Changes

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).

=Services= A job can be registered as ''service'' by supplying the {{Code|service}} option to {{Function|Jobs|jobs:eval}}: <syntaxhighlight lang="xquery">(: register job as service; 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() })</syntaxhighlight> '''Some more notes:''' * All job services will be scheduled for evaluation when the BaseX server or BaseX HTTP server is started.* If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time.* The job definitions are stored in a {{Code|jobs.xml}} file in the database directory. It can also be edited manually. =Basic Functions=

|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.

|* <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.

|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: <code>scheduled</code>, the state (<code>queued</code>, <code>running</code>, stopped, timeout, memory) and the <code>cached</code>* <code>user</code>: user who started the job.* <code>duration</code>: evaluation time (included if a job is running or if the result was cached)* <code>start</code>: next start of job (included if a job will be executed repeatedly)* <code>time</code>: time when job was registered

|* <code>jobs:list-details()</code> returns information on the currently running job and possibly others:<pre classsyntaxhighlight lang="brush:xml"><job id="job1" type="XQuery" duration="PT0S" state="running" user="admin" duration="PT0.001S">

</presyntaxhighlight>

|Indicates if the 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> indicates that the job has either finished, or that the id is for unknownjobs.* <code>false</code> indicates that the job id is still 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:stopservices==

|{{Func|jobs:stopservices|$id as xs:string|empty-sequenceelement(job)*}}

|Cancels the execution Returns a list of a job with the specified all jobs that have been persistently registered as [[#Services|Services]].|-| '''Errors'''|{{CodeError|services|$id#Errors}}, or drops the cached result of a query. Unknown ids are ignored. All jobs are gracefully stopped; it is up to the process to decide when it is safe to shut downRegistered services cannot be parsed.<br/>

=Asynchronous Execution=

Asynchronous query execution is recommendable if There are cases in which a client does not, or cannot, wait until a request is fully processed. This is e. g. the case with web browsersThe client may be a browser, which will usually cancel a sends an HTTP request after a specific timeout. In such cases, you can use asynchronous execution to trigger another the server-side process, which will in order to start the another time-consuming processquery job. The functions in this section allow you to register a new query job from a running query. Jobs can be executed immediately (i.e., and fetch the result later on as soon as the [[Transaction Management#Concurrency Control|Concurrency Control]] allows it is available) or scheduled for repeated execution. Each registered job gets a job id, and the id can be used to retrieve a query result, stop a job, or wait for its termination.

==jobs:scheduleeval== {{Mark|Updated with Version 9.5}}: Integers added as valid start and end times.

|{{Func|jobs:scheduleeval|$query as xs:stringanyAtomicItem|xs:string}}<br />{{Func|jobs:scheduleeval|$query as xs:stringanyAtomicItem, $bindings as map(*)?|xs:string}}<br />{{Func|jobs:scheduleeval|$query as xs:stringanyAtomicItem, $bindings as map(*)?, $options as map(xs:string, xs:string*)?|xs:string}}<br />

|Schedules the execution evaluation of the supplied {{Code|$query}} and returns a query id. The query will be queued, and the result will optionally be cached. Queries may can be updating. Variables The query can be a URI or a string, and variables and context items can be declared via {{Code|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details). The following {{Code|$options}} parameter contains schedules optionscan be supplied:

** If the query raises an error, it will be cached and returned instead.** If the result will not be cached, the query id will immediately be discarded after query execution.* {{Code|start}}: a dayTimeDuration, time , dateTime or dateTime integer can be specified to delay the execution of the query:

** 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.** If a time is specified, the query will be queued executed at this timeof 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.** An integer will be interpreted as minutes. If a dateTime is the specifiednumber exceeds the minutes of the current hour, the query will be queued 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 pastexecuted one hour later.

* {{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 by functions , such as with {{Code|fn:doc}} (default.* {{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]]. Registered services must have no variable bindings.* {{Code|log}}: ''empty writes the specified string'')to the [[Logging|database logs]]. Two log entries are stored, one at the beginning and another one after the execution of the job.

|{{Error|overflow|#Errors}} Too Query execution is rejected, because too many queries or query results jobs are queuedor 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.

* {{CodeCache query result. The returned id can be used to pick up the result with [[#jobs:result|jobs:scheduleresult]]:<syntaxhighlight lang="xquery">jobs:eval("1+3", (), map { 'cache': true() })}} returns a query id, e.g. {{Code|Job-123}}. The result can </syntaxhighlight>* A happy birthday mail will be retrieved via a second query in sent at the same BaseX contextgiven date: {{Code|<syntaxhighlight lang="xquery">jobs:resulteval("import module namespace mail='mail'; mail:send('Happy birthday!')"Job, (), map { 'start': '2018-09-123"01T06:00:00' })}}<br /syntaxhighlight>* The following [[RESTXQ]] function functions can be called to execute a query at 2 am every day. An id will return be returned by the id of the query threadfirst function, which evaluates can be used to stop the query that has been specified in scheduler via the body of a POST requestsecond function:<pre classsyntaxhighlight lang='brush:"xquery'">declare %rest:POST("{$query}") %rest:path('/schedulestart-queryscheduling') function local:schedulestart($query) { jobs:scheduleeval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })};declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { jobs:stop($id)

</presyntaxhighlight>* A maintenance function 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 called at 2am executed every daysecond time:<pre classsyntaxhighlight lang="brush:xquery">jobs:scheduleeval("import module namespace m='maintain'; mprof:cleanupsleep(1500)", (), map { 'startinterval': '02:00:00PT1S', 'intervalend': 'P1DPT10S' })}}</presyntaxhighlight>* Query execution is scheduled for every second. As The query in the query itself specified file will take 1be evaluated once:<syntaxhighlight lang="xquery">jobs:eval(xs:anyURI('cleanup.5 secondsxq'))</syntaxhighlight>* The following expression, if stored in a file, it will only be executed evaluated every second time5 seconds:<pre classsyntaxhighlight lang="brush:xquery">jobs:scheduleeval("prof:sleep static-base-uri(1500)", () map { }, map { 'intervalstart': 'PT1SPT5S' })</presyntaxhighlight>

|Returns the cached result of a query job with the specified job {{Code|$id}}:

* If the original query job has raised an error, the cached error will be raised instead.

* The following [[RESTXQ]] function will either return the result of a previously started query job or raise an error:<pre classsyntaxhighlight lang='brush:"xquery'">

</presyntaxhighlight>* The following query demonstrates how the results of an asynchronously executed query can be returned within the same query. Please remember that (see below why you should avoid this is not the common way how these functions will be used pattern in practice):<pre classsyntaxhighlight lang='brush:"xquery'">let $query := jobs:scheduleeval('(1 to 10000000)[. = 1]', map{}, map{ 'cache': true() })

hof:until( function($f) { jobs:finishedwait($query) }, function($f) { prof:sleep(10) }, () ),

</presyntaxhighlight>Queries of this kind can cause deadlocks! If the original query and the new query perform updates on the same database, the second query will only be run after the first one has been executed, and the first query will wait for the second query forever. You should resort to [[XQuery Module#xquery:fork-join|xquery:fork-join]] if you want to have full control on parallel query execution.|} ==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:resultswait==

|{{Func|jobs:results|wait|$id as xs:string*|empty-sequence()}}

|Returns 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 ids id of all jobs for which results are cacheda queued job, or repeatedly executed job, it may stall and never terminate.|-| '''Errors'''|{{Error|self|#Errors}} The current job is addressed.<br/>

|{{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|range}}