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@ -4,10 +4,20 @@ import ( |
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"context" |
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"crypto/rand" |
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"encoding/base64" |
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"errors" |
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"github.com/go-redis/redis/v8" |
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) |
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type LockResult int |
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const ( |
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_ LockResult = iota |
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LockResultSuccess |
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LockResultRenewalSuccess |
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LockResultFail |
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) |
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type RedisPreempt struct { |
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key string |
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password string |
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@ -31,10 +41,15 @@ func (p *RedisPreempt) init() { |
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_, _ = rand.Read(byt) |
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p.password = base64.StdEncoding.EncodeToString(byt) |
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p.lockScript = redis.NewScript(` |
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if redis.call('get',KEYS[1]) == ARGV[1] then |
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return redis.call('expire', KEYS[1], ARGV[2]) |
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local val = redis.call('get', KEYS[1]) |
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if (val==nil or (type(val) == "boolean" and not val)) then |
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redis.call('set', KEYS[1], ARGV[1], 'ex', ARGV[2]) |
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return 'LockResultSuccess' |
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elseif (val == ARGV[1]) then |
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redis.call('expire', KEYS[1], ARGV[2]) |
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return 'LockResultRenewalSuccess' |
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else
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return redis.call('set', KEYS[1], ARGV[1], 'ex', ARGV[2], 'nx') |
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return 'LockResultFail' |
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end |
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`) |
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p.unlockScript = redis.NewScript(` |
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@ -47,10 +62,23 @@ func (p *RedisPreempt) init() { |
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} |
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// TryLock attempt to lock the master for ttlSecond
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func (p *RedisPreempt) TryLock(ttlSecond int) (ok bool, err error) { |
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ok, err = p.lockScript.Run(context.Background(), redisInstance, []string{p.key}, p.password, ttlSecond).Bool() |
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p.lastLockStatus = ok |
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return |
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func (p *RedisPreempt) TryLock(ttlSecond int) (result LockResult, err error) { |
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ret, err := p.lockScript.Run(context.Background(), redisInstance, []string{p.key}, p.password, ttlSecond).Text() |
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if err != nil { |
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return LockResultFail, err |
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} |
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switch ret { |
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case "LockResultRenewalSuccess": |
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p.lastLockStatus = true |
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return LockResultRenewalSuccess, nil |
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case "LockResultSuccess": |
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p.lastLockStatus = true |
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return LockResultSuccess, nil |
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case "LockResultFail": |
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return LockResultFail, nil |
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default: |
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return LockResultFail, errors.New("fixme: unknown return") |
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} |
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} |
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// Unlock try to release the master permission
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