Difference between revisions of "Job Module"
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Please remember that this query will cause a deadlock if the asynchronously executed query will be queued. In practice. In practice, you should avoid this pattern and resort to [[XQuery Module#xquery:fork-join|xquery:fork-join]] if you want to do things in parallel. | Please remember that this query will cause a deadlock if the asynchronously executed query will be queued. In practice. In practice, you should avoid this pattern and resort to [[XQuery Module#xquery:fork-join|xquery:fork-join]] if you want to do things in parallel. | ||
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Revision as of 11:25, 4 February 2017
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.
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 jobs, and cached jobs. |
Examples |
|
jobs:list-details
Signatures | jobs:list-details() as element(job)* jobs:list-details($id as xs:string) as element(job)*
|
Summary | Returns information on all jobs that are currently registered. The list includes scheduled, queued, running jobs, and cached jobs. A string representation of the job will be returned in the text node. The returned elements have additional attributes:
|
Examples |
<job id="job1" type="XQuery" state="running" user="admin" duration="PT0.001S"> XQUERY jobs:list-details() </job> |
jobs:finished
Signatures | jobs:finished($id as xs:string) as xs:boolean
|
Summary | Indicates if the evaluation of an already running job with the specified $id has finished. As the ids of finished jobs will usually be discarded, unless caching is enabled, the function will also return true for unknown jobs.
|
jobs:stop
Signatures | jobs:stop($id as xs:string) as empty-sequence()
|
Summary | Triggeres the cancelation of a job with the specified $id , drops the cached result of a query, or cancels a scheduled job. Unknown ids are ignored. All jobs are gracefully stopped; it is up to the process to decide when it is safe to shut down.
|
jobs:wait
Signatures | jobs:wait($id as xs:string) as empty-sequence()
|
Summary | Waits for the completion of a job with the specified $id . If the function is called with the id of a repeatedly executed job, it may never terminate.
|
Errors | self : if the current job is addressed. |
Asynchronous Execution
Asynchronous query execution is recommendable if a client does not, or cannot, wait until a request is fully processed. This is e. g. the case with web browsers, which will usually cancel a request after a specific timeout. In such cases, you can use asynchronous execution to trigger another server-side process, which will start the time-consuming process, and fetch the result later on as soon as it is available.
jobs:eval
Template:Mark: id
option added.
Signatures | jobs:eval($query as xs:string) as xs:string jobs:eval($query as xs:string, $bindings as map(*)?) as xs:string jobs:eval($query as xs:string, $bindings as map(*)?, $options as map(xs:string, xs:string)) as xs:string |
Summary | Schedules the evaluation of the supplied $query and returns a query id. The query will be queued, and the result will optionally be cached. Queries can be updating. Variables and context items can be declared via $bindings (see xquery:eval for more details). The $options parameter contains scheduling options:
|
Errors | overflow : Query execution is rejected, because too many jobs are queued or being executed. CACHETIMEOUT can be decreased if the default setting is too restrictive.range : A specified time or duration is out of range.id : The specified id is invalid or has already been assigned.
|
Examples |
jobs:eval("1+3", (), map { 'cache': true() })
jobs:eval("import module namespace mail='mail'; mail:send('Happy birthday!')", (), map { 'start': '2018-09-01T06:00:00' })}}
declare %rest:POST("{$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($id) };
jobs:eval("prof:sleep(1500)", (), map { 'interval': 'PT1S', 'end': 'PT10S' }) |
jobs:result
Signatures | jobs:result($id as xs:string) as item()*
|
Summary | Returns the cached result of a job with the specified job $id :
|
Errors | running : the job is still running.unknown : the supplied id is unknown: The id is unknown, or the result has already been retrieved. |
Examples |
declare %rest:path('/result/{$id}') function local:result($id) { jobs:result($id) };
let $query := jobs:eval('(1 to 10000000)[. = 1]', map{}, map{ 'cache': true() }) return ( jobs:wait($query), jobs:result($query) ) Please remember that this query will cause a deadlock if the asynchronously executed query will be queued. In practice. In practice, you should avoid this pattern and resort to xquery:fork-join if you want to do things in parallel. |
Errors
Code | Description |
---|---|
unknown
|
The supplied query id is unknown or not available anymore. |
running
|
A query is still running. |
overflow
|
Too many queries or query results are queued. |
range
|
A specified time or duration is out of range. |
id
|
The specified is invalid or has already been assigned. |
self
|
The current job cannot be addressed. |
Changelog
- Version 8.6
- Updated: jobs:eval:
id
option added.
The module was introduced with Version 8.5.