Difference between revisions of "Job Module"

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=Services=
 
=Services=
  
−
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}}:
+
A job can be registered as ''service'' by supplying the {{Code|service}} option to {{Function|Jobs|jobs:eval}}:
  
−
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
−
(: register job, which will be run every day at 1 am :)
+
(: 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() }),
 
jobs:eval('db:drop("tmp")', (), map { 'id':'cleanup', 'start':'01:00:00', 'interval':'P1D', 'service': true() }),
  
Line 19: Line 19:
 
(: unregister job :)
 
(: unregister job :)
 
jobs:stop('cleanup', map { 'service': true() })
 
jobs:stop('cleanup', map { 'service': true() })
−
</pre>
+
</syntaxhighlight>
  
 
'''Some more notes:'''
 
'''Some more notes:'''
  
−
* All registered jobs will be scheduled for evaluation when the BaseX server or BaseX HTTP server is started.
+
* 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* If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time.
 
* If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time.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.
 
* The job definitions are stored in a {{Code|jobs.xml}} file in the database directory. It can also be edited manually.
  
Line 56: Line 55:
  
 
==jobs:list-details==
 
==jobs:list-details==
−
 
−
{{Mark|Updated with Version 9.1:}} registration time added
 
  
 
{| width='100%'
 
{| width='100%'
Line 76: Line 73:
 
| '''Examples'''
 
| '''Examples'''
 
| <code>jobs:list-details()</code> returns information on the currently running job and possibly others:
 
| <code>jobs:list-details()</code> returns information on the currently running job and possibly others:
−
<pre class="brush:xml">
+
<syntaxhighlight lang="xml">
 
<job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S">
 
<job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S">
 
   XQUERY jobs:list-details()
 
   XQUERY jobs:list-details()
 
</job>
 
</job>
−
</pre>
+
</syntaxhighlight>
 
|}
 
|}
  
Line 115: Line 112:
  
 
==jobs:eval==
 
==jobs:eval==
−
 
−
{{Mark|Updated with 9.2}}: First argument can be a URI (jobs:invoke was removed).
 
  
 
{| width='100%'
 
{| width='100%'
Line 124: Line 119:
 
|-
 
|-
 
| '''Summary'''
 
| '''Summary'''
−
|Schedules the evaluation of the supplied {{Code|$query}} and returns a query id. The query will be queued, and the result will optionally be cached. Queries can be updating. The query can be a URI or a string, and variables and context items can be declared via {{Code|$bindings}} (see [[XQuery Module#xquery:eval|xquery:eval]] for more details). The following {{Code|$options}} can be supplied:
+
|Schedules the evaluation of the supplied {{Code|$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>):
 
* {{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.
 
** 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.
 
** If the query raises an error, it will be cached and returned instead.
−
* {{Code|start}}: a dayTimeDuration, time or dateTime can be specified to delay the execution of the query:
+
* {{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 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.
 
** 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.
+
** An integer will be interpreted as minutes. If the specified number exceeds the 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|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|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|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|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]].
+
* {{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'''
 
| '''Errors'''
Line 144: Line 141:
 
|
 
|
 
* Cache query result. The returned id can be used to pick up the result with [[#jobs:result|jobs:result]]:
 
* Cache query result. The returned id can be used to pick up the result with [[#jobs:result|jobs:result]]:
−
<pre class='brush:xquery'>
+
<syntaxhighlight lang="xquery">
 
jobs:eval("1+3", (), map { 'cache': true() })
 
jobs:eval("1+3", (), map { 'cache': true() })
−
</pre>
+
</syntaxhighlight>
 
* A happy birthday mail will be sent at the given date:
 
* A happy birthday mail will be sent at the given date:
−
<pre class="brush:xquery">
+
<syntaxhighlight lang="xquery">
 
jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')",
 
jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')",
 
   (), map { 'start': '2018-09-01T06:00:00' })}}
 
   (), map { 'start': '2018-09-01T06:00:00' })}}
−
</pre>
+
</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:
 
