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72 lines
1.6 KiB
72 lines
1.6 KiB
package dao |
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import ( |
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"context" |
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"fmt" |
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"go-common/library/cache/memcache" |
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"go-common/library/log" |
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"go-common/library/stat/prom" |
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) |
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func (d *Dao) Lock(c context.Context, key string, val string) (err error) { |
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if val == "" { |
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return |
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} |
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conn := d.mc.Get(c) |
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defer conn.Close() |
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obj := &struct { |
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Value string |
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}{ |
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Value: val, |
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} |
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item := &memcache.Item{Key: key, Object: obj, Expiration: d.cacheTTL.LockTTL, Flags: memcache.FlagJSON} |
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if err = conn.Add(item); err != nil { |
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prom.BusinessErrCount.Incr("mc:Lock") |
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log.Errorv(c, log.KV("Lock", fmt.Sprintf("%+v", err)), log.KV("key", key)) |
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return |
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} |
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return |
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} |
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// no thread-safe, but it's works. |
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// bad case of unlocking： |
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// 1, process-a gets lock |
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// 2, lock expires |
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// 3, process-b gets lock |
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// 4, process-a releases lock |
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func (d *Dao) Unlock(c context.Context, key string, val string) (err error) { |
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conn := d.mc.Get(c) |
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defer conn.Close() |
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reply, err := conn.Get(key) |
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if err != nil { |
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if err == memcache.ErrNotFound { |
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err = nil |
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return |
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} |
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prom.BusinessErrCount.Incr("mc:Unlock") |
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log.Errorv(c, log.KV("Unlock", fmt.Sprintf("%+v", err)), log.KV("key", key)) |
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return |
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} |
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res := &struct { |
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Value string |
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}{} |
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err = conn.Scan(reply, &res) |
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if err != nil { |
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prom.BusinessErrCount.Incr("mc:Unlock") |
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log.Errorv(c, log.KV("Unlock", fmt.Sprintf("%+v", err)), log.KV("key", key)) |
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return |
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} |
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if res.Value != val { |
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return nil |
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} |
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if err = conn.Delete(key); err != nil { |
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if err == memcache.ErrNotFound { |
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err = nil |
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return |
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} |
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prom.BusinessErrCount.Incr("mc:Unlock") |
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log.Errorv(c, log.KV("Unlock", fmt.Sprintf("%+v", err)), log.KV("key", key)) |
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return |
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} |
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return |
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}
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