sim-ephemeral

Helpers for Simulant's process state service

Background

Agents have access to a temporary in-memory Datomic database during a sim run (via the process-state service). Certain information (like current auth credentials) needs to be remembered during a sim run, but is irrelevant to validation.

Usage:

1. Add [io.homegrown/sim-ephemeral "1.0.0"] to your Simulant project's :dependencies
2. During sim setup invoke simulant.sim/create-process-state after simulant.sim/create-sim.
3. Inside an agent action, invoke io.homegrown.sim-ephemeral's retrieve, store, or clear as necessary. These functions will automatically gain access to a process-local, in-memory Datomic database. See individual function docs for more information on usage.

For example:

(ns my.ns
  (:require [io.homegrown.sim-ephemeral :refer [store]]
            [simulant.util :as util :refer [e solo]]))

(declare do-something)
(declare extract-value)

(defmethod sim/perform-action :action.type/myAction [action process]
  (try
    (let [agent        (-> action :agent/_actions solo)
          [resp nsecs] (timed (do-something))]
      (store agent :some-info :db.cardinality/one :db.type/string (extract-value resp))
      (log action process resp nsecs))
    (catch Throwable t
      (log-error action process t 0))))

Caveats

Because process-state stores are local to a Simulant process, agents running on separate processes will not be able to access each other's keys/values."

Attribution

• Simulant by Metadata Partners. Licensed Under: EPL.
• simulant-example by mtnygard. Licensed Under: EPL. sim-ephemeral is inspired by Michael's take on utilizing the process service.

License

The MIT License (MIT)

Copyright (c) 2015 Homegrown Labs

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.