+*For discussion and the branch please see [[todo/transient pages]]. If this
+plugin is merged, this page can be renamed to act as its documentation. --[[smcv]]*
+
[[!template id=plugin name=transient author="[[Simon_McVittie|smcv]]"]]
-[[!template id=gitbranch branch=smcv/ready/transient author="[[Simon_McVittie|smcv]]"]]
[[!tag type/special-purpose]]
-The `transient` plugin is an implementation of [[todo/transient pages]]
-in an underlay. It's mostly useful as something other plugins can depend on;
-[[plugins/contrib/album]] puts photo-album "viewer" pages there,
-and the versions of [[plugins/autoindex]] and [[plugins/tag]] on the
-same branch optionally put their auto-generated pages there.
+The `transient` plugin adds an underlay in `.ikiwiki/transient`, which is
+intended for pages that are automatically created and should not be committed
+to the [[RCS]]. It works in the same way as the [[basewiki]] and the underlays
+set up by the [[plugins/underlay]] plugin, so if a page in the transient
+underlay is edited via the web, the edited version is committed to the RCS
+as usual. Unlike other underlays, if a page in the transient underlay is
+superseded by an edited version in the RCS, the old transient version
+is deleted automatically.
+
+This plugin is mostly useful as something that other plugins can depend on:
+
+* [[plugins/contrib/album]] always writes photo-album "viewer" pages to the
+ transient underlay
+
+Likely future users of this plugin (the appropriate branches need to be
+merged first):
+
+* with a patch (which exists but hasn't yet been tested), [[plugins/aggregate]]
+ always writes aggregated posts into the transient underlay
+* with a patch, [[plugins/autoindex]] can be configured to auto-create missing
+ pages that have a [[ikiwiki/subpage]] or an [[plugins/attachment]], but not
+ commit them, in which case they go in the transient underlay
+* [[plugins/comments]] can be configured to not commit comments: if so, it
+ should probably put them in the transient underlay
+* with a patch, [[plugins/recentchanges]] always writes new changes into the
+ transient underlay
+* with a patch, [[plugins/tag]] can be configured to auto-create missing
+ tag pages but not commit them, in which case they go in the transient
+ underlay
reasoning behind the autofile and autoindex implementations, but now I'm
mostly confused.
+## autofile
+
The autofile machinery records a list of every file that has ever been proposed
as an autofile: for instance, the tag plugin has a list of every tag that
has ever been named in a \[[!tag]] or \[[!taglink]], even if no file was
updated, and files in this list are never auto-created again unless the wiki
is rebuilt.
+This avoids re-creating the tag `create-del` in this situation, which is
+the third one that I noted on
+[[todo/auto-create tag pages according to a template]]:
+
+* create tags/create-del manually
+* tag a page as create-del
+* delete tags/create-del
+
+and also avoids re-creating `auto-del` in this similar situation (which I
+think is probably the most important one to get right):
+
+* tag a page as auto-del, which is created automatically
+* delete tags/auto-del
+
+I think both of these are desirable.
+
+However, this infrastructure also results in the tag page not being
+re-created in either of these situations (the first and second that I noted
+on the other page):
+
+* tag a page as auto-del-create-del, which is created automatically
+* delete tags/auto-del-create-del
+* create tags/auto-del-create-del manually
+* delete tags/auto-del-create-del again
+
+or
+
+* create tags/create-del-auto
+* delete tags/create-del-auto
+* tag a page as create-del-auto
+
+I'm less sure that these shouldn't create the tag page: we deleted the
+manually-created version, but that doesn't necessarily mean we don't want
+*something* to exist.
+
+## autoindex
+
The autoindex machinery records a more complex set. Items are added to the
set when they are deleted, but would otherwise have been added as an autoindex
(don't exist, do have children (by which I mean subpages or attachments),
and are a directory in the srcdir). They're removed if this particular run
wouldn't have added them as an autoindex (they exist, or don't have children).
-Still researching why there's this difference, and whether one or the other
-would be better for all cases...
+Here's what happens in situations mirroring those above.
+
+The "create-del" case still doesn't create the page:
+
+* create create-del manually
+* create create-del/child
+* delete create-del
+* it's added to `%deleted` and not re-created
+
+Neither does the "auto-del" case:
+
+* create auto-del/child, resulting in auto-del being created automatically
+* delete auto-del
+* it's added to `%deleted` and not re-created
+
+However, unlike the generic autofile infrastructure, `autoindex` forgets
+that it shouldn't re-create the deleted page in the latter two situations:
+
+* create auto-del-create-del/child, resulting in auto-del-create-del being
+ created automatically
+* delete auto-del-create-del; it's added to `%deleted` and not re-created
+* create auto-del-create-del manually; it's removed from `%deleted`
+* delete auto-del-create-del again (it's re-created)
+
+and
+
+* create create-del-auto
+* delete create-del-auto; it's not added to `%deleted` because there's no
+ child that would cause it to exist
+* create create-del-auto/child
--------------------------
-[[!template id=gitbranch branch=smcv/transient-only author="[[smcv]]"]]
-[[!template id=gitbranch branch=smcv/transient-recentchanges author="[[smcv]]"]]
+[[!template id=gitbranch branch=smcv/ready/transient author="[[smcv]]"]]
+[[!template id=gitbranch branch=smcv/ready/transient-recentchanges author="[[smcv]]"]]
+[[!template id=gitbranch branch=smcv/ready/transient-tag author="[[smcv]]"]]
[[!tag patch]]
I think this branch is now enough to be useful. It adds the following:
I erred on the side of more plugins; I think it's "on the edge of the core",
like goto.
