diff options
| -rw-r--r-- | doc/bugs/transitive_dependencies.mdwn | 2 | ||||
| -rw-r--r-- | doc/todo/dependency_types.mdwn | 46 | ||||
| -rw-r--r-- | doc/todo/tracking_bugs_with_dependencies.mdwn | 86 |
3 files changed, 50 insertions, 84 deletions
diff --git a/doc/bugs/transitive_dependencies.mdwn b/doc/bugs/transitive_dependencies.mdwn index d5571cb6a..546f4f3aa 100644 --- a/doc/bugs/transitive_dependencies.mdwn +++ b/doc/bugs/transitive_dependencies.mdwn @@ -59,6 +59,6 @@ Downsides here: pass, plugins/map is then updated, because it depends on plugins/brokenlinks. (Of course, this is just a special case of the issue that a real modification to plugins/brokenlinks causes an unnecessary update of plugins/map, - because we have only one kind of dependency.) + because we have [[only_one_kind_of_dependency|todo/dependency_types]].) --[[Joey]] diff --git a/doc/todo/dependency_types.mdwn b/doc/todo/dependency_types.mdwn index db7d06914..6d722aab9 100644 --- a/doc/todo/dependency_types.mdwn +++ b/doc/todo/dependency_types.mdwn @@ -1,5 +1,24 @@ -Moved this relevant discussion to here from -[[tracking_bugs_with_dependencies]]: --[[Joey]] +Ikiwiki currently only has one type of dependency between pages +(plus wikilinks special cased in on the side). This has resulted in various +problems, and it's seemed for a long time to me that ikiwiki needs to get +smarter about what types of dependencies are supported. + +### unnecessary work + +The current single dependency type causes the depending page to be rebuilt +whenever a matching dependency is added, removed, or *modified*. But a +great many things don't care about the modification case, and often cause +unnecessary page rebuilds: + +* meta only cares if the pages are added or removed. Content change does + not matter (unless show=title is used). +* brokenlinks, orphans, pagecount, ditto +* inline in archive mode cares about page title, author changing, but + not content. (Ditto for meta with show=title.) +* Causes extra work when solving the [[bug/transitive_dependencies]] + problem. + +### two types of dependencies needed for [[tracking_bugs_with_dependencies]] >> it seems that there are two types of dependency, and ikiwiki >> currently only handles one of them. The first type is "Rebuild this @@ -81,3 +100,26 @@ Moved this relevant discussion to here from >>>>> For old-style pagespecs without backlinks, the dependency set for a pagespec is the same as the set of pages the pagespec matches. >>>>> Unfortunately, with existential matching, the set of pages that each >>>>> pagespec depends upon can quickly become "*", which is not very useful. -- [[Will]] + +### proposal + +I propose the following. --[[Joey]] + +* Add a second type of dependency, call it an "contentless dependency". +* `add_depends` defaults to adding a regular ("full") dependency, as + before. (So nothing breaks.) +* `add_depends($page, $spec, content => 0)` adds an contentless dependency. +* Contentless dependencies are stored in `%depends_contentless` and + `%depends_contentless_simple`, which are stored in the index similarly + to the existing hashes. +* `refresh` only looks at added/removed pages when resolving contentless + dependencies. + +This seems straightforwardly doable. I'd like [[Will]]'s feedback on it, if +possible. The type types of dependencies I am proposing are not identical +to the two types he talks about above, but I hope are close enough that +they can be used. + +This doesn't deal with the stuff that only depend on the metadata of a +page, as collected in the scan pass, changing. But it does leave a window +open for adding such a dependency type later. diff --git a/doc/todo/tracking_bugs_with_dependencies.mdwn b/doc/todo/tracking_bugs_with_dependencies.mdwn index 3894df5f6..5f3ece290 100644 --- a/doc/todo/tracking_bugs_with_dependencies.mdwn +++ b/doc/todo/tracking_bugs_with_dependencies.mdwn @@ -360,7 +360,10 @@ account all comments above (which doesn't mean it is above reproach :) ). --[[W > --[[Joey]] >> There is one issue that I've been thinking about that I haven't raised anywhere (or checked myself), and that is how this all interacts with page dependencies. ->> Firstly, I'm not sure anymore that the `pagespec_merge` function will continue to work in all cases. +>> +>>> I've moved the discussion of that to [[dependency_types]]. --[[Joey]] +>> +>> I'm not sure anymore that the `pagespec_merge` function will continue to work in all cases. >>> The problem I can see there is that if two pagespecs >>> get merged and both use `~foo` but define it differently, @@ -413,86 +416,7 @@ account all comments above (which doesn't mean it is above reproach :) ). --[[W >>> My [[remove-pagespec-merge|should_optimise_pagespecs]] branch has now >>> solved all this by deleting the offending function :-) --[[smcv]] ->> Secondly, it seems that there are two types of dependency, and ikiwiki ->> currently only handles one of them. The first type is "Rebuild this ->> page when any of these other pages changes" - ikiwiki handles this. ->> The second type is "rebuild this page when set of pages referred to by ->> this pagespec changes" - ikiwiki doesn't seem to handle this. I ->> suspect that named pagespecs would make that second type of dependency ->> more important. I'll try to come up with a good example. -- [[Will]] - ->>> Hrm, I was going to build an example of this with backlinks, but it ->>> looks like that is handled as a special case at the moment (line 458 of ->>> render.pm). I'll see if I can breapk ->>> things another way. Fixing this properly would allow removal of that special case. -- [[Will]] - ->>>> I can't quite understand the distinction you're