Difference between revisions of "Job Module"
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* All job services 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* If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time. | * If a job service is outdated (e.g. because a supplied end time has been exceeded), it will be removed from the jobs file at startup time. | ||
− | |||
* 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. | ||
− | = | + | =Executing Jobs= |
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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. | 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:eval== | ==jobs:eval== | ||
− | |||
− | |||
{| width='100%' | {| width='100%' | ||
Line 124: | Line 39: | ||
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | |Schedules the evaluation of the supplied {{Code|$query}} and returns a query id. The query will be queued, and the result will optionally be cached. Queries can be updating. | + | |Schedules the evaluation of the supplied {{Code|$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 | + | * {{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 | + | ** 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|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. | ||
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==jobs:result== | ==jobs:result== | ||
+ | |||
+ | {{Mark|Updated with Version 9.7:}} Return empty sequence if no result is cached. | ||
{| width='100%' | {| width='100%' | ||
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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}}: | ||
+ | * 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 | + | * If the result has already been retrieved, or if it has not been cached, an empty sequence is returned. |
− | |||
− | |||
− | |||
|- | |- | ||
| '''Examples''' | | '''Examples''' | ||
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| '''Errors''' | | '''Errors''' | ||
|{{Error|self|#Errors}} The current job is addressed.<br/> | |{{Error|self|#Errors}} The current job is addressed.<br/> | ||
+ | |} | ||
+ | |||
+ | =Listing Jobs= | ||
+ | |||
+ | ==jobs:current== | ||
+ | |||
+ | {| width='100%' | ||
+ | |- | ||
+ | | width='120' | '''Signatures''' | ||
+ | |{{Func|jobs:current||xs:string}} | ||
+ | |- | ||
+ | | '''Summary''' | ||
+ | |Returns the id of the current job. | ||
+ | |} | ||
+ | |||
+ | ==jobs:list== | ||
+ | |||
+ | {| width='100%' | ||
+ | |- | ||
+ | | width='120' | '''Signatures''' | ||
+ | |{{Func|jobs:list||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''' | ||
+ | | <code>jobs:list()</code> returns the same job id as {{Function|Jobs|jobs:current}} if no other job is registered. | ||
+ | |} | ||
+ | |||
+ | ==jobs:list-details== | ||
+ | |||
+ | {| width='100%' | ||
+ | |- | ||
+ | | width='120' | '''Signatures''' | ||
+ | |{{Func|jobs:list-details||element(job)*}}<br/>{{Func|jobs:list-details|$id as xs:string|element(job)*}} | ||
+ | |- | ||
+ | | '''Summary''' | ||
+ | |Returns information on all jobs that are currently registered, or on a job with the specified {{Code|$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: | ||
+ | * <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: <code>scheduled</code>, <code>queued</code>, <code>running</code>, <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 | ||
+ | |- | ||
+ | | '''Examples''' | ||
+ | | <code>jobs:list-details()</code> 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 jobs:list-details() | ||
+ | </job> | ||
+ | </syntaxhighlight> | ||
+ | |} | ||
+ | |||
+ | ==jobs:bindings== | ||
+ | |||
+ | {{Mark|Introduced with Version 10.0}} | ||
+ | |||
+ | {| width='100%' | ||
+ | |- | ||
+ | | width='120' | '''Signatures''' | ||
+ | |{{Func|jobs:bindings|$id as xs:string|map(*)}} | ||
+ | |- | ||
+ | | '''Summary''' | ||
+ | |Returns the variable bindings of an existing job with the specified {{Code|$id}}. If no variables have been bound to this job, an empty map is returned. | ||
+ | |} | ||
+ | |||
+ | ==jobs:finished== | ||
+ | |||
+ | {| width='100%' | ||
+ | |- | ||
+ | | width='120' | '''Signatures''' | ||
+ | |{{Func|jobs:finished|$id as xs:string|xs:boolean}} | ||
+ | |- | ||
+ | | '''Summary''' | ||
+ | |Indicates if the evaluation of an already running job with the specified {{Code|$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. | ||
+ | * <code>false</code> indicates that the job id is 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:services== | ||
+ | |||
+ | {| width='100%' | ||
+ | |- | ||
+ | | width='120' | '''Signatures''' | ||
+ | |{{Func|jobs:services||element(job)*}} | ||
+ | |- | ||
+ | | '''Summary''' | ||
+ | |Returns a list of all jobs that have been persistently registered as [[#Services|Services]]. | ||
+ | |- | ||
+ | | '''Errors''' | ||
+ | |{{Error|services|#Errors}} Registered services cannot be parsed.<br/> | ||
|} | |} | ||
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|{{Code|service}} | |{{Code|service}} | ||
| Registered services cannot be parsed, added or removed. | | Registered services cannot be parsed, added or removed. | ||
− | |||
− | |||
− | |||
|} | |} | ||
=Changelog= | =Changelog= | ||
+ | |||
+ | ;Version 10.0 | ||
+ | * Added: {{Function|Jobs|jobs:bindings}} | ||
+ | |||
+ | ;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 | ;Version 9.4 | ||
− | * Updated: {{Function|Jobs|jobs:eval}}: option added. | + | * Updated: {{Function|Jobs|jobs:eval}}: option added for writing log entries. |
* Updated: {{Function|Jobs|jobs:list-details}}: interval added. | * Updated: {{Function|Jobs|jobs:list-details}}: interval added. | ||
Revision as of 15:31, 13 May 2022
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/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
:
<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
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 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 $options can be supplied:
|
Errors | overflow : Query execution is rejected, because too many jobs are queued or being executed. CACHETIMEOUT can be decreased if the default setting is too restrictive.range : A specified time or duration is out of range.id : The specified id is invalid or has already been assigned.options : The specified options are conflicting.