* 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'>
+
<syntaxhighlight lang="xquery">
 
declare %rest:POST("{$query}") %rest:path('/start-scheduling') function local:start($query) {
 
declare %rest:POST("{$query}") %rest:path('/start-scheduling') function local:start($query) {
 
   jobs:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })
 
   jobs:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' })
Line 160: Line 157:
 
   jobs:stop($id)
 
   jobs:stop($id)
 
};
 
};
−
</pre>
+
</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:
 
* 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">
+
<syntaxhighlight lang="xquery">
 
jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })
 
jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })
−
</pre>
+
</syntaxhighlight>
−
* The following expression, if stored as a file, calls and evaluates itself every 5 seconds:
+
* The query in the specified file will be evaluated once:
−
<pre class="brush:xquery">
+
<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(
 
jobs:eval(
−
   file:read-text(static-base-uri()),
+
   static-base-uri(),
 
   map { },
 
   map { },
 
   map { 'start': 'PT5S' }
 
   map { 'start': 'PT5S' }
 
)
 
)
−
</pre>
+
</syntaxhighlight>
−
* Evaluate query in specified file:
 
−
<pre class='brush:xquery'>
 
−
jobs:eval(xs:anyURI('cleanup.xq'), (), ())
 
−
</pre>
 
 
|}
 
|}
  
 
==jobs:result==
 
==jobs:result==
 +
 +
{{Mark|Updated with Version 9.7:}} Return empty sequence if no result is cached.
  
 
{| width='100%'
 
{| width='100%'
Line 188: Line 187:
 
| '''Summary'''
 
| '''Summary'''
 
|Returns the cached result of a job with the specified job {{Code|$id}}:
 
|Returns the cached result of 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.
 
* Results can only be retrieved once. After retrieval, the cached result will be dropped.
−
* If the original job has raised an error, the cached error will be raised instead.
+
* If the result has already been retrieved, or if it has not been cached, an empty sequence is returned.
−
|-
 
−
| '''Errors'''
 
−
|{{Error|running|#Errors}} the job is still running.<br/>{{Error|unknown|#Errors}} the supplied id is unknown: The id is unknown, or the result has already been retrieved.<br/>
 
 
|-
 
|-
 
| '''Examples'''
 
| '''Examples'''
 
|
 
|
 
* The following [[RESTXQ]] function will either return the result of a previously started job or raise an error:
 
* The following [[RESTXQ]] function will either return the result of a previously started job or raise an error:
−
<pre class='brush:xquery'>
+
<syntaxhighlight lang="xquery">
 
declare %rest:path('/result/{$id}') function local:result($id) {
 
declare %rest:path('/result/{$id}') function local:result($id) {
 
   jobs:result($id)
 
   jobs:result($id)
 
};
 
};
−
</pre>
+
</syntaxhighlight>
 
* The following query demonstrates how the results of an executed query can be returned within the same query (see below why you should avoid this pattern in practice):
 
* The following query demonstrates how the results of an executed query can be returned within the same query (see below why you should avoid this pattern in practice):
−
<pre class='brush:xquery'>
+
<syntaxhighlight lang="xquery">
 
let $query := jobs:eval('(1 to 10000000)[. = 1]', map { }, map { 'cache': true() })
 
let $query := jobs:eval('(1 to 10000000)[. = 1]', map { }, map { 'cache': true() })
 
return (
 
return (
Line 209: Line 206:
 
   jobs:result($query)
 
   jobs:result($query)
 
)
 
)
−
</pre>
+
</syntaxhighlight>
 
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.
 
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.
 
|}
 
|}
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|{{Code|service}}
 
|{{Code|service}}
 
| Registered services cannot be parsed, added or removed.
 
| Registered services cannot be parsed, added or removed.
−
|-
 
−
|{{Code|unknown}}
 
−
| The supplied query id is unknown or not available anymore.
 
 
|}
 
|}
  
 
=Changelog=
 
=Changelog=
 +
 +
;Version 9.7
 +
* Updated: {{Function|Jobs|jobs:result}}: return empty sequence if no result is cached.
 +
 +
;Version 9.5
 +
* Updated: {{Function|Jobs|jobs:eval}}: integers added as valid start and end times.
 +
 +
;Version 9.4
 +
* Updated: {{Function|Jobs|jobs:eval}}: option added for writing log entries.
 +
* Updated: {{Function|Jobs|jobs:list-details}}: interval added.
  
