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Copy pathbuffermanager.go
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150 lines (134 loc) · 3.42 KB
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Copy pathbuffermanager.go
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150 lines (134 loc) · 3.42 KB
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package Buffermanager
import "sync"
import "os"
import "fmt"
const GoFlushNum = 5 // 最多使用5个协程处理flush
const blockSize = 8192
var blockBuffer *LRUCache
var connector = "*"
var fileNamePos2Int map[nameAndPos]int
var query2IntLock sync.Mutex //
var blockNumLock sync.Mutex //互斥锁，不加读写锁
var posNum = 0
type nameAndPos struct {
filename string
blockid uint16
}
// InitBuffer
func InitBuffer() {
blockBuffer = NewLRUCache()
fileNamePos2Int = make(map[nameAndPos]int, InitSize*4)
posNum = 0
}
//BlockRead 读byte，不检查blockid和filename， 同时加互斥锁（为什么不加读写锁？
func BlockRead(filename string, block_id uint16) (*block, error) {
t := Query2Int(nameAndPos{filename: filename, blockid: block_id})
ok, block_t := blockBuffer.findBlock(t)
if ok {
block_t.Lock()
return block_t, nil
}
newBlock := block{
blockid: block_id,
filename: filename,
Data: make([]byte, blockSize),
}
err := newBlock.read()
if err != nil {
return nil, err
}
blockPtr := blockBuffer.insertBlock(&newBlock, t)
blockPtr.Lock()
return blockPtr, nil
}
// GetBlockNumber 返回当前块数 大小为BlockSize 的倍数, 当前文件大小为 BlockSize * BlockNumber
func GetBlockNumber(filename string) (uint16, error) {
blockNumLock.Lock()
defer blockNumLock.Unlock()
return findBlockNumber(filename)
}
// NewBlock 返回block_id指新的块在文件中的block id
func NewBlock(filename string) (uint16, error) {
blockNumLock.Lock()
defer blockNumLock.Unlock()
block_id, err := findBlockNumber(filename)
if err != nil {
return 0, err
}
newBlock := block{
blockid: block_id,
filename: filename,
Data: make([]byte, blockSize),
}
newBlock.setDirty()
newBlock.flush()
t := Query2Int(nameAndPos{filename: filename, blockid: block_id})
blockBuffer.insertBlock(&newBlock, t)
return block_id, nil
}
func findBlockNumber(filename string) (uint16, error) {
fileInfo, err := os.Stat(filename)
if err != nil {
return 0, err
}
fmt.Println("the size is ", fileInfo.Size())
tmp := fileInfo.Size() / blockSize
return uint16(tmp), nil
}
// BlockFlushALL 刷新所有块，使用协程处理
func BlockFlushAll() (bool, error) {
blockBuffer.Lock()
defer blockBuffer.Unlock()
flushChannel := make(chan int)
for i := 0; i < GoFlushNum; i++ {
go func(channel chan int) {
for id := range channel {
item := blockBuffer.blockMap[id]
item.Lock()
item.flush()
item.reset()
item.Unlock()
}
}(flushChannel)
}
for index, item := range blockBuffer.blockMap {
if item.isDirty {
flushChannel <- index
}
}
return true, nil
}
// BeginBlockFlush 每次结束一条指令， channel接受指令并且开始刷新
func BeginBlockFlush(channel chan struct{}) {
for _ = range channel {
_, err := BlockFlushAll()
if err != nil {
fmt.Println(err)
}
}
}
// DeleteOldBlock
func DeleteOldBlock(filename string) error {
blockBuffer.Lock()
defer blockBuffer.Unlock()
for index, item := range blockBuffer.blockMap {
if item.filename == filename {
item.Lock()
delete(blockBuffer.blockMap, index)
blockBuffer.root.remove(item)
item.Unlock()
}
}
return nil
}
// 将filename和pos转换为buffer内部的int，如果不存在则创建一个int
func Query2Int(pos nameAndPos) int {
query2IntLock.Lock()
defer query2IntLock.Unlock()
if index, err := fileNamePos2Int[pos]; !err {
return index
}
posNum += 1
fileNamePos2Int[pos] = posNum
return posNum
}