Foswiki::Store

internal package Foswiki::Store

This class is a pure virtual base class that specifies the interface between the actual store implementation and the rest of the Foswiki system.

Subclasses of this class (known as "store implementations") are responsible for checking for topic existance, access permissions, and all the other general admin tasks required of a store.

This class knows nothing about how the data is actually stored - that knowledge is entirely encapsulated in the implementation.

The general contract for methods in the class requires that errors are signalled using exceptions. Foswiki::AccessControlException is used for access control exceptions, and Error::Simple for all other types of error.

Reference implementations of this base class are Foswiki::Store::RcsWrap and Foswiki::Store::RcsLite (these are both implemented in terms of VC::Store, which is an abstract implementation of a store based on a version control system).

Methods of this class and all subclasses should only be called from Foswiki and Foswiki::Meta. All other system components must delegate store interactions via Foswiki::Meta.

For readers who are familiar with Foswiki version 1.0.0, this class describes the interface to the old Foswiki::Store without actually implementing it.

Note that most methods are passed a Foswiki::Meta object. This pattern is employed to reinforce the encapsulation of a "path" in a meta object, and also to allow the store to modify META fields in the object, something it would be unable to do if passed $web, $topic.

Version numbers are required to be positive, non-zero integers. When passing in version numbers to the methods of a store implementation, 0, undef and '' are treated as referring to the latest (most recent) revision of the object. Version numbers are required to increase (later version numbers are greater than earlier) but are not required to be sequential.

ClassMethod new()

Construct a Store module.

ObjectMethod finish()

Break circular references.

StaticMethod cleanUpRevID( $rev ) → $integer

Cleans up (maps) a user-supplied revision ID and converts it to an integer number that can be incremented to create a new revision number.

This method should be used to sanitise user-provided revision IDs.

Returns 0 if it was unable to determine a valid rev number from the string passed.

ObjectMethod getWorkArea( $key ) → $directorypath

Gets a private directory uniquely identified by $key. The directory is intended as a work area for plugins.

The standard is a directory named the same as "key" under $Foswiki::cfg{WorkingDir}/work_areas

ObjectMethod readTopic($topicObject, $version) → ($rev, $isLatest)

• $topicObject - Foswiki::Meta object
• $version - revision identifier, or undef

Reads the given version of a topic, and populates the $topicObject. If the $version is undef, then reads the most recent version.

Returns the version identifier of the topic that was actually read. If the topic does not exist in the store, or $version refers to a version that does not exist, then $rev is undef. $isLatest should be set to perl true if the version loaded (or not loaded) is the latest available version.

ObjectMethod moveAttachment( $oldTopicObject, $oldAttachment, $newTopicObject, $newAttachment )

• $oldTopicObject, $oldAttachment - spec of attachment to move
• $newTopicObject, $newAttachment= - where to move to

Move an attachment from one topic to another.

The caller to this routine should check that all topics are valid, and access is permitted.

ObjectMethod copyAttachment( $oldTopicObject, $oldAttachment, $newTopicObject, $newAttachment )

• $oldTopicObject, $oldAttachment - spec of attachment to copy
• $newTopicObject, $newAttachment= - where to move to

Copy an attachment from one topic to another.

The caller to this routine should check that all topics are valid, and access is permitted.

ObjectMethod attachmentExists( $topicObject, $att ) → $boolean

Determine if the attachment already exists on the given topic

ObjectMethod moveTopic( $oldTopicObject, $newTopicObject, $cUID )

All parameters must be defined and must be untainted.

ObjectMethod moveWeb( $oldWebObject, $newWebObject, $cUID )

Move a web.

ObjectMethod testAttachment( $topicObject, $attachment, $test ) → $value

Performs a type test on the given attachment file. * $attachment - name of the attachment to test e.g lolcat.gif * $test - the test to perform e.g. 'r'

The return value is the value that would be returned by the standard perl file operations, as indicated by $type

* r File is readable by current user (tests Foswiki permissions) * w File is writable by current user (tests Foswiki permissions) * e File exists. * z File has zero size. * s File has nonzero size (returns size). * T File is an ASCII text file (heuristic guess). * B File is a "binary" file (opposite of T). * M Last modification time (epoch seconds). * A Last access time (epoch seconds).

Note that all these types should behave as the equivalent standard perl operator behaves, except M and A which are independent of the script start time (see perldoc -f -X for more information)

Other standard Perl file tests may also be supported on some store implementations, but cannot be relied on.

Errors will be signalled by an Error::Simple exception.

ObjectMethod openAttachment( $topicObject, $attachment, $mode, %opts ) → $text

Opens a stream onto the attachment. This method is primarily to support virtual file systems, and as such access controls are not checked, plugin handlers are not called, and it does not update the meta-data in the topicObject.

