98 lines
1.8 KiB
Go
98 lines
1.8 KiB
Go
package services
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import (
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"errors"
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"io"
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"sync"
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"time"
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)
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type Cache interface {
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Put(key string, reader io.Reader) error
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Get(key string) (io.ReadSeekCloser, error)
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Delete(pattern string) error
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io.Closer
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}
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var ErrCacheOutOfMemory = errors.New("内容无法被缓存，超过最大限定值")
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type CacheMemory struct {
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l sync.RWMutex
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data map[string][]byte
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maxAge time.Duration
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sizeGl int
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sizeOne int
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current int
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cache []byte
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ordered []string
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}
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func NewCacheMemory(maxUsage, maxGlobalUsage int) *CacheMemory {
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return &CacheMemory{
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data: make(map[string][]byte),
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l: sync.RWMutex{},
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sizeGl: maxGlobalUsage,
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sizeOne: maxUsage,
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cache: make([]byte, maxUsage+1),
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ordered: make([]string, 0),
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}
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}
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func (c *CacheMemory) Put(key string, reader io.Reader) error {
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c.l.Lock()
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defer c.l.Unlock()
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size, err := io.ReadAtLeast(reader, c.cache, 0)
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if err != nil {
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return err
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}
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if size == len(c.cache) {
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return ErrCacheOutOfMemory
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}
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needed := c.sizeGl - c.current + size
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if needed < 0 {
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// 清理旧的内容
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count := 0
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for i, k := range c.ordered {
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needed += len(c.data[k])
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if needed > 0 {
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break
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}
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count = i + 1
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}
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if needed < 0 {
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// 清理全部内容也无法留出空间
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return ErrCacheOutOfMemory
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}
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for _, s := range c.ordered[:count] {
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delete(c.data, s)
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c.current -= len(c.data)
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}
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c.ordered = c.ordered[count:]
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}
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dest := make([]byte, size)
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copy(dest, c.cache[:size])
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c.data[key] = dest
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c.ordered = append(c.ordered, key)
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c.current += len(dest)
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return nil
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}
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func (c *CacheMemory) Get(key string) (io.ReadSeekCloser, error) {
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//TODO implement me
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panic("implement me")
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}
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func (c *CacheMemory) Delete(key string) error {
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//TODO implement me
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panic("implement me")
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}
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func (c *CacheMemory) Close() error {
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//TODO implement me
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panic("implement me")
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}
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