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diff --git a/CONTRIBUTING b/CONTRIBUTING new file mode 100644 index 0000000..60a78ba --- /dev/null +++ b/CONTRIBUTING @@ -0,0 +1,1020 @@ + 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 IGNORED IN ORDER TO PROTECT ALL OTHER +RESPECTFUL CONTRIBUTORS' VALUABLE TIME. + + +Abstract +-------- + +If you have never contributed to HAProxy before, or if you did so and noticed +that nobody seems to be interested in reviewing your submission, please do read +this long document carefully. HAProxy maintainers are particularly demanding on +respecting certain simple rules related to general code and documentation style +as well as splitting your patches and providing high quality commit messages. +The reason behind this is that your patch will be met multiple times in the +future, when doing some backporting work or when bisecting a bug, and it is +critical that anyone can quickly decide if the patch is right, wrong, if it +misses something, if it must be reverted or needs to be backported. Maintainers +are generally benevolent with newcomers and will help them provided their work +indicates they have at least read this document. Some have improved over time, +to the point of being totally trusted and gaining commit access so they don't +need to depend on anyone to pick their code. On the opposite, those who insist +not making minimal efforts however will simply be ignored. + + +Background +---------- + +HAProxy is a community-driven project. But like most highly technical projects +it takes a lot of time to develop the skills necessary to be autonomous in the +project, and there is a very small core team helped by a small set of very +active participants. While most of the core team members work on the code as +part of their day job, most participants do it on a voluntary basis during +their spare time. The ideal model for developers is to spend their time: + 1) developing new features + 2) fixing bugs + 3) doing maintenance backports + 4) reviewing other people's code + +It turns out that on a project like HAProxy, like many other similarly complex +projects, the time spent is exactly the opposite: + 1) reviewing other people's code + 2) doing maintenance backports + 3) fixing bugs + 4) developing new features + +A large part of the time spent reviewing code often consists in giving basic +recommendations that are already explained in this file. In addition to taking +time, it is not appealing for people willing to spend one hour helping others +to do the same thing over and over instead of discussing the code design, and +it tends to delay the start of code reviews. + +Regarding backports, they are necessary to provide a set of stable branches +that are deployed in production at many places. Load balancers are complex and +new features often induce undesired side effects in other areas, which we will +call bugs. Thus it's common for users to stick to a branch featuring everything +they need and not to upgrade too often. This backporting job is critical to the +ecosystem's health and must be done regularly. Very often the person devoting +some time on backports has little to no information about the relevance (let +alone importance) of a patch and is unlikely to be an expert in the area +affected by the patch. It's the role of the commit message to explain WHAT +problem the patch tries to solve, WHY it is estimated that it is a problem, and +HOW it tries to address it. With these elements, the person in charge of the +backports can decide whether or not to pick the patch. And if the patch does +not apply (which is common for older versions) they have information in the +commit message about the principle and choices that the initial developer made +and will try to adapt the patch sticking to these principles. Thus, the time +spent backporting patches solely depends on the code quality and the commit +message details and accuracy. + +When it turns to fixing bugs, before declaring a bug, there is an analysis +phase. It starts with "is this behaviour expected", "is it normal", "under what +circumstances does it happen", "when did it start to happen", "was it intended", +"was it just overlooked", and "how to fix it without breaking the initial +intent". A utility called "git bisect" is usually involved in determining when +the behaviour started to happen. It determines the first patch which introduced +the new behaviour. If the patch is huge, touches many areas, is really difficult +to read because it needlessly reindents code or adds/removes line breaks out of +context, it will be very difficult to figure what part of this patch broke the +behaviour. Then once the part is figured, if the commit message doesn't provide +a detailed description about the intent of the patch, i.e. the problem it was +trying to solve, why and how, the developer landing on that patch will really +feel powerless. And very often in this case, the fix for the problem will break +something else or something that depended on the original patch. + +But contrary to what it could look like, providing great quality patches is not +difficult, and developers will always help contributors improve their patches +quality because it's in their interest as well. History has shown that first +time contributors can provide an excellent work when they have carefully read +this document, and that people coming from projects with different practices +can grow from first-time contributor to trusted committer in about 6 months. + + +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 + +It is not even necessary to subscribe, you can post there and verify via the +public list archives that your message was properly delivered. In this case you +should indicate in your message that you'd like responders to keep you CCed. +Please visit http://haproxy.org/ to figure available options to join the list. + +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 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. Just prefix your mail subject with "RFC" (it stands for +"request for comments") and everyone will understand you'd like some opinion +on your work in progress. 