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HashFile.cs
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247 lines (232 loc) · 7.72 KB
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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
namespace NSmartProxy.Database
{
public class HashFile
{
private FileStream rf;
private BinaryWriter bw;
private BinaryReader br;
private long tableSize = 1024L * 1024; //1M
public HashFile(String file)
{
rf = new FileStream(file, FileMode.OpenOrCreate);
bw = new BinaryWriter(rf);
br = new BinaryReader(rf);
if (rf.Length == 0)
{
rf.SetLength(tableSize * 8);
}
}
public void Put(byte[] k, byte[] v)
{
//key的hash位置
long i = (Math.Abs(ComputeHash(k)) % tableSize) * 8;
rf.Position = i;
Trace.WriteLine($"{ComputeHash(k)}/{tableSize} ={i}");
byte[] key = new byte[k.Length];
bool removeFlag = false;
for (long p = br.ReadInt64(); p != 0;)
{
rf.Position = p;
int keyLen = br.ReadInt32();
if (keyLen == k.Length)
{
rf.Read(key);
int valueLen = br.ReadInt32();//判断该位置是否有值
if (Enumerable.SequenceEqual(key, k))
{
if (valueLen == v.Length)
{ //有值且大小相同，则直接复写重用
bw.Write(v);
return;
}
else
{ //有值且大小不同，则标记删除 (not physically)
removeFlag = true;
break;
}
}
else
{
rf.Seek(valueLen, SeekOrigin.Current);
p = br.ReadInt64();
}
}
else
{
//key|value
rf.Seek(keyLen, SeekOrigin.Current);
int valueLen = br.ReadInt32();
bw.Seek(valueLen, SeekOrigin.Current);
p = br.ReadInt64();
}
}
if (removeFlag)
{
Remove(k);
}
rf.Position = i;
long head = br.ReadInt64();
long pos = rf.Length;
// 插入新的数据keylength|key|valuelength|value|head
rf.Position = pos;
bw.Write(k.Length);
bw.Write(k);
bw.Write(v.Length);
bw.Write(v);
bw.Write(head);
rf.Position = i;
bw.Write(pos);
}
public byte[] Get(byte[] k)
{
long i = Math.Abs(ComputeHash(k)) % tableSize * 8;
rf.Position = i;
byte[] key = new byte[k.Length];
for (long p = br.ReadInt64(); p != 0;)
{
rf.Position = p;
int keyLen = br.ReadInt32();
if (keyLen == k.Length)
{
br.Read(key);
int valueLen = br.ReadInt32();
if (Enumerable.SequenceEqual(key, k))
{
byte[] v = new byte[valueLen];
br.Read(v);
return v;
}
else
{
bw.Seek(valueLen, SeekOrigin.Current);
p = br.ReadInt64();
}
}
else
{
bw.Seek(keyLen,SeekOrigin.Current);
int valueLen = br.ReadInt32();
bw.Seek( valueLen, SeekOrigin.Current);
p = br.ReadInt64();
}
}
return null;
}
public bool Exist(byte[] k)
{
long i = Math.Abs(ComputeHash(k)) % tableSize * 8;
rf.Position = i;
byte[] key = new byte[k.Length];
for (long p = br.ReadInt64(); p != 0;)
{
rf.Position = p;
int keyLen = br.ReadInt32();
if (keyLen == k.Length)
{
br.Read(key);
int valueLen = br.ReadInt32();
if (Enumerable.SequenceEqual(key, k))
{
return true;
}
else
{
bw.Seek(valueLen, SeekOrigin.Current);
p = br.ReadInt64();
}
}
else
{
bw.Seek(keyLen, SeekOrigin.Current);
int valueLen = br.ReadInt32();
bw.Seek(valueLen, SeekOrigin.Current);
p = br.ReadInt64();
}
}
return false;
}
public void Remove(byte[] k)
{
long i = Math.Abs(ComputeHash(k)) % tableSize * 8;
rf.Position = i;
byte[] key = new byte[k.Length];
for (long p = br.ReadInt64(), pre = i; p != 0;)
{
rf.Position = p;
int keyLen = br.ReadInt32();
if (keyLen == k.Length)
{
br.Read(key);
int valueLen = br.ReadInt32();
if (Enumerable.SequenceEqual(key, k))
{
bw.Seek(valueLen, SeekOrigin.Current);
long next = br.ReadInt64();
rf.Position = pre;
bw.Write(next);
return;
}
else
{
bw.Seek(valueLen, SeekOrigin.Current);
p = br.ReadInt32();
pre = rf.Position - 8;
}
}
else
{
bw.Seek(keyLen, SeekOrigin.Current);
int valueLen = br.ReadInt32();
bw.Seek(valueLen, SeekOrigin.Current);
p = br.ReadInt64();
pre = rf.Position - 8;
}
}
}
public void Close()
{
bw.Close();
br.Close();
rf.Close();
}
public void ManageFragment()
{
// garbage collection, compact the data file
}
public int ComputeHash(params byte[] data)
{
unchecked
{
const int p = 16777619;
int hash = (int)2166136261;
for (int i = 0; i < data.Length; i++)
hash = (hash ^ data[i]) * p;
hash += hash << 13;
hash ^= hash >> 7;
hash += hash << 3;
hash ^= hash >> 17;
hash += hash << 5;
return hash;
}
//int ulValue = 0;
//int ulHi;
//// Size of CRC window (hashing bytes, ssstr, sswstr, numeric)
//const int x_cbCrcWindow = 4;
//// const int iShiftVal = (sizeof ulValue) * (8*sizeof(char)) - x_cbCrcWindow;
//const int iShiftVal = 4 * 8 - x_cbCrcWindow;
//for (int i = 0; i < data.Length; i++)
//{
// ulHi = (ulValue >> iShiftVal) & 0xff;
// ulValue <<= x_cbCrcWindow;
// ulValue = ulValue ^ data[i] ^ ulHi;
//}
//return ulValue;
}
}
}