| Overview |  |
Copyright © (C) 2011 - 2015, Jim Rosenblum
Behaviours: gen_server.
Authors: Jim Rosenblum.
jc_psub 1) allows clients to subscribe to j_cache changes; 2) notifies clients of changes to j_cache items; and 3) allows clients to subscribe to, and broadcast, topic events.
Subscriptions are a local afair so if a node goes down, clients that were using that node's jc_psub will need to re-subscribe.
Mnesia LOCAL tables, ps_sub and ps_client, are used:
ps_sub maps a subscription to a list of listening Pids ps_client maps a unique, subscriber's pid to a reference or link.
The server subscribes to mnesia key_to_value, table changes thereby allowing it to notice cache changes, construct the corresponding subscription message and look for relevant subscribers to whom to send a message.key() = any()
map_name() = any()
value() = any()
| client_count/0 | Return the number of distinct, subscribing Pids being served by the server. |
| load/0 | Return an estimate of how much load the server is under. |
| map_subscribe/4 | Adds a subscription on behalf of the process indicated by the supplied Pid. |
| map_unsubscribe/4 | Client unsubcribes from notifiction. |
| start_link/0 | Starts the jc_psub server and links the caller to it. |
| topic_event/2 | Push a topic message to the server for broadcast to its local subscribers. |
| topic_subscribe/3 | Client subscribes to notifications regarding the given Topic. |
| topic_unsubscribe/3 | Client unsubscribes to notifications regarding the given Topic. |
client_count() -> non_neg_integer() | {error, any()}
Return the number of distinct, subscribing Pids being served by the server. Under extreme load this function can time-out.
load() -> non_neg_integer() | {error, any()}
Return an estimate of how much load the server is under. It counts the number of subscriptions + the number of Pids that are currenlty subscribed to anything. Under extreme load this can time-out resulting in an error.
map_subscribe(Client::pid(), Map::map_name(), Key::key() | any, Ops::write | delete | any) -> ok | {error, badarg}
Adds a subscription on behalf of the process indicated by the supplied Pid.
map_unsubscribe(Client::pid(), Map::map_name(), Key::key() | any, Ops::write | delete | any) -> ok | {error, badarg}
Client unsubcribes from notifiction.
start_link() -> {ok, pid()} | ignore | {error, any()}
Starts the jc_psub server and links the caller to it.
topic_event(Topic::atom(), Value::value()) -> ok
Push a topic message to the server for broadcast to its local subscribers. If the event is a node event, then the other jc_psubs will know about it via their monitoring of foreign jc_sup's, so there is no need to propagate the event to other nodes' jc_psub servers; else propagate it.
topic_subscribe(Client::pid(), Topic::atom(), Value::value() | any) -> ok | {error, badarg}
Client subscribes to notifications regarding the given Topic.
topic_unsubscribe(Client::pid(), Topic::atom(), Value::value() | any) -> ok | {error, badarg}
Client unsubscribes to notifications regarding the given Topic.
Generated by EDoc, May 24 2016, 22:38:41.