github.com/whtcorpsinc/milevadb-prod@v0.0.0-20211104133533-f57f4be3b597/soliton/localpool/localpool.go (about)

     1  // Copyright 2020 WHTCORPS INC, 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 localpool
    15  
    16  import (
    17  	"runtime"
    18  	_ "unsafe" // required by go:linkname
    19  )
    20  
    21  // LocalPool is an thread local object pool.
    22  // It's similar to sync.Pool but has some difference
    23  // - It can define the size of the pool.
    24  // - It never get GCed.
    25  type LocalPool struct {
    26  	sizePerProc int
    27  	slots       []*slot
    28  	newFn       func() interface{}
    29  	resetFn     func(obj interface{})
    30  }
    31  
    32  type slot struct {
    33  	objs    []interface{}
    34  	getHit  int
    35  	getMiss int
    36  	putHit  int
    37  	putMiss int
    38  }
    39  
    40  // NewLocalPool creates a pool.
    41  // The sizePerProc is pool size for each PROC, so total pool size is (GOMAXPROCS * sizePerProc)
    42  // It can only be used when the GOMAXPROCS never change after the pool created.
    43  // newFn is the function to create a new object.
    44  // resetFn is the function called before put back to the pool, it can be nil.
    45  func NewLocalPool(sizePerProc int, newFn func() interface{}, resetFn func(obj interface{})) *LocalPool {
    46  	slots := make([]*slot, runtime.GOMAXPROCS(0))
    47  	for i := 0; i < len(slots); i++ {
    48  		slots[i] = &slot{
    49  			objs: make([]interface{}, 0, sizePerProc),
    50  		}
    51  	}
    52  	return &LocalPool{
    53  		sizePerProc: sizePerProc,
    54  		slots:       slots,
    55  		newFn:       newFn,
    56  		resetFn:     resetFn,
    57  	}
    58  }
    59  
    60  //go:linkname procPin runtime.procPin
    61  func procPin() int
    62  
    63  //go:linkname procUnpin runtime.procUnpin
    64  func procUnpin() int