 
;Version 9.2
 
;Version 9.2
−
 
+
* Deleted: jobs:invoke (merged with {{Function|Jobs|jobs:eval}})
−
* Deleted: jobs:invoke (merged with [[#jobs:eval|jobs:eval]])
 
  
 
;Version 9.1
 
;Version 9.1
−
 
 
* Updated: {{Function|Jobs|jobs:list-details}}: registration time added.
 
* Updated: {{Function|Jobs|jobs:list-details}}: registration time added.
  
 
;Version 9.0
 
;Version 9.0
−
 
 
* Added: {{Function|Jobs|jobs:invoke}}, [[#Services|Services]]
 
* Added: {{Function|Jobs|jobs:invoke}}, [[#Services|Services]]
  
 
;Version 8.6
 
;Version 8.6
−
 
+
* Updated: {{Function|Jobs|jobs:eval}}: <code>id</code> option added.
−
* Updated: [[#jobs:eval|jobs:eval]]: <code>id</code> option added.
 
  
 
The module was introduced with Version 8.5.
 
The module was introduced with Version 8.5.

Revision as of 13:41, 6 November 2021

This XQuery Module provides functions for organizing scheduled, queued, running and cached jobs. Jobs can be commands, queries, client or HTTP requests.

Conventions

All functions in this module are assigned to the http://basex.org/modules/jobs namespace, which is statically bound to the jobs prefix. Errors will be bound to the same prefix.

Services

A job can be registered as service by supplying the service option to jobs:eval: 

(: 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() })

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 jobs.xml file in the database directory. It can also be edited manually.

Basic Functions

jobs:current

Signatures jobs:current() as xs:string
Summary Returns the id of the current job.

jobs:list

Signatures jobs:list() as xs:string*
Summary Returns the ids of all jobs that are currently registered. The list includes scheduled, queued, running, stopped, and finished jobs with cached results.
Examples jobs:list() returns the same job id as jobs:current if no other job is registered.

jobs:list-details

Signatures jobs:list-details() as element(job)*
jobs:list-details($id as xs:string) as element(job)*
Summary Returns information on all jobs that are currently registered, or on a job with the specified $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:
  • id: job id
  • type: type of the job (command, query, REST, RESTXQ, etc.)
  • state: current state of the job: scheduled, queued, running, cached
  • user: user who started the job
  • duration: evaluation time (included if a job is running or if the result was cached)
  • start: next start of job (included if a job will be executed repeatedly)
  • time: time when job was registered
Examples jobs:list-details() returns information on the currently running job and possibly others: 
<job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S">
  XQUERY jobs:list-details()
</job>

jobs:finished

Signatures jobs:finished($id as xs:string) as xs:boolean
Summary Indicates if the evaluation of an already running job with the specified $id has finished. As the ids of finished jobs will usually be discarded, unless caching is enabled, the function will also return true for unknown jobs.
  • false indicates that the job id is scheduled, queued, or currently running.
  • true 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:services

Signatures jobs:services() as element(job)*
Summary Returns a list of all jobs that have been persistently registered as Services.
Errors services: Registered services cannot be parsed.

