pg2

19972013 Ericsson AB. All Rights Reserved. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. pg2 mbj@erlang.ericsson.se mbj@erlang.ericsson.se Bjarne Däcker mbj@erlang.ericsson.se 1997-08-18 A2 pg2.sgml

pg2 Distributed Named Process Groups

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

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) which are all members of the group foobar. There are no special functions for sending a message to the group. Instead, client functions should be written with the functions get_members/1 and get_local_members/1 to find out which processes are members of the group. Then the message can be sent to one or more members of the group.

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

This module is used by the disk_log module for managing distributed disk logs. The disk log names are used as group names, which means that some action may need to be taken to avoid name clashes.

The name of a process group.

Create a new, empty process group

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

Delete a process group

Deletes a process group.

Common dispatch function

This is a useful dispatch function which can be used from client functions. It returns a process on the local node, if such a process exist. Otherwise, it chooses one randomly.

Return all processes in a group

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

Return all local processes in a group

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

Join a process to a group

Joins the process Pid to the group Name. A process can join a group several times; it must then leave the group the same number of times.

Make a process leave a group

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

Return a list of all known groups

Returns a list of all known groups.

Start the pg2 server

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 should be started explicitly. Use configuration parameters for kernel for this.