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authorHumble Devassy Chirammal <hchiramm@redhat.com>2015-04-01 17:09:28 +0530
committerKaleb KEITHLEY <kkeithle@redhat.com>2015-04-02 07:48:18 -0700
commit08d35497e30714058002b4b0095171f1dad73ddc (patch)
tree22b7a6fe6adaa2f7ca1b19daf6abad7b2cd92fec /doc/developer-guide/coding-standard.tex
parent664604742770f7fcce2c7293074aa1e2d04b797b (diff)
doc: remove latex and pdf files
Change-Id: I45443e763836c440f9e1ed83f34de486dbfe8ac8 BUG: 1206539 Signed-off-by: Humble Devassy Chirammal <hchiramm@redhat.com> Reviewed-on: http://review.gluster.org/10089 Tested-by: Gluster Build System <jenkins@build.gluster.com> Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
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-\documentclass{article}[12pt]
-\usepackage{color}
-
-\begin{document}
-
-
-\hrule
-\begin{center}\textbf{\Large{GlusterFS Coding Standards}}\end{center}
-\begin{center}\textbf{\large{\textcolor{red}{Z} Research}}\end{center}
-\begin{center}{July 14, 2008}\end{center}
-\hrule
-
-\vspace{8ex}
-
-\section*{$\bullet$ Structure definitions should have a comment per member}
-
-Every member in a structure definition must have a comment about its
-purpose. The comment should be descriptive without being overly verbose.
-
-\vspace{2ex}
-\textsl{Bad}:
-
-\begin{verbatim}
- gf_lock_t lock; /* lock */
-\end{verbatim}
-
-\textsl{Good}:
-
-\begin{verbatim}
- DBTYPE access_mode; /* access mode for accessing
- * the databases, can be
- * DB_HASH, DB_BTREE
- * (option access-mode <mode>)
- */
-\end{verbatim}
-
-\section*{$\bullet$ Declare all variables at the beginning of the function}
-All local variables in a function must be declared immediately after the
-opening brace. This makes it easy to keep track of memory that needs to be freed
-during exit. It also helps debugging, since gdb cannot handle variables
-declared inside loops or other such blocks.
-
-\section*{$\bullet$ Always initialize local variables}
-Every local variable should be initialized to a sensible default value
-at the point of its declaration. All pointers should be initialized to NULL,
-and all integers should be zero or (if it makes sense) an error value.
-
-\vspace{2ex}
-
-\textsl{Good}:
-
-\begin{verbatim}
- int ret = 0;
- char *databuf = NULL;
- int _fd = -1;
-\end{verbatim}
-
-\section*{$\bullet$ Initialization should always be done with a constant value}
-Never use a non-constant expression as the initialization value for a variable.
-
-\vspace{2ex}
-
-\textsl{Bad}:
-
-\begin{verbatim}
- pid_t pid = frame->root->pid;
- char *databuf = malloc (1024);
-\end{verbatim}
-
-\section*{$\bullet$ Validate all arguments to a function}
-All pointer arguments to a function must be checked for \texttt{NULL}.
-A macro named \texttt{VALIDATE} (in \texttt{common-utils.h})
-takes one argument, and if it is \texttt{NULL}, writes a log message and
-jumps to a label called \texttt{err} after setting op\_ret and op\_errno
-appropriately. It is recommended to use this template.
-
-\vspace{2ex}
-
-\textsl{Good}:
-
-\begin{verbatim}
- VALIDATE(frame);
- VALIDATE(this);
- VALIDATE(inode);
-\end{verbatim}
-
-\section*{$\bullet$ Never rely on precedence of operators}
-Never write code that relies on the precedence of operators to execute
-correctly. Such code can be hard to read and someone else might not
-know the precedence of operators as accurately as you do.
-\vspace{2ex}
-
-\textsl{Bad}:
-
-\begin{verbatim}
- if (op_ret == -1 && errno != ENOENT)
-\end{verbatim}
-
-\textsl{Good}:
-
-\begin{verbatim}
- if ((op_ret == -1) && (errno != ENOENT))
-\end{verbatim}
-
-\section*{$\bullet$ Use exactly matching types}
-Use a variable of the exact type declared in the manual to hold the
-return value of a function. Do not use an ``equivalent'' type.
