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Acquire read lock instead of exclusive lock for langBaseCache. #4279

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merged 3 commits into from
Nov 19, 2019
Merged

Acquire read lock instead of exclusive lock for langBaseCache. #4279

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33f6d5a
Acquire read lock instead of exclusive lock for langBaseCache.
Nov 15, 2019
b6864ad
Recheck cache after acquiring the exclusive lock.
Nov 18, 2019
19cd0e2
Release lock instead of defering it.
Nov 18, 2019
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25 changes: 20 additions & 5 deletions tok/langbase.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ const enBase = "en"

// langBaseCache keeps a copy of lang -> base conversions.
var langBaseCache struct {
sync.Mutex
sync.RWMutex
m map[string]string
}

Expand All @@ -38,15 +38,26 @@ func langBase(lang string) string {
if lang == "" {
return enBase // default to this
}

// Acquire the read lock and lookup for the lang in cache.
langBaseCache.RLock()

// check if we already have this
if s, found := langBaseCache.m[lang]; found {
langBaseCache.RUnlock()
return s
}

// Upgrade the lock only since the lang is not found in cache.
langBaseCache.RUnlock()
langBaseCache.Lock()
defer langBaseCache.Unlock()
if langBaseCache.m == nil {
langBaseCache.m = make(map[string]string)
}
// check if we already have this

// Recheck if the lang is added to the cache.
if s, found := langBaseCache.m[lang]; found {
return s
}

// Parse will return the best guess for a language tag.
// It will return undefined, or 'language.Und', if it gives up. That means the language
// tag is either new (to the standard) or simply invalid.
Expand All @@ -71,3 +82,7 @@ func langBase(lang string) string {
langBaseCache.m[lang] = enBase
return enBase
}

func init() {
langBaseCache.m = make(map[string]string)
}