com.fbeyer.broker
A simple in-process message/event broker for Clojure.
A simple in-process message/event broker for Clojure.
publish!clj
(publish! broker msg)Publishes msg to subscribers, who will be notified asynchronously.
msg must not be nil. Returns true unless broker is stopped.
Under high load, this will block the caller to respect back-pressure.
As such, this should not be called from (go ...) blocks.
When blocking is not desired, use core.async/put! on the channel
returned by publish-chan, or install a dropping or sliding buffer
in the broker using the :buf-or-n option of start.
Publishes `msg` to subscribers, who will be notified asynchronously. `msg` must not be `nil`. Returns `true` unless `broker` is stopped. Under high load, this will block the caller to respect back-pressure. As such, this should not be called from `(go ...)` blocks. When blocking is not desired, use `core.async/put!` on the channel returned by [[publish-chan]], or install a dropping or sliding buffer in the broker using the `:buf-or-n` option of [[start]].
publish-chanclj
(publish-chan broker)Returns the channel used for publishing messages to the broker.
Intended for publishing from a (go ...) block or advanced usage such as bulk publishing / piping into the broker.
Closing the channel will stop the broker.
Returns the channel used for publishing messages to the broker. Intended for publishing from a (go ...) block or advanced usage such as bulk publishing / piping into the broker. Closing the channel will stop the broker.
startclj
(start)(start opts)Starts a broker.
Supported options:
:topic-fn- function used to determine the topic of an incoming message forsubscribe; default::key.:xform- a transducer to transform/filter messages as they are published.:buf-or-n- async buffer or fixed buffer size to use for the publish channel. Defaults to a1024.:buf-fn- function to create async buffers for subscribing functions. By default, uses small fixed-size buffers.:error-fn- when a subscribing function throws an exception, this function will be called with two arguments: the exception and a map with keys:broker,:fn, and:msg. With no:error-fn(default), exceptions are passed to the current thread'sUncaughtExceptionHandler.
Starts a broker. Supported options: * `:topic-fn` - function used to determine the topic of an incoming message for [[subscribe]]; default: `:key`. * `:xform` - a transducer to transform/filter messages as they are published. * `:buf-or-n` - async buffer or fixed buffer size to use for the publish channel. Defaults to a `1024`. * `:buf-fn` - function to create async buffers for subscribing functions. By default, uses small fixed-size buffers. * `:error-fn` - when a subscribing function throws an exception, this function will be called with two arguments: the exception and a map with keys `:broker`, `:fn`, and `:msg`. With no `:error-fn` (default), exceptions are passed to the current thread's `UncaughtExceptionHandler`.
stop!clj
(stop! broker)Stops the broker, closing all internal async channels.
After that, the broker will no longer accept messages. Any priorly
published messages will still be delivered. Returns nil.
Stops the broker, closing all internal async channels. After that, the broker will no longer accept messages. Any priorly published messages will still be delivered. Returns `nil`.
subscribeclj
(subscribe broker topic fn-or-ch)Subscribes a function or channel to a topic.
If fn-or-ch is already subscribed to this topic, this is a no-op.
When fn-or-ch is a function, it will be run in an async (go ...) block
and should not block. Exceptions will be reported to the broker's
:error-fn (see start).
Subscribes a function or channel to a topic. If `fn-or-ch` is already subscribed to this topic, this is a no-op. When `fn-or-ch` is a function, it will be run in an async `(go ...)` block and should not block. Exceptions will be reported to the broker's `:error-fn` (see [[start]]).
subscribe-allclj
(subscribe-all broker fn-or-ch)Subscribes a function or channel to all messages published to the broker.
When fn-or-ch is already subscribed to all messages, this is a no-op.
When fn-or-ch is also subscribed explicitly to a topic, it will receive
messages twice.
When fn-or-ch is a function, it will be run in an async (go ...) block
and should not block. Exceptions will be reported to the broker's
:error-fn (see start).
Subscribes a function or channel to all messages published to the broker. When `fn-or-ch` is already subscribed to all messages, this is a no-op. When `fn-or-ch` is also subscribed explicitly to a topic, it will receive messages twice. When `fn-or-ch` is a function, it will be run in an async `(go ...)` block and should not block. Exceptions will be reported to the broker's `:error-fn` (see [[start]]).
thread-uncaught-exc-handlerclj
(thread-uncaught-exc-handler e _)Passes exceptions to the current thread's UncaughtExceptionHandler.
Passes exceptions to the current thread's `UncaughtExceptionHandler`.
unsubscribeclj
(unsubscribe broker fn-or-ch)(unsubscribe broker topic fn-or-ch)Unsubscribes a function or channel.
If a topic is given, unsubscribes only from this topic. Otherwise,
unsubscribes from all topics, i.e. clears all subscriptions from
subscribe and subscribe-all.
If fn-or-ch is not a subscriber, this is a no-op. Returns nil.
Unsubscribes a function or channel. If a `topic` is given, unsubscribes only from this topic. Otherwise, unsubscribes from all topics, i.e. clears all subscriptions from [[subscribe]] and [[subscribe-all]]. If `fn-or-ch` is not a subscriber, this is a no-op. Returns `nil`.
unsubscribe-allclj
(unsubscribe-all broker)(unsubscribe-all broker topic)Unsubscribes all subscribers.
When a topic is given, only subscribers to the given topic will be
unsubscribed. Returns nil.
Unsubscribes all subscribers. When a `topic` is given, only subscribers to the given topic will be unsubscribed. Returns `nil`.
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