As part of the .eap to .desktop conversion, raster wants me to redo the relevant caching to suit. He has made many "eap caching needs fixing" noises in the recent past, so maybe a fresh start is needed at this point. This is a discussion and design document. Major parts of it where sent to the devel list but got no response. Raster said to put it in here, and keep it up to date with whatever information and design is relevant. The problem - It's really the E_App structure as defined in e_apps.h that may need caching, no matter what their source. I say "no matter what their source" because at the moment the sources are .eap files and .desktop files, and at some unspecified date in the future .eap files might go away. I say "may need caching" because this is a fresh start, do they really need caching? To answer that last question we need to look at all the places that use E_Apps and check to see if those uses are performance critical. Then we need to see how much time it takes to load an E_App from it's source. Grepping through the source code shows that E_App is used in the ibar, engage, and mbar modules, plus in E itself. Devilhorns tells me that mbar will be replaced, so I will ignore that for now. HandyAndE tells me that the stand alone version of engage is deprecated, so I can ignore that. Both ibar and engage essentially do the same things with E_App, so I'll speak about those in generic terms. I'll also try to avoid spending time fully groking all the code that uses E_Apps, as I have some time pressure here. That's why I'm thinking out loud, if I miss something, other devs will point it out. Interesting that neither entangle, nor the stand alone eapp_edit came up in the grep results. There may be other things that deal with application icons in their own way. I'll ignore them for now. I know raster will say "engage entangle and such ar not part of corr e, ignre them". Entangle and the stand alone eapp_edit are now obsolete, as they where not included in the .desktop update. Ibar and engage both display a handful of application icons, allow the user to click on those icons to start the application. Ibar runs a "starting application" animation, and engage keeps track of open windows that belong to all applications, but tries to keep the open window icons next to the application icon if it has one for that application. I don't know if ibar uses the freedesktop.org startup notification spec, some other method, or just runs the animation for an arbitrary time. Either way, there are three operations in these modules that use E_Apps - show the icon, start the application, and match newly created windows with the E_App. E also needs to do those three operations, and more. Menus, winlist, pager, exebuf, and borders all need to show the icon. Menus and exebuf need to start the application. When a window is opened, it needs to be matched to it's E_App to show it's icon and other things. Exebuf needs to search through all the E_Apps looking for matches to the partially typed in command. EFM needs to show an icon for any .eap or .desktop it is currently displaying, maybe needs to run the application. The built in eap editor needs to read, display, and save all the application icon information. These operations fall into two distinct categories - dealing with one E_App at a time, or searching through all E_Apps with arbitrary search criteria. One at a time is often done in user time (the user only operates one icon at a time) so caching is not so important there. Searching through all E_Apps is an expensive operation that should be optimised as much as possible. Note that I count the showing of menus as the later category, as the user may want to quickly access many sub menus full of E_Apps. Since the source of the image data used for the icon can be something that needs time to decode, at the times when lots of icons are being used at once (exebuf and menus mostly) we probably want that image data cached for speed as well. The searching through all E_Apps can occur on data that is part of the original file that is the source, so an in memory search will be a lot faster than any file searching. So the problem is - as fast as possible search through all the E_Apps, no matter what their source, and give access to all the information they have ,including image data. Since this is useful in the "one at a time" category, might as well use the same method there to. The issues with possible solutions - An in memory cache of all E_App information is needed. Since the information that could be used to search this cache can be quite arbitrary, hashes and other such structures may not be useful. On the other hand, some sort of index mechanism may be useful for the most common searches, and those that need to be quickest. Lets try to come up with some numbers. The eap torture test involves over two thousand .eaps, and that's from a full install of SuSE 9.3 Pro. Certain distros have just as many applications, or more, and they are growing all the time. 120x120 pixels is probably the largest commonly used icon size, 32 bits per pixel to include the alpha channel. I have seen .desktop files up to 25 KB in size, but that includes all the translations for name, comment, and keywords, something that is not currently stored in E_App. A much more common size is 2 - 4 KB, but that still mostly is for the name translations. Note, .desktop files only include the name of the icon, not the image data itself. I use the .desktop files for this part of the discussion because they include all the non image data that is typically in an E_App. 1 KB is probably maximum storage requirement for non image, single translation E_App data. That could be a maximum of 56 KB per E_App, and possibly 100 MB for the entire cache including image data. Ouch, no wonder raster suggested mmaping the cache file. Note, this is a likely maximum for those people that install two thousand applications and like really big icons. I have over two thousand applications installed, and I like the icons in engage to zoom out really big. B-) Typical users will require a much smaller amount of data. The original caching strategy uses multiple caches, on a per directory basis, but still has a single cache for the all directory, the one with all the .eaps in it. raster