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1,625 bytes added ,  15:46, 1 March 2018
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All functions in this module are assigned to the <code><nowiki>http://basex.org/modules/jobs</nowiki></code> namespace, which is statically bound to the {{Code|jobs}} prefix. Errors will be bound to the same prefix.
=Services= With {{Version|9.0}} of BaseX, jobs can be registered as persistent services. An additional {{Code|service}} option has been added to the options list of {{Function|Jobs|jobs:eval}} and {{Function|Jobs|jobs:invoke}}: <pre class="brush:xquery">(: register job, which will be run every day at 1 am :)jobs:eval('db:drop("tmp")', (), map { 'id':'cleanup', 'start':'01:00:00', 'interval':'P1D', 'service': true() }), (: list registered services :)jobs:services(),(: result: <job base-uri="..." id="cleanup" interval="P1D" start="01:00:00">db:drop("tmp")</job> :) (: unregister job :)jobs:stop('cleanup', map { 'service': true() })</pre> '''Some notes:''' * All registered jobs will be scheduled for evaluation when the BaseX server or BaseX HTTP server is started.* Job services can be updated: If a new job is registered, and if there is already a job with the same id, the old entry will be replaced.* The job definitions are stored in a {{Code|jobs.xml}} file in the database directory. It can also be edited manually. =Basic Functions=
==jobs:current==
</pre>
|}
 
==jobs:finished==
 
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:finished|$id as xs:string|xs:boolean}}
|-
| '''Summary'''
|Indicates if the evaluation of an already running job with the specified {{Code|$id}} has finished. As the ids of finished jobs will usually be discarded, unless caching is enabled, the function will also return <code>true</code> for unknown jobs.
* <code>false</code> indicates that the job id is scheduled, queued, or currently running.
* <code>true</code> will be returned if the job has either finished, or if the id is unknown (because the ids of all finished jobs will not be cached).
|}
 
==jobs:stop==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:stopservices|$id as xs:string|empty-sequenceelement(job)*}}
|-
| '''Summary'''
|Triggers the cancelation of Returns a job with the specified {{Code|$id}}, drops the cached result list of a query, or cancels a scheduled job. Unknown ids are ignored. All all jobs are gracefully stopped; it is up to the process to decide when it is safe to shut downthat have been persistently registered as [[#Services|Services]].
|-
| '''ExamplesErrors'''| <code>jobs:list()[{{Error|services|#Errors}} Registered services cannot be parsed. != jobs:current()] ! jobs:stop(.)<br/code> stops and discards all jobs except for the current one.
|}
==jobs:waitfinished==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:waitfinished|$id as xs:string|empty-sequence()xs:boolean}}
|-
| '''Summary'''
|Waits for Indicates if the completion evaluation of a an already running job with the specified {{Code|$id}}:has finished. As the ids of finished jobs will usually be discarded, unless caching is enabled, the function will also return <code>true</code> for unknown jobs.* The function will terminate immediately if <code>false</code> indicates that the job id is unknownscheduled, queued, or currently running. This is * <code>true</code> will be returned if the case if a future job has not been queued yeteither finished, or if the id has already been discarded after job evaluation.* If the function is called with unknown (because the id ids of a queued job, or repeatedly executed job, it may stall and never terminate.|-| '''Errors'''|{{Error|self|#Errors}} The current job is addressedall finished jobs will not be cached).<br/>
|}
|-
| '''Summary'''
|Schedules the evaluation of the supplied {{Code|$query}} and returns a query id. The query will be queued, and the result will optionally be cached. Queries can be updating. Variables and context items can be declared via {{Code|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details). The following {{Code|$options}} parameter contains scheduling optionscan be supplied:
* {{Code|cache}}: indicates if the query result will be cached or ignored (default: <code>false</code>):
** The result will be cached in main-memory until it is fetched via [[#jobs:result|jobs:result]], or until {{Option|CACHETIMEOUT}} is exceeded.
* {{Code|base-uri}}: sets the [https://www.w3.org/TR/xquery-31/#dt-static-base-uri base-uri property] for the query. This URI will be used when resolving relative URIs, such as with {{Code|fn:doc}}.
* {{Code|id}}: sets a custom job id. The id must not start with the standard <code>job</code> prefix, and it can only be assigned if no job with the same name exists.
* {{Code|service}}: additionally registers the job as [[#Services|Service]].
|-
| '''Errors'''
|-
| '''Summary'''
|Schedules the evaluation of the XQuery expression located at {{Code|$uri}} and returns a query id. The semantics and remaining arguments are identical to For further details, see [[#jobs:eval|jobs:eval]].
|-
| '''Errors'''
</pre>
Please note that queries of this kind can cause deadlocks. For example, if both the original query and the query to be executed asynchronously perform updates on the same database, the second query would only be run after the first one has been executed, and the first query will wait forever. This is why you should avoid this pattern in practice and resort to [[XQuery Module#xquery:fork-join|xquery:fork-join]] if you want to do things in parallel.
|}
 
==jobs:stop==
 
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:stop|$id as xs:string|empty-sequence()}}
|-
| '''Summary'''
|Triggers the cancelation of a job with the specified {{Code|$id}}, drops the cached result of a query, or cancels a scheduled job. Unknown ids are ignored. All jobs are gracefully stopped; it is up to the process to decide when it is safe to shut down. The following {{Code|$options}} can be supplied:
* {{Code|service}}: additionally removes the job from the [[#Services|job services]] list.
|-
| '''Examples'''
| <code>jobs:list()[. != jobs:current()] ! jobs:stop(.)</code> stops and discards all jobs except for the current one.
|}
 
==jobs:wait==
 
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:wait|$id as xs:string|empty-sequence()}}
|-
| '''Summary'''
|Waits for the completion of a job with the specified {{Code|$id}}:
* The function will terminate immediately if the job id is unknown. This is the case if a future job has not been queued yet, or if the id has already been discarded after job evaluation.
* If the function is called with the id of a queued job, or repeatedly executed job, it may stall and never terminate.
|-
| '''Errors'''
|{{Error|self|#Errors}} The current job is addressed.<br/>
|}
|{{Code|self}}
| The current job cannot be addressed.
|-
|{{Code|service}}
| Registered services cannot be parsed, added or removed.
|-
|{{Code|unknown}}
;Version 9.0
* Added: {{Function|Jobs|jobs:invoke}}, [[#jobs:invokeServices|jobs:invokeServices]]
;Version 8.6
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