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adjustOpenFilesLimit() refactoring.

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In this commit:
* Decrement steps are semantically differentiated from the reserved FDs.
  Previously both values were 32 but the meaning was different.
* Make it clear that we save setrlimit errno.
* Don't explicitly handle wrapping of 'f', but prevent it from
  happening.
* Add comments to make the function flow more readable.

This integrates PR #1630
This commit is contained in:
antirez 2014-03-25 09:01:46 +01:00
parent 72c5ebcba4
commit 6e33c908dd
1 changed files with 17 additions and 15 deletions
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32
src/redis.c
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@ -1512,29 +1512,31 @@ void adjustOpenFilesLimit(void) {
* for our needs. */
if (oldlimit < maxfiles) {
rlim_t f;
int setrlimit_error = 0;
/* Try to set the file limit to match 'maxfiles' or at least
* to the higher value supported less than maxfiles. */
f = maxfiles;
while(f > oldlimit) {
int decr_step = 16;
limit.rlim_cur = f;
limit.rlim_max = f;
if (setrlimit(RLIMIT_NOFILE,&limit) != -1) break;
f -= REDIS_MIN_RESERVED_FDS;
if (f > limit.rlim_cur) {
/* Instead of getting smaller, f just got bigger.
* That means it wrapped around its unsigned floor
* and is now closer to 2^64. We can't help anymore. */
redisLog(REDIS_WARNING,"Failed to set max file limit. "
"You requested maxclients of %d "
"but your 'ulimit -n' is set to %llu. "
"Please increase your 'ulimit -n' to at least %llu.",
server.maxclients, oldlimit, maxfiles);
exit(1);
}
setrlimit_error = errno;
/* We failed to set file limit to 'f'. Try with a
* smaller limit decrementing by a few FDs per iteration. */
if (f < decr_step) break;
f -= decr_step;
}
/* Assume that the limit we get initially is still valid if
* our last try was even lower. */
if (f < oldlimit) f = oldlimit;
if (f != maxfiles) {
int old_maxclients = server.maxclients;
int original_errno = errno;
server.maxclients = f-REDIS_MIN_RESERVED_FDS;
if (server.maxclients < 1) {
redisLog(REDIS_WARNING,"Your current 'ulimit -n' "
@ -1548,7 +1550,7 @@ void adjustOpenFilesLimit(void) {
old_maxclients, maxfiles);
redisLog(REDIS_WARNING,"Redis can't set maximum open files "
"to %llu because of OS error: %s.",
maxfiles, strerror(original_errno));
maxfiles, strerror(setrlimit_error));
redisLog(REDIS_WARNING,"Current maximum open files is %llu. "
"maxclients has been reduced to %d to compensate for "
"low ulimit. "