has mentioned that a single cache might be a better solution. With .desktop files scattered all over the place, a single cache is more desirable for searching purposes. This does raise some interesting issues. While .eap files have in the past been per user, the majority of .desktop files are likely to be system files, mostly unchanging, but with new ones added whenever new software is installed. The user can create their own, and override system ones. There is also the translations to deal with. Do we include only one translation in the cache? Do we have a system cache and per user caches that allow overrides? Do we really need image data in the cache? Although the freedesktop.org spec says that the user chooses a single icon size, in practise the various things that render icons render them at different sizes. There is the cache update strategy to consider. The current one causes problems. Raster has thought about changing to no auto update, but with a manually triggered update. I would prefer automatic updates that work smoothly and without great pauses in the operation of the wm, as that gives the users less to complain about. Maybe we can make use of the thumb nailing stuff? Answers to these questions will help choose a caching mechanism. ----------------------------------------------------------------------- ecore_desktop_paths USED BY: All of the ecore_desktop code. WHEN: At startup. They hardly ever change. ISSUES: The use of GNOME and KDE apps to figure out some of the paths. They are curently commented out, and guesses are made. SOLUTION: Go with the guesses, run the apps later to correct the guesses. Cache the results to disk. ----------------------------------------------------------------------- ecore_desktop_menu USED BY: "Applications" menu and "Applications" config dialog. WHEN: The menus are parsed at first startup, then manually by the dialog. ISSUES: When new applications are installed, will need to update. SOLUTION: Parse them during idle time, maybe as a separate process. Monitor relevant directories. ~/.e/e/applications/menu/all is the results cached to disk. ----------------------------------------------------------------------- icon themes USED BY: The icon theme config dialog. WHEN: When the icon theme config dialog is started. ISSUES: The actual icon theme currently in use is a small amount of info that can always be in ram, and is quick to get at startup or theme change. It's the complete list of themes that are currently installed that can take ages to find. The list itself should also be small. SOLUTION: Find them during idle time, and finish the job async when the dialog is started. Monitor the icon paths for the installation of new themes. Keep them all in a hash. ----------------------------------------------------------------------- icons USED BY: Whenever an E_App is displayed and others. WHEN: On demand. ISSUES: Combined .edj and FDO searching. FDO searching can take a long time. Things that display lots of icons wont want to wait for all those complex searches. Searching for icons that don't exist is what takes the longest, as the FDO algo means we have to look through all the directories, in this theme, and the next theme. SOLUTION: e_app_icon_add() should be used everywhere, and it should register a rectangle for use by the icon. The caller then shows an empty icon. A thumbnailing style process then does all the searching, and does the fm2 bouncy icon thing when the icon is found. raster forbids this method. The results of the search should be cached somewhere on disk for future reference. That needs to be nuked when the user changes icon theme. Changing the icon theme currently does not update all displayed icons, it just does a restart like wm theme changing does. The X-Enlightenment-IconPath field of the .desktop file could be used for the on disk cache. X-Enlightenment-Icon-Theme and X-Enlightenment-Icon-TimeStamp can be used to determine if the icon path stored on disk is out of date, or in a different theme. An idle task can go through all the .desktops in ~/.e/e/applications/all and check if the icons need updating. The spec allows caching of dirs, and we can monitor just the top level icon theme directory. ----------------------------------------------------------------------- .desktop files USED BY: E_Apps and others. WHEN: Whenever the E_App needs to be read from disk. ISSUES: Currently a fairly simple in memory hash of them is kept. Since each Ecore_Desktop holds a hash of the fields, this can be expensive in memory. Also, we would like a pre parsed binary on disk cache for the sheer speed. ~/.e/e/applications/all is a directory with all of them that are for E_Apps, some are just links to system files. SOLUTION: Remove after implementing the E_App cache then see if these still needs caching. Note that the menu generation probably reads the .desktop files twice each. ----------------------------------------------------------------------- .order files USED BY: Menus, bars, startup, restart. WHEN: When displaying the menu or bar. At startup and restart. When editing them. ISSUES: SOLUTION: ----------------------------------------------------------------------- E_Apps USED BY: Menus, bars, borders, exebuf, lots of other places. WHEN: Currently all read in at startup time. Should change this to an idle time task. Still need to read in them all near startup time though. We need all of them for searching. a_actions searches for filename, name, generic, and exe to find an app to execute. Updates the most recently used list. e_border searches for border and pid to find the border icon. The border search involves searching all E_Apps for win_* and exe that match the app in the border. The pid search involves searching all instances of all E_Apps, looking for a matching pid. Both searches update the most recently used list. None of this is needed for remember stuff. e_exebuf searches/lists all apps and most recently used apps based on a partially typed in string. It globs name, exe, generic, and comment. When actually listing the matches, it searches for exe. When showing an icon for the current match, it searches exe, name, then generic. Updates the most recently used list. e_zone searches for exe to find a matching E_App when it is executing things. Updates