erl_global.3erl man page

erl_global ā€” Access globally registered names.

Description

Note:

The support for VxWorks is deprecated as of OTP 22, and will be removed in OTP 23.

Note:

The old legacy erl_interface library (functions with prefix erl_) is deprecated as of OTP 22, and will be removed in OTP 23. This does not apply to the ei library. Reasonably new gcc compilers will issue deprecation warnings. In order to disable these warnings, define the macro EI_NO_DEPR_WARN.

This module provides support for registering, looking up, and unregistering names in the global module. For more information, see kernel:global.

Notice that the functions below perform an RPC using an open file descriptor provided by the caller. This file descriptor must not be used for other traffic during the global operation, as the function can then receive unexpected data and fail.

Exports

char **erl_global_names(fd,count)

Types:

int fd;
int *count;

Retrieves a list of all known global names.

  • fd is an open descriptor to an Erlang connection.
  • count is the address of an integer, or NULL. If count is not NULL, it is set by the function to the number of names found.

On success, the function returns an array of strings, each containing a single registered name, and sets count to the number of names found. The array is terminated by a single NULL pointer. On failure, the function returns NULL and count is not modified.

Note:

It is the caller's responsibility to free the array afterwards. It has been allocated by the function with a single call to malloc(), so a single free() is all that is necessary.

int erl_global_register(fd,name,pid)

Types:

int fd;
const char *name;
ETERM *pid;

Registers a name in global.

  • fd is an open descriptor to an Erlang connection.
  • name is the name to register in global.
  • pid is the pid that is to be associated with name. This value is returned by global when processes request the location of name.

Returns 0 on success, otherwise -1.

int erl_global_unregister(fd,name)

Types:

int fd;
const char *name;

Unregisters a name from global.

  • fd is an open descriptor to an Erlang connection.
  • name is the name to unregister from global.

Returns 0 on success, otherwise -1.

ETERM *erl_global_whereis(fd,name,node)

Types:

int fd;
const char *name;
char *node;

Looks up a name in global.

  • fd is an open descriptor to an Erlang connection.
  • name is the name that is to be looked up in global.

If node is not NULL, it is a pointer to a buffer where the function can fill in the name of the node where name is found. node can be passed directly to erl_connect() if necessary.

On success, the function returns an Erlang pid containing the address of the specified name, and the node is initialized to the node name where name is found. On failure, NULL is returned and node is not modified.

Info

erl_interface 3.12 Ericsson AB C Library Functions