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 (unless you need some help on the doc itself, of course). + +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. Please read doc/coding-style.txt for all the +details. + +When modifying some optional subsystem (SSL, Lua, compression, device detection +engines), please make sure the code continues to build (and to work) when these +features are disabled. Similarly, when modifying the SSL stack, please always +ensure that supported OpenSSL versions continue to build and to work, especially +if you modify support for alternate libraries. Clean support for the legacy +OpenSSL libraries is mandatory, support for its derivatives is a bonus and may +occasionally break even though a great care is taken. In other words, if you +provide a patch for OpenSSL you don't need to test its derivatives, but if you +provide a patch for a derivative you also need to test with OpenSSL. + +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, if you get a response at +all. Retransmit if you don't get a response by one week. Please note that +direct sent e-mails to this address for non-confidential subjects may simply +be forwarded to the list or be deleted without notification. An auto-responder +bot is in place to try to detect e-mails from people asking for help and to +redirect them to the mailing list. Do not be surprised if this happens to you. + +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. + +The version control system used by the project (Git) keeps authorship +information in the form of the patch author's e-mail address. This way you will +be credited for your work in the project's history. If you contract with +someone to implement your idea you may have to discuss such modalities with +the person doing the work as by default this person will be mentioned as the +work's author. + + +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) Comply with the license + + 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 mentioned 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) Develop on development branch, not stable ones + + 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) Read and respect the coding style + + You have read and understood "doc/coding-style.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 formatted 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) Present clean work + + 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) Documentation is very important + + 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 them 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) US-ASCII only! + + 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) Comments + + 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) Short, readable identifiers + + 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 differentiate between + their multiple variants. + +9) Unified diff only + + The best way to build your patches is to use "git format-patch". This means + that you have committed your patch to a local branch, with an appropriate + subject line and a useful commit message explaining what the patch attempts + to do. It is not strictly required to use git, but what is strictly required + is to have all these elements in the same mail, easily distinguishable, and + a patch 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), + 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) One patch per feature + + Please cut your work in series of patches that can be independently 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. + + If you can, please always put all the bug fixes at the beginning of the + series. This often makes it easier to backport them because they will not + depend on context that your other patches changed. As a hint, if you can't + do this, there are little chances that your bug fix can be backported. + +11) Real commit messages please! + + The commit message is how you're trying to convince a maintainer to adopt + your work and maintain it as long as possible. A dirty commit message almost + always comes with dirty code. Too short a commit message indicates that too + short an analysis was done and that side effects are extremely likely to be + encountered. It's the maintainer's job to decide to accept this work in its + current form or not, with the known constraints. Some patches which rework + architectural parts or fix sensitive bugs come with 20-30 lines of design + explanations, limitations, hypothesis or even doubts, and despite this it + happens when reading them 6 months later while trying to identify a bug that + developers still miss some information about corner cases. + + So please properly format your commit messages. To get an idea, just run + "git log" on the file you've just modified. Patches always have the format + of an e-mail made of a subject, a description and the actual patch. If you + are sending a patch as an e-mail formatted this way, it can quickly be + applied with limited effort so that's acceptable : + + - A subject line (may wrap to the next line, but please read below) + - an empty line (subject delimiter) + - a non-empty description (the body of the e-mail) + - the patch itself + + The subject describes the "What" of the change ; the description explains + the "why", the "how" and sometimes "what next". For example a commit message + looking like this will be rejected : + + | From: Mr Foobar <foobar@example.com> + | Subject: BUG: fix typo in ssl_sock + | + + This one as well (too long subject, not the right place for the details) : + + | From: Mr Foobar <foobar@example.com> + | Subject: BUG/MEDIUM: ssl: use an error flag to prevent ssl_read() from + | returning 0 when dealing with large buffers because that can cause + | an infinite loop + | + + This one ought to be used instead : + + | From: Mr Foobar <foobar@example.com> + | Subject: BUG/MEDIUM: ssl: fix risk of infinite loop in ssl_sock + | + | ssl_read() must not return 0 on error or the caller may loop forever. + | Instead we add a flag to the connection to notify about the error and + | check it at all call places. This situation can only happen with large + | buffers so a workaround is to limit buffer sizes. Another option would + | have been to return -1 but it required