MINOR: threads: make MAX_THREADS configurable at build time
There's some value in being able to limit MAX_THREADS, either to save
precious resources in embedded environments, or to protect certain
deployments against accidently incorrect settings.
With this patch, if MAX_THREADS is defined at build time, it will be
used. However, given that LONGBITS is not a macro but is defined
according to sizeof(long), we can't check the value range at build
time and instead we need to perform the check at early boot time.
However, the compiler is able to optimize away the constant comparisons
and doesn't even emit the check code when values are correct.
The output message regarding threading support was improved to report
the number of threads.
diff --git a/src/hathreads.c b/src/hathreads.c
index 39ff7e8..a21bddd 100644
--- a/src/hathreads.c
+++ b/src/hathreads.c
@@ -108,13 +108,22 @@
__attribute__((constructor))
static void __hathreads_init(void)
{
+ char *ptr = NULL;
+
+ if (MAX_THREADS < 1 || MAX_THREADS > LONGBITS) {
+ ha_alert("MAX_THREADS value must be between 1 and %d inclusive; "
+ "HAProxy was built with value %d, please fix it and rebuild.\n",
+ LONGBITS, MAX_THREADS);
+ exit(1);
+ }
+ memprintf(&ptr, "Built with multi-threading support (MAX_THREADS=%d).", MAX_THREADS);
+ hap_register_build_opts(ptr, 1);
+
#if defined(DEBUG_THREAD) || defined(DEBUG_FULL)
memset(lock_stats, 0, sizeof(lock_stats));
#endif
}
-REGISTER_BUILD_OPTS("Built with multi-threading support.");
-
#else
REGISTER_BUILD_OPTS("Built without multi-threading support (USE_THREAD not set).");