github.com/klaytn/klaytn@v1.10.2/blockchain/vm/intpool.go (about)

     1  // Modifications Copyright 2018 The klaytn Authors
     2  // Copyright 2015 The go-ethereum Authors
     3  // This file is part of the go-ethereum library.
     4  //
     5  // The go-ethereum library is free software: you can redistribute it and/or modify
     6  // it under the terms of the GNU Lesser General Public License as published by
     7  // the Free Software Foundation, either version 3 of the License, or
     8  // (at your option) any later version.
     9  //
    10  // The go-ethereum library is distributed in the hope that it will be useful,
    11  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    12  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    13  // GNU Lesser General Public License for more details.
    14  //
    15  // You should have received a copy of the GNU Lesser General Public License
    16  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    17  //
    18  // This file is derived from core/vm/intpool.go (2018/06/04).
    19  // Modified and improved for the klaytn development.
    20  
    21  package vm
    22  
    23  import (
    24  	"math/big"
    25  	"sync"
    26  )
    27  
    28  var checkVal = big.NewInt(-42)
    29  
    30  const poolLimit = 256
    31  
    32  // intPool is a pool of big integers that
    33  // can be reused for all big.Int operations.
    34  type intPool struct {
    35  	pool *Stack
    36  }
    37  
    38  func newIntPool() *intPool {
    39  	return &intPool{pool: newstack()}
    40  }
    41  
    42  // get retrieves a big int from the pool, allocating one if the pool is empty.
    43  // Note, the returned int's value is arbitrary and will not be zeroed!
    44  func (p *intPool) get() *big.Int {
    45  	if p.pool.len() > 0 {
    46  		return p.pool.pop()
    47  	}
    48  	return new(big.Int)
    49  }
    50  
    51  // getZero retrieves a big int from the pool, setting it to zero or allocating
    52  // a new one if the pool is empty.
    53  func (p *intPool) getZero() *big.Int {
    54  	if p.pool.len() > 0 {
    55  		return p.pool.pop().SetUint64(0)
    56  	}
    57  	return new(big.Int)
    58  }
    59  
    60  // put returns an allocated big int to the pool to be later reused by get calls.
    61  // Note, the values as saved as is; neither put nor get zeroes the ints out!
    62  func (p *intPool) put(is ...*big.Int) {
    63  	if len(p.pool.data) > poolLimit {
    64  		return
    65  	}
    66  	for _, i := range is {
    67  		// verifyPool is a build flag. Pool verification makes sure the integrity
    68  		// of the integer pool by comparing values to a default value.
    69  		if verifyPool {
    70  			i.Set(checkVal)
    71  		}
    72  		p.pool.push(i)
    73  	}
    74  }
    75  
    76  // The intPool pool's default capacity
    77  const poolDefaultCap = 25
    78  
    79  // intPoolPool manages a pool of intPools.
    80  type intPoolPool struct {
    81  	pools []*intPool
    82  	lock  sync.Mutex
    83  }
    84  
    85  var poolOfIntPools = &intPoolPool{
    86  	pools: make([]*intPool, 0, poolDefaultCap),
    87  }
    88  
    89  // get is looking for an available pool to return.
    90  func (ipp *intPoolPool) get() *intPool {
    91  	ipp.lock.Lock()
    92  	defer ipp.lock.Unlock()
    93  
    94  	if len(poolOfIntPools.pools) > 0 {
    95  		ip := ipp.pools[len(ipp.pools)-1]
    96  		ipp.pools = ipp.pools[:len(ipp.pools)-1]
    97  		return ip
    98  	}
    99  	return newIntPool()
   100  }
   101  
   102  // put a pool that has been allocated with get.
   103  func (ipp *intPoolPool) put(ip *intPool) {
   104  	ipp.lock.Lock()
   105  	defer ipp.lock.Unlock()
   106  
   107  	if len(ipp.pools) < cap(ipp.pools) {
   108  		ipp.pools = append(ipp.pools, ip)
   109  	}
   110  }