|
Size: 7418
Comment:
|
Size: 428
Comment:
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 1: | Line 1: |
| '''fncache''' is a new repository layout (or format) for Mercurial that solves the following issues: * http://www.selenic.com/mercurial/bts/issue839 - Hg local store creates paths too long for Windows * http://www.selenic.com/mercurial/bts/issue793 - Can't clone repos that use Windows reserved names in paths Status: in [http://selenic.com/repo/index.cgi/hg/rev/7946503ec76e main] and crew repos === Usage === With this change, all new repositories on all platforms will be fncache repositories. You don't have to do anything (besides using a version of Mercurial containing this change, which currently is in main code line of Mercurial but has not yet been included in an official release). '''The new layout does not affect the wire (or bundle) protocol(s) in any way.''' So you can push/pull/clone over the wire to/from any repo being in any layout using any Mercurial version on both ends. New repositories are for example created by non-hardlink cloning of existing repos or if you clone over the wire (http, ssh). For example, if you have a current non-fncache repo and you do a local `clone --pull` you will end up with an fncache repo. If you do a plain local clone (without `--pull`) of an existing non-fncache repo, you will get a non-fncache repo with hardlinks to the existing repo. In short, use `clone --pull` to convert repos (in case you want to convert repos to the fncache repo format, which will almost never be needed). Of course old versions of Mercurial will not be able to read fncache repos. If you try to access an fncache repo with an old version of Mercurial it will abort with: {{{ abort: requirement 'fncache' not supported! }}} Which tells you that the repo at hand requires knowledge of the fncache repo format in Mercurial. (BTW, if, for whatever reason, the fnache file in the repo becomes corrupted, you can do a `clone --pull` to rebuild it. The fncache file contains a list of all revlog files in the repo). Existing non-fncache repositories will remain as they are, as Mercurial will still be able to write and read non-fncache repositories with this patch. In current Mercurial there is already a hgrc option `[format] usestore` [1], which enables the current 'store' format, which is the default in current Mercurial. The "store" format encodes filenames with uppercase chars '''X''' as '''_x''' (underbar + x). If you disable that, you will have to make sure that the repo is only used on a platform that does not fold case (that is, don't use or copy it to/on Windows). The fncache repo layout is a descendant of the store format, so if you disable the store format you implicitly disable the fncache layout. With the patch as it is, there is currently no option to disable the fncache layout for new repos (as a hackaround, you can manually remove the 'fncache' entry in the requires file after hg init). You can only disable the 'store' format, which implicitly disables fncache too. But there is no separate option to only disable 'fncache' and keep 'store'. [1] http://www.selenic.com/mercurial/hgrc.5.html#format === Technical details === The fncache repo layout uses a new encoding for path names inside the store. ==== Encoding of Windows reserved names ==== Path elements consisting of Windows reserved names are now encoded using {{{~xx}}} where {{{xx}}} is the two digit ASCII hex code of the third character of that reserved name. For example "{{{aux}}}" is encoded as "{{{au~78}}}". Windows reserved names are: {{{'con', 'prn', 'aux', 'nul', 'com1'..'com9'}}} and {{{'lpt1'..'lpt9'}}}. For example the path {{{ data/aux.bla/bla.aux/prn/PRN/lpt/com3/nul/coma/foo.NUL/normal.c.i }}} is encoded as {{{ data/au~78.bla/bla.aux/pr~6e/_p_r_n/lpt/co~6d3/nu~6c/coma/foo._n_u_l/normal.c.i }}} Note that {{{'aux.bla'}}} needs to be encoded, but not {{{'bla.aux'}}}. ==== Hashing of long paths ==== Paths inside the store that would be longer than 120 chars are now hash encoded. For the encoding used