Difference between revisions of "Job Module"
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{| width='100%' | {| width='100%' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|job:eval|$query as xs: | + | |{{Func|job:eval|$query as xs:anyAtomicType|xs:string}}<br />{{Func|job:eval|$query as xs:anyAtomicType, $bindings as map(*)?|xs:string}}<br />{{Func|job:eval|$query as xs:anyAtomicType, $bindings as map(*)?, $options as map(*)?|xs:string}}<br /> |
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| '''Summary''' | | '''Summary''' | ||
|Schedules the evaluation of the supplied {{Code|$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|$bindings}} (see {{Function|XQuery|xquery:eval}} for more details). The following {{Code|$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 {{Function|XQuery|xquery:eval}} for more details). The following {{Code|$options}} can be supplied: | ||
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* {{Code|service}}: additionally registers the job as [[#Services|service]]. Registered services must have no variable bindings. | * {{Code|service}}: additionally registers the job as [[#Services|service]]. Registered services must have no variable bindings. | ||
* {{Code|log}}: writes the specified string to the [[Logging|database logs]]. Two log entries are stored, one at the beginning and another one after the execution of the job. | * {{Code|log}}: writes the specified string to the [[Logging|database logs]]. Two log entries are stored, one at the beginning and another one after the execution of the job. | ||
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| '''Errors''' | | '''Errors''' | ||
|{{Error|overflow|#Errors}} Query execution is rejected, because too many jobs are queued or being executed. {{Option|CACHETIMEOUT}} can be decreased if the default setting is too restrictive.<br/>{{Error|range|#Errors}} A specified time or duration is out of range.<br/>{{Error|id|#Errors}} The specified id is invalid or has already been assigned.<br/>{{Error|options|#Errors}} The specified options are conflicting. | |{{Error|overflow|#Errors}} Query execution is rejected, because too many jobs are queued or being executed. {{Option|CACHETIMEOUT}} can be decreased if the default setting is too restrictive.<br/>{{Error|range|#Errors}} A specified time or duration is out of range.<br/>{{Error|id|#Errors}} The specified id is invalid or has already been assigned.<br/>{{Error|options|#Errors}} The specified options are conflicting. | ||
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| '''Examples''' | | '''Examples''' | ||
| | | | ||
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{| width='100%' | {| width='100%' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|job:result|$id as xs:string|item()*}} | |{{Func|job:result|$id as xs:string|item()*}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Returns the cached result of a job with the specified job {{Code|$id}}: | |Returns the cached result of a job with the specified job {{Code|$id}}: | ||
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* Results can only be retrieved once. After retrieval, the cached result will be dropped. | * Results can only be retrieved once. After retrieval, the cached result will be dropped. | ||
* If the result has already been retrieved, or if it has not been cached, an empty sequence is returned. | * If the result has already been retrieved, or if it has not been cached, an empty sequence is returned. | ||
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| '''Examples''' | | '''Examples''' | ||
| | | | ||
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{| width='100%' | {| width='100%' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|job:stop|$id as xs:string|empty-sequence()}} | |{{Func|job:stop|$id as xs:string|empty-sequence()}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Triggers the cancelation of a job with the specified {{Code|$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|$options}} can be supplied: | |Triggers the cancelation of a job with the specified {{Code|$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|$options}} can be supplied: | ||
* {{Code|service}}: additionally removes the job from the [[#Services|job services]] list. | * {{Code|service}}: additionally removes the job from the [[#Services|job services]] list. | ||
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| '''Examples''' | | '''Examples''' | ||
| <code>job:list()[. != job:current()] ! job:stop(.)</code> stops and discards all jobs except for the current one. | | <code>job:list()[. != job:current()] ! job:stop(.)</code> stops and discards all jobs except for the current one. | ||
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{| width='100%' | {| width='100%' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|job:wait|$id as xs:string|empty-sequence()}} | |{{Func|job:wait|$id as xs:string|empty-sequence()}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Waits for the completion of a job with the specified {{Code|$id}}: | |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. | * 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. | * If the function is called with the id of a queued job, or repeatedly executed job, it may stall and never terminate. | ||
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| '''Errors''' | | '''Errors''' | ||
|{{Error|self|#Errors}} The current job is addressed.<br/> | |{{Error|self|#Errors}} The current job is addressed.<br/> | ||
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{| width='100%' | {| width='100%' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|job:current||xs:string}} | |{{Func|job:current||xs:string}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Returns the id of the current job. | |Returns the id of the current job. | ||