-Pages with the default extension in the transient underlay are automatically
+Pages in the transient underlay are automatically
deleted if a page of the same name is created in the srcdir (or an underlay
closer to the srcdir in stacking order).
-With the additional `transient-tag` branch,
+With the additional `ready/transient-tag` branch,
`tag` enables `transient`, and if `tag_autocreate_commit` is set to 0
(default 1), autocreated tags are written to the transient underlay.
There is a regression test.
With the additional `transient-autoindex` branch,
`autoindex` uses autofiles. It also enables `transient`, and if
`autoindex_commit` is set to 0 (default 1), autoindexes are written to
-the transient underlay. There is a regression test.
+the transient underlay. There is a regression test. However, this branch
+is blocked by working out what the desired behaviour is, on
+[[todo/autoindex_should_use_add__95__autofile]].
> I wonder why this needs to be configurable? I suppose that gets back to
> whether it makes sense to check these files in or not. The benefits of
> commit clutter is really worth it.
>> According to the last section of
->> [[todo/auto-create_tag_pages_according_to_a_template]], chrysn and
+>> [[todo/auto-create_tag_pages_according_to_a_template]], [[chrysn]] and
>> Eric both feel rather strongly that it should be possible to
->> not commit any tags. I made it configurable because, as you point out,
+>> not commit any tags; in [[plugins/autoindex/discussion]],
+>> lollipopman and [[JoeRayhawk]] both requested the same for autoindex.
+>> I made it configurable because, as you point out,
>> there are also reasons why it makes sense to check these
>> automatically-created files in. I'm neutral on this, personally.
>>
autoindex ignores pages in the transient underlay when deciding whether
to generate an index.
-With the additional `transient-recentchanges` branch, new recent changes
-go in the transient underlay; I tested this manually.
+With the additional `ready/transient-recentchanges` branch, new recent
+changes go in the transient underlay; I tested this manually.
Not done yet (in that branch, at least):
>> Here are some other things I'd like to think about first: --[[Joey]]
>>
>> * There's a FIXME in autoindex.
-
->>> Right, the extra logic for preventing autoindex pages from being
->>> re-created. This is taking a while, so I'm going to leave out the
->>>> autoindex part for the moment. The FIXME is only relevant
->>>> because I tried to solve
->>>> [[todo/autoindex should use add__95__autofile]] first, but
->>>> strictly speaking, that's an orthogonal change. --s
+>>
+>> > Right, the extra logic for preventing autoindex pages from being
+>> > re-created. This is taking a while, so I'm going to leave out the
+>> > autoindex part for the moment. The FIXME is only relevant
+>> > because I tried to solve
+>> > [[todo/autoindex should use add__95__autofile]] first, but
+>> > strictly speaking, that's an orthogonal change. --s
>> * Suggest making recentchanges unlink the transient page
>> first, and only unlink from the old location if it wasn't
>> in the transient location. Ok, it only saves 1 syscall :)
-
->>> Is an unlink() really that expensive? But, OK, fixed in the
->>> `transient-recentchanges` branch. --s
+>>
+>> > Is an unlink() really that expensive? But, OK, fixed in the
+>> > `ready/transient-recentchanges` branch. --s
>> * Similarly it's a bit worrying for performance that it
>> needs to pull in and use `Cwd` on every ikiwiki startup now.
>> I really don't see the need; `wikistatedir` should
>> mostly be absolute, and ikiwiki should not chdir in ways
>> that break it anyway.
-
->>> The reason to make it absolute is that relative underlays
->>> are interpreted as relative to the base underlay directory,
->>> not the cwd.
->>>
->>> The updated `transient-only` branch only loads `Cwd` if
->>> the path is relative; an extra commit on branch
->>> `smcv/transient-relative` goes behind `add_underlay`'s
->>> back to allow use of a cwd-relative underlay. Which direction
->>> would you prefer? --s
+>>
+>> > The reason to make it absolute is that relative underlays
+>> > are interpreted as relative to the base underlay directory,
+>> > not the cwd, by `add_underlay`.
+>> >
+>> > The updated `ready/transient-only` branch only loads `Cwd` if
+>> > the path is relative; an extra commit on branch
+>> > `smcv/transient-relative` goes behind `add_underlay`'s
+>> > back to allow use of a cwd-relative underlay. Which direction
+>> > would you prefer?
+>> >
+>> > I note in passing that [[plugins/autoindex]] and `IkiWiki::Render`
+>> > both need to use `Cwd` and `File::Find` on every refresh, so
+>> > there's only any point in avoiding `Cwd` for runs that don't
+>> > actually refresh, like simple uses of the CGI. --s
>> * Unsure about the use of `default_pageext` in the `change`
>> hook. Is everything in the transientdir really going
>> to use that pageext? Would it be better to look up the
>> complete source filename?
-
->>> At the moment everything in the transientdir will either
->>> have the `default_pageext` or be internal, although I
->>> did wonder whether to make [[plugins/contrib/album]]
->>> viewer pages optionally be `html`, for better performance
->>> when there's a very large number of photos.
->>>
->>> A more thorough garbage-collection mechanism would be to
->>> use File::Find on the transient directory; I'll get there
->>> eventually. --s
+>>
+>> > I've updated `ready/transient` to do a more thorough GC by
+>> > using File::Find on the transient directory. This does
+>> > require `File::Find` and `Cwd`, but only when pages change,
+>> > and `refresh` loads both of those in that situation anyway.
+>> >
+>> > At the moment everything in the transientdir will either
+>> > have the `default_pageext` or be internal, although I
+>> > did wonder whether to make [[plugins/contrib/album]]
+>> > viewer pages optionally be `html`, for better performance
+>> > when there's a very large number of photos. --s
--------------------------