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39 lines
1.0 KiB
39 lines
1.0 KiB
package dao |
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import ( |
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"context" |
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"go-common/app/service/main/ugcpay-rank/internal/conf" |
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"go-common/library/cache/memcache" |
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) |
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// CASCacheElecPrepRank cas的方式存储预备榜单，防止分布式脏写 |
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func (d *Dao) CASCacheElecPrepRank(c context.Context, val interface{}, rawItem *memcache.Item) (ok bool, err error) { |
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var ( |
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conn = d.mc.Get(c) |
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) |
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defer conn.Close() |
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rawItem.Object = val |
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rawItem.Expiration = conf.Conf.CacheTTL.ElecPrepAVRankTTL |
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rawItem.Flags = memcache.FlagProtobuf |
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if err = conn.CompareAndSwap(rawItem); err != nil { |
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if err == memcache.ErrCASConflict { // CAS冲突, 则返回ok == false, 准备重试 |
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err = nil |
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return |
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} |
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if err == memcache.ErrNotStored { // 如果CAS中恰好失效，尝试Add |
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if err = conn.Add(rawItem); err != nil { |
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if err == memcache.ErrNotStored { // 在Add时恰好又被其他实例Add过, 则返回ok == false, 准备重试 |
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err = nil |
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return |
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} |
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return // 在Add时发生未知错误 |
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} |
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} |
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return // 在CAS时发生未知错误 |
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} |
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ok = true |
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return |
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}
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