github.com/insionng/yougam@v0.0.0-20170714101924-2bc18d833463/libraries/pingcap/tidb/server/tokenlimiter.go (about)

     1  // Copyright 2015 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package server
    15  
    16  // Token is used as a permission to keep on running.
    17  type Token struct {
    18  }
    19  
    20  // TokenLimiter is used to limit the number of concurrent tasks.
    21  type TokenLimiter struct {
    22  	count int
    23  	ch    chan *Token
    24  }
    25  
    26  // Put releases the token.
    27  func (tl *TokenLimiter) Put(tk *Token) {
    28  	tl.ch <- tk
    29  }
    30  
    31  // Get obtains a token.
    32  func (tl *TokenLimiter) Get() *Token {
    33  	return <-tl.ch
    34  }
    35  
    36  // NewTokenLimiter creates a TokenLimiter with count tokens.
    37  func NewTokenLimiter(count int) *TokenLimiter {
    38  	tl := &TokenLimiter{count: count, ch: make(chan *Token, count)}
    39  	for i := 0; i < count; i++ {
    40  		tl.ch <- &Token{}
    41  	}
    42  
    43  	return tl
    44  }