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Refactor the handling of isc_mem overmem condition

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Previously, there were two methods of working with the overmem
condition:

1. hi/lo water callback - when the overmem condition was reached
   for the first time, the water callback was called with HIWATER
   mark and .is_overmem boolean was set internally.  Similarly,
   when the used memory went below the lo water mark, the water
   callback would be called with LOWATER mark and .is_overmem
   was reset.  This check would be called **every** time memory
   was allocated or freed.

2. isc_mem_isovermem() - a simple getter for the internal
   .is_overmem flag

This commit refactors removes the first method and move the hi/lo water
checks to the isc_mem_isovermem() function, thus we now have only a
single method of checking overmem condition and the check for hi/lo
water is removed from the hot path for memory contexts that doesn't use
overmem checks.
This commit is contained in:
Ondřej Surý
2023-11-29 09:01:56 +01:00
parent 669800342d
commit 14bdd21e0a
5 changed files with 63 additions and 207 deletions
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25
lib/dns/adb.c
View File

@@ -116,7 +116,6 @@ struct dns_adb {
isc_stats_t *stats;
atomic_bool exiting;
atomic_bool is_overmem;
uint32_t quota;
uint32_t atr_freq;
@@ -346,8 +345,6 @@ shutdown_names(dns_adb_t *);
static void
shutdown_entries(dns_adb_t *);
static void
water(void *, int);
static void
dump_entry(FILE *, dns_adb_t *, dns_adbentry_t *, bool, isc_stdtime_t);
static void
adjustsrtt(dns_adbaddrinfo_t *addr, unsigned int rtt, unsigned int factor,
@@ -1290,7 +1287,7 @@ get_attached_and_locked_name(dns_adb_t *adb, const dns_name_t *name,
last_update = adb->names_last_update;
if (last_update + ADB_STALE_MARGIN >= now ||
atomic_load_relaxed(&adb->is_overmem))
isc_mem_isovermem(adb->mctx))
{
last_update = now;
UPGRADELOCK(&adb->names_lock, locktype);
@@ -1384,7 +1381,7 @@ get_attached_and_locked_entry(dns_adb_t *adb, isc_stdtime_t now,
last_update = adb->entries_last_update;
if (now - last_update > ADB_STALE_MARGIN ||
atomic_load_relaxed(&adb->is_overmem))
isc_mem_isovermem(adb->mctx))
{
last_update = now;
@@ -1617,7 +1614,7 @@ maybe_expire_entry(dns_adbentry_t *adbentry, isc_stdtime_t now) {
*/
static void
purge_stale_names(dns_adb_t *adb, isc_stdtime_t now) {
bool overmem = atomic_load_relaxed(&adb->is_overmem);
bool overmem = isc_mem_isovermem(adb->mctx);
int max_removed = overmem ? 2 : 1;
int scans = 0, removed = 0;
dns_adbname_t *prev = NULL;
@@ -1722,7 +1719,7 @@ cleanup_names(dns_adb_t *adb, isc_stdtime_t now) {
*/
static void
purge_stale_entries(dns_adb_t *adb, isc_stdtime_t now) {
bool overmem = atomic_load_relaxed(&adb->is_overmem);
bool overmem = isc_mem_isovermem(adb->mctx);
int max_removed = overmem ? 2 : 1;
int scans = 0, removed = 0;
dns_adbentry_t *prev = NULL;
@@ -3478,18 +3475,6 @@ dns_adb_flushnames(dns_adb_t *adb, const dns_name_t *name) {
RWUNLOCK(&adb->names_lock, isc_rwlocktype_write);
}
static void
water(void *arg, int mark) {
dns_adb_t *adb = arg;
REQUIRE(DNS_ADB_VALID(adb));
atomic_store_release(&adb->is_overmem, (mark == ISC_MEM_HIWATER));
DP(ISC_LOG_DEBUG(1), "adb reached %s water mark",
(mark == ISC_MEM_HIWATER) ? "high" : "low");
}
void
dns_adb_setadbsize(dns_adb_t *adb, size_t size) {
size_t hiwater, lowater;
@@ -3506,7 +3491,7 @@ dns_adb_setadbsize(dns_adb_t *adb, size_t size) {
if (size == 0U || hiwater == 0U || lowater == 0U) {
isc_mem_clearwater(adb->mctx);
} else {
isc_mem_setwater(adb->mctx, water, adb, hiwater, lowater);
isc_mem_setwater(adb->mctx, hiwater, lowater);
}
}