Redis static function not used at all

Question

When I am browsing Redis source on github, I found lost of static functions in source files that are not referenced by anyone within the same file at which it was defined. Since the static function can be only accessed within the same file, these functions are not used at all!

Following is a example code snippet from src/ae_epoll.c:

static int aeApiAddEvent(aeEventLoop *eventLoop, int fd, int mask) {
    aeApiState *state = eventLoop->apidata;
    struct epoll_event ee = {0}; /* avoid valgrind warning */
    /* If the fd was already monitored for some event, we need a MOD
     * operation. Otherwise we need an ADD operation. */
    int op = eventLoop->events[fd].mask == AE_NONE ?
        EPOLL_CTL_ADD : EPOLL_CTL_MOD;
    ee.events = 0;
    mask |= eventLoop->events[fd].mask; /* Merge old events */
    if (mask & AE_READABLE) ee.events |= EPOLLIN;
    if (mask & AE_WRITABLE) ee.events |= EPOLLOUT;
    ee.data.fd = fd;
    if (epoll_ctl(state->epfd,op,fd,&ee) == -1) return -1;
    return 0;
}

And you will find that the function aeApiAddEvent is not used locally. Such unused static functions are found in many difference files.

Why defined but not used ? Am I missing some points ?

alinsoar · Accepted Answer · 2019-03-16T17:11:08.493

0

the static function can be only accessed within the same file

This is false. Correct is to say that they can be accessed only inside the same translation unit.

The file can be included from somewhere.

So, the reason that they include .c files is that, depending on some configuration parameter, they will choose different code to compile.

See here.

They are included from the file here.

edited Mar 16 '19 at 17:11

answered Mar 16 '19 at 16:52

alinsoar

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Who does include .c files? Definitely not – 0___________ Mar 16 '19 at 16:53
@P__J__ There are lots of situations where the .C files are included – alinsoar Mar 16 '19 at 16:54
No - including .c files is wrong for many reasons - you can find many posts about here on the SO. If you include .c file it is a very bad practice. – 0___________ Mar 16 '19 at 16:55
@P__J__ Then Fabrice Bellard, who wrote a lot of C code, is an idiot. Hehe :) – alinsoar Mar 16 '19 at 16:57
Very bad habit. This should be done on the autoconf/makefile level - ie the correct project should be generated and the correct files should be compiled and linked but not included. Maybe he does not know how to use autoconf? – 0___________ Mar 16 '19 at 16:58
Correct answer. I miss this line `#include "ae_epoll.c"` where magic happens. I remember that there are similar usage in Linux kernel but the static function are located in .h files. – Chengsheng Wen Mar 16 '19 at 17:09
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@ChengshengWen - Then consider accepting this answer (the checkbox next to it). – StoryTeller - Unslander Monica Mar 16 '19 at 17:14

Redis static function not used at all

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