DOC: add a CONTRIBUTING file
This file tries to explain in the most detailed way how to contribute
patches. A few parts of it were moved from the README. .gitignore was
updated.
diff --git a/CONTRIBUTING b/CONTRIBUTING
new file mode 100644
index 0000000..0f6b9ed
--- /dev/null
+++ b/CONTRIBUTING
@@ -0,0 +1,654 @@
+ HOW TO GET YOUR CODE ACCEPTED IN HAPROXY
+ READ THIS CAREFULLY BEFORE SUBMITTING CODE
+
+THIS DOCUMENT PROVIDES SOME RULES TO FOLLOW WHEN SENDING CONTRIBUTIONS. PATCHES
+NOT FOLLOWING THESE RULES WILL SIMPLY BE REJECTED IN ORDER TO PROTECT ALL OTHER
+RESPECTFUL CONTRIBUTORS' VALUABLE TIME.
+
+
+Background
+----------
+
+During the development cycle of version 1.6, much more time was spent reviewing
+poor quality submissions, fixing them and troubleshooting the bugs they
+introduced than doing any development work. This is not acceptable as it ends
+up with people actually slowing down the project for the features they're the
+only ones interested in. On the other end of the scale, there are people who
+make the effort of polishing their work to contribute excellent quality work
+which doesn't even require a review. Contrary to what newcomers may think, it's
+very easy to reach that level of quality and get your changes accepted quickly,
+even late in the development cycle. It only requires that you make your homework
+and not rely on others to do it for you. The most important point is that
+HAProxy is a community-driven project, all involved participants must respect
+all other ones' time and work.
+
+
+Preparation
+-----------
+
+It is possible that you'll want to add a specific feature to satisfy your needs
+or one of your customers'. Contributions are welcome, however maintainers are
+often very picky about changes. Patches that change massive parts of the code,
+or that touch the core parts without any good reason will generally be rejected
+if those changes have not been discussed first.
+
+The proper place to discuss your changes is the HAProxy Mailing List. There are
+enough skilled readers to catch hazardous mistakes and to suggest improvements.
+There is no other place where you'll find as many skilled people on the project,
+and these people can help you get your code integrated quickly. You can
+subscribe to it by sending an empty e-mail at the following address :
+
+ haproxy+subscribe@formilux.org
+
+If you have an idea about something to implement, *please* discuss it on the
+list first. It has already happened several times that two persons did the same
+thing simultaneously. This is a waste of time for both of them. It's also very
+common to see some changes rejected because they're done in a way that will
+conflict with future evolutions, or that does not leave a good feeling. It's
+always unpleasant for the person who did the work, and it is unpleasant in
+general because value people's time and efforts are valuable and would be better
+spent working on something else. That would not happen if these were discussed
+first. There is no problem posting work in progress to the list, it happens
+quite often in fact. Also, don't waste your time with the doc when submitting
+patches for review, only add the doc with the patch you consider ready to merge.
+
+Another important point concerns code portability. Haproxy requires gcc as the
+C compiler, and may or may not work with other compilers. However it's known to
+build using gcc 2.95 or any later version. As such, it is important to keep in
+mind that certain facilities offered by recent versions must not be used in the
+code :
+
+ - declarations mixed in the code (requires gcc >= 3.x and is a bad practice)
+ - GCC builtins without checking for their availability based on version and
+ architecture ;
+ - assembly code without any alternate portable form for other platforms
+ - use of stdbool.h, "bool", "false", "true" : simply use "int", "0", "1"
+ - in general, anything which requires C99 (such as declaring variables in
+ "for" statements)
+
+Since most of these restrictions are just a matter of coding style, it is
+normally not a problem to comply.
+
+If your work is very confidential and you can't publicly discuss it, you can
+also mail willy@haproxy.org directly about it, but your mail may be waiting
+several days in the queue before you get a response. Retransmit if you don't
+get a response by one week.
+
+If you'd like a feature to be added but you think you don't have the skills to
+implement it yourself, you should follow these steps :
+
+ 1. discuss the feature on the mailing list. It is possible that someone
+ else has already implemented it, or that someone will tell you how to
+ proceed without it, or even why not to do it. It is also possible that
+ in fact it's quite easy to implement and people will guide you through
+ the process. That way you'll finally have YOUR patch merged, providing
+ the feature YOU need.
