Changes

This [[Module Library|XQuery Module]] provides functions for organizing scheduled, queued, running and cached jobs. Jobs can be commands and , queries (…more to come), client or HTTP requests.

|Returns the ids of all jobs that are currently registered. The list includes scheduled, queued or executed, running jobs, and cached jobs.

* <code>jobs:list()</code> returns the same job id as [[#jobs:current|jobs:current]] if no other job is runningregistered.

|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 its URI, will be returned as value. The returned elements have additional attributes:* <code>id</code>: job id* <code>type</code>: type of the job (command, query, REST, RESTXQ, etc.)* <code>state</code>: current state of the job (scheduled, queued, running, or cached)* <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)

<job id="job1" type="XQuery" duration="PT0S" state="running" user="admin" duration="PT0.001S"> XQUERY jobs:list-details()</job>

|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).

|Cancels Triggeres the execution cancelation of a job with the specified {{Code|$id}}, or drops the cached result of a query, or cancels a scheduled job. Unknown ids are ignored. All jobs are gracefully stopped; it is up to the process to decide when it is safe to shut down.|} ==jobs:wait== {| width='100%'|-| width='120' | '''Signatures'''|{{Func|jobs:wait|$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}} if the current job is addressed.<br/>

==jobs:scheduleeval== {{Mark|Updated with Version 8.6}}: <code>id</code> option added.

|{{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 />

|Prepares Schedules the evaluation of the supplied {{Code|$query}} string for asynchronous execution and returns a query id. The query will be queued as described in the article on [[Transaction Management]], and the result will optionally be cached in main-memory until it is fetched via [[#jobs:result|jobs:result]], or until {{Option|CACHETIMEOUT}} is exceeded. Queries may can be updating.<br/>Variables and context items can be declared via {{Code|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details). The {{Code|$options}} parameter contains evaluation scheduling options:* {{Code|cache}}: indicates if the query result will be cached or ignored (default: <code>truefalse</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 result raises an error, it will not be cachedand returned instead.* {{Code|start}}: a dayTimeDuration, time or dateTime can be specified to delay the execution of the query:** If a dayTimeDuration is specified, the query id will immediately be discarded 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> (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.** 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 executionwith the same id is still running, tooit 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 by functions , such as with {{Code|fn:doc}} (default.* {{Code|id}}: ''empty string'')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.

|{{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.

* {{Code|jobs:schedule("1+3", map{}, map{ 'cache': true() })}} returns a Cache query id, e.g. {{Code|Job-123}}result. The result returned id can be retrieved via a second query in used to pick up the same BaseX contextresult with [[#jobs: {{Coderesult|jobs:result("Job-123")}}<br />* The following [[RESTXQ]] function will return the id of the query thread, which evaluates the query that has been specified in the body of a POST request:

jobs:eval("1+3", (), map { 'cache': true() })</pre>* A happy birthday mail will be sent at the given date:<pre class="brush:xquery">jobs:eval("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 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:<pre class='brush:xquery'>declare %rest:POST("{$query}") %rest:path('/evalstart-scheduling') function local:schedulestart($query) { jobs:scheduleeval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })

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

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

|{{Error|running|#Errors}} the query job is still running.<br/>{{Error|unknown|#Errors}} the supplied query id is unknown: The query id is unknown, or the result may has already have been retrieved, or query execution may have been stopped.<br/>

* The following [[RESTXQ]] function will either return the result of a previously started query job or raise an error:

* The following query demonstrates how the results of an asynchronously executed query can be returned in a single within the same query. Please remember that this is not the common way how these functions are used in practice:

let $query := jobs:scheduleeval('(1 to 10000000)[. = 1]', map{}, map{ 'cache': true() })

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

|} ==jobsPlease 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:results== {| width='100%'|fork-join| width='120' | '''Signatures'''|{{Func|jobs:results||xsxquery:string*}}|fork-| '''Summary'''|Returns the ids of all jobs for which results are cachedjoin]] if you want to do things in parallel.