非确定性计算引擎转化为C#版本并重构
这是之前我写的原始的 VB.NET 版本：
http://www.cnblogs.com/RChen/archive/2010/05/17/1737587.html
转化为 C# 版本后，还进行了一些重构。包括修改成了强类型，以及使用了 Parallel.ForEach，但是发现没有收到预期的效果。性能提升比较少。
研究后发现，其实问题的关键在于要通过某种方式对遍历的可能性进行剪枝，这样才能减少遍历次数，从而提升性能。而且，由于结果是通过 yield return 和 IEnumerable 实现的，并没有实现 IList 或者 Array. 所以它本质上并不支持按索引范围拆分的 Parallel.ForEach 工作方式，而实际估计是使用的几个 chunk 轮番读取的低效方式，这样在各个 chunk 之间就有线程同步的开销，如前文所说。这个性能优化只好留待后面有空再继续研究。
下面是目前的状况的实现代码：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections;
namespace NonDeterministicEngineCS
{
class Program
{
static void Main(string[] args)
{
Benchmarking(new Action(Test1), "Test1() 执行完成，花费：{0}毫秒。");
Console.WriteLine("====================================================");
Benchmarking(new Action(Test2), "Test2() 执行完成，花费：{0}毫秒。");
Console.WriteLine("====================================================");
Benchmarking(new Action(Test3), "Test3() 执行完成，花费：{0}毫秒。");
Console.ReadLine();
}
// 一个简单的测试例子
public static void Test1()
{
NonDeterministicEngine engine = new NonDeterministicEngine();
engine.AddParam("a", new int[] { 1, 2, 3, 4, 5, 6 });
engine.AddParam("b", new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 });
engine.AddRequire((int a) => a > 2 && a < 9);
engine.AddRequire((int b) => b > 5 && b <= 10);
engine.AddRequire((int a, int b) => a == b - 1);
engine.EachResult(
result => Console.WriteLine("a = {0}, b = {1}", result["a"], result["b"]));
}
// 爱因斯坦谜题
public static void Test2()
{
NonDeterministicEngine engine = new NonDeterministicEngine();
engine.AddParam("baker", new int[] { 1, 2, 3, 4, 5 });
engine.AddParam("cooper", new int[] { 1, 2, 3, 4, 5 });
engine.AddParam("fletcher", new int[] { 1, 2, 3, 4, 5 });
engine.AddParam("miller", new int[] { 1, 2, 3, 4, 5 });
engine.AddParam("smith", new int[] { 1, 2, 3, 4, 5 });
engine.AddRequire((int baker) => baker != 5);
engine.AddRequire((int cooper) => cooper != 1);
engine.AddRequire((int fletcher) => fletcher != 1 && fletcher != 5);
engine.AddRequire((int miller, int cooper) => miller > cooper);
engine.AddRequire((int smith, int fletcher) =>
smith != fletcher + 1
&& smith != fletcher - 1);
engine.AddRequire((int fletcher, int cooper) => fletcher != cooper + 1
&& fletcher != cooper - 1);
engine.AddRequire((int baker, int cooper, int fletcher, int miller, int smith) =>
baker != cooper && baker != fletcher && baker != miller
&& baker != smith && cooper != fletcher && cooper != miller
&& cooper != smith && fletcher != miller && fletcher != smith && miller != smith);
engine.EachResult(
result =>
Console.WriteLine("baker: {0}, cooper: {1}, fletcher: {2}, miller: {3}, smith: {4}",
result["baker"],
result["cooper"],
result["fletcher"],
result["miller"],
result["smith"])
);
}
// 八皇后问题的解法
public static void Test3()
{
var engine = new NonDeterministicEngine();
engine.AddParam("a", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("b", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("c", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("d", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("e", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("f", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("g", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddParam("h", new int[] { 1, 2, 3, 4, 5, 6, 7, 8 });
engine.AddRequire((int a, int b, int c, int d, int e, int f, int g, int h) =>
a != b && a != c && a != d
&& a != e && a != f && a != g && a != h
&& b != c && b != d && b != e && b != f && b != g && b != h
&& c != d && c != e && c != f && c != g && c != h
&& d != e && d != f && d != g && d != h
&& e != f && e != g && e != h
&& f != g && f != h
&& g != h
&& NotInTheSameDiagonalLine(new int[] { a, b, c, d, e, f, g, h }));
