mirror of https://github.com/mpolden/echoip
100 lines
1.7 KiB
Go
100 lines
1.7 KiB
Go
package http
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import (
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"container/list"
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"fmt"
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"hash/fnv"
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"net"
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"sync"
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)
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type Cache struct {
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capacity int
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mu sync.RWMutex
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entries map[uint64]*list.Element
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values *list.List
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evictions uint64
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}
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type CacheStats struct {
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Capacity int
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Size int
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Evictions uint64
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}
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func NewCache(capacity int) *Cache {
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if capacity < 0 {
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capacity = 0
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}
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return &Cache{
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capacity: capacity,
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entries: make(map[uint64]*list.Element),
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values: list.New(),
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}
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}
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func key(ip net.IP) uint64 {
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h := fnv.New64a()
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h.Write(ip)
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return h.Sum64()
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}
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func (c *Cache) Set(ip net.IP, resp Response) {
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if c.capacity == 0 {
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return
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}
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k := key(ip)
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c.mu.Lock()
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defer c.mu.Unlock()
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minEvictions := len(c.entries) - c.capacity + 1
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if minEvictions > 0 { // At or above capacity. Shrink the cache
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evicted := 0
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for el := c.values.Front(); el != nil && evicted < minEvictions; {
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value := el.Value.(Response)
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delete(c.entries, key(value.IP))
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next := el.Next()
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c.values.Remove(el)
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el = next
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evicted++
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}
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c.evictions += uint64(evicted)
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}
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current, ok := c.entries[k]
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if ok {
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c.values.Remove(current)
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}
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c.entries[k] = c.values.PushBack(resp)
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}
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func (c *Cache) Get(ip net.IP) (Response, bool) {
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k := key(ip)
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c.mu.RLock()
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defer c.mu.RUnlock()
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r, ok := c.entries[k]
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if !ok {
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return Response{}, false
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}
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return r.Value.(Response), true
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}
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func (c *Cache) Resize(capacity int) error {
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if capacity < 0 {
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return fmt.Errorf("invalid capacity: %d\n", capacity)
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}
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c.mu.Lock()
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defer c.mu.Unlock()
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c.capacity = capacity
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c.evictions = 0
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return nil
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}
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func (c *Cache) Stats() CacheStats {
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c.mu.RLock()
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defer c.mu.RUnlock()
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return CacheStats{
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Size: len(c.entries),
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Capacity: c.capacity,
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Evictions: c.evictions,
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}
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}
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