Execution

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 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:eval

Signatures jobs:eval($query as xs:anyAtomicItem) as xs:string
jobs:eval($query as xs:anyAtomicItem, $bindings as map(*)?) as xs:string
jobs:eval($query as xs:anyAtomicItem, $bindings as map(*)?, $options as map(*)?) as xs:string
Summary Schedules the evaluation of the supplied $query (xs:string, or of type 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 $bindings (see xquery:eval for more details). The following $options can be supplied:
  • cache: indicates if the query result will be cached or ignored (default: false):
    • The result will be cached in main-memory until it is fetched via jobs:result, or until CACHETIMEOUT is exceeded.
    • If the query raises an error, it will be cached and returned instead.
  • 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: P1D (1 day), PT5M (5 minutes), PT0.1S (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: 2018-12-31T23:59:59 (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: 02:00:00 (2am local time), 12:00:00Z (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 exceeds the minutes of the current hour, the query will be executed one hour later.
  • 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 (PT1S). If the next scheduled call is due, and if a query with the same id is still running, it will be skipped.
  • end: scheduling can be stopped after a given time or duration. The string format is the same as for start. An error is raised if the resulting end time is smaller than the start time.
  • base-uri: sets the base-uri property for the query. This URI will be used when resolving relative URIs, such as with fn:doc.
  • id: sets a custom job id. The id must not start with the standard job prefix, and it can only be assigned if no job with the same name exists.
  • service: additionally registers the job as service. Registered services must have no variable bindings.
  • log: writes the specified string to the database logs. Two log entries are stored, one at the beginning and another one after the execution of the job.
Errors overflow: Query execution is rejected, because too many jobs are queued or being executed. CACHETIMEOUT can be decreased if the default setting is too restrictive.
range: A specified time or duration is out of range.
id: The specified id is invalid or has already been assigned.
options: The specified options are conflicting.
Examples
  • Cache query result. The returned id can be used to pick up the result with jobs:result:
jobs:eval("1+3", (), map { 'cache': true() })
  • A happy birthday mail will be sent at the given date:
jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')",
  (), map { 'start': '2018-09-01T06:00:00' })}}
  • 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:
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)
};
  • 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:
jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' })
  • The query in the specified file will be evaluated once:
jobs:eval(xs:anyURI('cleanup.xq'))
  • The following expression, if stored in a file, will be evaluated every 5 seconds:
jobs:eval(
  static-base-uri(),
  map { },
  map { 'start': 'PT5S' }
)

jobs:result

Template:Mark Return empty sequence if no result is cached.

Signatures jobs:result($id as xs:string) as item()*
Summary Returns the cached result of a job with the specified job $id:
  • If the original job has raised an error, the cached error will be raised instead.
  • Results can only be retrieved once. After retrieval, the cached result will be dropped.
  • If the result has already been retrieved, or if it has not been cached, an empty sequence is returned.
Examples
  • The following RESTXQ function will either return the result of a previously started job or raise an error:
declare %rest:path('/result/{$id}') function local:result($id) {
  jobs:result($id)
};
  • The following query demonstrates how the results of an executed query can be returned within the same query (see below why you should avoid this pattern in practice):
let $query := jobs:eval('(1 to 10000000)[. = 1]', map { }, map { 'cache': true() })
return (
  jobs:wait($query),
  jobs:result($query)
)

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:fork-join if you want to have full control on parallel query execution.

jobs:stop

Signatures jobs:stop($id as xs:string) as empty-sequence()
Summary Triggers the cancelation of a job with the specified $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 $options can be supplied:
  • service: additionally removes the job from the job services list.
Examples jobs:list()[. != jobs:current()] ! jobs:stop(.) stops and discards all jobs except for the current one.

jobs:wait

Signatures jobs:wait($id as xs:string) as empty-sequence()
Summary Waits for the completion of a job with the specified $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 self: The current job is addressed.

Errors

Code Description
options The specified options are conflicting.
id The specified id is invalid or has already been assigned.
overflow Too many queries or query results are queued.
range A specified time or duration is out of range.
running A query is still running.
self The current job cannot be addressed.
service Registered services cannot be parsed, added or removed.

Changelog

Version 9.7
  • Updated: jobs:result: return empty sequence if no result is cached.
Version 9.5
  • Updated: jobs:eval: integers added as valid start and end times.
Version 9.4
Version 9.2
Version 9.1
Version 9.0
Version 8.6

The module was introduced with Version 8.5.

Retrieved from "http://docs.basex.org/index.php?title=Job_Module&oldid=15538"