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jruby_agents.clj
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jruby_agents.clj
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(ns puppetlabs.services.jruby-pool-manager.impl.jruby-agents
(:require [schema.core :as schema]
[puppetlabs.services.jruby-pool-manager.impl.jruby-internal :as jruby-internal]
[clojure.tools.logging :as log]
[puppetlabs.kitchensink.core :as ks]
[puppetlabs.services.jruby-pool-manager.jruby-schemas :as jruby-schemas]
[puppetlabs.i18n.core :as i18n])
(:import (clojure.lang IFn IDeref)
(puppetlabs.services.jruby_pool_manager.jruby_schemas PoisonPill JRubyInstance)
(java.util.concurrent TimeUnit TimeoutException)))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Private
(schema/defn ^:always-validate
next-instance-id :- schema/Int
[id :- schema/Int
pool-context :- jruby-schemas/PoolContext]
(let [pool-size (jruby-internal/get-pool-size pool-context)
next-id (+ id pool-size)]
(if (> next-id Integer/MAX_VALUE)
(mod next-id pool-size)
next-id)))
(schema/defn get-shutdown-on-error-fn :- IFn
[pool-context :- jruby-schemas/PoolContext]
(get-in pool-context [:config :lifecycle :shutdown-on-error]))
(schema/defn get-modify-instance-agent :- jruby-schemas/JRubyPoolAgent
[pool-context :- jruby-schemas/PoolContext]
(get-in pool-context [:internal :modify-instance-agent]))
(schema/defn ^:always-validate
send-agent :- jruby-schemas/JRubyPoolAgent
"Utility function; given a JRubyPoolAgent, send the specified function.
Ensures that the function call is wrapped in a `shutdown-on-error`."
[jruby-agent :- jruby-schemas/JRubyPoolAgent
f :- IFn]
(letfn [(agent-fn [agent-ctxt]
(let [shutdown-on-error (:shutdown-on-error agent-ctxt)]
(shutdown-on-error f))
agent-ctxt)]
(send jruby-agent agent-fn)))
(declare send-flush-instance!)
(schema/defn add-instance
[{:keys [config] :as pool-context} :- jruby-schemas/PoolContext
id :- schema/Int]
(let [pool (jruby-internal/get-pool pool-context)]
(try
(jruby-internal/create-pool-instance! pool id config
(:splay-instance-flush config))
(catch Exception e
(.clear pool)
(jruby-internal/insert-poison-pill pool e)
(throw (IllegalStateException.
(i18n/tru "There was a problem adding a JRubyInstance to the pool.")
e))))))
(schema/defn ^:always-validate
prime-pool!
"Sequentially fill the pool with new JRubyInstances. NOTE: this
function should never be called except by the modify-instance-agent
to create a pool's initial jruby instances."
[{:keys [config] :as pool-context} :- jruby-schemas/PoolContext]
(log/debug (format "%s\n%s"
(i18n/trs "Initializing JRubyInstances with the following settings:")
(ks/pprint-to-string config)))
(let [pool (jruby-internal/get-pool pool-context)
count (.remainingCapacity pool)]
(dotimes [i count]
(let [id (inc i)]
(log/debug (i18n/trs "Priming JRubyInstance {0} of {1}"
id count))
(add-instance pool-context id)
(log/info (i18n/trs "Finished creating JRubyInstance {0} of {1}"
id count))))))
(schema/defn ^:always-validate
flush-instance!
"Flush a single JRubyInstance. Create a new replacement instance
and insert it into the specified pool. Should only be called from
the modify-instance-agent"
[pool-context :- jruby-schemas/PoolContext
instance :- JRubyInstance
new-id :- schema/Int
config :- jruby-schemas/JRubyConfig]
(let [cleanup-fn (get-in pool-context [:config :lifecycle :cleanup])
pool (jruby-internal/get-pool pool-context)]
(jruby-internal/cleanup-pool-instance! instance cleanup-fn)
(jruby-internal/create-pool-instance! pool new-id config)))
(schema/defn borrow-all-jrubies*
"The core logic for borrow-all-jrubies. Should only be called from borrow-all-jrubies"
[pool-context :- jruby-schemas/PoolContext
borrow-exception :- IDeref]
(let [pool-size (jruby-internal/get-pool-size pool-context)
pool (jruby-internal/get-pool pool-context)
borrow-fn (partial jruby-internal/borrow-from-pool pool-context)]
(try
(into [] (repeatedly pool-size borrow-fn))
; We catch the exception here, place it in the borrow-exception atom
; for use in the calling fn, and then throw it again so that
; shutdown-on-error will also catch it and shutdown the app
(catch Exception e
(.clear pool)
(jruby-internal/insert-poison-pill pool e)
(let [exception (IllegalStateException.
(i18n/tru "There was a problem borrowing a JRubyInstance from the pool.")
e)]
(reset! borrow-exception exception)
(throw exception)))
(finally
(.unlock pool)))))
(schema/defn borrow-all-jrubies :- [JRubyInstance]
"Locks the pool and borrows all the instances"
[pool-context :- jruby-schemas/PoolContext]
(let [pool (jruby-internal/get-pool pool-context)
flush-timeout (jruby-internal/get-flush-timeout pool-context)
shutdown-on-error (get-shutdown-on-error-fn pool-context)
borrow-exception (atom nil)]
; If lock fails, abort and throw an exception
(try
(.lockWithTimeout pool flush-timeout TimeUnit/MILLISECONDS)
(catch TimeoutException e
(jruby-internal/throw-jruby-lock-timeout e)))
; Bit of a hack to work around shutdown-on-error behavior:
; shutdown-on-error will either return the jrubies as expected,
; or if there was an error, it will shutdown the server and return a promise.
