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// Copyright 2017 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package vm
import (
"math/big"
"sync"
)
var checkVal = big.NewInt(-42)
const PoolLimit = 256
// IntPool is a Pool of big integers that
// can be reused for all big.Int operations.
type IntPool struct {
Pool *Stack
}
func newIntPool() *IntPool {
return &IntPool{Pool: &Stack{Data: make([]*big.Int, 0, 1024)}}
}
// get retrieves a big int from the Pool, allocating one if the Pool is empty.
// Note, the returned int's value is arbitrary and will not be zeroed!
func (p *IntPool) Get() *big.Int {
if p.Pool.Len() > 0 {
return p.Pool.Pop()
}
return new(big.Int)
}
// getZero retrieves a big int from the Pool, setting it to zero or allocating
// a new one if the Pool is empty.
func (p *IntPool) GetZero() *big.Int {
if p.Pool.Len() > 0 {
return p.Pool.Pop().SetUint64(0)
}
return new(big.Int)
}
// put returns an allocated big int to the Pool to be later reused by get calls.
// Note, the values as saved as is; neither put nor get zeroes the ints out!
func (p *IntPool) Put(is ...*big.Int) {
if len(p.Pool.Data) > PoolLimit {
return
}
for _, i := range is {
// verifyPool is a build flag. Pool verification makes sure the integrity
// of the integer Pool by comparing values to a default value.
if VerifyPool {
i.Set(checkVal)
}
p.Pool.Push(i)
}
}
// The IntPool Pool's default capacity
const PoolDefaultCap = 25
// IntPoolPool manages a Pool of IntPools.
type IntPoolPool struct {
Pools []*IntPool
lock sync.Mutex
}
var PoolOfIntPools = &IntPoolPool{
Pools: make([]*IntPool, 0, PoolDefaultCap),
}
// get is looking for an available Pool to return.
func (ipp *IntPoolPool) Get() *IntPool {
ipp.lock.Lock()
defer ipp.lock.Unlock()
if len(PoolOfIntPools.Pools) > 0 {
ip := ipp.Pools[len(ipp.Pools)-1]
ipp.Pools = ipp.Pools[:len(ipp.Pools)-1]
return ip
}
return newIntPool()
}
// put a Pool that has been allocated with get.
func (ipp *IntPoolPool) Put(ip *IntPool) {
ipp.lock.Lock()
defer ipp.lock.Unlock()
if len(ipp.Pools) < cap(ipp.Pools) {
ipp.Pools = append(ipp.Pools, ip)
}
}
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