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Fusion for Kdb+

Prometheus metric event handlers

KxSystems/prometheus-kdb-exporter

Metric updates are generally carried out inside event handlers. By overwriting these handlers, users can update metric values in response to various triggers ranging from HTTP requests to timer events.

The functions outlined below can be modified to allow a user to monitor events outside those exposed in exporter.q 

.prom.      event handlers
 on_poll      Prometheus poll request
 on_pc        IPC socket connection closing
 on_po        IPC socket connection opening
 on_wc        Websocket connection closing
 on_wo        Websocket connection opening
 afer_pg      Syncronous IPC socket request handler, call after execution
 before_pg    Syncronous IPC socket request handler, call before execution
 after_ps     Asynchronous IPC socket request handler, call after execution
 before_ps    Asynchronous IPC socket request handler, call before execution
 after_ph     HTTP GET request handler, call after execution
 before_ph    HTTP GET request handler, call before execution
 after_pp     HTTP POST request handler, call after execution
 before_pp    HTTP POST request handler, call before execution
 after_ws     Websocket request handler, call after execution
 before_ws    Websocket request handler, call before execution
 after_ts     Timer event handler, call after execution
 before_ts    Timer event handler, call after execution

Example invocations of these event handlers

Once the relevant event handlers have been defined to update the metric values, the library can by initialized with a call to .prom.init

Updating .z.* handlers after the call to .prom.init will overwrite the Prometheus logic. Correct usage is to load all process logic before loading the Prometheus library.

.prom.after_pg

Synchronous IPC socket request handler, called after execution

Syntax: .prom.after_pg[tmp;msg;res]

Where

  • tmp is the object returned by .prom.before_pg
  • msg is the object that was executed
  • res is the object returned by the execution of msg

.prom.after_ph

HTTP GET request handler, called after execution

Syntax: .prom.after_ph[tmp;(requestText;requestHeaderAsDictionary);res]

Where

  • tmp is the object returned by .prom.before_ph
  • (requestText;requestHeaderAsDictionary) is a HTTP GET request
  • res is the object returned by the execution of msg

.prom.after_pp

HTTP POST request handler, called after execution

Syntax: .prom.after_pp[tmp;(requestText;requestHeaderAsDictionary);res]

Where

  • tmp is the object returned by .prom.before_pp
  • (requestText;requestHeaderAsDictionary) is a HTTP POST request
  • res is the object returned by the execution of msg

.prom.after_ps

Asynchronous IPC socket request handler, called after execution

Syntax: .prom.after_ps[tmp;msg;res]

Where

  • tmp is the object returned by .prom.before_ps
  • msg is the object that was executed
  • res is the object returned by the execution of msg

.prom.after_ts

Timer event handler, called after execution

Syntax: .prom.after_ts[tmp;dtm;res]

Where

  • tmp is the object returned by .prom.before_ts
  • dtm is the timestamp at the start of execution
  • res is the object returned by the execution of dtm

.prom.after_ws

Websocket request handler, called after execution

Syntax: .prom.after_ws[tmp;msg;res]

Where

  • tmp is the object returned by .prom.before_ws
  • msg is the object that was executed
  • res is the object returned by the execution of msg

.prom.before_pg

Synchronous IPC socket request handler, called before execution

Syntax: .prom.before_pg msg

Where msg is the object to be executed, returns a tmp object to be passed to the after handler.

.prom.before_ph

HTTP GET request handler, called before execution

Syntax: .prom.before_ph(requestText;requestHeaderAsDictionary)

Where (requestText;requestHeaderAsDictionary) is an HTTP GET request, returns a tmp object to be passed to the after handler.

.prom.before_pp

HTTP POST request handler, called before execution

Syntax: .prom.before_pp(requestText;requestHeaderAsDictionary)

Where (requestText;requestHeaderAsDictionary) is an HTTP POST request, returns a tmp object to be passed to the after handler.

.prom.before_ps

Asynchronous IPC socket request handler, called before execution

Syntax: .prom.before_ps msg

Where msg is the object to be executed, returns a tmp object to be passed to the after handler.

.prom.before_ts

Timer event handler, called before execution

Syntax: .prom.before_ts dtm

Where dtm is the timestamp at the start of execution, returns a tmp object to be passed to the after handler.

.prom.before_ws

Websocket request handler, called before execution

Syntax: .prom.before_ws msg

Where msg is the object to be executed, returns a tmp object to be passed to the after handler.

.prom.on_pc

Socket close handler

Syntax: .prom.on_pc hdl

Where hdl is the handle of a socket connection, closes the socket.

.prom.on_po

Socket open handler

Syntax: .prom.on_po hdl

Where hdl is the handle of a socket connection, opens the socket.

.prom.on_poll

Prometheus poll request handler

Syntax: .prom.on_poll(requestText;requestHeaderAsDictionary)

Where (requestText;requestHeaderAsDictionary) is an HTTP request