+
+ 2. if you really can't code it yourself after discussing it, then you may
+ consider contacting someone to do the job for you. Some people on the
+ list might sometimes be OK with trying to do it.
+
+
+Rules : the 12 laws of patch contribution
+-----------------------------------------
+
+People contributing patches must apply the following rules. That may sound heavy
+at the beginning but it's common sense more than anything else and contributors
+do not think about them anymore after a few patches.
+
+1) Before modifying some code, you have read the LICENSE file ("main license")
+ coming with the sources, and all the files this file references. Certain
+ files may be covered by different licenses, in which case it will be
+ indicated in the files themselves. In any case, you agree to respect these
+ licenses and to contribute your changes under the same licenses. If you want
+ to create new files, they will be under the main license, or any license of
+ your choice that you have verified to be compatible with the main license,
+ and that will be explicitly mentionned in the affected files. The project's
+ maintainers are free to reject contributions proposing license changes they
+ feel are not appropriate or could cause future trouble.
+
+2) Your work may only be based on the latest development version. No development
+ is made on a stable branch. If your work needs to be applied to a stable
+ branch, it will first be applied to the development branch and only then will
+ be backported to the stable branch. You are responsible for ensuring that
+ your work correctly applies to the development version. If at any moment you
+ are going to work on restructuring something important which may impact other
+ contributors, the rule that applies is that the first sent is the first
+ served. However it is considered good practice and politeness to warn others
+ in advance if you know you're going to make changes that may force them to
+ re-adapt their code, because they did probably not expect to have to spend
+ more time discovering your changes and rebasing their work.
+
+3) You have read and understood "doc/codingstyle.txt", and you're actively
+ determined to respect it and to enforce it on your coworkers if you're going
+ to submit a team's work. We don't care what text editor you use, whether it's
+ an hex editor, cat, vi, emacs, Notepad, Word, or even Eclipse. The editor is
+ only the interface between you and the text file. What matters is what is in
+ the text file in the end. The editor is not an excuse for submitting poorly
+ indented code, which only proves that the person has no consideration for
+ quality and/or has done it in a hurry (probably worse). Please note that most
+ bugs were found in low-quality code. Reviewers know this and tend to be much
+ more reluctant to accept poorly formated code because by experience they
+ won't trust their author's ability to write correct code. It is also worth
+ noting that poor quality code is painful to read and may result in nobody
+ willing to waste their time even reviewing your work.
+
+4) The time it takes for you to polish your code is always much smaller than the
+ time it takes others to do it for you, because they always have to wonder if
+ what they see is intended (meaning they didn't understand something) or if it
+ is a mistake that needs to be fixed. And since there are less reviewers than
+ submitters, it is vital to spread the effort closer to where the code is
+ written and not closer to where it gets merged. For example if you have to
+ write a report for a customer that your boss wants to review before you send
+ it to the customer, will you throw on his desk a pile of paper with stains,
+ typos and copy-pastes everywhere ? Will you say "come on, OK I made a mistake
+ in the company's name but they will find it by themselves, it's obvious it
+ comes from us" ? No. When in doubt, simply ask for help on the mailing list.
+
+5) There are four levels of importance of quality in the project :
+
+ - The most important one, and by far, is the quality of the user-facing
+ documentation. This is the first contact for most users and it immediately
+ gives them an accurate idea of how the project is maintained. Dirty docs
+ necessarily belong to a dirty project. Be careful to the way the text you
+ add is presented and indented. Be very careful about typos, usual mistakes
+ such as double consonants when only one is needed or "it's" instead of
+ "its", don't mix US english and UK english in the same paragraph, etc.
+ When in doubt, check in a dictionary. Fixes for existing typos in the doc
+ are always welcome and chasing them is a good way to become familiar with
+ the project and to get other participants' respect and consideration.
+
+ - The second most important level is user-facing messages emitted by the
+ code. You must try to see all the messages your code produces to ensure
+ they are understandable outside of the context where you wrote them,
+ because the user often doesn't expect them. That's true for warnings, and
+ that's even more important for errors which prevent the program from
+ working and which require an immediate and well understood fix in the
+ configuration. It's much better to say "line 35: compression level must be
+ an integer between 1 and 9" than "invalid argument at line 35". In HAProxy,
+ error handling roughly represents half of the code, and that's about 3/4 of
+ the configuration parser. Take the time to do something you're proud of. A
+ good rule of thumb is to keep in mind that your code talks to a human and
+ tries to teach him/her how to proceed. It must then speak like a human.
