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).

=FunctionsServices=

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services will be scheduled for evaluation when the BaseX server or BaseX HTTP server is started.* If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time.* The job definitions are stored in a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. =Executing Jobs= There are cases in which a client does not, or cannot, wait until a request is fully processed. The client may be a browser, which sends an HTTP request to the server in order to start another time-consuming query 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., as soon as the [[Transaction Management#Concurrency Control|Concurrency Control]] allows it) 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:currenteval==

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

|Returns Schedules the evaluation of the supplied {{Code|$query}} ({{Code|xs:string}}, or of type {{Code|xs:anyURI}}, pointing to a resource), and returns a query id . The query will be queued, and the result will optionally be cached. Queries can be updating. Variables and the context value can be declared via {{Code|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details). The following {{Code|$options}} can 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.** If the query raises an error, it will be cached and returned instead.* {{Code|start}}: a dayTimeDuration, time, dateTime or integer 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 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 executed at this time of the day. Examples for valid times are: <code>02:00:00</code> (2am local time), <code>12:00:00Z</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 the specified number is greater than the elapsed minutes of the current hour, the query will be executed one hour later.* {{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}}: 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 jobwith the same name exists.* {{Code|service}}: additionally registers the job as [[#Services|service]]. Registered services must have no variable bindings.* {{Code|log}}: 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.|-| '''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. The returned id can be used to pick up the result with [[#jobs:result|jobs:result]]:<syntaxhighlight lang="xquery">jobs:eval("1+3", (), map { 'cache': true() })</syntaxhighlight>* A happy birthday mail will be sent at the given date:<syntaxhighlight lang="xquery">jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')", (), map { 'start': '2018-09-01T06:00:00' })}}</syntaxhighlight>* The following [[RESTXQ]] functions can be called to execute a query at 2 am every day. An id will be returned by the first function, which can be used to stop the scheduler via the second function:<syntaxhighlight lang="xquery">declare %rest:POST("{$query}") %rest:path('/start-scheduling') function local:start($query) { jobs:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })};declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { jobs:stop($id)};</syntaxhighlight>* 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:<syntaxhighlight lang="xquery">jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })</syntaxhighlight>* The query in the specified file will be evaluated once:<syntaxhighlight lang="xquery">jobs:eval(xs:anyURI('cleanup.xq'))</syntaxhighlight>* The following expression, if stored in a file, will be evaluated every 5 seconds:<syntaxhighlight lang="xquery">jobs:eval( static-base-uri(), map { }, map { 'start': 'PT5S' })</syntaxhighlight>

==jobs:listresult== {{Mark|Updated with Version 9.7:}} Return empty sequence if no result is cached.

|{{Func|jobs:list|result|$id as xs:string|item()*}}

|Returns the ids cached result of all jobs that are currently queued a job with the specified job {{Code|$id}}:* If the original job has raised an error, the cached error will be raised instead.* Results can only be retrieved once. After retrieval, the cached result will be dropped.* If the result has already been retrieved, or executedif it has not been cached, an empty sequence is returned.

* The following [[RESTXQ]] function will either return the result of a previously started job or raise an error:<codesyntaxhighlight lang="xquery">declare %rest:path('/result/{$id}') function local:result($id) { jobs:listresult($id)};</codesyntaxhighlight> returns * The following query demonstrates how the results of an executed query can be returned within the same job id as [[#jobsquery (see below why you should avoid this pattern in practice):current|jobs:current]] if no other job is running.* <codesyntaxhighlight lang="xquery">let $query := jobs:listeval('(1 to 10000000)[. != 1]', map { }, map { 'cache': true() })return ( jobs:currentwait($query)] ! , jobs:stopresult(.$query))</codesyntaxhighlight> stops Queries of this kind can cause deadlocks! If the original query and invalidates all asynchronous queries the new query perform updates on the same database, the second query will only be run after the first one has been executed, and results except the first query will wait for the current onesecond 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:list-detailsstop==

|{{Func|jobs:list-details||element(job)*}}<br/>{{Func|jobs:list-detailsstop|$id as xs:string|elementempty-sequence(job)*}}

|Returns information on all jobs that are currently queued or executed. The input comprises Triggers the cancelation of a job with the specified {{Code|$id}}, drops the type (XQuery, cached result of a commandquery, REST, RESTXQ), the time or cancels a scheduled job . Unknown ids are ignored. All jobs are gracefully stopped; it is already being evaluated, up to the state (queued, running, stopped, timeout, memory) and process to decide when it is safe to shut down. The following {{Code|$options}} can be supplied:* {{Code|service}}: additionally removes the user who started job from the [[#Services|jobservices]] list.