-
-\vspace{2ex}
-
-\textsl{Bad}:
-
-\begin{verbatim}
- int len = strlen (path);
-\end{verbatim}
-
-\textsl{Good}:
-
-\begin{verbatim}
- size_t len = strlen (path);
-\end{verbatim}
-
-\section*{$\bullet$ Never write code such as \texttt{foo->bar->baz}; check every pointer}
-Do not write code that blindly follows a chain of pointer
-references. Any pointer in the chain may be \texttt{NULL} and thus
-cause a crash. Verify that each pointer is non-null before following
-it.
-
-\section*{$\bullet$ Check return value of all functions and system calls}
-The return value of all system calls and API functions must be checked
-for success or failure.
-
-\vspace{2ex}
-\textsl{Bad}:
-
-\begin{verbatim}
- close (fd);
-\end{verbatim}
-
-\textsl{Good}:
-
-\begin{verbatim}
- op_ret = close (_fd);
- if (op_ret == -1) {
- gf_log (this->name, GF_LOG_ERROR,
- "close on file %s failed (%s)", real_path,
- strerror (errno));
- op_errno = errno;
- goto out;
- }
-\end{verbatim}
-
-
-\section*{$\bullet$ Gracefully handle failure of malloc}
-GlusterFS should never crash or exit due to lack of memory. If a
-memory allocation fails, the call should be unwound and an error
-returned to the user.
-
-\section*{$\bullet$ Use result args and reserve the return value to indicate success or failure}
-The return value of every functions must indicate success or failure (unless
-it is impossible for the function to fail --- e.g., boolean functions). If
-the function needs to return additional data, it must be returned using a
-result (pointer) argument.
-
-\vspace{2ex}
-\textsl{Bad}:
-
-\begin{verbatim}
- int32_t dict_get_int32 (dict_t *this, char *key);
-\end{verbatim}
-
-\textsl{Good}:
-
-\begin{verbatim}
- int dict_get_int32 (dict_t *this, char *key, int32_t *val);
-\end{verbatim}
-
-\section*{$\bullet$ Always use the `n' versions of string functions}
-Unless impossible, use the length-limited versions of the string functions.
-
-\vspace{2ex}
-\textsl{Bad}:
-
-\begin{verbatim}
- strcpy (entry_path, real_path);
-\end{verbatim}
-
-\textsl{Good}:
-
-\begin{verbatim}
- strncpy (entry_path, real_path, entry_path_len);
-\end{verbatim}
-
-\section*{$\bullet$ No dead or commented code}
-There must be no dead code (code to which control can never be passed) or
-commented out code in the codebase.
-
-\section*{$\bullet$ Only one unwind and return per function}
-There must be only one exit out of a function. \texttt{UNWIND} and return
-should happen at only point in the function.
-
-\section*{$\bullet$ Function length or Keep functions small}
-We live in the UNIX-world where modules do one thing and do it well.
-This rule should apply to our functions also. If a function is very long, try splitting it
-into many little helper functions. The question is, in a coding
-spree, how do we know a function is long and unreadable. One rule of
-thumb given by Linus Torvalds is that, a function should be broken-up
-if you have 4 or more levels of indentation going on for more than 3-4
-lines.
-
-\vspace{2ex}
-\textsl{Example for a helper function}:
-\begin{verbatim}
- static int
- same_owner (posix_lock_t *l1, posix_lock_t *l2)
- {
- return ((l1->client_pid == l2->client_pid) &&
- (l1->transport == l2->transport));
- }
-\end{verbatim}
-
-\section*{$\bullet$ Defining functions as static}
-Define internal functions as static only if you're
-very sure that there will not be a crash(..of any kind..) emanating in
-that function. If there is even a remote possibility, perhaps due to
-pointer derefering, etc, declare the function as non-static. This
-ensures that when a crash does happen, the function name shows up the
-in the back-trace generated by libc. However, doing so has potential
-for polluting the function namespace, so to avoid conflicts with other
-components in other parts, ensure that the function names are
-prepended with a prefix that identify the component to which it
-belongs. For eg. non-static functions in io-threads translator start
-with iot\_.