+
+ - The third most important level is the code and its accompanying comments,
+ including the commit message which is a complement to your code and
+ comments. It's important for all other contributors that the code is
+ readable, fluid, understandable and that the commit message describes what
+ was done, the choices made, the possible alternatives you thought about,
+ the reason for picking this one and its limits if any. Comments should be
+ written where it's easy to have a doubt or after some error cases have been
+ wiped out and you want to explain what possibilities remain. All functions
+ must have a comment indicating what they take on input and what they
+ provide on output. Please adjust the comments when you copy-paste a
+ function or change its prototype, this type of lazy mistake is too common
+ and very confusing when reading code later to debug an issue. Do not forget
+ that others will feel really angry at you when they have to dig into your
+ code for a bug that your code caused and they feel like this code is dirty
+ or confusing, that the commit message doesn't explain anything useful and
+ that the patch should never have been accepted in the first place. That
+ will strongly impact your reputation and will definitely affect your
+ chances to contribute again!
+
+ - The fourth level of importance is in the technical documentation that you
+ may want to add with your code. Technical documentation is always welcome
+ as it helps others make the best use of your work and to go exactly in the
+ direction you thought about during the design. This is also what reduces
+ the risk that your design gets changed in the near future due to a misuse
+ and/or a poor understanding. All such documentation is actually considered
+ as a bonus. It is more important that this documentation exists than that
+ it looks clean. Sometimes just copy-pasting your draft notes in a file to
+ keep a record of design ideas is better than losing them. Please do your
+ best so that other ones can read your doc. If these docs require a special
+ tool such as a graphics utility, ensure that the file name makes it
+ unambiguous how to process it. So there are no rules here for the contents,
+ except one. Please write the date in your file. Design docs tend to stay
+ forever and to remain long after they become obsolete. At this point that
+ can cause harm more than it can help. Writing the date in the document
+ helps developers guess the degree of validity and/or compare them with the
+ date of certain commits touching the same area.
+
+6) All text files and commit messages are written using the US-ASCII charset.
+ Please be careful that your contributions do not contain any character not
+ printable using this charset, as they will render differently in different
+ editors and/or terminals. Avoid latin1 and more importantly UTF-8 which some
+ editors tend to abuse to replace some US-ASCII characters with their
+ typographic equivalent which aren't readable anymore in other editors. The
+ only place where alternative charsets are tolerated is in your name in the
+ commit message, but it's at your own risk as it can be mangled during the
+ merge. Anyway if you have an e-mail address, you probably have a valid
+ US-ASCII representation for it as well.
+
+7) Be careful about comments when you move code around. It's not acceptable that
+ a block of code is moved to another place leaving irrelevant comments at the
+ old place, just like it's not acceptable that a function is duplicated without
+ the comments being adjusted. The example below started to become quite common
+ during the 1.6 cycle, it is not acceptable and wastes everyone's time :
+
+ /* Parse switching <str> to build rule <rule>. Returns 0 on error. */
+ int parse_switching_rule(const char *str, struct rule *rule)
+ {
+ ...
+ }
+
+ /* Parse switching <str> to build rule <rule>. Returns 0 on error. */
+ void execute_switching_rule(struct rule *rule)
+ {
+ ...
+ }
+
+ This patch is not acceptable either (and it's unfortunately not that rare) :
+
+ + if (!session || !arg || list_is_empty(&session->rules->head))
+ + return 0;
+ +
+ /* Check if session->rules is valid before dereferencing it */
+ if (!session->rules_allocated)
+ return 0;
+
+ - if (!arg || list_is_empty(&session->rules->head))
+ - return 0;
+ -
+
+8) Limit the length of your identifiers in the code. When your identifiers start
+ to sound like sentences, it's very hard for the reader to keep on track with
+ what operation they are observing. Also long names force expressions to fit
+ on several lines which also cause some difficulties to the reader. See the
+ example below :
+
+ int file_name_len_including_global_path;
+ int file_name_len_without_global_path;
+ int global_path_len_or_zero_if_default;
+
+ if (global_path)
+ global_path_len_or_zero_if_default = strlen(global_path);
+ else
+ global_path_len_or_zero_if_default = 0;
+
+ file_name_len_without_global_path = strlen(file_name);
+ file_name_len_including_global_path =
+ file_name_len_without_global_path + 1 + /* for '/' */
+ global_path_len_or_zero_if_default ?
