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Add malloc_conf_2_conf_harder

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This comes in handy when you're just a user of a canary system who wants to
change settings set by the configuration system itself.
This commit is contained in:
David T. Goldblatt
2020-03-29 10:41:23 -07:00
committed by David Goldblatt
parent 3b4a03b92b
commit d936b46d3a
5 changed files with 65 additions and 4 deletions
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35
src/jemalloc.c
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@@ -32,6 +32,29 @@ const char *je_malloc_conf
JEMALLOC_ATTR(weak)
#endif
;
/*
* The usual rule is that the closer to runtime you are, the higher priority
* your configuration settings are (so the jemalloc config options get lower
* priority than the per-binary setting, which gets lower priority than the /etc
* setting, which gets lower priority than the environment settings).
*
* But it's a fairly common use case in some testing environments for a user to
* be able to control the binary, but nothing else (e.g. a performancy canary
* uses the production OS and environment variables, but can run any binary in
* those circumstances). For these use cases, it's handy to have an in-binary
* mechanism for overriding environment variable settings, with the idea that if
* the results are positive they get promoted to the official settings, and
* moved from the binary to the environment variable.
*
* We don't actually want this to be widespread, so we'll give it a silly name
* and not mention it in headers or documentation.
*/
const char *je_malloc_conf_2_conf_harder
#ifndef _WIN32
JEMALLOC_ATTR(weak)
#endif
;
bool opt_abort =
#ifdef JEMALLOC_DEBUG
true
@@ -975,7 +998,7 @@ malloc_slow_flag_init(void) {
}
/* Number of sources for initializing malloc_conf */
#define MALLOC_CONF_NSOURCES 4
#define MALLOC_CONF_NSOURCES 5
static const char *
obtain_malloc_conf(unsigned which_source, char buf[PATH_MAX + 1]) {
@@ -1053,6 +1076,9 @@ obtain_malloc_conf(unsigned which_source, char buf[PATH_MAX + 1]) {
ret = NULL;
}
break;
} case 4: {
ret = je_malloc_conf_2_conf_harder;
break;
} default:
not_reached();
ret = NULL;
@@ -1069,7 +1095,9 @@ malloc_conf_init_helper(sc_data_t *sc_data, unsigned bin_shard_sizes[SC_NBINS],
"string pointed to by the global variable malloc_conf",
"\"name\" of the file referenced by the symbolic link named "
"/etc/malloc.conf",
"value of the environment variable MALLOC_CONF"
"value of the environment variable MALLOC_CONF",
"string pointed to by the global variable "
"malloc_conf_2_conf_harder",
};
unsigned i;
const char *opts, *k, *v;
@@ -1506,7 +1534,8 @@ malloc_conf_init_helper(sc_data_t *sc_data, unsigned bin_shard_sizes[SC_NBINS],
static void
malloc_conf_init(sc_data_t *sc_data, unsigned bin_shard_sizes[SC_NBINS]) {
const char *opts_cache[MALLOC_CONF_NSOURCES] = {NULL, NULL, NULL, NULL};
const char *opts_cache[MALLOC_CONF_NSOURCES] = {NULL, NULL, NULL, NULL,
NULL};
char buf[PATH_MAX + 1];
/* The first call only set the confirm_conf option and opts_cache */