93 lines
1.8 KiB
Go
93 lines
1.8 KiB
Go
package email
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import (
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"crypto/sha256"
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"encoding/hex"
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"sync"
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"github.com/golang/groupcache/lru"
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"github.com/prometheus/client_golang/prometheus"
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)
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type EmailCache struct {
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sync.Mutex
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cache *lru.Cache
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requests *prometheus.CounterVec
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}
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func NewHashedEmailCache(maxEntries int, stats prometheus.Registerer) *EmailCache {
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requests := prometheus.NewCounterVec(prometheus.CounterOpts{
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Name: "email_cache_requests",
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}, []string{"status"})
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stats.MustRegister(requests)
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return &EmailCache{
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cache: lru.New(maxEntries),
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requests: requests,
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}
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}
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func hashEmail(email string) string {
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sum := sha256.Sum256([]byte(email))
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return hex.EncodeToString(sum[:])
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}
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func (c *EmailCache) Seen(email string) bool {
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if c == nil {
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// If the cache is nil we assume it was not configured.
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return false
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}
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hash := hashEmail(email)
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c.Lock()
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defer c.Unlock()
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_, ok := c.cache.Get(hash)
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if !ok {
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c.requests.WithLabelValues("miss").Inc()
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return false
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}
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c.requests.WithLabelValues("hit").Inc()
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return true
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}
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func (c *EmailCache) Remove(email string) {
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if c == nil {
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// If the cache is nil we assume it was not configured.
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return
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}
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hash := hashEmail(email)
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c.Lock()
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defer c.Unlock()
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c.cache.Remove(hash)
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}
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// StoreIfAbsent stores the email in the cache if it is not already present, as
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// a single atomic operation. It returns true if the email was stored and false
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// if it was already in the cache. If the cache is nil, true is always returned.
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func (c *EmailCache) StoreIfAbsent(email string) bool {
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if c == nil {
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// If the cache is nil we assume it was not configured.
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return true
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}
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hash := hashEmail(email)
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c.Lock()
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defer c.Unlock()
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_, ok := c.cache.Get(hash)
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if ok {
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c.requests.WithLabelValues("hit").Inc()
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return false
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}
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c.cache.Add(hash, nil)
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c.requests.WithLabelValues("miss").Inc()
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return true
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}
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