NN_SYMBOL_INFO(3)NAMEnn_symbol_info - query the names and properties of nanomsg symbols
SYNOPSIS
#include <nanomsg/nn.h>
int nn_symbol_info (int i, struct nn_symbol_properties *buf, int
buflen);
DESCRIPTION
Retrieves the symbol name and value at index i. Indices start at 0. An
index has no significance to its associated symbol; the mappings may
change between library versions.
The nn_symbol_properties has the following definition:
struct nn_symbol_properties {
/* The constant value */
int value;
/* The constant name */
const char* name;
/* The constant namespace, or zero for namespaces themselves */
int ns;
/* The option type for socket option constants */
int type;
/* The unit for the option value for socket option constants */
int unit;
};
More structure members may be added in future, but input pointer will
be written only up to buflen so ABI is forward-compatible.
Typically a client will iterate through the symbols until
nn_symbol_info returns NULL in order to collect all the symbols.
All symbols exposed by nn_symbol_info are available directly in the C
API, generally as preprocessor macros. Thus, this function is useful
mostly for language bindings that can’t parse the header file and rely
on retrieving the symbols in the runtime.
Note that the NN_MSG symbol is not exported by the nn_symbol_info
function. First, it is a pointer rather than an integer; second, the
symbol is not supposed to be exported from language bindings to the
user. Instead, language bindings should provide the zero-copy
functionality in a language-specific way, if at all (zero-copy
functionality may not make sense for some languages/bindings).
AVAILABLE NAMESPACES
NN_NS_NAMESPACE
Equals to zero and denotes the NN_NS_* constants themselves
NN_NS_VERSION
Nanomsg version constants
NN_NS_DOMAIN
Socket domain (or address family) constants AF_SP, AF_SP_RAW
NN_NS_TRANSPORT
Transport name constants (used for socket options mainly)
NN_NS_PROTOCOL
Socket protocol constants
NN_NS_OPTION_LEVEL
Socket option level constants (NN_SOL_SOCKET)
NN_NS_SOCKET_OPTION
Socket options for NN_SOL_SOCKET level
NN_NS_TRANSPORT_OPTION
Socket options for transport level (used with transport constants)
NN_NS_OPTION_TYPE
The option types (described below)
NN_NS_FLAG
The nn_send/nn_recv flags (only NN_DONTWAIT for now)
NN_NS_ERROR
The errno values
NN_NS_LIMIT
Various nanomsg limits (only NN_SOCKADDR_MAX for now)
NN_NS_EVENT
Event flags (bit mask) for use with nn_poll (NN_POLLIN, NN_POLLOUT)
AVAILABLE OPTION TYPES
NN_TYPE_NONE
No type, is returned for constants that are not socket options
NN_TYPE_INT
The integer type
NN_TYPE_STR
String (char *) type
More types may be added in future nanomsg. You may enumerate all of
them using the nn_symbol_info itself by checking NN_NS_OPTION_TYPE
namespace.
AVAILABLE OPTION UNITS
NN_UNIT_NONE
No unit, is returned for constants that are not socket options, or
do not have any meaningful unit (strings, integer values)
NN_UNIT_BYTES
The option value is expressed in bytes
NN_UNIT_MILLISECONDS
The option value is expressed in milliseconds
NN_UNIT_PRIORITY
The option value is a priority, an integer from 1 to 16
NN_UNIT_BOOLEAN
The option value is boolean, an integer 0 or 1
More types may be added in future nanomsg. You may enumerate all of
them using the nn_symbol_info itself by checking NN_NS_OPTION_TYPE
namespace.
RETURN VALUE
If i is valid, returns the number of bytes stored at the structure. The
maximum value that can be returned is buflen.
If i is out-of-range, nn_symbol_info returns zero.
EXAMPLE
int i;
for (i = 0; ; ++i) {
struct nn_symbol_properties sym;
int rc = nn_symbol_info (i, &sym, sizeof (sym));
if(rc == 0)
break;
assert (rc == sizeof (sym));
printf ("'%s' = %d\n", sym.name, sym.value);
}
SEE ALSOnn_symbol(3)nn_errno(3)nn_strerror(3)nanomsg(7)AUTHORS
Paul Colomiets <paul@colomiets.name[1]> Garrett D’Amore
<garrett@damore.org[2]>
NOTES
1. paul@colomiets.name
mailto:paul@colomiets.name
2. garrett@damore.org
mailto:garrett@damore.org
nanomsg Unknown 12/23/2015 NN_SYMBOL_INFO(3)
