在 C# 中使用并行编程
本文关键字：并行 编程 | 更新日期: 2023-09-27 17:56:00
我需要并行执行一个具有不同参数的方法（使用 c#）。
我使用此处的说明：
http://www.codeproject.com/Articles/189374/The-Basics-of-Task-Parallelism-via-C
但是代替Sum(100)，Sum(200)，Sum(300)我想执行更复杂的方法Oracle(JIBitArray bits, int rounds, int[] weak_bits_positions)。
Grain类的代码片段：
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace GrainApproximations
{
class Grain
{
JIBitArray NFSR;
JIBitArray LFSR;
JIBitArray key;
const int keysize = 128;
JIBitArray iv;
const int ivsize = 96;
public void Init(JIBitArray key, JIBitArray iv, int rounds)
{
this.key = key;
this.iv = iv;
NFSR = new JIBitArray(keysize);
LFSR = new JIBitArray(keysize);
/* load registers */
//fill NFSR bits with key bits
for (int i = 0; i < keysize; ++i)
{
NFSR.Set(i, this.key.Get(i));
}
for (int i = 0; i < ivsize; ++i)
{
LFSR.Set(i, this.iv.Get(i));
}
//96 < i < 128 bits of LFSR - filling with 1
for (int i = ivsize; i < keysize; i++)
{
LFSR.Set(i, true);
}
/* do initial clockings */
bool outbit;
bool Lbit;
bool Nbit;
for (int i = 0; i < rounds; ++i)
{
outbit = grain_keystream();
Lbit = LFSR.Get(127);
Nbit = NFSR.Get(127);
LFSR.Set(127, outbit ^ Lbit);
NFSR.Set(127, outbit ^ Nbit);
}
}
private bool grain_keystream()
{
bool outbit = NFSR.Get(2) ^ NFSR.Get(15) ^ NFSR.Get(36) ^ NFSR.Get(45) ^ NFSR.Get(64) ^ NFSR.Get(73) ^ NFSR.Get(89) ^ LFSR.Get(93) ^ (NFSR.Get(12) & LFSR.Get(8)) ^ (LFSR.Get(13) & LFSR.Get(20)) ^ (NFSR.Get(95) & LFSR.Get(42)) ^ (LFSR.Get(60) & LFSR.Get(79)) ^ (NFSR.Get(12) & NFSR.Get(95) & LFSR.Get(95));
bool Nbit = LFSR.Get(0) ^ NFSR.Get(0) ^ NFSR.Get(26) ^ NFSR.Get(56) ^ NFSR.Get(91) ^ NFSR.Get(96) ^ (NFSR.Get(3) & NFSR.Get(67)) ^ (NFSR.Get(11) & NFSR.Get(13)) ^ (NFSR.Get(17) & NFSR.Get(18)) ^ (NFSR.Get(27) & NFSR.Get(59)) ^ (NFSR.Get(40) & NFSR.Get(48)) ^ (NFSR.Get(61) & NFSR.Get(65)) ^ (NFSR.Get(68) & NFSR.Get(84));
bool Lbit = LFSR.Get(0) ^ LFSR.Get(7) ^ LFSR.Get(38) ^ LFSR.Get(70) ^ LFSR.Get(81) ^ LFSR.Get(96);
NFSR = NFSR.ShiftLeft(1);
LFSR = LFSR.ShiftLeft(1);
NFSR.Set(keysize - 1, Nbit);
LFSR.Set(keysize - 1, Lbit);
return outbit;
}
public JIBitArray Generate_Gamma_Bits(int length_in_bits)
{
JIBitArray ret = new JIBitArray(length_in_bits);
for (int i = 0; i < length_in_bits; i++)
{
ret.Set(i, grain_keystream());
}
return ret;
}
public JIBitArray Oracle(JIBitArray bits, int rounds, int[] weak_bits_positions)
{
JIBitArray key_bits = bits.SubJIBitArray(0, 128);
JIBitArray iv_bits = bits.SubJIBitArray(128, 96);
JIBitArray[] L_subspace = Build_L_subspace(iv_bits, weak_bits_positions);
for (int i = 0; i < weak_bits_positions.Length; i++)
{
iv_bits.Set(weak_bits_positions[i], false);
}
int count = 0;
bool outbit = false;
JIBitArray gamma = new JIBitArray(1);
for (int i = 0; i < L_subspace.Length; i++)