+ global_path_len_or_zero_if_default : default_path_len;
+
+ Compare it to this one :
+
+ int f, p;
+
+ p = global_path ? strlen(global_path) : default_path_len;
+ f = p + 1 + strlen(file_name); /* 1 for '/' */
+
+ A good rule of thumb is that if your identifiers start to contain more than
+ 3 words or more than 15 characters, they can become confusing. For function
+ names it's less important especially if these functions are rarely used or
+ are used in a complex context where it is important to differenciate between
+ their multiple variants.
+
+9) Your patches should be sent in "diff -up" format, which is also the format
+ used by Git. This means the "unified" diff format must be used exclusively,
+ and with the function name printed in the diff header of each block. That
+ significantly helps during reviews. Keep in mind that most reviews are done
+ on the patch and not on the code after applying the patch. Your diff must
+ keep some context (3 lines above and 3 lines below) so that there's no doubt
+ where the code has to be applied. Don't change code outside of the context of
+ your patch (eg: take care of not adding/removing empty lines once you remove
+ your debugging code). If you are using Git (which is strongly recommended),
+ please produce your patches using "git format-patch" and not "git diff", and
+ always use "git show" after doing a commit to ensure it looks good, and
+ enable syntax coloring that will automatically report in red the trailing
+ spaces or tabs that your patch added to the code and that must absolutely be
+ removed. These ones cause a real pain to apply patches later because they
+ mangle the context in an invisible way. Such patches with trailing spaces at
+ end of lines will be rejected.
+
+10) Please cut your work in series of patches that can be independantly reviewed
+ and merged. Each patch must do something on its own that you can explain to
+ someone without being ashamed of what you did. For example, you must not say
+ "This is the patch that implements SSL, it was tricky". There's clearly
+ something wrong there, your patch will be huge, will definitely break things
+ and nobody will be able to figure what exactly introduced the bug. However
+ it's much better to say "I needed to add some fields in the session to store
+ the SSL context so this patch does this and doesn't touch anything else, so
+ it's safe". Also when dealing with series, you will sometimes fix a bug that
+ one of your patches introduced. Please do merge these fixes (eg: using git
+ rebase -i and squash or fixup), as it is not acceptable to see patches which
+ introduce known bugs even if they're fixed later. Another benefit of cleanly
+ splitting patches is that if some of your patches need to be reworked after
+ a review, the other ones can still be merged so that you don't need to care
+ about them anymore. When sending multiple patches for review, prefer to send
+ one e-mail per patch than all patches in a single e-mail. The reason is that
+ not everyone is skilled in all areas nor has the time to review everything
+ at once. With one patch per e-mail, it's easy to comment on a single patch
+ without giving an opinion on the other ones, especially if a long thread
+ starts about one specific patch on the mailing list. "git send-email" does
+ that for you though it requires a few trials before getting it right.
+
+11) Please properly format your commit messages. While it's not strictly
+ required to use Git, it is strongly recommended because it helps you do the
+ cleanest job with the least effort. Patches always have the format of an
+ e-mail made of a subject, a description and the actual patch. If you're
+ sending a patch as an e-mail formated this way, it can quickly be applied
+ with limited effort so that's acceptable. But in any case, it is important
+ that there is a clean description of what the patch does, the motivation for
+ what it does, why it's the best way to do it, its impacts, and what it does
+ not yet cover. Also, in HAProxy, like many projects which take a great care
+ of maintaining stable branches, patches are reviewed later so that some of
+ them can be backported to stable releases. While reviewing hundreds of
+ patches can seem cumbersome, with a proper formating of the subject line it
+ actually becomes very easy. For example, here's how one can find patches
+ that need to be reviewed for backports (bugs and doc) between since commit
+ ID 827752e :
+
+ $ git log --oneline 827752e.. | grep 'BUG\|DOC'
+ 0d79cf6 DOC: fix function name
+ bc96534 DOC: ssl: missing LF
+ 10ec214 BUG/MEDIUM: lua: the lua fucntion Channel:close() causes a segf
+ bdc97a8 BUG/MEDIUM: lua: outgoing connection was broken since 1.6-dev2
+ ba56d9c DOC: mention support for RFC 5077 TLS Ticket extension in start
+ f1650a8 DOC: clarify some points about SSL and the proxy protocol
+ b157d73 BUG/MAJOR: peers: fix current table pointer not re-initialized
+ e1ab808 BUG/MEDIUM: peers: fix wrong message id on stick table updates
+ cc79b00 BUG/MINOR: ssl: TLS Ticket Key rotation broken via socket comma
+ d8e42b6 DOC: add new file intro.txt
+ c7d7607 BUG/MEDIUM: lua: bad error processing
+ 386a127 DOC: match several lua configuration option names to those impl
+ 0f4eadd BUG/MEDIUM: counters: ensure that src_{inc,clr}_gpc0 creates a
+
+ It is made possible by the fact that subject lines are properly formated and
+ always respect the same principle : one part indicating the nature and
+ severity of the patch, another one to indicate which subsystem is affected,
+ and the last one is a succint description of the change, with the important
+ part at the beginning so that it's obvious what it does even when lines are
+ truncated like above. The whole stable maintenance process relies on this.
