bionic (3) pg2.3erl.gz

NAME

       pg2 - Distributed named process groups.

DESCRIPTION

       This module implements process groups. Each message can be sent to one, some, or all group members.

       A  group  of  processes  can be accessed by a common name. For example, if there is a group named foobar,
       there can be a set of processes (which can be located on different nodes) that are  all  members  of  the
       group  foobar.  There  are  no  special  functions  for  sending  a message to the group. Instead, client
       functions are to be written with the functions get_members/1 and get_local_members/1 to  determine  which
       processes are members of the group. Then the message can be sent to one or more group members.

       If a member terminates, it is automatically removed from the group.

   Warning:
       This module is used by module disk_log for managing distributed disk logs. The disk log names are used as
       group names, which means that some action can be needed to avoid name clashes.

DATA TYPES

       name() = any()

              The name of a process group.

EXPORTS

       create(Name :: name()) -> ok

              Creates a new, empty process group. The group is globally visible  on  all  nodes.  If  the  group
              exists, nothing happens.

       delete(Name :: name()) -> ok

              Deletes a process group.

       get_closest_pid(Name) -> pid() | {error, Reason}

              Types:

                 Name = name()
                 Reason = {no_process, Name} | {no_such_group, Name}

              A  useful  dispatch  function  that can be used from client functions. It returns a process on the
              local node, if such a process exists. Otherwise, it selects one randomly.

       get_local_members(Name) ->
                            [pid()] | {error, {no_such_group, Name}}

              Types:

                 Name = name()

              Returns all processes running on the local node in the group Name. This function  is  to  be  used
              from within a client function that accesses the group. It is therefore optimized for speed.

       get_members(Name) -> [pid()] | {error, {no_such_group, Name}}

              Types:

                 Name = name()

              Returns all processes in the group Name. This function is to be used from within a client function
              that accesses the group. It is therefore optimized for speed.

       join(Name, Pid :: pid()) -> ok | {error, {no_such_group, Name}}

              Types:

                 Name = name()

              Joins the process Pid to the group Name. A process can join a group many times and must then leave
              the group the same number of times.

       leave(Name, Pid :: pid()) -> ok | {error, {no_such_group, Name}}

              Types:

                 Name = name()

              Makes  the  process  Pid  leave the group Name. If the process is not a member of the group, ok is
              returned.

       start() -> {ok, pid()} | {error, any()}

       start_link() -> {ok, pid()} | {error, any()}

              Starts the pg2 server. Normally, the server does not need to  be  started  explicitly,  as  it  is
              started dynamically if it is needed. This is useful during development, but in a target system the
              server is to be started explicitly. Use the configuration parameters for kernel(7) for this.

       which_groups() -> [Name :: name()]

              Returns a list of all known groups.

SEE ALSO

       kernel(7)