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==jobs:finished==
hof:until( function($f) { jobs:finishedwait($query) }, function($f) { prof:sleep(10) }, () ),
→Services
This [[Module Library|XQuery Module]] provides functions for organizing scheduled, queued , running and running cached jobs (. Jobs can be commands, queries, REST, RESTXQ and WebDAV client or HTTP requests).
=Conventions=
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= {{Mark|Introduced with Version 9.0:}} Jobs can additionally 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 more notes:''' * All registered jobs will be scheduled for evaluation when the BaseX server or BaseX HTTP server is started.* If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time.* Job services can be updated: If a new job is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==
|-
| '''Summary'''
|Returns the ids of all jobs that are currently registered. The list includes scheduled, queued or executed, running, stopped, and finished jobs with cached results.
|-
| '''Examples'''
|* <code>jobs:list()</code> returns the same job id as [[#jobs:current{{Function|Jobs|jobs:current]] }} if no other job is running.* <code>jobs:list()[. != jobs:current()] ! jobs:stop(.)</code> stops and invalidates all asynchronous queries and results except for the current oneregistered.
|}
|-
| '''Summary'''
|Returns information on all jobs that are currently registered, or on a job with the specified {{Code|$id}} (or an empty sequence if this job is not found). The list includes scheduled, queued , running jobs, and cached jobs. A string representation of the job, or executedits URI, will be returned as value. The input comprises the returned elements have additional attributes:* <code>id</code>: job id, * <code>type</code>: type of the type job (XQuerycommand, a commandquery, REST, RESTXQ, etc.), * <code>state</code>: current state of the time a job is already being evaluated(scheduled, the state (queued, running, stopped, timeout, memoryor cached) and * <code>user</code>: the user who started the job.* <code>duration</code>: evaluation time (for running and cached jobs)* <code>start</code>: dateTime string with next start (for jobs that will be executed repeatedly)
|-
| '''Examples'''
|* <code>jobs:list-details()</code> returns information on the currently running job and possibly others:
<pre class="brush:xml">
<job id="job1" type="XQuery" duration="PT0S" state="running" user="admin" duration="PT0.001S">
XQUERY jobs:list-details()
</job>
</pre>
|}
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:finishedservices|$id as xs:string|xs:booleanelement(job)*}}
|-
| '''Summary'''
|Indicates if the evaluation Returns a list of a job with the specified all jobs that have been persistently registered as [[#Services|Services]].|-| '''Errors'''|{{CodeError|$idservices|#Errors}} has finished:* <code>true</code> indicates that the job has either finished, or that the id is unknownRegistered services cannot be parsed.* <code>false<br/code> indicates that the job id is still queued or currently running.
|}
==jobs:stopfinished==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:stopfinished|$id as xs:string|empty-sequence()xs:boolean}}
|-
| '''Summary'''
|Cancels Indicates if the execution evaluation of a an already running job with the specified {{Code|$id}}has finished. As the ids of finished jobs will usually be discarded, unless caching is enabled, drops the cached result of a queryfunction will also return <code>true</code> for unknown jobs.* <code>false</code> indicates that the job id is scheduled, queued, or cancels a scheduled currently running.* <code>true</code> will be returned if the job. Unknown has either finished, or if the id is unknown (because the ids are ignored. All of all finished jobs are gracefully stopped; it is up to the process to decide when it is safe to shut downwill not be cached).
|}
=Asynchronous Execution=
Asynchronous query execution is recommendable if a client does not, or cannot, wait until a request is fully processed. This is e. g. the case with web browsers, which will usually cancel a request after a specific timeout. In such cases, you can use asynchronous execution to trigger another server-side process, which will start the time-consuming process, and fetch the result later on as soon as it is available.
==jobs:scheduleeval==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:scheduleeval|$query as xs:string|xs:string}}<br />{{Func|jobs:scheduleeval|$query as xs:string, $bindings as map(*)?|xs:string}}<br />{{Func|jobs:scheduleeval|$query as xs:string, $bindings as map(*)?, $options as map(xs:string, xs:string*)?|xs:string}}<br />
|-
| '''Summary'''
|Schedules the execution evaluation of the supplied {{Code|$query}} and returns a query id. The query will be queued, and the result will optionally be cached. Queries may 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|start}}: a dayTimeDuration, time or dateTime can be specified to delay the execution of the query:
** If a dayTimeDuration is specified, the query will be queued after the specified duration has passed. Examples for valid values are: <code>P1D</code> (1 day), <code>PT5M</code> (5 minutes), <code>PT0.1S</code> (100 ms). An error will be raised if a negative value is specified.
** If a time is specified, the query will be executed at this time of the day. Examples for valid times are: <code>02:00:00</code> (2amlocal time), <code>12:00:0000Z</code> (noon, UTC). If the time lies in the past, the query will be executed the next day.
** If a dateTime is specified, the query will be executed at this date. Examples for valid values are: <code>2018-12-31T23:59:59</code> (New Year's Eve 2018, close to midnight). An error will be raised if the specified time lies in the past.
* {{Code|interval}}: a dayTimeDuration string can be specified to execute the query periodically. An error is raised if the specified interval is less than one second (<code>PT1S</code>). If the next scheduled call is due, and if a query with the same id is still running, it will be skipped.