+ For this reason, it is mandatory to respect some easy rules regarding the
+ way the subject is built. Please see the section below for more information
+ regarding this formating.
+
+12) When submitting changes, please always CC the mailing list address so that
+ everyone gets a chance to spot any issue in your code. It will also serve
+ as an advertisement for your work, you'll get more testers quicker and
+ you'll feel better knowing that people really use your work. It is also
+ important to CC any author mentionned in the file you change, or a subsystem
+ maintainers whose address is mentionned in a MAINTAINERS file. Not everyone
+ reads the list on a daily basis so it's very easy to miss some changes.
+ Don't consider it as a failure when a reviewer tells you you have to modify
+ your patch, actually it's a success because now you know what is missing for
+ your work to get accepted. That's why you should not hesitate to CC enough
+ people. Don't copy people who have no deal with your work area just because
+ you found their address on the list. That's the best way to appear careless
+ about their time and make them reject your changes in the future.
+
+
+Patch classifying rules
+-----------------------
+
+There are 3 criteria of particular importance in any patch :
+ - its nature (is it a fix for a bug, a new feature, an optimization, ...)
+ - its importance, which generally reflects the risk of merging/not merging it
+ - what area it applies to (eg: http, stats, startup, config, doc, ...)
+
+It's important to make these 3 criteria easy to spot in the patch's subject,
+because it's the first (and sometimes the only) thing which is read when
+reviewing patches to find which ones need to be backported to older versions.
+It also helps when trying to find which patch is the most likely to have caused
+a regression.
+
+Specifically, bugs must be clearly easy to spot so that they're never missed.
+Any patch fixing a bug must have the "BUG" tag in its subject. Most common
+patch types include :
+
+ - BUG fix for a bug. The severity of the bug should also be indicated
+ when known. Similarly, if a backport is needed to older versions,
+ it should be indicated on the last line of the commit message. If
+ the bug has been identified as a regression brought by a specific
+ patch or version, this indication will be appreciated too. New
+ maintenance releases are generally emitted when a few of these
+ patches are merged. If the bug is a vulnerability for which a CVE
+ identifier was assigned before you publish the fix, you can mention
+ it in the commit message, it will help distro maintainers.
+
+ - CLEANUP code cleanup, silence of warnings, etc... theorically no impact.
+ These patches will rarely be seen in stable branches, though they
+ may appear when they remove some annoyance or when they make
+ backporting easier. By nature, a cleanup is always of minor
+ importance and it's not needed to mention it.
+
+ - DOC updates to any of the documentation files, including README. Many
+ documentation updates are backported since they don't impact the
+ product's stability and may help users avoid bugs. So please
+ indicate in the commit message if a backport is desired. When a
+ feature gets documented, it's preferred that the doc patch appears
+ in the same patch or after the feature patch, but not before, as it
+ becomes confusing when someone working on a code base including
+ only the doc patch won't understand why a documented feature does
+ not work as documented.
+
+ - REORG code reorganization. Some blocks may be moved to other places,
+ some important checks might be swapped, etc... These changes
+ always present a risk of regression. For this reason, they should
+ never be mixed with any bug fix nor functional change. Code is
+ only moved as-is. Indicating the risk of breakage is highly
+ recommended. Minor breakage is tolerated in such patches if trying
+ to fix it at once makes the whole change even more confusing. That
+ may happen for example when some #ifdefs need to be propagated in
+ every file consecutive to the change.
