108 lines
2.1 KiB
Go
108 lines
2.1 KiB
Go
package handler
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import (
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"container/list"
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"sync"
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"time"
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)
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type subtitleCacheEntry struct {
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key string
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data []byte
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contentType string
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expiresAt time.Time
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}
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// subtitleCache is a small TTL+LRU cache to avoid unbounded memory usage when
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// proxying subtitles.
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type subtitleCache struct {
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mu sync.Mutex
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ttl time.Duration
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maxEntries int
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entries map[string]*list.Element
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lru *list.List
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}
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func newSubtitleCache(ttl time.Duration, maxEntries int) *subtitleCache {
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if ttl <= 0 {
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ttl = 10 * time.Minute
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}
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if maxEntries <= 0 {
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maxEntries = 256
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}
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return &subtitleCache{
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ttl: ttl,
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maxEntries: maxEntries,
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entries: make(map[string]*list.Element, maxEntries),
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lru: list.New(),
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}
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}
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func (c *subtitleCache) Get(key string, now time.Time) (data []byte, contentType string, ok bool) {
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c.mu.Lock()
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defer c.mu.Unlock()
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el := c.entries[key]
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if el == nil {
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return nil, "", false
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}
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entry, ok := el.Value.(subtitleCacheEntry)
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if !ok {
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c.removeElement(el)
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return nil, "", false
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}
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if !entry.expiresAt.IsZero() && now.After(entry.expiresAt) {
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c.removeElement(el)
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return nil, "", false
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}
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c.lru.MoveToFront(el)
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return entry.data, entry.contentType, true
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}
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func (c *subtitleCache) Set(key string, data []byte, contentType string, now time.Time) {
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c.mu.Lock()
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defer c.mu.Unlock()
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if el := c.entries[key]; el != nil {
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entry, ok := el.Value.(subtitleCacheEntry)
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if !ok {
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c.removeElement(el)
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return
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}
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entry.data = data
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entry.contentType = contentType
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entry.expiresAt = now.Add(c.ttl)
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el.Value = entry
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c.lru.MoveToFront(el)
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return
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}
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entry := subtitleCacheEntry{
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key: key,
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data: data,
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contentType: contentType,
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expiresAt: now.Add(c.ttl),
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}
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el := c.lru.PushFront(entry)
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c.entries[key] = el
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for len(c.entries) > c.maxEntries {
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back := c.lru.Back()
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if back == nil {
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break
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}
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c.removeElement(back)
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}
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}
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func (c *subtitleCache) removeElement(el *list.Element) {
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entry, ok := el.Value.(subtitleCacheEntry)
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if !ok {
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c.lru.Remove(el)
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return
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}
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delete(c.entries, entry.key)
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c.lru.Remove(el)
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}
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