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Version 1.17.5

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# pg

### MODULE

pg

### MODULE SUMMARY

Distributed, Named Process Groups

### DESCRIPTION

This (experimental) module implements process groups. A process group is a group of processes that can be accessed by a common name. For example, a group named foobar can include a set of processes as members of this group and they can be located on different nodes.

When messages are sent to the named group, all members of the group receive the message. The messages are serialized. If the process P1 sends the message M1 to the group, and process P2 simultaneously sends message M2, then all members of the group receive the two messages in the same order. If members of a group terminate, they are automatically removed from the group.

This module is not complete. The module is inspired by the ISIS system and the causal order protocol of the ISIS system should also be implemented. At the moment, all messages are serialized by sending them through a group master process.

### EXPORTS

create(PgName) -> ok | {error, Reason}

Types:

PgName = term()
Reason = already_created | term()

Creates an empty group named PgName on the current node.

create(PgName, Node) -> ok | {error, Reason}

Types:

PgName = term()
Node = node()
Reason = already_created | term()

Creates an empty group named PgName on the node Node.

join(PgName, Pid) -> Members

Types:

PgName = term()
Pid = pid()
Members = [pid()]

Joins the pid Pid to the process group PgName. Returns a list of all old members of the group.

send(PgName, Msg) -> ok

Types:

PgName = Msg = term()

Sends the tuple {pg_message, From, PgName, Msg} to all members of the process group PgName.

Failure: {badarg, {PgName, Msg}} if PgName is not a process group (a globally registered name).

esend(PgName, Msg) -> ok

Types:

PgName = Msg = term()

Sends the tuple {pg_message, From, PgName, Msg} to all members of the process group PgName, except ourselves.

Failure: {badarg, {PgName, Msg}} if PgName is not a process group (a globally registered name).

members(PgName) -> Members

Types:

PgName = term()
Members = [pid()]

Returns a list of all members of the process group PgName.