-
-\section*{$\bullet$ Ensure function calls wrap around after
-80-columns.}
-Place remaining arguments on the next line if needed.
-
-\section*{$\bullet$ Functions arguments and function definition}
-Place all the arguments of a function definition on the same line
-until the line goes beyond 80-cols. Arguments that extend beyind
-80-cols should be placed on the next line.
-
-\section*{Style issues}
-
-\subsection*{Brace placement}
-Use K\&R/Linux style of brace placement for blocks.
-
-\textsl{Example}:
-\begin{verbatim}
- int some_function (...)
- {
- if (...) {
- /* ... */
- } else if (...) {
- /* ... */
- } else {
- /* ... */
- }
-
- do {
- /* ... */
- } while (cond);
- }
-\end{verbatim}
-
-\subsection*{Indentation}
-Use \textbf{eight} spaces for indenting blocks. Ensure that your
-file contains only spaces and not tab characters. You can do this
-in Emacs by selecting the entire file (\texttt{C-x h}) and
-running \texttt{M-x untabify}.
-
-To make Emacs indent lines automatically by eight spaces, add this
-line to your \texttt{.emacs}:
-
-\begin{verbatim}
- (add-hook 'c-mode-hook (lambda () (c-set-style "linux")))
-\end{verbatim}
-
-\subsection*{Comments}
-Write a comment before every function describing its purpose (one-line),
-its arguments, and its return value. Mention whether it is an internal
-function or an exported function.
-
-Write a comment before every structure describing its purpose, and
-write comments about each of its members.
-
-Follow the style shown below for comments, since such comments
-can then be automatically extracted by doxygen to generate
-documentation.
-
-\textsl{Example}:
-\begin{verbatim}
-/**
- * hash_name -hash function for filenames
- * @par: parent inode number
- * @name: basename of inode
- * @mod: number of buckets in the hashtable
- *
- * @return: success: bucket number
- * failure: -1
- *
- * Not for external use.
- */
-\end{verbatim}
-
-\subsection*{Indicating critical sections}
-To clearly show regions of code which execute with locks held, use
-the following format:
-
-\begin{verbatim}
- pthread_mutex_lock (&mutex);
- {
- /* code */
- }
- pthread_mutex_unlock (&mutex);
-\end{verbatim}
-
-\section*{A skeleton fop function}
-This is the recommended template for any fop. In the beginning come
-the initializations. After that, the `success' control flow should be
-linear. Any error conditions should cause a \texttt{goto} to a single
-point, \texttt{out}. At that point, the code should detect the error
-that has occurred and do appropriate cleanup.
-
-\begin{verbatim}
-int32_t
-sample_fop (call_frame_t *frame, xlator_t *this, ...)
-{
- char * var1 = NULL;
- int32_t op_ret = -1;
- int32_t op_errno = 0;
- DIR * dir = NULL;
- struct posix_fd * pfd = NULL;
-
- VALIDATE_OR_GOTO (frame, out);
- VALIDATE_OR_GOTO (this, out);
-
- /* other validations */
-
- dir = opendir (...);
-
- if (dir == NULL) {
- op_errno = errno;
- gf_log (this->name, GF_LOG_ERROR,
- "opendir failed on %s (%s)", loc->path,
- strerror (op_errno));
- goto out;
- }
-
- /* another system call */
- if (...) {
- op_errno = ENOMEM;
- gf_log (this->name, GF_LOG_ERROR,
- "out of memory :(");
- goto out;
- }
-
- /* ... */
-
- out:
- if (op_ret == -1) {
-
- /* check for all the cleanup that needs to be
- done */
-
- if (dir) {
- closedir (dir);
- dir = NULL;
- }
-
- if (pfd) {
- FREE (pfd->path);
- FREE (pfd);
- pfd = NULL;
- }
- }
-
- STACK_UNWIND (frame, op_ret, op_errno, fd);
- return 0;
-}
-\end{verbatim}
-
-\end{document}