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lib/bytesutil: make sure that the cleanup code is performed only by a single goroutine out of many concurrently running goroutines

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Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3466
This commit is contained in:
Aliaksandr Valialkin 2022-12-21 12:57:28 -08:00
parent ad010726fb
commit fcee36081b
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GPG key ID: A72BEC6CD3D0DED1
4 changed files with 41 additions and 12 deletions
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17
lib/bytesutil/fast_string_matcher.go
View file

@ -62,10 +62,8 @@ func (fsm *FastStringMatcher) Match(s string) bool {
s = strings.Clone(s)
fsm.m.Store(s, e)
if atomic.LoadUint64(&fsm.lastCleanupTime)+61 < ct {
// Perform a global cleanup for fsm.m by removing items, which weren't accessed
// during the last 5 minutes.
atomic.StoreUint64(&fsm.lastCleanupTime, ct)
if needCleanup(&fsm.lastCleanupTime, ct) {
// Perform a global cleanup for fsm.m by removing items, which weren't accessed during the last 5 minutes.
m := &fsm.m
m.Range(func(k, v interface{}) bool {
e := v.(*fsmEntry)
@ -78,3 +76,14 @@ func (fsm *FastStringMatcher) Match(s string) bool {
return b
}
func needCleanup(lastCleanupTime *uint64, currentTime uint64) bool {
lct := atomic.LoadUint64(lastCleanupTime)
if lct+61 >= currentTime {
return false
}
// Atomically compare and swap the current time with the lastCleanupTime
// in order to guarantee that only a single goroutine out of multiple
// concurrently executing goroutines gets true from the call.
return atomic.CompareAndSwapUint64(lastCleanupTime, lct, currentTime)
}

24
lib/bytesutil/fast_string_matcher_test.go
View file

@ -23,3 +23,27 @@ func TestFastStringMatcher(t *testing.T) {
f("a_b-C", false)
f("foobar", true)
}
func TestNeedCleanup(t *testing.T) {
f := func(lastCleanupTime, currentTime uint64, resultExpected bool) {
t.Helper()
lct := lastCleanupTime
result := needCleanup(&lct, currentTime)
if result != resultExpected {
t.Fatalf("unexpected result for needCleanup(%d, %d); got %v; want %v", lastCleanupTime, currentTime, result, resultExpected)
}
if result {
if lct != currentTime {
t.Fatalf("unexpected value for lct; got %d; want currentTime=%d", lct, currentTime)
}
} else {
if lct != lastCleanupTime {
t.Fatalf("unexpected value for lct; got %d; want lastCleanupTime=%d", lct, lastCleanupTime)
}
}
}
f(0, 0, false)
f(0, 61, false)
f(0, 62, true)
f(10, 100, true)
}

6
lib/bytesutil/fast_string_transformer.go
View file

@ -67,10 +67,8 @@ func (fst *FastStringTransformer) Transform(s string) string {
}
fst.m.Store(s, e)
if atomic.LoadUint64(&fst.lastCleanupTime)+61 < ct {
// Perform a global cleanup for fst.m by removing items, which weren't accessed
// during the last 5 minutes.
atomic.StoreUint64(&fst.lastCleanupTime, ct)
if needCleanup(&fst.lastCleanupTime, ct) {
// Perform a global cleanup for fst.m by removing items, which weren't accessed during the last 5 minutes.
m := &fst.m
m.Range(func(k, v interface{}) bool {
e := v.(*fstEntry)

6
lib/bytesutil/internstring.go
View file

@ -30,10 +30,8 @@ func InternString(s string) string {
}
internStringsMap.Store(sCopy, e)
if atomic.LoadUint64(&internStringsMapLastCleanupTime)+61 < ct {
// Perform a global cleanup for internStringsMap by removing items, which weren't accessed
// during the last 5 minutes.
atomic.StoreUint64(&internStringsMapLastCleanupTime, ct)
if needCleanup(&internStringsMapLastCleanupTime, ct) {
// Perform a global cleanup for internStringsMap by removing items, which weren't accessed during the last 5 minutes.
m := &internStringsMap
m.Range(func(k, v interface{}) bool {
e := v.(*ismEntry)