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memcacherl.go
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/
memcacherl.go
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// Package memcacherl is a memcache client wrapper for rate limiting.
package memcacherl
import (
"time"
"github.com/bradfitz/gomemcache/memcache"
)
// Client is a memcache client wrapper suitable for rate limiting.
type Client struct {
mc *memcache.Client
}
// New creates and initializes a new Client.
func New(mc *memcache.Client) *Client {
return &Client{mc}
}
// Hit implements the httprl.Backend interface.
func (c *Client) Hit(key string, ttlsec int32) (count uint64, remttl int32, err error) {
item, err := c.mc.Get(key)
if err != nil {
if err == memcache.ErrCacheMiss {
return c.create(key, ttlsec)
}
return 0, 0, err
}
n, err := c.mc.Increment(key, 1)
if err != nil {
if err == memcache.ErrCacheMiss {
return c.create(key, ttlsec)
}
return 0, 0, err
}
rem := int32(item.Flags) - int32(time.Now().Unix())
if rem < 0 {
rem = 0
}
return n, rem, nil
}
func (c *Client) create(key string, ttlsec int32) (uint64, int32, error) {
exp := uint32(time.Now().Unix()) + uint32(ttlsec)
item := &memcache.Item{
Key: key,
Value: []byte{'1'},
Flags: exp, // unix time of exp date
Expiration: ttlsec,
}
err := c.mc.Set(item)
if err != nil {
return 0, 0, err
}
return 1, ttlsec, nil
}