|* <code>jobs:list-details()</code> returns information on the currently running job and possibly others:<pre class[. !="brushjobs:xml"><job id="job1" type="XQuery" duration="PT0S" state="running" user="admin"> XQUERY current()] ! jobs:list-detailsstop(.)</job></precode>stops and discards all jobs except for the current one.

==jobs:finishedwait==

|{{Func|jobs:finishedwait|$id as xs:string|xs:booleanempty-sequence()}}

|Indicates if Waits for the evaluation completion of a job with the specified {{Code|$id}} has finished:* <code>true</code> indicates that The function will terminate immediately if the job id is unknown. This is the case if a future job has either finishednot been queued yet, or that if the id is unknownhas already been discarded after job evaluation.* <code>false</code> indicates that If the function is called with the job id is still of a queued job, or currently runningrepeatedly executed job, it may stall and never terminate.|-| '''Errors'''|{{Error|self|#Errors}} The current job is addressed.<br/>

=Listing Jobs= ==jobs:stopcurrent==

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

|Cancels Returns the execution of a job with the specified {{Code|$id}}, 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 downcurrent job.

=Asynchronous Execution=jobs:list==

Asynchronous query execution is recommendable if a client does not, or cannot, wait until a request is fully processed. This is e. g{| width='100%'|-| width='120' | '''Signatures'''|{{Func|jobs:list||xs:string*}}|-| '''Summary'''|Returns the ids of all jobs that are currently registered. the case with web browsers The list includes scheduled, which will usually cancel a request after a specific timeout. In such casesqueued, you can use asynchronous execution to trigger another server-side processrunning, which will start the time-consuming processstopped, and fetch finished jobs with cached results.|-| '''Examples'''| <code>jobs:list()</code> returns the result later on same job id as soon as it {{Function|Jobs|jobs:current}} if no other job is availableregistered.|}

==jobs:schedulelist-details==

|{{Func|jobs:schedulelist-details|$query as xs:string|xs:string}}<br />{{Func|jobs:schedule|$query as xs:string, $bindings as mapelement(job)*)?|xs:string}}<br />{{Func|jobs:schedulelist-details|$query id as xs:string, $bindings as map|element(job)*)?, $options as map(xs:string, xs:string)|xs:string}}<br />

|Schedules Returns information on all jobs that are currently registered, or on a job with the execution of the supplied specified {{Code|$queryid}} and returns a query id(or an empty sequence if this job is not found). The query will be list includes scheduled, queued, running jobs, and cached jobs. A string representation of the result job, or its URI, will optionally be cached. Queries may be updating. Variables and context items can be declared via {{Code|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details)returned as value. The {{Code|$options}} parameter contains scheduling optionsreturned elements have additional attributes:* {{Code|cache}}: indicates if the query result will be cached or ignored (default: <code>falseid</code>):job id** The result will be cached in main-memory until it is fetched via [[#jobs<code>type</code>:result|jobs:result]]type of the job (command, or until {{Option|CACHETIMEOUT}} is exceeded.** If the query raises an error, it will be cached and returned insteadREST, RESTXQ, etc.)* {{Code|start}}<code>state</code>: a dayTimeDuration, time or dateTime can be specified to delay the execution current state of the query:** If a dayTimeDuration is specified, the query will be queued after the specified duration has passed. Examples for valid values arejob: <code>P1Dscheduled</code> (1 day), <code>PT5Mqueued</code> (5 minutes), <code>PT0.1Srunning</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>02:00:00cached</code> (2am), * <code>12:00:00user</code> (noon). If : user who started the time lies in the past, the query will be executed next day.job** If a dateTime is specified, the query will be executed at this date. Examples for valid values are: <code>2018-12-31T23:59:59duration</code> : evaluation time (New Year's Eve 2018, close to midnight). An error will be raised included if the specified time lies in the past.* {{Code|interval}}: a dayTimeDuration string can be specified to execute the query periodically. An error job is raised running or if the specified interval is less than one second (result was cached)* <code>PT1Sstart</code>). If the : next scheduled call is due, and start of job (included if a query with the same id is still running, it job will be skipped.executed repeatedly)* {{Code|base-uri}}: set 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}}.|-| '''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.<brcode>time</code>{{Error|range|#Errors}} A specified : time or duration is out of range.when job was registered