engine.EachResult(
result =>
Console.WriteLine("(1,{0}), (2,{1}), (3,{2}), (4,{3}), (5,{4}), (6,{5}), (7,{6}), (8,{7})",
result["a"],
result["b"],
result["c"],
result["d"],
result["e"],
result["f"],
result["g"],
result["h"])
);
}
static bool NotInTheSameDiagonalLine(int[] cols)
{
for (int i = 0; i < cols.Length - 1; i++)
{
for (int j = i + 1; j < cols.Length; j++)
{
if (j - i == Math.Abs(cols[j] - cols[i]))
return false;
}
}
return true;
}
public static void Benchmarking(Action f, string messageFormat)
{
DateTime time1 = DateTime.Now;
f();
DateTime time2 = DateTime.Now;
Console.WriteLine(messageFormat, (time2 - time1).TotalMilliseconds);
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
namespace NonDeterministicEngineCS
{
public class Param
{
public string Name
{
get;
set;
}
public IEnumerator Values
{
get;
set;
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace NonDeterministicEngineCS
{
public abstract class Condition
{
public IList<string> ParamNames
{
get;
protected set;
}
public abstract bool Call(params object[] args);
public Condition(Delegate predicate)
{
ParamNames = predicate.Method.GetParameters().Select(p => p.Name).ToArray();
}
}
public class Condition<T> : Condition
{
public Condition(Func<T, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T)args[0]);
}
}
public class Condition<T1, T2> : Condition
{
public Condition(Func<T1, T2, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1]);
}
}
public class Condition<T1, T2, T3> : Condition
{
public Condition(Func<T1, T2, T3, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2]);
}
}
public class Condition<T1, T2, T3, T4> : Condition
{
public Condition(Func<T1, T2, T3, T4, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4) args[3]);
}
}
public class Condition<T1, T2, T3, T4, T5> : Condition
{
public Condition(Func<T1, T2, T3, T4, T5, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, T5, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4)args[3], (T5)args[4]);
}
}
public class Condition<T1, T2, T3, T4, T5, T6> : Condition
{
public Condition(Func<T1, T2, T3, T4, T5, T6, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, T5, T6, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4)args[3], (T5)args[4], (T6)args[5]);
}
}
public class Condition<T1, T2, T3, T4, T5, T6, T7> : Condition
{
public Condition(Func<T1, T2, T3, T4, T5, T6, T7, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, T5, T6, T7, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4)args[3], (T5)args[4], (T6)args[5], (T7)args[6]);
}
}
public class Condition<T1, T2, T3, T4, T5, T6, T7, T8> : Condition
{
public Condition(Func<T1, T2, T3, T4, T5, T6, T7, T8, bool> predicate)
: base(predicate)
{
m_func = predicate;
}
Func<T1, T2, T3, T4, T5, T6, T7, T8, bool> m_func;
public override bool Call(params object[] args)
{
return m_func((T1)args[0], (T2)args[1], (T3)args[2], (T4)args[3], (T5)args[4], (T6)args[5], (T7)args[6], (T8)args[7]);
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
using System.Threading.Tasks;
using System.Linq.Expressions;
namespace NonDeterministicEngineCS
{
public class NonDeterministicEngine
{
private List<Param> m_paramDict = new List<Param>();
private List<Condition> m_predicateDict = new List<Condition>();
public void AddParam(string name, IEnumerable values)
{
m_paramDict.Add(new Param { Name = name, Values = values.GetEnumerator() });
}
#region Add Require
public void AddRequire<T>(Func<T, bool> predicate)
{
m_predicateDict.Add(new Condition<T>(predicate));
}
public void AddRequire<T1, T2>(Func<T1, T2, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2>(predicate));
}
