Thijs/wiki.techinc.nl

History

Umherirrender 226264adfa Use LocalFile::getHookRunner instead of LocalFile::hookRunner Do not depend on File::__get() Follow-Up: Iaa84edfe215e71d3d5fd814053d4b787652fa3b5 Change-Id: Ib344a2fa7681e176de863d99e8df13ec37eb143d		2021-10-18 17:50:05 +00:00
..
file	Use LocalFile::getHookRunner instead of LocalFile::hookRunner	2021-10-18 17:50:05 +00:00
Hook	Deprecate LocalFile::getHistory hook	2021-06-17 08:33:31 +02:00
FileBackendDBRepoWrapper.php	Replace uses of DB_MASTER with DB_PRIMARY	2021-04-29 09:24:31 -07:00
FileRepo.php	Using @return never documentation on always-throw-function	2021-09-07 17:29:03 +02:00
ForeignAPIRepo.php	Using @return never documentation on always-throw-function	2021-09-07 17:29:03 +02:00
ForeignDBRepo.php	Replace getMasterDB methods with getPrimaryDB	2021-07-14 16:21:04 -07:00
ForeignDBViaLBRepo.php	Follow-up I68198bc3: Hard-deprecate getMasterDB() methods	2021-07-15 09:12:17 +01:00
LocalRepo.php	Tag various new 'primary' methods as `@since 1.37`	2021-09-02 11:58:19 -07:00
NullRepo.php	Set method visibility for various constructors	2019-12-03 20:17:30 +01:00
README.md	docs: Remove ingroup tag from Markdown files	2019-11-12 16:11:30 -08:00
RepoGroup.php	Remove deprecated RepoGroup methods	2021-09-17 00:23:59 +02:00
TempFileRepo.php	Using @return never documentation on always-throw-function	2021-09-07 17:29:03 +02:00

README.md

FileRepo Architecture

Some quick notes on the file/repository architecture.

Functionality is, as always, driven by data model.

The repository object stores configuration information about a file storage method.
The file object is a process-local cache of information about a particular file.

Thus the file object is the primary public entry point for obtaining information about files, since access via the file object can be cached, whereas access via the repository should not be cached.

Functions which can act on any file specified in their parameters typically find their place either in the repository object, where reference to repository-specific configuration is needed, or in static members of File or FileRepo, where no such configuration is needed.

File objects are generated by a factory function from the repository. The repository thus has full control over the behavior of its subsidiary file class, since it can subclass the file class and override functionality at its whim. Thus there is no need for the File subclass to query its parent repository for information about repository-class-dependent behavior -- the file subclass is generally fully aware of the static preferences of its repository. Limited exceptions can be made to this rule to permit sharing of functions, or perhaps even entire classes, between repositories.

These rules alone still do lead to some ambiguity -- it may not be clear whether to implement some functionality in a repository function with a filename parameter, or in the file object itself.

So we introduce the following rule: the file subclass is smarter than the repository subclass. The repository should in general provide a minimal API needed to access the storage backend efficiently.

In particular, note that I have not implemented any database access in LocalRepo.php. LocalRepo provides only file access, and LocalFile provides database access and higher-level functions such as cache management.

Tim Starling, June 2007