trying to draw ->>>> between the two types of dependencies. Backlinks are a very special ->>>> case though and I'll be suprised if they fit well into pagespecs. ->>>> --[[Joey]] - ->>>>> The issue is that the existential pagespec matching allows you to build things that have similar ->>>>> problems to backlinks. ->>>>> e.g. the following inline: - - \[[!inline pages="define(~done, link(done)) and link(~done)" archive=yes]] - ->>>>> includes any page that links to a page that links to done. Now imagine I add a new link to 'done' on ->>>>> some random page somewhere - a page which some other page links to which didn't previously get included - the set of pages accepted by the pagespec, and hence the set of ->>>>> pages inlined, will change. But, there is no dependency anywhere on the page that I altered, so ->>>>> ikiwiki will not rebuild the page with the inline in it. What is happening is that the page that I altered affects ->>>>> the set of pages matched by the pagespec without itself being matched by the pagespec, and hence included in the dependency list. - ->>>>> To make this work well, I think you need to recognise two types of dependencies for each page (and no ->>>>> special cases for particular types of links, eg backlinks). The first type of dependency says, "The content of ->>>>> this page depends upon the content of these other pages". The `add_depends()` in the shortcuts ->>>>> plugin is of this form: any time the shortcuts page is edited, any page with a shortcut on it ->>>>> is rebuilt. The inline plugin also needs to add dependencies of this form to detect when the inlined ->>>>> content changes. By contrast, the map plugin does not need a dependency of this form, because it ->>>>> doesn't actually care about the content of any pages, just which pages it needs to include (which we'll handle next). - ->>>>> The second type of dependency says, "The content of this page depends upon the exact set of pages matched ->>>>> by this pagespec". The first type of dependency was about the content of some pages, the second type is about ->>>>> which pages get matched by a pagespec. This is the type of dependency tracking that the map plugin needs. ->>>>> If the set of pages matched by map pagespec changes, then the page with the map on it needs to be rebuilt to show a different list of pages. ->>>>> Inline needs this type of dependency as well as the previous type - This type handles a change in which pages ->>>>> are inlined, the previous type handles a change in the content of any of those pages. Shortcut does not need this type of ->>>>> dependency. Most of the places that use `add_depends()` seem to need this type of dependency rather than the first type. - ->>>>>> Note that inline and map currently achieve the second type of dependency by ->>>>>> explicitly calling `add_depends` for each page the displayed. ->>>>>> If any of those pages are removed, the regular pagespec would not ->>>>>> match them -- since they're gone. However, the explicit dependency ->>>>>> on them does cause them to match. It's an ugly corner I'd like to ->>>>>> get rid of. --[[Joey]] - ->>>>> Implementation Details: The first type of dependency can be handled very similarly to the current ->>>>> dependency system. You just need to keep a list of pages that the content depends upon. You could ->>>>> keep that list as a pagespec, but if you do this you might want to check that the pagespec doesn't change, ->>>>> possibly by adding a dependency of the second type along with the dependency of the first type. - ->>>>>> An example of the current system not tracking enough data is ->>>>>> described in [[bugs/transitive_dependencies]]. ->>>>>> --[[Joey]] - ->>>>> The second type of dependency is a little more tricky. For each page, we'd need a list of pagespecs that ->>>>> the page depended on, and for each pagespec you'd want to store the list of pages that currently match it. ->>>>> On refresh, you'd need to check each pagespec to see if the set of pages that match it has changed, and if ->>>>> that set has changed, then rebuild the dependent page(s). Oh, and for this second type of dependency, I ->>>>> don't think you can merge pagespecs. If I wanted to know if either "\*" or "link(done)" changes, then just checking ->>>>> to see if the set of pages matched by "\* or link(done)" changes doesn't work. - ->>>>> The current system works because even though you usually want dependencies of the second type, the set of pages ->>>>> referred to by a pagespec can only change if one of those pages itself changes. i.e. A dependency check of the ->>>>> first type will catch a dependency change of the second type with current pagespecs. ->>>>> This doesn't work with backlinks, and it doesn't work with existential matching. Backlinks are currently special-cased. I don't know ->>>>> how to special-case existential matching - I suspect you're better off just getting the dependency tracking right. - ->>>>> I also tried to come up with other possible solutions: e.g. can we find the dependencies for a pagespec? That ->>>>> would be the set of pages where a change on one of those pages could lead to a change in the set of pages matched by the pagespec. ->>>>> For old-style pagespecs without backlinks, the dependency set for a pagespec is the same as the set of pages the pagespec matches. ->>>>> Unfortunately, with existential matching, the set of pages that each ->>>>> pagespec depends upon can quickly become "*", which is not very useful. -- [[Will]] + Patch updated to use closures rather than inline generated code for named pagespecs. Also includes some new use of ErrorReason where appropriate. -- [[Will]] |