; We want to rethrow whatever exception it encountered so that it can bubble
; up to whatever code requested this flush, so borrow-all-jrubies* will put
; that exception into the borrow-exception atom
(let [jrubies (shutdown-on-error #(borrow-all-jrubies* pool-context borrow-exception))]
(if-let [exception @borrow-exception]
(throw exception)
jrubies))))
(schema/defn cleanup-and-refill-pool
"Cleans up the given instances and optionally refills the pool with
new instances. Should only be called from the modify-instance-agent"
[pool-context :- jruby-schemas/PoolContext
old-instances :- [JRubyInstance]
refill? :- schema/Bool]
(let [pool (jruby-internal/get-pool pool-context)
pool-size (jruby-internal/get-pool-size pool-context)
new-instance-ids (map inc (range pool-size))
config (:config pool-context)
cleanup-fn (get-in config [:lifecycle :cleanup])]
(doseq [[old-instance new-id] (zipmap old-instances new-instance-ids)]
(try
(jruby-internal/cleanup-pool-instance! old-instance cleanup-fn)
(when refill?
(jruby-internal/create-pool-instance! pool new-id config
(:splay-instance-flush config))
(log/info (i18n/trs "Finished creating JRubyInstance {0} of {1}"
new-id pool-size)))
(catch Exception e
(.clear pool)
(jruby-internal/insert-poison-pill pool e)
(throw (IllegalStateException.
(i18n/trs "There was a problem creating a JRubyInstance for the pool.")
e))))))
(if refill?
(log/info (i18n/trs "Finished draining and refilling pool."))
(log/info (i18n/trs "Finished draining pool."))))
(schema/defn ^:always-validate
drain-and-refill-pool!
"Borrow and destroy all the jruby instances, optionally refilling the
pool with fresh jrubies. Locks the pool in order to drain it, but releases
the lock before destroying the instances and refilling the pool
If an on-complete promise is given, it can be used by the caller to make
this function syncronous. Otherwise it only blocks until the pool instances
have been borrowed and the cleanup-and-refill-pool fn is sent to the agent"
([pool-context :- jruby-schemas/PoolContext
refill? :- schema/Bool]
(drain-and-refill-pool! pool-context refill? (promise)))
([pool-context :- jruby-schemas/PoolContext
refill? :- schema/Bool
on-complete :- IDeref]
(if refill?
(log/info (i18n/trs "Draining and refilling JRuby pool."))
(log/info (i18n/trs "Draining JRuby pool.")))
(let [old-instances (borrow-all-jrubies pool-context)
modify-instance-agent (get-modify-instance-agent pool-context)
; Make sure the promise is delivered even if cleanup fails
try-cleanup-and-refill #(try
(cleanup-and-refill-pool pool-context old-instances refill?)
(finally (deliver on-complete true)))]
(log/info (i18n/trs "Borrowed all JRuby instances, proceeding with cleanup."))
(send-agent modify-instance-agent try-cleanup-and-refill))))
(schema/defn ^:always-validate
flush-pool-for-shutdown!
"Flush of the current JRuby pool when shutting down during a stop."
;; Since the drain-pool! function takes the pool lock, we know that if we
;; receive multiple flush requests before the first one finishes, they will
;; be queued up waiting for the lock, which will never be granted because this
;; function does not refill the pool, but instead inserts a shutdown poison pill
[pool-context :- jruby-schemas/PoolContext]
(log/debug (i18n/trs "Beginning flush of JRuby pools for shutdown"))
(let [pool-state (jruby-internal/get-pool-state pool-context)
pool (:pool pool-state)
on-complete (promise)]
(drain-and-refill-pool! pool-context false on-complete)
(jruby-internal/insert-shutdown-poison-pill pool)
; Wait for flush to complete
@on-complete
(log/debug (i18n/trs "Finished flush of JRuby pools for shutdown"))))
(schema/defn ^:always-validate
flush-and-repopulate-pool!
"Flush of the current JRuby pool. Blocks until all the instances have
been borrowed from the pool, but does not wait for the instances
to be flushed or recreated"
[pool-context :- jruby-schemas/PoolContext]
;; Since the drain-and-refill-pool! function takes the pool lock, we know that if we
;; receive multiple flush requests before the first one finishes, they will
;; be queued up waiting for the lock, which can't be granted until all the instances
;; are returned to the pool, which won't be done until sometimes after
;; this function exits
(log/info (i18n/trs "Flush request received; flushing old JRuby instances."))
(drain-and-refill-pool! pool-context true))
(schema/defn ^:always-validate
send-flush-instance! :- jruby-schemas/JRubyPoolAgent
"Sends requests to the flush-instance agent to flush the instance and create a new one."
[pool-context :- jruby-schemas/PoolContext
instance :- JRubyInstance]
;; We use an agent to syncronize jruby creation and destruction to mitigate
;; any possible race conditions in the underlying jruby scripting container
(let [{:keys [config]} pool-context
modify-instance-agent (get-modify-instance-agent pool-context)
id (next-instance-id (:id instance) pool-context)]
(send-agent modify-instance-agent #(flush-instance! pool-context instance id config))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Public
(schema/defn ^:always-validate
pool-agent :- jruby-schemas/JRubyPoolAgent
"Given a shutdown-on-error function, create an agent suitable for use in managing
JRuby pools."
[shutdown-on-error-fn :- (schema/pred ifn?)]
(agent {:shutdown-on-error shutdown-on-error-fn}))