[JavaScript] 纯文本查看 复制代码
/*
* Created by Wu Jian Ping on - 2022/07/22.
*/
const fs = require('fs')
const VectorIndexSize = 8
const VectorIndexCols = 256
const VectorIndexLength = 256 * 256 * (4 + 4)
const SegmentIndexSize = 14
const IP_REGEX = /^((\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.){3}(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])$/
const getStartEndPtr = Symbol('#getStartEndPtr')
const getBuffer = Symbol('#getBuffer')
const openFilePromise = Symbol('#openFilePromise')
class Searcher {
constructor (dbFile, vectorIndex, buffer) {
this._dbFile = dbFile
this._vectorIndex = vectorIndex
this._buffer = buffer
if (this._buffer) {
this._vectorIndex = this._buffer.subarray(256, 256 + VectorIndexLength)
}
}
async [getStartEndPtr] (idx, fd, ioStatus) {
if (this._vectorIndex) {
const sPtr = this._vectorIndex.readUInt32LE(idx)
const ePtr = this._vectorIndex.readUInt32LE(idx + 4)
return { sPtr, ePtr }
} else {
const buf = await this[getBuffer](256 + idx, 8, fd, ioStatus)
const sPtr = buf.readUInt32LE()
const ePtr = buf.readUInt32LE(4)
return { sPtr, ePtr }
}
}
async [getBuffer] (offset, length, fd, ioStatus) {
if (this._buffer) {
return this._buffer.subarray(offset, offset + length)
} else {
const buf = Buffer.alloc(length)
return new Promise((resolve, reject) => {
ioStatus.ioCount += 1
fs.read(fd, buf, 0, length, offset, (err) => {
if (err) {
reject(err)
} else {
resolve(buf)
}
})
})
}
}
[openFilePromise] (fileName) {
return new Promise((resolve, reject) => {
fs.open(fileName, 'r', (err, fd) => {
if (err) {
reject(err)
} else {
resolve(fd)
}
})
})
}
async search (ip) {
const startTime = process.hrtime()
const ioStatus = {
ioCount: 0
}
if (!isValidIp(ip)) {
throw new Error(`IP: ${ip} is invalid`)
}
let fd = null
if (!this._buffer) {
fd = await this[openFilePromise](this._dbFile)
}
const ps = ip.split('.')
const i0 = parseInt(ps[0])
const i1 = parseInt(ps[1])
const i2 = parseInt(ps[2])
const i3 = parseInt(ps[3])
const ipInt = i0 * 256 * 256 * 256 + i1 * 256 * 256 + i2 * 256 + i3
const idx = i0 * VectorIndexCols * VectorIndexSize + i1 * VectorIndexSize
const { sPtr, ePtr } = await this[getStartEndPtr](idx, fd, ioStatus)
let l = 0
let h = (ePtr - sPtr) / SegmentIndexSize
let result = null
while (l <= h) {
const m = (l + h) >> 1
const p = sPtr + m * SegmentIndexSize
const buff = await this[getBuffer](p, SegmentIndexSize, fd, ioStatus)
const sip = buff.readUInt32LE(0)
if (ipInt < sip) {
h = m - 1
} else {
const eip = buff.readUInt32LE(4)
if (ipInt > eip) {
l = m + 1
} else {
const dataLen = buff.readUInt16LE(8)
const dataPtr = buff.readUInt32LE(10)
const data = await this[getBuffer](dataPtr, dataLen, fd, ioStatus)
result = data.toString('utf-8')
break
}
}
}
if (fd) {
fs.close(fd,function(){})
}
const diff = process.hrtime(startTime)
const took = (diff[0] * 1e9 + diff[1]) / 1e3
return { region: result, ioCount: ioStatus.ioCount, took }
}
}
const _checkFile = dbPath => {
try {
fs.accessSync(dbPath, fs.constants.F_OK)
} catch (err) {
throw new Error(`${dbPath} ${err ? 'does not exist' : 'exists'}`)
}
try {
fs.accessSync(dbPath, fs.constants.R_OK)
} catch (err) {
throw new Error(`${dbPath} ${err ? 'is not readable' : 'is readable'}`)
}
}
const isValidIp = ip => {
return IP_REGEX.test(ip)
}
const newWithFileOnly = dbPath => {
_checkFile(dbPath)
return new Searcher(dbPath, null, null)
}
const newWithVectorIndex = (dbPath, vectorIndex) => {
_checkFile(dbPath)
if (!Buffer.isBuffer(vectorIndex)) {
throw new Error('vectorIndex is invalid')
}
return new Searcher(dbPath, vectorIndex, null)
}
const newWithBuffer = buffer => {
if (!Buffer.isBuffer(buffer)) {
throw new Error('buffer is invalid')
}
return new Searcher(null, null, buffer)
}
const loadVectorIndexFromFile = dbPath => {
const fd = fs.openSync(dbPath, 'r')
const buffer = Buffer.alloc(VectorIndexLength)
fs.readSync(fd, buffer, 0, VectorIndexLength, 256)
fs.close(fd,function(){})
return buffer
}
const loadContentFromFile = dbPath => {
const stats = fs.statSync(dbPath)
const buffer = Buffer.alloc(stats.size)
const fd = fs.openSync(dbPath, 'r')
fs.readSync(fd, buffer, 0, stats.size, 0)
fs.close(fd,function(){})
return buffer
}
module.exports = {
isValidIp,
loadVectorIndexFromFile,
loadContentFromFile,
newWithFileOnly,
newWithVectorIndex,
newWithBuffer
}