the most recently used list. e_int_config_apps shows a sorted list of all apps. Everything else loads E_Apps by file name or directory name. Some have .order files. ISSUES: The current eap caching code is not up to scratch, and the .desktop conversion didn't help. It does hide some other bugs though, so that needs to be cleaned up first. How this all hangs together is complex. Evas_List *_e_app_repositories; Only contains ~/.e/e/applications/all for now. E_App *_e_apps_all = ~/.e/e/applications/all Currently has all the E_Apps as subbapps, but only used as if it was a single E_App. On the other hand, this is scanned at startup time, so is used to preload the caches. _e_apps_list = Most recently used list / all apps list. E_App members - E_App *parent; /* the parent e_app node */ e_apps.c internal This is in a directory, the parent is the E_App for that directory. Evas_List *subapps; /* if this a directory, a list of more E_App's */ e_apps.c internal except for _e_startup and _e_int_menus_apps_scan This will be a directory with a .order file, subapps points to the content E_Apps. Evas_List *references; /* If this app is in a main repository, this would be a list to other eapp pointing to this */ e_apps.c internal E_Apps in a repository are copied before use, this points to those copies. E_App *orig; /* if this is a copy, point to the original */ e_apps.c internal except for _e_border_menu_cb_icon_edit E_Apps in a repository are copied before use, this points to the original. Evas_List *instances; /* a list of all the exe handles for executions */ e_apps.c internal except for e_zone_exec Tracks E_Apps that are currently running. Ecore_File_Monitor *monitor; /* Check for changes and files */ e_apps.c internal Only E_Apps that are directories are monitored. SOLUTION: Start by putting all filenames in ~/.e/e/applications/all in a hash with "empty" E_Apps. Fill the "empty" E_Apps during idle time, also as needed. Everytime a new .desktop file is created, add it to the hash and put it in the directory. The most recently used list can be built from whatever gets used, it could actually speed things up if it does not contain everything, as it is usually a linear search. On the other hand, we could reuse the subapps of _e_apps_all as this list, since it already exists, and it doesn't care what order its subapps are in. Executing an app can probably afford to use a slow search. Border icons could make use of bouncy icon thumbnailing. e_int_config_apps can just show ~/.e/e/applications/all, but e_fm will need to know to sort based on visible name. e_exebuf can also use bouncy icon thumbnailing, but may need more speedups for its globbing. Later we shall see if an on disk copy is needed. ------------------------------------------------------------------------------ comments on cache doc: 1. ignore caching of image data - evas already does that. just provide file paths and "keys" if inside .edj/eap/eet files. don't duplicate image data or do anything "smart" as it will invariably end up less smart that the existing evas cache :) so don't worry about icons and their pixels - just the file paths/keys 2. instead of "in memory" let's try a new idea. lets put it in a flat mmap'ed file (not eet). let's not make it architecture dependent (write any integers in a fixed byte order) and make it all offset based. fill the file with strings and indexes and fast search indexes etc. 1 big flat file for the whole cache.. the eap structs themselves are "in memory" and allocated but all strings and "content" are pointed to this mmaped file - map and unmap this file whenever needed (need to add calls that implicitly map it when you want to access eap struct contents and then unmap when done - refcount) and on map check the header of the file for some "modification count) and keep the last mod count value - if they don't match re-evaluate all internal tabels in the map file. re-evaluate all pointers in eap structs. always try and map the file to the same mem address (remember it and try map TO that addr so you don't need to do address fixups). if you can't map to there map to unspecified address (let mmap choose) and now keep trying to map to this addr from now on. if the addr changes or the mmap file changes all eap files need a fixup of their str pointers done. so now you have a e_app_use() and e_app_unuse() thatg basically makes sure the apps map file is mappeed after a use and unmapped after an unuse (when refcount goes to 0 for the maps file - maybe with a timeout to avoid map thrashing). the advantage of all this is most of the time e is not accessing eapp data - it just has references TO them so during this time no memory is consumed by the data and no kernel mappings. we should bring mem use down to a tiny fraction. this is a quick braindump... so it may need more discussion. nb - this is just a bug flat dump for all ".desktop files" - hash it for fast lookup - have fast search hash indexes for lookup by exe, name, class etc. other cache files for menu structures etc. would implicitly reference data in this big fat cache. 3. on any change of .desktop files on the system or by users - rewrite the whole cache and re-fix pointers etc. - this shouldn't happen often. 4. same mmap setup for lookups of icon name in .desktop -> fully resolved path based on icon themes and inheritance. if the themes change then re-evaluate this cache. 5. .order files and menu structs can just live in the same cache. 6. all eaps can be quickyl created at startup from an all apps cache that referenced the desktop content cache file as above. putting it into an idel taks means on addition of new eaps all window icons need re-evaluation as to all eap instances in ibar etc. etc. - makes life more complex (for now). maybe simpler on that front and better cache will work well here. 7. eap instances are created as you lanich apps - no need to cache or worry about these - the search by exe, win name/class etc. are what we need to worry about :) 8. the above should mean no need to fill in eaps in idlers - map the "big fat desktop cache" that contains everything - icon paths, labels exe strings etc. when needed - fox up all pointers in eapp structs if the contents or base address ever change - unmap when refcount goes to 0 (with a timeout to avoid thrashing).