Official Go implementation of the Ethereum protocol
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go-ethereum/swarm/storage/memstore.go

320 lines
7.1 KiB

// Copyright 2016 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/>.
// memory storage layer for the package blockhash
package storage
import (
"fmt"
"sync"
"github.com/ethereum/go-ethereum/log"
)
const (
memTreeLW = 2 // log2(subtree count) of the subtrees
memTreeFLW = 14 // log2(subtree count) of the root layer
dbForceUpdateAccessCnt = 1000
defaultCacheCapacity = 5000
)
type MemStore struct {
memtree *memTree
entryCnt, capacity uint // stored entries
accessCnt uint64 // access counter; oldest is thrown away when full
dbAccessCnt uint64
dbStore *DbStore
lock sync.Mutex
}
/*
a hash prefix subtree containing subtrees or one storage entry (but never both)
- access[0] stores the smallest (oldest) access count value in this subtree
- if it contains more subtrees and its subtree count is at least 4, access[1:2]
stores the smallest access count in the first and second halves of subtrees
(so that access[0] = min(access[1], access[2])
- likewise, if subtree count is at least 8,
access[1] = min(access[3], access[4])
access[2] = min(access[5], access[6])
(access[] is a binary tree inside the multi-bit leveled hash tree)
*/
func NewMemStore(d *DbStore, capacity uint) (m *MemStore) {
m = &MemStore{}
m.memtree = newMemTree(memTreeFLW, nil, 0)
m.dbStore = d
m.setCapacity(capacity)
return
}
type memTree struct {
subtree []*memTree
parent *memTree
parentIdx uint
bits uint // log2(subtree count)
width uint // subtree count
entry *Chunk // if subtrees are present, entry should be nil
lastDBaccess uint64
access []uint64
}
func newMemTree(b uint, parent *memTree, pidx uint) (node *memTree) {
node = new(memTree)
node.bits = b
node.width = 1 << b
node.subtree = make([]*memTree, node.width)
node.access = make([]uint64, node.width-1)
node.parent = parent
node.parentIdx = pidx
if parent != nil {
parent.subtree[pidx] = node
}
return node
}
func (node *memTree) updateAccess(a uint64) {
aidx := uint(0)
var aa uint64
oa := node.access[0]
for node.access[aidx] == oa {
node.access[aidx] = a
if aidx > 0 {
aa = node.access[((aidx-1)^1)+1]
aidx = (aidx - 1) >> 1
} else {
pidx := node.parentIdx
node = node.parent
if node == nil {
return
}
nn := node.subtree[pidx^1]
if nn != nil {
aa = nn.access[0]
} else {
aa = 0
}
aidx = (node.width + pidx - 2) >> 1
}
if (aa != 0) && (aa < a) {
a = aa
}
}
}
func (s *MemStore) setCapacity(c uint) {
s.lock.Lock()
defer s.lock.Unlock()
for c < s.entryCnt {
s.removeOldest()
}
s.capacity = c
}
// entry (not its copy) is going to be in MemStore
func (s *MemStore) Put(entry *Chunk) {
if s.capacity == 0 {
return
}
s.lock.Lock()
defer s.lock.Unlock()
if s.entryCnt >= s.capacity {
s.removeOldest()
}
s.accessCnt++
node := s.memtree
bitpos := uint(0)
for node.entry == nil {
l := entry.Key.bits(bitpos, node.bits)
st := node.subtree[l]
if st == nil {
st = newMemTree(memTreeLW, node, l)
bitpos += node.bits
node = st
break
}
bitpos += node.bits
node = st
}
if node.entry != nil {
if node.entry.Key.isEqual(entry.Key) {
node.updateAccess(s.accessCnt)
if entry.SData == nil {
entry.Size = node.entry.Size
entry.SData = node.entry.SData
}
if entry.Req == nil {
entry.Req = node.entry.Req
}
entry.C = node.entry.C
node.entry = entry
return
}
for node.entry != nil {
l := node.entry.Key.bits(bitpos, node.bits)
st := node.subtree[l]
if st == nil {
st = newMemTree(memTreeLW, node, l)
}
st.entry = node.entry
node.entry = nil
st.updateAccess(node.access[0])
l = entry.Key.bits(bitpos, node.bits)
st = node.subtree[l]
if st == nil {
st = newMemTree(memTreeLW, node, l)
}
bitpos += node.bits
node = st
}
}
node.entry = entry
node.lastDBaccess = s.dbAccessCnt
node.updateAccess(s.accessCnt)
s.entryCnt++
}
func (s *MemStore) Get(hash Key) (chunk *Chunk, err error) {
s.lock.Lock()
defer s.lock.Unlock()
node := s.memtree
bitpos := uint(0)
for node.entry == nil {
l := hash.bits(bitpos, node.bits)
st := node.subtree[l]
if st == nil {
return nil, notFound
}
bitpos += node.bits
node = st
}
if node.entry.Key.isEqual(hash) {
s.accessCnt++
node.updateAccess(s.accessCnt)
chunk = node.entry
if s.dbAccessCnt-node.lastDBaccess > dbForceUpdateAccessCnt {
s.dbAccessCnt++
node.lastDBaccess = s.dbAccessCnt
if s.dbStore != nil {
s.dbStore.updateAccessCnt(hash)
}
}
} else {
err = notFound
}
return
}
func (s *MemStore) removeOldest() {
node := s.memtree
for node.entry == nil {
aidx := uint(0)
av := node.access[aidx]
for aidx < node.width/2-1 {
if av == node.access[aidx*2+1] {
node.access[aidx] = node.access[aidx*2+2]
aidx = aidx*2 + 1
} else if av == node.access[aidx*2+2] {
node.access[aidx] = node.access[aidx*2+1]
aidx = aidx*2 + 2
} else {
panic(nil)
}
}
pidx := aidx*2 + 2 - node.width
if (node.subtree[pidx] != nil) && (av == node.subtree[pidx].access[0]) {
if node.subtree[pidx+1] != nil {
node.access[aidx] = node.subtree[pidx+1].access[0]
} else {
node.access[aidx] = 0
}
} else if (node.subtree[pidx+1] != nil) && (av == node.subtree[pidx+1].access[0]) {
if node.subtree[pidx] != nil {
node.access[aidx] = node.subtree[pidx].access[0]
} else {
node.access[aidx] = 0
}
pidx++
} else {
panic(nil)
}
//fmt.Println(pidx)
node = node.subtree[pidx]
}
if node.entry.dbStored != nil {
log.Trace(fmt.Sprintf("Memstore Clean: Waiting for chunk %v to be saved", node.entry.Key.Log()))
<-node.entry.dbStored
log.Trace(fmt.Sprintf("Memstore Clean: Chunk %v saved to DBStore. Ready to clear from mem.", node.entry.Key.Log()))
} else {
log.Trace(fmt.Sprintf("Memstore Clean: Chunk %v already in DB. Ready to delete.", node.entry.Key.Log()))
}
if node.entry.SData != nil {
node.entry = nil
s.entryCnt--
}
node.access[0] = 0
//---
aidx := uint(0)
for {
aa := node.access[aidx]
if aidx > 0 {
aidx = (aidx - 1) >> 1
} else {
pidx := node.parentIdx
node = node.parent
if node == nil {
return
}
aidx = (node.width + pidx - 2) >> 1
}
if (aa != 0) && ((aa < node.access[aidx]) || (node.access[aidx] == 0)) {
node.access[aidx] = aa
}
}
}
// Close memstore
func (s *MemStore) Close() {}