+
+ - BUILD updates or fixes for build issues. Changes to makefiles also fall
+ into this category. The risk of breakage should be indicated if
+ known. It is also appreciated to indicate what platforms and/or
+ configurations were tested after the change.
+
+ - OPTIM some code was optimised. Sometimes if the regression risk is very
+ low and the gains significant, such patches may be merged in the
+ stable branch. Depending on the amount of code changed or replaced
+ and the level of trust the author has in the change, the risk of
+ regression should be indicated.
+
+ - RELEASE release of a new version (development or stable).
+
+ - LICENSE licensing updates (may impact distro packagers).
+
+
+When the patch cannot be categorized, it's best not to put any type tag. This is
+commonly the case for new features, which development versions are mostly made
+of.
+
+Additionally, the importance of the patch or severity of the bug it fixes must
+be indicated when relevant. A single upper-case word is preferred, among :
+
+ - MINOR minor change, very low risk of impact. It is often the case for
+ code additions that don't touch live code. As a rule of thumb, a
+ patch tagged "MINOR" is safe enough to be backported to stable
+ branches. For a bug, it generally indicates an annoyance, nothing
+ more.
+
+ - MEDIUM medium risk, may cause unexpected regressions of low importance or
+ which may quickly be discovered. In short, the patch is safe but
+ touches working areas and it is always possible that you missed
+ something you didn't know existed (eg: adding a "case" entry or
+ an error message after adding an error code to an enum). For a bug,
+ it generally indicates something odd which requires changing the
+ configuration in an undesired way to work around the issue.
+
+ - MAJOR major risk of hidden regression. This happens when large parts of
+ the code are rearranged, when new timeouts are introduced, when
+ sensitive parts of the session scheduling are touched, etc... We
+ should only exceptionally find such patches in stable branches when
+ there is no other option to fix a design issue. For a bug, it
+ indicates severe reliability issues for which workarounds are
+ identified with or without performance impacts.
+
+ - CRITICAL medium-term reliability or security is at risk and workarounds,
+ if they exist, might not always be acceptable. An upgrade is
+ absolutely required. A maintenance release may be emitted even if
+ only one of these bugs are fixed. Note that this tag is only used
+ with bugs. Such patches must indicate what is the first version
+ affected, and if known, the commit ID which introduced the issue.
+
+The expected length of the commit message grows with the importance of the
+change. While a MINOR patch may sometimes be described in 1 or 2 lines, MAJOR
+or CRITICAL patches cannot have less than 10-15 lines to describe exactly the
+impacts otherwise the submitter's work will be considered as rough sabotage.
+
+For BUILD, DOC and CLEANUP types, this tag is not always relevant and may be
+omitted.
+
+The area the patch applies to is quite important, because some areas are known
+to be similar in older versions, suggesting a backport might be desirable, and
+conversely, some areas are known to be specific to one version. The area is a
+single-word lowercase name the contributor find clear enough to describe what
+part is being touched. The following tags are suggested but not limitative :
+
+ - examples example files. Be careful, sometimes these files are packaged.
+
+ - tests regression test files. No code is affected, no need to upgrade.
+
+ - init initialization code, arguments parsing, etc...
+
+ - config configuration parser, mostly used when adding new config keywords
+
+ - http the HTTP engine
+
+ - stats the stats reporting engine
+
+ - cli the stats socket CLI
+
+ - checks the health checks engine (eg: when adding new checks)
+
+ - sample the sample fetch system (new fetch or converter functions)
+
+ - acl the ACL processing core or some ACLs from other areas
+
+ - peers the peer synchronization engine
+
+ - lua the Lua scripting engine
+
+ - listeners everything related to incoming connection settings
+
+ - frontend everything related to incoming connection processing
+
+ - backend everything related to LB algorithms and server farm
+
+ - session session processing and flags (very sensible, be careful)
+
+ - server server connection management, queueing
+
+ - ssl the SSL/TLS interface
+
+ - proxy proxy maintenance (start/stop)
+
+ - log log management
+
+ - poll any of the pollers
+
+ - halog the halog sub-component in the contrib directory
+
+ - contrib any addition to the contrib directory
+
+Other names may be invented when more precise indications are meaningful, for
+instance : "cookie" which indicates cookie processing in the HTTP core. Last,
+indicating the name of the affected file is also a good way to quickly spot
+changes. Many commits were already tagged with "stream_sock" or "cfgparse" for
+instance.