$mode can be '<', '>' or '>>' for read, write, and append respectively. %

%opts can take different settings depending on $mode.

• $mode='<'
  • version - revision of the object to open e.g. version => 6
• $mode='>' or ='>>'
  • no options

Errors will be signalled by an Error exception.

ObjectMethod getRevisionHistory ( $topicObject [, $attachment] ) → $iterator

• $topicObject - Foswiki::Meta for the topic
• $attachment - name of an attachment (optional)

Get an iterator over the list of revisions of the object. The iterator returns the revision identifiers (which will usually be numbers) starting with the most recent revision.

MUST WORK FOR ATTACHMENTS AS WELL AS TOPICS

If the object does not exist, returns an empty iterator ($iterator->hasNext() will be false).

ObjectMethod getNextRevision ( $topicObject ) → $revision

• $topicObject - Foswiki::Meta for the topic

Get the ientifier for the next revision of the topic. That is, the identifier for the revision that we will create when we next save.

ObjectMethod getRevisionDiff ( $topicObject, $rev2, $contextLines ) → \@diffArray

Get difference between two versions of the same topic. The differences are computed over the embedded store form.

Return reference to an array of differences

• $topicObject - topic, first revision loaded
• $rev2 - second revision
• $contextLines - number of lines of context required

Each difference is of the form [ $type, $right, $left ] where

type	Means
+	Added
-	Deleted
c	Changed
u	Unchanged
l	Line Number

ObjectMethod getVersionInfo($topicObject, $rev, $attachment) → \%info

Get revision info of a topic or attachment.

• $topicObject Topic object, required
• $rev revision number. If 0, undef, or out-of-range, will get info about the most recent revision.
• $attachment (optional) attachment filename; undef for a topic

Return %info with at least:

date	in epochSec
user	user object
version	the revision number
comment	comment in the VC system, may or may not be the same as the comment in embedded meta-data

ObjectMethod saveAttachment( $topicObject, $attachment, $stream, $cUID ) → $revNum

• $topicObject - Foswiki::Meta for the topic
• $attachment - name of the attachment
• $stream - input stream delivering attachment data
• $cUID - user doing the save

Save a new revision of an attachment, the content of which will come from an input stream $stream.

Returns the number of the revision saved.

ObjectMethod saveTopic( $topicObject, $cUID, $options ) → $integer

Save a topic or attachment without invoking plugin handlers.

• $topicObject - Foswiki::Meta for the topic
• $cUID - cUID of user doing the saving
• $options - Ref to hash of options

$options may include:

• forcenewrevision - force a new revision even if one isn't needed
• forcedate - force the revision date to be this (epoch secs)
• minor - True if this is a minor change (used in log)
• author - cUID of author of the change

Returns the new revision identifier.

ObjectMethod repRev( $topicObject, $cUID, %options ) → $rev

• $topicObject - Foswiki::Meta topic object

Replace last (top) revision of a topic with different content. The different content is taken from the content currently loaded in $topicObject.

Parameters and return value as saveTopic, except

• %options - as for saveTopic, with the extra options:
  • forcedate - if we want to force the deposited revision to look as much like the revision specified in $rev as possible by reusing the original checkin date.
  • operation - set to the name of the operation performing the save. This is used only in the log, and is normally cmd or save. It defaults to save.

Used to try to avoid the deposition of 'unecessary' revisions, for example where a user quickly goes back and fixes a spelling error.

Also provided as a means for administrators to rewrite history (forcedate).

It is up to the store implementation if this is different to a normal save or not.

Returns the id of the latest revision.

ObjectMethod delRev( $topicObject, $cUID ) → $rev

• $topicObject - Foswiki::Meta topic object
• $cUID - cUID of user doing the deleting

Parameters and return value as saveTopic.

Provided as a means for administrators to rewrite history.

Delete last entry in repository, restoring the previous revision.

It is up to the store implementation whether this actually does delete a revision or not; some implementations will simply promote the previous revision up to the head.

ObjectMethod atomicLockInfo( $topicObject ) → ($cUID, $time)

If there is a lock on the topic, return it.

ObjectMethod atomicLock( $topicObject, $cUID )

• $topicObject - Foswiki::Meta topic object
• $cUID cUID of user doing the locking

Grab a topic lock on the given topic.

ObjectMethod atomicUnlock( $topicObject )

• $topicObject - Foswiki::Meta topic object

Release the topic lock on the given topic. A topic lock will cause other processes that also try to claim a lock to block. It is important to release a topic lock after a guard section is complete. This should normally be done in a 'finally' block. See man Error for more info.