{
Init(key_bits, iv_bits.Xor(L_subspace[i]), rounds);
outbit = Generate_Gamma_Bits(1).Get(0);
if (outbit)
{
count++;
}
//Console.ReadLine();
}
Console.Write("oracle:");
Console.Write(count % 2);
return count % 2 == 1 ? new JIBitArray(new bool[] { true }) : new JIBitArray(new bool[] { false });
}
public JIBitArray[] Build_L_subspace(JIBitArray iv_bits, int[] weak_bits)
{
JIBitArray[] L_subspace = new JIBitArray[(int)Math.Pow((double)2, (double)weak_bits.Length)];
JIBitArray[] vectors = VectorTable(weak_bits.Length);
for (int i = 0; i < (int)Math.Pow((double)2, (double)weak_bits.Length); i++)
{
L_subspace[i] = new JIBitArray(iv_bits.Count);
for (int j = 0; j < weak_bits.Length; j++)
{
L_subspace[i].Set(weak_bits[j], vectors[i].Get(j));
}
}
return L_subspace;
}
//build table of all vectors of k variables
public static JIBitArray[] VectorTable(int k)
{
int rows = (int)Math.Pow((double)2, (double)k);
bool[] tmp = new bool[k];
JIBitArray[] result = new JIBitArray[rows];
string x = string.Empty;
char[] characters = new char[0];
bool[] vector = new bool[0];
for (int i = 0; i < rows; i++)
{
x = Convert.ToString(i, 2);
x = x.PadLeft(k, '0');
characters = x.ToCharArray();
vector = new bool[characters.Length];
for (int j = 0; j < characters.Length; j++)
{
if (characters[j] == '1')
{
vector[j] = true;
}
else
{
vector[j] = false;
}
}
result[i] = new JIBitArray(vector);
}
return result;
}
}
}
JIBitArray - 它是标准 .NET 集合BitArray的修改版本：
http://www.codeproject.com/Articles/14430/My-BitArray-Class
在我尝试执行Main方法中：
Grain grain = new Grain();
Task<bool[]> parent = new Task<bool[]>(() =>
{
var results = new bool[5]; // Create an array for the results
// This tasks creates and starts 3 child tasks
for (int i = 0; i < results.Length; i++)
{
new Task(() => results[i] = grain.Oracle(bits[i], rounds, weak_bits).Get(0), TaskCreationOptions.AttachedToParent).Start();
}
// Returns a reference to the array
// (even though the elements may not be initialized yet)
return results;
});
// When the parent and its children have
// run to completion, display the results
var cwt = parent.ContinueWith(parentTask =>
Array.ForEach(parentTask.Result, Console.WriteLine));
// Start the parent Task so it can start its children
parent.Start();
cwt.Wait(); // For testing purposes
其中 bits - 它是一个由 5 个不同的 JIBitArray 二进制向量组成的数组，长度为 128 + 96 = 224 位。
但是我在计算时得到System.AggregateException和System.ArgumentOutOfRangeException。
我使用 TPL 是因为我需要使用不同的输入参数执行 2^20 个任务（bits有 2^20 个元素）
有人可以解释什么是错的吗？
一个问题是你没有捕获循环变量 i。当内部任务执行时，i 已经是 5。
但你似乎也没有在等待内心的任务结果。为什么不把内心的任务变成一个Task<bool>，这样你就可以得到（并等待）它的结果呢？
此外，正如所写，您的父任务完全没有意义，如果您只想启动其他一些任务（您那里没有长时间运行的计算），只需使用一种方法即可。如果您希望它有用，它将等待子任务完成，然后返回组合结果。
使用 Parallel.ForEach 将使此代码更简单，并且更有可能实现您要执行的操作。