+
+It is required that the type of change and the severity when relevant are
+indicated, as well as the touched area when relevant as well in the patch
+subject. Normally, we would have the 3 most often. The two first criteria should
+be present before a first colon (':'). If both are present, then they should be
+delimited with a slash ('/'). The 3rd criterion (area) should appear next, also
+followed by a colon. Thus, all of the following messages are valid :
+
+Examples of messages :
+ - DOC: document options forwardfor to logasap
+ - DOC/MAJOR: reorganize the whole document and change indenting
+ - BUG: stats: connection reset counters must be plain ascii, not HTML
+ - BUG/MINOR: stats: connection reset counters must be plain ascii, not HTML
+ - MEDIUM: checks: support multi-packet health check responses
+ - RELEASE: Released version 1.4.2
+ - BUILD: stats: stdint is not present on solaris
+ - OPTIM/MINOR: halog: make fgets parse more bytes by blocks
+ - REORG/MEDIUM: move syscall redefinition to specific places
+
+Please do not use square brackets anymore around the tags, because they induce
+more work when merging patches, which need to be hand-edited not to lose the
+enclosed part.
+
+In fact, one of the only square bracket tags that still makes sense is '[RFC]'
+at the beginning of the subject, when you're asking for someone to review your
+change before getting it merged. If the patch is OK to be merged, then it can
+be merge as-is and the '[RFC]' tag will automatically be removed. If you don't
+want it to be merged at all, you can simply state it in the message, or use an
+alternate 'WIP/' prefix in front of your tag tag ("work in progress").
+
+The tags are not rigid, follow your intuition first, and they may be readjusted
+when your patch is merged. It may happen that a same patch has a different tag
+in two distinct branches. The reason is that a bug in one branch may just be a
+cleanup or safety measure in the other one because the code cannot be triggered.
+
+
+Working with Git
+----------------
+
+For a more efficient interaction between the mainline code and your code, you
+are strongly encouraged to try the Git version control system :
+
+ http://git-scm.com/
+
+It's very fast, lightweight and lets you undo/redo your work as often as you
+want, without making your mistakes visible to the rest of the world. It will
+definitely help you contribute quality code and take other people's feedback
+in consideration. In order to clone the HAProxy Git repository :
+
+ $ git clone http://git.haproxy.org/git/haproxy.git/ (development)
+
+If you decide to use Git for your developments, then your commit messages will
+have the subject line in the format described above, then the whole description
+of your work (mainly why you did it) will be in the body. You can directly send
+your commits to the mailing list, the format is convenient to read and process.
+
+It is recommended to create a branch for your work that is based on the master
+branch :
+
+ $ git checkout -b 20150920-fix-stats master
+
+You can then do your work and even experiment with multiple alternatives if you
+are not completely sure that your solution is the best one :
+
+ $ git checkout -b 20150920-fix-stats-v2
+
+Then reorder/merge/edit your patches :
+
+ $ git rebase -i master
+
+When you think you're ready, reread your whole patchset to ensure there is no
+formating or style issue :
+
+ $ git show master..
+
+And once you're satisfied, you should update your master branch to be sure that
+nothing changed during your work (only neede if you left it unattended for days
+or weeks) :
+
+ $ git checkout -b 20150920-fix-stats-rebased
+ $ git fetch origin master:master
+ $ git rebase master
+
+They can build a list of patches ready for submission like this :
+
+ $ git format-patch master
+
+The output files are the patches ready to be sent over e-mail, either via a
+regular e-mail or via git send-email (carefully check the man page). Don't
+destroy your other work branches until your patches get merged, it may happen
+that earlier designs will be preferred for various reasons. Patches should be
+sent to the mailing list : haproxy@formilux.org and CCed to relevant subsystem
+maintainers or authors of the modified files if their address appears at the
+top of the file.
+
+Please don't send pull-requests, they are really unconvenient. First, a pull
+implies a merge operation and the code doesn't move fast enough to justify the
+use of merges. Second, pull requests are not easily commented on by the
+project's participants, contrary to e-mails where anyone is allowed to have an
+opinion and to express it.
+
+-- end