|* Cache query result. An id will be returned, which can be used to pick up the result via [[#jobs:result|jobs:result]]):<pre class='brush:xquery'code>jobs:schedule("1+3", (), map { 'cache': truelist-details() })</precode>* A happy birthday mail will be sent at returns information on the given datecurrently running job and possibly others:<pre classsyntaxhighlight lang="brush:xqueryxml">jobs:schedule(<job id="job1"import module namespace mailtype='mail'; mail:send('Happy birthday!')", (), map { 'start': '2018-09-01T06:00:00', 'interval': 'P1D' })}}</pre>* Query execution is scheduled for every second. As the query itself will take 1.5 seconds, it will only be executed every second time:<pre classXQuery" state="brush:xqueryrunning">jobs:schedule(user="prof:sleep(1500)admin", (), map { 'interval': 'PT1S' })</pre>* The following [[RESTXQ]] functions can be called to execute a specified query at 2am every day. An id will be returned, which can be used to stop the scheduler again:<pre classduration='brush:xquery'>declare %rest:POST("{$query}PT0.001S") %rest:path('/start-scheduling') function local:start($query) {> XQUERY jobs:schedule($query, list-details(), map { 'start': '02:00:00', 'interval': 'P1D' })};declare %rest:path('</stop-scheduling/{$id}') function local:stop($id) { jobs:stop($id)};job></presyntaxhighlight>

==jobs:resultbindings== {{Mark|Introduced with Version 10.0}}

|{{Func|jobs:resultbindings|$id as xs:string|itemmap(*)*}}

|Returns the cached result variable bindings of a query an existing job with the specified job {{Code|$id}}:* Results can only be retrieved once. After retrievalIf no variables have been bound to this job, the cached result will be droppedan empty map is returned.* If the original query has raised an error, the cached error will be raised instead.|} ==jobs:finished== {| width='100%'

| width='120' | '''ErrorsSignatures'''|{{ErrorFunc|runningjobs:finished|#Errors}} the job is still running.<br/>{{Error$id as xs:string|unknown|#Errorsxs:boolean}} the supplied id is unknown: The id is unknown, or the result has already been retrieved.<br/>

| '''ExamplesSummary'''|* The following [[RESTXQ]] function will either return Indicates if the result evaluation of a previously started query or an error:<pre class='brush:xquery'>declare %rest:path('/result/already running job with the specified {{Code|$id}') function local:result($id) { jobs:result($id)};</pre>* The following query demonstrates how has finished. As the results ids of an asynchronously executed query can finished jobs will usually be returned within the same query. Please remember that this discarded, unless caching is not enabled, the common way how these functions function will be used in practice:also return <code>true<pre class='brush:xquery'/code>let $query := for unknown jobs:schedule('(1 to 10000000)[. = 1]'* <code>false</code> indicates that the job id is scheduled, map{}queued, map{ 'cache': or currently running.* <code>true() })return ( hof:until( function($f) { jobs:</code> will be returned if the job has either finished($query) }, functionor if the id is unknown ($f) { prof:sleep(10) }, () ), because the ids of all finished jobs:result($querywill not be cached))</pre>.

==jobs:resultsservices==

|{{Func|jobs:resultsservices||xs:stringelement(job)*}}

|Returns the ids a list of all jobs for which results are cachedthat have been persistently registered as [[#Services|Services]].|-| '''Errors'''|{{Error|services|#Errors}} Registered services cannot be parsed.<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}}