Topic locks are used to make store operations atomic. They are note the locks used when a topic is edited; those are Leases (see getLease)

ObjectMethod webExists( $web ) → $boolean

Test if web exists

• $web - Web name, required, e.g. 'Sandbox'

ObjectMethod topicExists( $web, $topic ) → $boolean

Test if topic exists

• $web - Web name, optional, e.g. 'Main'
• $topic - Topic name, required, e.g. 'TokyoOffice', or "Main.TokyoOffice"

ObjectMethod getApproxRevTime ( $web, $topic ) → $epochSecs

Get an approximate rev time for the latest rev of the topic. This method is used to optimise searching. Needs to be as fast as possible.

ObjectMethod eachChange( $web, $time ) → $iterator

Get an iterator over the list of all the changes in the given web between $time and now. $time is a time in seconds since 1st Jan 1970, and is not guaranteed to return any changes that occurred before (now - {Store}{RememberChangesFor}). Changes are returned in most-recent-first order.

ObjectMethod eachAttachment( $topicObject ) → \$iterator

Return an iterator over the list of attachments stored for the given topic. This will get a list of the attachments actually stored for the topic, which may be a longer list than the list that comes from the topic meta-data, which only lists the attachments that are normally visible to the user.

the iterator iterates over attachment names.

ObjectMethod eachTopic( $webObject ) → $iterator

Get list of all topics in a web as an iterator

ObjectMethod eachWeb($webObject, $all ) → $iterator

Return an iterator over each subweb. If $all is set, will return a list of all web names under $web. The iterator returns web pathnames relative to $web.

The list of web names is sorted alphabetically by full path name e.g.

• AWeb
• AWeb/SubWeb
• AWeb/XWeb
• BWeb

ObjectMethod remove( $cUID, $om, $attachment )

• $cUID who is doing the removing
• $om - thing being removed (web or topic)
• $attachment - optional attachment being removed

Destroy a thing, utterly.

ObjectMethod query($query, $inputTopicSet, $session, \%options) → $outputTopicSet

Search for data in the store (not web based). $query must be a Foswiki::*::Node object.

my $query = $Foswiki::Plugins::SESSION->search->parseSearch($searchString, $options); #where $options->{type} is the type specifier as per SEARCH

• $inputTopicSet is a reference to an iterator containing a list of topic in this web, if set to undef, the search/query algo will create a new iterator using eachTopic() and the topic and excludetopics options

Returns an Foswiki::Search::InfoCache iterator

This will become a 'query engine' factory that will allow us to plug in different query 'types' (Sven has code for 'tag' and 'attachment' waiting for this)

ObjectMethod searchInWebMetaData($query, $web, $inputTopicSet, $session, \%options) → $outputTopicSet

Search for a meta-data expression in the content of a web. $query must be a Foswiki::Query object.

Returns an Foswiki::Search::InfoCache iterator

DEPRECATED: this is the old way to search, and should not be used in new code. instead, use query() - using the topicSet iterator interface allows optimistations

ObjectMethod searchInWebContent($searchString, $web, \@topics, $session, \%options ) → \%map

Search for a string in the content of a web. The search must be over all content and all formatted meta-data, though the latter search type is deprecated (use queries instead).

• $searchString - the search string, in egrep format if regex
• $web - The web to search in
• \@topics - reference to a list of topics to search
• $session - the session object that provides the context of this search.
• \%options - reference to an options hash

The \%options hash may contain the following options:

• type - if regex will perform a egrep-syntax RE search (default '')
• casesensitive - false to ignore case (default true)
• files_without_match - true to return files only (default false)
• wordboundaries - true to limit the ends of the match to word boundaries

The return value is a reference to a hash which maps each matching topic name to a list of the lines in that topic that matched the search, as would be returned by 'grep'. If files_without_match is specified, it will return on the first match in each topic (i.e. it will return only one match per topic, and will not return matching lines).

DEPRECATED: this is the old way to search, and should not be used in new code. instead, use query() - using the topicSet iterator interface allows optimistations

ObjectMethod getRevisionAtTime( $topicObject, $time ) → $rev

• $topicObject - topic
• $time - time (in epoch secs) for the rev

Get the revision identifier of a topic at a specific time. Returns a single-digit rev number or undef if it couldn't be determined (either because the topic isn't that old, or there was a problem)

ObjectMethod getLease( $topicObject ) → $lease

• $topicObject - topic

If there is an lease on the topic, return the lease, otherwise undef. A lease is a block of meta-information about a topic that can be recovered (this is a hash containing user, taken and expires). Leases are taken out when a topic is edited. Only one lease can be active on a topic at a time. Leases are used to warn if another user is already editing a topic.

ObjectMethod setLease( $topicObject, $length )

• $topicObject - Foswiki::Meta topic object

Take out an lease on the given topic for this user for $length seconds.

See getLease for more details about Leases.

ObjectMethod removeSpuriousLeases( $web )

Remove leases that are not related to a topic. These can get left behind in some store implementations when a topic is created, but never saved.