to use signed ints everywhere + | and would have made the patch larger and riskier. This fix should be + | backported to versions 1.2 and upper. + + It is important to understand that for any reader to guess the text above + when it's absent, it will take a huge amount of time. If you made the + analysis leading to your patch, you must explain it, including the ideas + you dropped if you had a good reason for this. + + 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. But if you + are comfortable with writing clean e-mails and inserting your patches, you + don't need to use Git. + + 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. And this is particularly + important for bugs. A patch tagged "BUG" must absolutely explain what the + problem is, why it is considered as a bug. Anybody, even non-developers, + should be able to tell whether or not a patch is likely to address an issue + they are facing. Indicating what the code will do after the fix doesn't help + if it does not say what problem is encountered without the patch. Note that + in some cases the bug is purely theoretical and observed by reading the code. + In this case it's perfectly fine to provide an estimate about possible + effects. 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 + formatting 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 function 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 formatted 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 succinct 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 formatting. + + As a rule of thumb, your patch MUST NEVER be made only of a subject line, + it *must* contain a description. Even one or two lines, or indicating + whether a backport is desired or not. It turns out that single-line commits + are so rare in the Git world that they require special manual (hence + painful) handling when they are backported, and at least for this reason + it's important to keep this in mind. + + Maintainers who pick your patch may slightly adjust the description as they + see fit. Do not see this as a failure to do a clean job, it just means they + think it will help them do their daily job this way. The code may also be + slightly adjusted before being merged (non-functional changes only, fix for + typos, tabs vs spaces for example), unless your patch contains a + Signed-off-By tag, in which case they will either modify it and mention the + changes after your Signed-off-By line, or (more likely) ask you to perform + these changes yourself. This ability to slightly adjust a patch before + merging is is the main reason for not using pull requests which do not + provide this facility and will require to iterate back and forth with the + submitter and significantly delay the patch inclusion. + + Each patch fixing a bug MUST be tagged with "BUG", a severity level, an + indication of the affected subsystem and a brief description of the nature + of the issue in the subject line, and a detailed analysis in the message + body. The explanation of the user-visible impact and the need for + backporting to stable branches or not are MANDATORY. Bug fixes with no + indication will simply be rejected as they are very likely to cause more + harm when nobody is able to tell whether or not the patch needs to be + backported or can be reverted in case of regression. + + When fixing a bug which is reproducible, if possible, the contributors are + strongly encouraged to write a regression testing VTC file for varnishtest + to add to reg-tests directory. More information about varnishtest may be + found in README file of reg-tests directory and in doc/regression-testing.txt + file. + +12) Discuss on the mailing list + + Note, some first-time contributors might feel impressed or scared by posting + to a list. This list is frequented only by nice people who are willing to + help you polish your work so that it is perfect and can last long. What you + think could be perceived as a proof of incompetence or lack of care will + instead be a proof of your ability to work with a community. You will not be + judged nor blamed for making mistakes. The project maintainers are the ones + creating the most bugs and mistakes anyway, and nobody knows the project in + its entirety anymore so you're just like anyone else. And people who have no + consideration for other's work are quickly ejected from the list so the + place is as safe and welcoming to new contributors as it is to long time + ones. + + 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's often + convenient to prepend "[PATCH]" in front of your mail's subject to mention + that this e-mail contains a patch (or a series of patches), because it will + easily catch reviewer's attention. It's automatically done by tools such as + "git format-patch" and "git send-email". If you don't want your patch to be + merged yet and prefer to show it for discussion, better tag it as "[RFC]" + (stands for "Request For Comments") and it will be reviewed but not merged + without your approval. It is also important to CC any author mentioned in + the file you change, or a subsystem maintainers whose address is mentioned + 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. The + commit message MUST ABSOLUTELY describe the problem and its impact + to non-developers. Any user must be able to guess if this patch is + likely to fix a problem they are facing. Even if the bug was + discovered by accident while reading the code or running an + automated tool, it is mandatory to try to estimate what potential + issue it might cause and under what circumstances. There may even + be security implications sometimes so a minimum analysis is really + required. Also please think about stable maintainers who have to + build the release notes, they need to have enough input about the + bug's impact to explain it. 