* {{Code|end}}: scheduling can be stopped after a given time or duration. The string format is the same as for {{Code|start}}. An error is raised if the resulting end time is smaller than the start time.* {{Code|base-uri}}: set 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'''
|{{Error|overflow|#Errors}} Query execution is rejected, because too many jobs are queued or being executed. {{Option|CACHETIMEOUT}} can be decreased if the default setting is too restrictive.<br/>{{Error|range|#Errors}} A specified time or duration is out of range.<br/>{{Error|id|#Errors}} The specified id is invalid or has already been assigned.<br/>{{Error|options|#Errors}} The specified options are conflicting.
|-
| '''Examples'''
|
* Cache query result. An The returned id will be returned, which can be used to pick up the result via with [[#jobs:result|jobs:result]]):
<pre class='brush:xquery'>
jobs:scheduleeval("1+3", (), map { 'cache': true() })
</pre>
* A happy birthday mail will be sent at the given date:
<pre class="brush:xquery">
jobs:scheduleeval("import module namespace mail='mail'; mail:send('Happy birthday!')",
(), map { 'start': '2018-09-01T06:00:00' })}}
</pre>
* The following [[RESTXQ]] functions can be called to execute a specified query at 2 am every day. An id will be returnedby the first function, which can be used to stop the scheduler againvia the second function:
<pre class='brush:xquery'>
declare %rest:POST("{$query}") %rest:path('/start-scheduling') function local:start($query) {
jobs:scheduleeval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })
};
declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) {
};
</pre>
* Query execution is scheduled for every second, and for 10 seconds in total. As the query itself will take 1.5 seconds, it will only be executed every second time:
<pre class="brush:xquery">
jobs:scheduleeval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })</pre>* The following expression, if stored as a file, calls and evaluates itself every 5 seconds:<pre class="brush:xquery">jobs:eval( file:read-text(static-base-uri()), map { }, map { 'start': 'PT5S' })</pre>|} ==jobs:invoke== {{Mark|Introduced with Version 9.0:}} {| width='100%'|-| width='120' | '''Signatures'''|{{Func|jobs:invoke|$uri as xs:string|xs:string}}<br />{{Func|jobs:invoke|$uri as xs:string, $bindings as map(*)?|xs:string}}<br />{{Func|jobs:invoke|$uri as xs:string, $bindings as map(*)?, $options as map(*)?|xs:string}}<br />|-| '''Summary'''|Schedules the evaluation of the XQuery expression located at {{Code|$uri}} and returns a query id. For further details, see [[#jobs:eval|jobs:eval]].|-| '''Errors'''|{{Error|overflow|#Errors}} Query execution is rejected, because too many jobs are queued or being executed. {{Option|CACHETIMEOUT}} can be decreased if the default setting is too restrictive.<br/>{{Error|range|#Errors}} A specified time or duration is out of range.<br/>{{Error|id|#Errors}} The specified id is invalid or has already been assigned.<br/>{{Error|options|#Errors}} The specified options are conflicting.|-| '''Examples'''| Run XQuery expression that may perform some cleanups:<pre class='brush:xquery'>jobs:invoke("cleanup.xq", (), ())
</pre>
|}
|-
| '''Summary'''
|Returns the cached result of a query job with the specified job {{Code|$id}}:
* Results can only be retrieved once. After retrieval, the cached result will be dropped.
* If the original query job has raised an error, the cached error will be raised instead.
|-
| '''Errors'''
| '''Examples'''
|
* The following [[RESTXQ]] function will either return the result of a previously started query job or raise an error:
<pre class='brush:xquery'>
declare %rest:path('/result/{$id}') function local:result($id) {
};
</pre>
* The following query demonstrates how the results of an asynchronously executed query can be returned within the same query. Please remember that this is not the common way how these functions will be used in practice:
<pre class='brush:xquery'>
let $query := jobs:scheduleeval('(1 to 10000000)[. = 1]', map{}, map{ 'cache': true() })
return (
jobs:result($query)
)
</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:resultsstop==
{| width='100%'
|-
| width='120' | '''Signatures'''
|{{Func|jobs:results|stop|$id as xs:string*|empty-sequence()}}
|-
| '''Summary'''
|Returns Triggers the cancelation of a job with the specified {{Code|$id}}, drops the cached result of a query, or cancels a scheduled job. Unknown ids of 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 which results are cachedthe 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/>
|}
|Description
|-
|{{Code|unknownoptions}}| The supplied query id is unknown or not available anymorespecified options are conflicting.
|-
|{{Code|runningid}}| A query The specified id is still runninginvalid or has already been assigned.
|-
|{{Code|overflow}}
| Too many queries or query results are queued.
|-
|{{Code|range}}
| A specified time or duration is out of range.
|-
|{{Code|running}}
| A query is still running.
|-
|{{Code|self}}
| The current job cannot be addressed.
|-
|{{Code|service}}
| Registered services cannot be parsed, added or removed.
|-
|{{Code|unknown}}
| The supplied query id is unknown or not available anymore.
|}
=Changelog=
;Version 9.0
* Added: {{Function|Jobs|jobs:invoke}}, [[#Services|Services]]
;Version 8.6
* Updated: [[#jobs:eval|jobs:eval]]: <code>id</code> option added.
The module was introduced with Version 8.5.
