public static void For(int from, int to, DelegateFor delFor)
{
DelegateProcess process = delegate(int chunkStart, int chunkEnd) {
for (int i = chunkStart; i < chunkEnd; ++i)
{
delFor(i);
}
};
int cores = Environment.ProcessorCount;
int chunks = (to - from) / cores;
IAsyncResult[] asyncResults = new IAsyncResult[cores];
int end = 0;
for (int i = 0; i < cores; ++i)
{
int start = i * chunks;
end = Math.Min(start + chunks, to);
asyncResults [i] = process.BeginInvoke(start, end, null, null);
}
for (int i = end; i < to; ++i)
{
delFor(i);
}
for (int i = 0; i < cores; ++i)
{
process.EndInvoke(asyncResults [i]);
}
}
/// <summary>
/// Parallel for loop. Invokes given action, passing arguments
/// fromInclusive - toExclusive on multiple threads.
/// Returns when loop finished.
/// </summary>
public static void For(int fromInclusive, int toExclusive, ForDelegate forDelegate)
{
// chunkSize = 1 makes items to be processed in order.
// Bigger chunk size should reduce lock waiting time and thus
// increase paralelism.
int chunkSize = 4;
// number of process() threads
int threadCount = Environment.ProcessorCount;
int index = fromInclusive - chunkSize;
// locker object shared by all the process() delegates
object locker = new object();
// processing function
// takes next chunk and processes it using action
DelegateProcess process = delegate()
{
while (true)
{
int chunkStart = 0;
lock (locker)
{
// take next chunk
index += chunkSize;
chunkStart = index;
}
// process the chunk
// (another thread is processing another chunk
// so the real order of items will be out-of-order)
for (int i = chunkStart; i < chunkStart + chunkSize; i++)
{
if (i >= toExclusive)
{
return;
}
forDelegate(i);
}
}
};
// launch process() threads
IAsyncResult[] asyncResults = new IAsyncResult[threadCount];
for (int i = 0; i < threadCount; ++i)
{
asyncResults[i] = process.BeginInvoke(null, null);
}
// wait for all threads to complete
for (int i = 0; i < threadCount; ++i)
{
process.EndInvoke(asyncResults[i]);
}
}
/// <summary>
/// Parallel for loop. Invokes given action, passing arguments
/// fromInclusive - toExclusive on multiple threads.
/// Returns when loop finished.
/// </summary>
/// <param name="chunkSize">
/// chunkSize = 1 makes items to be processed in order.
/// Bigger chunk size should reduce lock waiting time and thus
/// increase paralelism.
/// </param>
/// <param name="threadCount">number of process() threads</param>
public static void For(int fromInclusive, int toExclusive, int chunkSize, int threadCount, ForDelegate forDelegate)
{
int index = fromInclusive - chunkSize;
// locker object shared by all the process() delegates
object locker = new object();
// processing function
// takes next chunk and processes it using action
DelegateProcess process = delegate()
{
while (true)
{
int chunkStart = 0;
lock (locker)
{
// take next chunk
index += chunkSize;
chunkStart = index;
}
// process the chunk
// (another thread is processing another chunk
// so the real order of items will be out-of-order)
for (int i = chunkStart; i < chunkStart + chunkSize; i++)
{
if (i >= toExclusive)
{
return;
}
forDelegate(i);
}
}
};
// launch process() threads
IAsyncResult[] asyncResults = new IAsyncResult[threadCount];
for (int i = 0; i < threadCount; ++i)
{
asyncResults[i] = process.BeginInvoke(null, null);
}
// wait for all threads to complete
for (int i = 0; i < threadCount; ++i)
{
process.EndInvoke(asyncResults[i]);
}
}