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... theoretically 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. If the optimization depends on the + architecture or on build options, it is important to verify that + the code continues to work without it. + + - RELEASE release of a new version (development or stable). + + - LICENSE licensing updates (may impact distro packagers). + + - REGTEST updates to any of the regression testing files found in reg-tests + directory, including README or any documentation file. + + +When the patch cannot be categorized, it's best not to put any type tag, and to +only use a risk or complexity information only as below. This is commonly the +case for new features, which development versions are mostly made of. + +The importance, complexity 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. +If you are sending a new patch series after a review, it is generally good to +enumerate at the end of the commit description what changed from the previous +one as it helps reviewers quickly glance over such changes and not re-read the +rest. + +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 list of tags is suggested but not +exhaustive: + + - examples example files. Be careful, sometimes these files are packaged. + + - tests regression test files. No code is affected, no need to upgrade. + + - reg-tests regression test files for varnishtest. 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 + + - filters everything related to the filters core + + - 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 + + - spoe SPOE code + + - 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 admin directory + + - htx general HTX subsystem + + - mux-h1 HTTP/1.x multiplexer/demultiplexer + + - mux-h2 HTTP/2 multiplexer/demultiplexer + + - h1 general HTTP/1.x protocol parser + + - h2 general HTTP/2 protocol parser + +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 subject lines are valid : + +Examples of subject lines : + - 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 +formatting 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 needed if you left it unattended for days +or weeks) : + + $ git checkout -b 20150920-fix-stats-rebased + $ git fetch origin master:master + $ git rebase master + +You 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 inconvenient as they make it +much more complicate to perform minor adjustments, and nobody benefits from +any comment on the code while on a list all subscribers learn a little bit on +each review of anyone else's code. + + +What to do if your patch is ignored +----------------------------------- + +All patches merged are acknowledged by the maintainer who picked it. If you +didn't get an acknowledgement, check the mailing list archives to see if your +mail was properly delivered there and possibly if anyone responded and you did +not get their response (please look at http://haproxy.org/ for the mailing list +archive's address). + +If you see that your mail is there but nobody responded, please recheck: + - was the subject clearly indicating that it was a patch and/or that you were + seeking some review? + + - was your email mangled by your mail agent? If so it's possible that + nobody had the willingness yet to mention it. + + - was your email sent as HTML? If so it definitely ended in spam boxes + regardless of the archives. + + - did the patch violate some of the principles explained in this document? + +If none of these cases matches, it might simply be that everyone was busy when +your patch was sent and that it was overlooked. In this case it's fine to +either resubmit it or respond to your own email asking if anything's wrong +about it. In general don't expect a response after one week of silence, just +because your email will not appear in anyone else's current window. So after +one week it's time to resubmit. + +Among the mistakes that tend to make reviewers not respond are those who send +multiple versions of a patch in a row. It's natural for others then to wait for +the series to stabilize. And once it doesn't move anymore everyone forgot about +it. As a rule of thumb, if you have to update your original email more than +twice, first double-check that your series is really ready for submission, and +second, start a new thread and stop responding to the previous one. In this +case it is well appreciated to mention a version of your patch set in the +subject such as "[PATCH v2]", so that reviewers can immediately spot the new +version and not waste their time on the old one. + +If you still do not receive any response, it is possible that you've already +played your last card by not respecting the basic principles multiple times +despite being told about it several times, and that nobody is willing to spend +more of their time than normally needed with your work anymore. Your best +option at this point probably is to ask "did I do something wrong" than to +resend the same patches. + + +How to be sure to irritate everyone +----------------------------------- + +Among the best ways to quickly lose everyone's respect, there is this small +selection, which should help you improve the way you work with others, if +you notice you're already practising some of them: + - repeatedly send improperly formatted commit messages, with no type or + severity, or with no commit message body. These ones require manual + edition, maintainers will quickly learn to recognize your name. + + - repeatedly send patches which break something, and disappear or take a long + time to provide a fix. + + - fail to respond to questions related to features you have contributed in + the past, which can further lead to the feature being declared unmaintained + and removed in a future version. + + - send a new patch iteration without taking *all* comments from previous + review into consideration, so that the reviewer discovers they have to do + the exact same work again. + + - "hijack" an existing thread to discuss something different or promote your + work. This will generally make you look like a fool so that everyone wants + to stay away from your e-mails. + + - continue to send pull requests after having been explained why they are not + welcome. + + - give wrong advices to people asking for help, or sending them patches to + try which make no sense, waste their time, and give them a bad impression + of the people working on the project. + + - be disrespectful to anyone asking for help or contributing some work. This + may actually even get you kicked out of the list and banned from it. + +-- end |