diff options
Diffstat (limited to 'docs/deferred.txt')
| -rw-r--r-- | docs/deferred.txt | 59 |
1 files changed, 34 insertions, 25 deletions
diff --git a/docs/deferred.txt b/docs/deferred.txt index 06155c56..495e6594 100644 --- a/docs/deferred.txt +++ b/docs/deferred.txt @@ -1,27 +1,36 @@ - deferred.txt -A few of the database updates required by various functions here -can be deferred until after the result page is displayed to the -user. For example, updating the view counts, updating the -linked-to tables after a save, etc. PHP does not yet have any -way to tell the server to actually return and disconnect while -still running these updates (as a Java servelet could), but it -might have such a feature in the future. - -We handle these by creating a deferred-update object (in a real -O-O language these would be classes that implement an interface) -and putting those objects on a global list, then executing the -whole list after the page is displayed. We don't do anything -smart like collating updates to the same table or such because -the list is almost always going to have just one item on it, if -that, so it's not worth the trouble. - - -Since 1.6 there is a 'job queue' in the jobs table, which is used -to update link tables of transcluding pages after edits; this -may be extended in the future to more general background tasks. - -Job queue items are fetched out of the queue and run either -at a random rate during regular page views (by default) or by -a batch process which can be run via maintenance/runJobs.php. +A few of the database updates required by various functions here can be +deferred until after the result page is displayed to the user. For example, +updating the view counts, updating the linked-to tables after a save, etc. PHP +does not yet have any way to tell the server to actually return and disconnect +while still running these updates (as a Java servelet could), but it might have +such a feature in the future. + +We handle these by creating a deferred-update object and putting those objects +on a global list, then executing the whole list after the page is displayed. We +don't do anything smart like collating updates to the same table or such +because the list is almost always going to have just one item on it, if that, +so it's not worth the trouble. + +Since 1.6 there is a 'job queue' in the jobs table, which is used to update +link tables of transcluding pages after edits; this may be extended in the +future to more general background tasks. + +Job queue items are fetched out of the queue and run either at a random rate +during regular page views (by default) or by a batch process which can be run +via maintenance/runJobs.php. + +Currently there are a few different types of jobs: + + refreshLinks + Used to refresh the database tables that store the links between pages. + When a page is changed, all pages using that page are also cleared by + inserting a new job for all those pages. Each job refreshes only one page. + + htmlCacheUpdate + Clear caches when a template is changed to ensure that changes can be seen. + Each job clears $wgUpdateRowsPerJob pages (500 by default). + + enotifNotify + Used when $wgEnotifUseJobQ is true to send mail using the job queue. |