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49 lines
1.1 KiB
Go
49 lines
1.1 KiB
Go
package syncx
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import (
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"errors"
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"github.com/tal-tech/go-zero/core/lang"
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)
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// ErrLimitReturn indicates that the more than borrowed elements were returned.
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var ErrLimitReturn = errors.New("discarding limited token, resource pool is full, someone returned multiple times")
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// Limit controls the concurrent requests.
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type Limit struct {
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pool chan lang.PlaceholderType
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}
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// NewLimit creates a Limit that can borrow n elements from it concurrently.
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func NewLimit(n int) Limit {
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return Limit{
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pool: make(chan lang.PlaceholderType, n),
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}
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}
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// Borrow borrows an element from Limit in blocking mode.
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func (l Limit) Borrow() {
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l.pool <- lang.Placeholder
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}
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// Return returns the borrowed resource, returns error only if returned more than borrowed.
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func (l Limit) Return() error {
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select {
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case <-l.pool:
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return nil
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default:
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return ErrLimitReturn
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}
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}
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// TryBorrow tries to borrow an element from Limit, in non-blocking mode.
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// If success, true returned, false for otherwise.
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func (l Limit) TryBorrow() bool {
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select {
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case l.pool <- lang.Placeholder:
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return true
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default:
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return false
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}
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}
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