mirror of https://github.com/stashapp/stash.git
43 lines
1.0 KiB
Go
43 lines
1.0 KiB
Go
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package database
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import (
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"regexp"
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lru "github.com/hashicorp/golang-lru"
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)
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// size of the regex LRU cache in elements.
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// A small number number was chosen because it's most likely use is for a
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// single query - this function gets called for every row in the (filtered)
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// results. It's likely to only need no more than 1 or 2 in any given query.
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// After that point, it's just sitting in the cache and is unlikely to be used
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// again.
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const regexCacheSize = 10
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var regexCache *lru.Cache
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func init() {
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regexCache, _ = lru.New(regexCacheSize)
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}
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// regexFn is registered as an SQLite function as "regexp"
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// It uses an LRU cache to cache recent regex patterns to reduce CPU load over
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// identical patterns.
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func regexFn(re, s string) (bool, error) {
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entry, ok := regexCache.Get(re)
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var compiled *regexp.Regexp
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if !ok {
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var err error
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compiled, err = regexp.Compile(re)
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if err != nil {
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return false, err
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}
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regexCache.Add(re, compiled)
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} else {
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compiled = entry.(*regexp.Regexp)
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}
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return compiled.MatchString(s), nil
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}
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