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{| width='100%' | {| width='100%' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|job:list||xs:string*}} | |{{Func|job:list||xs:string*}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Returns the ids of all jobs that are currently registered. The list includes scheduled, queued, running, stopped, and finished jobs with cached results. | |Returns the ids of all jobs that are currently registered. The list includes scheduled, queued, running, stopped, and finished jobs with cached results. | ||
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| '''Examples''' | | '''Examples''' | ||
| <code>job:list()</code> returns the same job id as {{Function||job:current}} if no other job is registered. | | <code>job:list()</code> returns the same job id as {{Function||job:current}} if no other job is registered. | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|job:list-details||element(job)*}}<br/>{{Func|job:list-details|$id as xs:string|element(job)*}} | |{{Func|job:list-details||element(job)*}}<br/>{{Func|job:list-details|$id as xs:string|element(job)*}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Returns information on all jobs that are currently registered, or on a job with the specified {{Code|$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 its URI, will be returned as value. The returned elements have additional attributes: | |Returns information on all jobs that are currently registered, or on a job with the specified {{Code|$id}} (or an empty sequence if this job is not found). The list includes scheduled, queued, running jobs, and cached jobs. A string representation of the job, or its URI, will be returned as value. The returned elements have additional attributes: | ||
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* <code>start</code>: next start of job (included if a job will be executed repeatedly) | * <code>start</code>: next start of job (included if a job will be executed repeatedly) | ||
* <code>time</code>: time when job was registered | * <code>time</code>: time when job was registered | ||
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| '''Examples''' | | '''Examples''' | ||
| <code>job:list-details()</code> returns information on the currently running job and possibly others: | | <code>job:list-details()</code> returns information on the currently running job and possibly others: | ||
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==job:bindings== | ==job:bindings== | ||
− | {{Announce|Introduced with Version 10. | + | {{Announce|Introduced with Version 10.}} |
{| width='100%' | {| width='100%' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|job:bindings|$id as xs:string|map(*)}} | |{{Func|job:bindings|$id as xs:string|map(*)}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Returns the variable bindings of an existing job with the specified {{Code|$id}}. If no variables have been bound to this job, an empty map is returned. | |Returns the variable bindings of an existing job with the specified {{Code|$id}}. If no variables have been bound to this job, an empty map is returned. | ||
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{| width='100%' | {| width='100%' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|job:finished|$id as xs:string|xs:boolean}} | |{{Func|job:finished|$id as xs:string|xs:boolean}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Indicates if the evaluation of an already running job with the specified {{Code|$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> for unknown jobs. | |Indicates if the evaluation of 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> for unknown jobs. | ||
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{| width='100%' | {| width='100%' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|job:services||element(job)*}} | |{{Func|job:services||element(job)*}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Returns a list of all jobs that have been persistently registered as [[#Services|Services]]. | |Returns a list of all jobs that have been persistently registered as [[#Services|Services]]. | ||
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| '''Errors''' | | '''Errors''' | ||
|{{Error|services|#Errors}} Registered services cannot be parsed.<br/> | |{{Error|services|#Errors}} Registered services cannot be parsed.<br/> | ||
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! width="110"|Code | ! width="110"|Code | ||
|Description | |Description | ||
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|{{Code|options}} | |{{Code|options}} | ||
| The specified options are conflicting. | | The specified options are conflicting. | ||
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|{{Code|id}} | |{{Code|id}} | ||
| The specified id is invalid or has already been assigned. | | The specified id is invalid or has already been assigned. | ||
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|{{Code|overflow}} | |{{Code|overflow}} | ||
| Too many queries or query results are queued. | | Too many queries or query results are queued. | ||
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|{{Code|range}} | |{{Code|range}} | ||
| A specified time or duration is out of range. | | A specified time or duration is out of range. | ||
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|{{Code|running}} | |{{Code|running}} | ||
| A query is still running. | | A query is still running. | ||
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|{{Code|self}} | |{{Code|self}} | ||
| The current job cannot be addressed. | | The current job cannot be addressed. | ||
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|{{Code|service}} | |{{Code|service}} | ||
| Registered services cannot be parsed, added or removed. | | Registered services cannot be parsed, added or removed. |
Revision as of 14:18, 20 July 2022
Updated with Version 10: Renamed from Jobs Module to Job Module. The namespace URI has been updated as well.
This XQuery Module provides functions for organizing scheduled, queued, running and cached jobs. Jobs can be commands, queries, client or HTTP requests.
Contents
Conventions
All functions in this module are assigned to the http://basex.org/modules/job
namespace, which is statically bound to the job
prefix. Errors will be bound to the same prefix.