public void AddRequire<T1, T2, T3>(Func<T1, T2, T3, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3>(predicate));
}
public void AddRequire<T1, T2, T3, T4>(Func<T1, T2, T3, T4, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4>(predicate));
}
public void AddRequire<T1, T2, T3, T4, T5>(Func<T1, T2, T3, T4, T5, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4, T5>(predicate));
}
public void AddRequire<T1, T2, T3, T4, T5, T6>(Func<T1, T2, T3, T4, T5, T6, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4, T5, T6>(predicate));
}
public void AddRequire<T1, T2, T3, T4, T5, T6, T7>(Func<T1, T2, T3, T4, T5, T6, T7, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4, T5, T6, T7>(predicate));
}
public void AddRequire<T1, T2, T3, T4, T5, T6, T7, T8>(Func<T1, T2, T3, T4, T5, T6, T7, T8, bool> predicate)
{
m_predicateDict.Add(new Condition<T1, T2, T3, T4, T5, T6, T7, T8>(predicate));
}
#endregion
public IEnumerable<Dictionary<string, object>> GetResults()
{
var em = new CombinationEnumerable(this);
foreach (var item in em)
{
if (Satisfy(item))
yield return item;
}
}
public void EachResult(Action<Dictionary<string, object>> action)
{
var em = new CombinationEnumerable(this);
Parallel.ForEach(
em,
result =>
{
if (Satisfy(result))
{
action(result);
}
}
);
}
bool Satisfy(Dictionary<string, object> result)
{
foreach (Condition item in m_predicateDict)
{
var args = item.ParamNames.Select(
name => result[name]
).ToArray();
if (item.Call(args))
continue;
return false;
}
return true;
}
private class CombinationEnumerable : IEnumerable<Dictionary<string, object>>
{
NonDeterministicEngine m_engine;
public CombinationEnumerable(NonDeterministicEngine engine)
{
m_engine = engine;
}
public IEnumerator<Dictionary<string, object>> GetEnumerator()
{
return new CombinationEnumerator(m_engine);
}
IEnumerator IEnumerable.GetEnumerator()
{
return new CombinationEnumerator(m_engine);
}
}
/// <summary>
/// 组合多个 iterator 为一个复合的 iterator.
/// MoveNext 实现为：移动到下一个所有变量值可能的组合。
/// </summary>
private class CombinationEnumerator : IEnumerator<Dictionary<string, object>>
{
private bool m_firstTime = true;
private NonDeterministicEngine m_target;
public CombinationEnumerator(NonDeterministicEngine engine)
{
m_target = engine;
}
public void Dispose()
{
}
public Dictionary<string, object> GetCurrent()
{
if (IterationOver)
return null;
return m_target.m_paramDict.ToDictionary
(param => param.Name, param => param.Values.Current);
}
public bool MoveNext()
{
if (IterationOver)
return false;
if (m_firstTime)
{
// 首次执行时，需要将所有变量的 enumerator 都前进到起始位置
foreach (Param item in m_target.m_paramDict)
{
item.Values.MoveNext();
}
m_firstTime = false;
return true;
}
// 首先尝试最后一个变量的 iterator，看能否 MoveNext() （是否还有没有尝试过的值）。
int iterIndex = m_target.m_paramDict.Count - 1;
bool canMoveNext = m_target.m_paramDict[iterIndex].Values.MoveNext();
if (canMoveNext)
return true;
// 否则依次回溯到前一个变量，看该变量的 iterator 能否 MoveNext()
while (!canMoveNext)
{
iterIndex--;
// 表明已尝试了所有变量的所有可能值，退无可退，则终止枚举过程。
if (iterIndex == -1)
{
IterationOver = true;
return false;
}
canMoveNext = m_target.m_paramDict[iterIndex].Values.MoveNext();
// 如果往前退到某个可以前进的位置
if (canMoveNext)
{
// 则需要将这个位置之后的所有其他变量的 iterator 复位，并前进到第一种可能性。
for (int i = iterIndex + 1; i < m_target.m_paramDict.Count; i++)
{
var iter = m_target.m_paramDict[i].Values;
iter.Reset();
iter.MoveNext();
}
return true;
}
}
return false;
}
public void Reset()
{
IterationOver = false;
m_firstTime = true;
foreach (var param in m_target.m_paramDict)
{
param.Values.Reset();
}
}
public Dictionary<string, object> Current
{
get
{
return GetCurrent();
}
}
/// <summary>
/// 标记枚举是否已经结束
/// </summary>
public bool IterationOver
{
get;
set;
}
object IEnumerator.Current
{
get
{
return GetCurrent();
}
}
}
}
}
