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Philipp Heckel
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,65 @@ | ||
| package util | ||
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||
| import ( | ||
| "errors" | ||
| "sync" | ||
| ) | ||
|
|
||
| // ErrLimitReached is the error returned by the Limiter and LimitWriter when the predefined limit has been reached | ||
| var ErrLimitReached = errors.New("limit reached") | ||
|
|
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| // Limiter is a helper that allows adding values up to a well-defined limit. Once the limit is reached | ||
| // ErrLimitReached will be returned. Limiter may be used by multiple goroutines. | ||
| type Limiter struct { | ||
| value int64 | ||
| limit int64 | ||
| mu sync.Mutex | ||
| } | ||
|
|
||
| // NewLimiter creates a new Limiter | ||
| func NewLimiter(limit int64) *Limiter { | ||
| return &Limiter{ | ||
| limit: limit, | ||
| } | ||
| } | ||
|
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| // Add adds n to the limiters internal value, but only if the limit has not been reached. If the limit would be | ||
| // exceeded after adding n, ErrLimitReached is returned. | ||
| func (l *Limiter) Add(n int64) error { | ||
| l.mu.Lock() | ||
| defer l.mu.Unlock() | ||
| if l.limit == 0 { | ||
| l.value += n | ||
| return nil | ||
| } else if l.value+n <= l.limit { | ||
| l.value += n | ||
| return nil | ||
| } else { | ||
| return ErrLimitReached | ||
| } | ||
| } | ||
|
|
||
| // Sub subtracts a value from the limiters internal value | ||
| func (l *Limiter) Sub(n int64) { | ||
| l.Add(-n) | ||
| } | ||
|
|
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| // Set sets the value of the limiter to n. This function ignores the limit. It is meant to set the value | ||
| // based on reality. | ||
| func (l *Limiter) Set(n int64) { | ||
| l.mu.Lock() | ||
| l.value = n | ||
| l.mu.Unlock() | ||
| } | ||
|
|
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| // Value returns the internal value of the limiter | ||
| func (l *Limiter) Value() int64 { | ||
| l.mu.Lock() | ||
| defer l.mu.Unlock() | ||
| return l.value | ||
| } | ||
|
|
||
| // Limit returns the defined limit | ||
| func (l *Limiter) Limit() int64 { | ||
| return l.limit | ||
| } |