Services
A job can be registered as service by supplying the service
option to job:eval
:
<syntaxhighlight lang="xquery"> (: register job as service; will be run every day at 1 am :) job:eval('db:drop("tmp")', (), map { 'id':'cleanup', 'start':'01:00:00', 'interval':'P1D', 'service': true() }),
(: list registered services :) job:services(), (: result: <job base-uri="..." id="cleanup" interval="P1D" start="01:00:00">db:drop("tmp")</job> :)
(: unregister job :) job: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
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 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.
job:eval
Signatures | job:eval($query as xs:anyAtomicType) as xs:string job:eval($query as xs:anyAtomicType, $bindings as map(*)?) as xs:string job:eval($query as xs:anyAtomicType, $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 $options can be supplied:
|
Errors | overflow : Query execution is rejected, because too many jobs are queued or being executed. CACHETIMEOUT can be decreased if the default setting is too restrictive.range : A specified time or duration is out of range.id : The specified id is invalid or has already been assigned.options : The specified options are conflicting.
|
Examples |
<syntaxhighlight lang="xquery"> job:eval("1+3", (), map { 'cache': true() }) </syntaxhighlight>
<syntaxhighlight lang="xquery"> job:eval("import module namespace mail='mail'; mail:send('Happy birthday!')", (), map { 'start': '2018-09-01T06:00:00' })}} </syntaxhighlight>
<syntaxhighlight lang="xquery"> declare %rest:POST("{$query}") %rest:path('/start-scheduling') function local:start($query) { job:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' }) }; declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { job:stop($id) }; </syntaxhighlight>
<syntaxhighlight lang="xquery"> job:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' }) </syntaxhighlight>
<syntaxhighlight lang="xquery"> job:eval(xs:anyURI('cleanup.xq')) </syntaxhighlight>
<syntaxhighlight lang="xquery"> job:eval( static-base-uri(), map { }, map { 'start': 'PT5S' } ) </syntaxhighlight> |
job:result
Signatures | job:result($id as xs:string) as item()*
|
Summary | Returns the cached result of a job with the specified job $id :
|
Examples |
<syntaxhighlight lang="xquery"> declare %rest:path('/result/{$id}') function local:result($id) { job:result($id) }; </syntaxhighlight>
<syntaxhighlight lang="xquery"> let $query := job:eval('(1 to 10000000)[. = 1]', map { }, map { 'cache': true() }) return ( job:wait($query), job:result($query) )
</syntaxhighlight>
Queries of this kind can cause deadlocks! If the original query and the new query perform updates on the same database, the second query will only be run after the first one has been executed, and the first query will wait for the second query forever. You should resort to |
job:stop
Signatures | job:stop($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 $options can be supplied:
|
Examples | job:list()[. != job:current()] ! job:stop(.) stops and discards all jobs except for the current one.
|
job:wait
Signatures | job:wait($id as xs:string) as empty-sequence()
|
Summary | Waits for the completion of a job with the specified $id :
|
Errors | self : The current job is addressed. |
Listing Jobs
job:current
Signatures | job:current() as xs:string
|
Summary | Returns the id of the current job. |
job:list
Signatures | job:list() as xs:string*
|
Summary | Returns the ids of all jobs that are currently registered. The list includes scheduled, queued, running, stopped, and finished jobs with cached results. |
Examples | job:list() returns the same job id as job:current if no other job is registered.
|
job:list-details
Signatures | job:list-details() as element(job)* job:list-details($id as xs:string) as element(job)*
|
Summary | Returns information on all jobs that are currently registered, or on a job with the specified $id (or an empty sequence if this job is not found). The list includes scheduled, queued, running jobs, and cached jobs. A string representation of the job, or its URI, will be returned as value. The returned elements have additional attributes:
|
Examples | job:list-details() returns information on the currently running job and possibly others:
<syntaxhighlight lang="xml"> <job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S"> XQUERY job:list-details() </job> </syntaxhighlight> |
job:bindings
Introduced with Version 10.
Signatures | job:bindings($id as xs:string) as map(*)
|
Summary | Returns the variable bindings of an existing job with the specified $id . If no variables have been bound to this job, an empty map is returned.
|
job:finished
Signatures | job:finished($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.
|
job:services
Signatures | job: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. |
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 10.0
- Updated: Renamed from Jobs Module to Job Module. The namespace URI has been updated as well.
- Added:
job:bindings
- Version 9.7
- Updated:
job:result
: return empty sequence if no result is cached.
- Version 9.5
- Updated:
job:eval
: integers added as valid start and end times.
- Version 9.4
- Updated:
job:eval
: option added for writing log entries. - Updated:
job:list-details
: interval added.
- Version 9.2
- Deleted: job:invoke (merged with
job:eval
)
- Version 9.1
- Updated:
job:list-details
: registration time added.
- Version 9.0
- Added:
job:invoke
, Services
- Version 8.6
- Updated:
job:eval
:id
option added.
The module was introduced with Version 8.5.