|
Examples |
<syntaxhighlight lang="xquery"> jobs:eval("1+3", (), map { 'cache': true() }) </syntaxhighlight>
<syntaxhighlight lang="xquery"> jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')", (), map { 'start': '2018-09-01T06:00:00' })}} </syntaxhighlight>
<syntaxhighlight lang="xquery"> declare %rest:POST("{$query}") %rest:path('/start-scheduling') function local:start($query) { jobs:eval($query, (), map { 'start': '02:00:00', 'interval': 'P1D' }) }; declare %rest:path('/stop-scheduling/{$id}') function local:stop($id) { jobs:stop($id) }; </syntaxhighlight>
<syntaxhighlight lang="xquery"> jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' }) </syntaxhighlight>
<syntaxhighlight lang="xquery"> jobs:eval(xs:anyURI('cleanup.xq')) </syntaxhighlight>
<syntaxhighlight lang="xquery"> jobs:eval( static-base-uri(), map { }, map { 'start': 'PT5S' } ) </syntaxhighlight> |
jobs:result
Template:Mark Return empty sequence if no result is cached.
Signatures | jobs:result($id as xs:string) as item()*
|
Summary | Returns the cached result of a job with the specified job $id :
|
Examples |
<syntaxhighlight lang="xquery"> declare %rest:path('/result/{$id}') function local:result($id) { jobs:result($id) }; </syntaxhighlight>
<syntaxhighlight lang="xquery"> let $query := jobs:eval('(1 to 10000000)[. = 1]', map { }, map { 'cache': true() }) return ( jobs:wait($query), jobs:result($query) ) </syntaxhighlight> Queries of this kind can cause deadlocks! If the original query and the new query perform updates on the same database, the second query will only be run after the first one has been executed, and the first query will wait for the second query forever. You should resort to xquery:fork-join if you want to have full control on parallel query execution. |
jobs:stop
Signatures | jobs:stop($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 $options can be supplied:
|
Examples | jobs:list()[. != jobs:current()] ! jobs:stop(.) stops and discards all jobs except for the current one.
|
jobs:wait
Signatures | jobs:wait($id as xs:string) as empty-sequence()
|
Summary | Waits for the completion of a job with the specified $id :
|
Errors | self : The current job is addressed. |
Listing Jobs
jobs:current
Signatures | jobs:current() as xs:string
|
Summary | Returns the id of the current job. |
jobs:list
Signatures | jobs:list() as xs:string*
|
Summary | Returns the ids of all jobs that are currently registered. The list includes scheduled, queued, running, stopped, and finished jobs with cached results. |
Examples | jobs:list() returns the same job id as jobs:current if no other job is registered.
|
jobs:list-details
Signatures | jobs:list-details() as element(job)* jobs:list-details($id as xs:string) as element(job)*
|
Summary | Returns information on all jobs that are currently registered, or on a job with the specified $id (or an empty sequence if this job is not found). The list includes scheduled, queued, running jobs, and cached jobs. A string representation of the job, or its URI, will be returned as value. The returned elements have additional attributes:
|
Examples | jobs:list-details() returns information on the currently running job and possibly others:
<syntaxhighlight lang="xml"> <job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S"> XQUERY jobs:list-details() </job> </syntaxhighlight> |
jobs:bindings
Signatures | jobs:bindings($id as xs:string) as map(*)
|
Summary | Returns the variable bindings of an existing job with the specified $id . If no variables have been bound to this job, an empty map is returned.
|
jobs:finished
Signatures | jobs:finished($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.
|
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. |
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
- Added:
jobs:bindings
- 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
- Updated:
jobs:eval
: option added for writing log entries. - Updated:
jobs:list-details
: interval added.
- Version 9.2
- Deleted: jobs:invoke (merged with
jobs:eval
)
- Version 9.1
- Updated:
jobs:list-details
: registration time added.
- Version 9.0
- Added:
jobs:invoke
, Services
- Version 8.6
- Updated:
jobs:eval
:id
option added.
The module was introduced with Version 8.5.