see the function {{{mercurial.store.hybridencode}}}. Some encoding examples for paths that are hashed (A1→B1, A2→B2, ...): {{{ (A1) data/AUX/SECOND/X.PRN/FOURTH/FI:FTH/SIXTH/SEVENTH/EIGHTH/NINETH/TENTH/ELEVENTH/LOREMIPSUM.TXT.i (B1) dh/au~78/second/x.prn/fourth/fi~3afth/sixth/seventh/eighth/nineth/tenth/loremia20419e358ddff1bf8751e38288aff1d7c32ec05.i (A2) data/enterprise/openesbaddons/contrib-imola/corba-bc/netbeansplugin/wsdlExtension/src/main/java/META-INF/services/org.netbeans.modules.xml.wsdl.bindingsupport.spi.ExtensibilityElementTemplateProvider.i (B2) dh/enterpri/openesba/contrib-/corba-bc/netbeans/wsdlexte/src/main/java/org.net7018f27961fdf338a598a40c4683429e7ffb9743.i (A3) data/AUX.THE-QUICK-BROWN-FOX-JU:MPS-OVER-THE-LAZY-DOG-THE-QUICK-BROWN-FOX-JUMPS-OVER-THE-LAZY-DOG.TXT.i (B3) dh/au~78.the-quick-brown-fox-ju~3amps-over-the-lazy-dog-the-quick-brown-fox-jud4dcadd033000ab2b26eb66bae1906bcb15d4a70.i }}} All paths that are hashed are stored in the directory {{{'dh'}}} inside {{{'.hg/store'}}}. Non-hashed paths are stored inside {{{'.hg/store/data'}}}. The hashing used is the sha1 digest (40 characters) of the direncoded path below {{{'.hg/store'}}}, as pre-encoded by {{{mercurial.filelog.encodedir}}}. For the hashencoded path, the first eight characters of the first n directory levels are taken (converted to lowercase), where n is adapted slightly to use more levels if space allows (see {{{store.hybridencode}}}). If space allows, the filename before the hash value is filled up with to lowercase converted chars from the filename of the input path. As you can see, the path encoding done may fold multiple files originating from different input path directories into the same encoded path directory. The sha1 digest part of the filename ensures that the filenames are distinct and no name clashes occur. ==== The fncache file ==== For the fncache repository format Mercurial maintains a new file {{{'fncache'}}} (thus the name of the format) inside {{{'.hg/store'}}}. The fncache file contains the paths of all filelog files in the store as encoded by {{{mercurial.filelog.encodedir}}}. The paths are separated by {{{'\n'}}} (LF). The fncache file is used to enumerate all filelog files in the store, for example when doing a {{{clone --uncompressed}}}. The fncache file may contain duplicates or inexistent entries (this can happen when using the {{{strip}}} or {{{rollback}}} commmands). During a {{{clone --uncompressed}}} or a {{{hg verify}}} the fncache file is read and rewritten '''if''' duplicates or entries with missing filelog files are detected, so even operations that don't modify the history of the repository may lead to modifying the fncache file (this was a deliberate design decision as discussed with mpm). The fncache file is not read by a {{{hg clone --pull}}}, so that command may be used to resurrect a damaged fncache file, since {{{hg clone --pull}}} rewrites the fncache file from the information found in all manifest revisions. That's also the reason why it is basically cached information. The {{{verify}}} command checks the fncache file and removes non-existent or duplicate entries. If a filelog file referenced in a manifest revision is not found in the fncache file, {{{hg verify}}} reports an error. |
Greetings! I am Todd and I [[http://www.yourdictionary.com/tremendously|tremendously]] love this name.<<BR>> <<BR>> My house is now in Iowa. I am really fond of cinema but I can't to become my profession really.http://farm2.staticflickr.com/1243/1359129671_9eca6c2ca7.jpg After being out of a good job for years I came to be an administrative assistant. You can get a hold of my website here: http://6000amonthclubincome.com |
Greetings! I am Todd and I tremendously love this name.
My house is now in Iowa. I am really fond of cinema but I can't to become my profession really.http://farm2.staticflickr.com/1243/1359129671_9eca6c2ca7.jpg After being out of a good job for years I came to be an administrative assistant. You can get a hold of my website here: http://6000amonthclubincome.com
