public static ParallelLoopResult For <TLocal> (int fromInclusive,
int toExclusive,
ParallelOptions parallelOptions,
Func <TLocal> localInit,
Func <int, ParallelLoopState, TLocal, TLocal> body,
Action <TLocal> localFinally)
{
if (body == null)
{
throw new ArgumentNullException("body");
}
if (localInit == null)
{
throw new ArgumentNullException("localInit");
}
if (localFinally == null)
{
throw new ArgumentNullException("localFinally");
}
if (parallelOptions == null)
{
throw new ArgumentNullException("options");
}
if (fromInclusive >= toExclusive)
{
return(new ParallelLoopResult(null, true));
}
// Number of task toExclusive be launched (normally == Env.ProcessorCount)
int step;
int num = GetBestWorkerNumber(fromInclusive, toExclusive, parallelOptions, out step);
Task[] tasks = new Task [num];
StealRange[] ranges = new StealRange[num];
for (int i = 0; i < num; i++)
{
ranges[i] = new StealRange(fromInclusive, i, step);
}
ParallelLoopState.ExternalInfos infos = new ParallelLoopState.ExternalInfos();
int currentIndex = -1;
Action workerMethod = delegate {
int localWorker = Interlocked.Increment(ref currentIndex);
StealRange range = ranges[localWorker];
int index = range.V64.Actual;
int stopIndex = localWorker + 1 == num ? toExclusive : Math.Min(toExclusive, index + step);
TLocal local = localInit();
ParallelLoopState state = new ParallelLoopState(infos);
CancellationToken token = parallelOptions.CancellationToken;
try {
for (int i = index; i < stopIndex;)
{
if (infos.IsStopped)
{
return;
}
token.ThrowIfCancellationRequested();
if (i >= stopIndex - range.V64.Stolen)
{
break;
}
if (infos.LowestBreakIteration != null && infos.LowestBreakIteration > i)
{
return;
}
state.CurrentIteration = i;
local = body(i, state, local);
if (i + 1 >= stopIndex - range.V64.Stolen)
{
break;
}
range.V64.Actual = ++i;
}
bool sixtyfour = IntPtr.Size == 8; // Environment.Is64BitProcess;
// Try toExclusive steal fromInclusive our right neighbor (cyclic)
int len = num + localWorker;
for (int sIndex = localWorker + 1; sIndex < len; ++sIndex)
{
int extWorker = sIndex % num;
range = ranges[extWorker];
stopIndex = extWorker + 1 == num ? toExclusive : Math.Min(toExclusive, fromInclusive + (extWorker + 1) * step);
int stolen = -1;
do
{
do
{
long old;
StealValue64 val = new StealValue64();
old = sixtyfour ? range.V64.Value : Interlocked.CompareExchange(ref range.V64.Value, 0, 0);
val.Value = old;
if (val.Actual >= stopIndex - val.Stolen - 2)
{
goto next;
}
stolen = (val.Stolen += 1);
if (Interlocked.CompareExchange(ref range.V64.Value, val.Value, old) == old)
{
break;
}
} while (true);
stolen = stopIndex - stolen;
if (stolen > range.V64.Actual)
{
local = body(stolen, state, local);
}
else
{
break;
}
} while (true);
next:
continue;
}
} finally {
localFinally(local);
}
};
InitTasks(tasks, num, workerMethod, parallelOptions);
try {
Task.WaitAll(tasks);
} catch {
HandleExceptions(tasks, infos);
}
return(new ParallelLoopResult(infos.LowestBreakIteration, !(infos.IsStopped || infos.IsExceptional)));
}
public static ParallelLoopResult For <TLocal> (int from,
int to,
ParallelOptions options,
Func <TLocal> init,
Func <int, ParallelLoopState, TLocal, TLocal> action,
Action <TLocal> destruct)
{
if (action == null)
{
throw new ArgumentNullException("action");
}
if (init == null)
{
throw new ArgumentNullException("localInit");
}
if (destruct == null)
{
throw new ArgumentNullException("localFinally");
}
if (options == null)
{
throw new ArgumentNullException("options");
}
if (from >= to)
{
return(new ParallelLoopResult(null, true));
}
// Number of task to be launched (normally == Env.ProcessorCount)
int step;
int num = GetBestWorkerNumber(from, to, options, out step);
Task[] tasks = new Task [num];
StealRange[] ranges = new StealRange[num];
for (int i = 0; i < num; i++)
{
ranges[i] = new StealRange(from, i, step);
}
ParallelLoopState.ExternalInfos infos = new ParallelLoopState.ExternalInfos();
int currentIndex = -1;
Action workerMethod = delegate {
int localWorker = Interlocked.Increment(ref currentIndex);
StealRange range = ranges[localWorker];
int index = range.Actual;
int stopIndex = localWorker + 1 == num ? to : Math.Min(to, index + step);
TLocal local = init();
ParallelLoopState state = new ParallelLoopState(infos);
CancellationToken token = options.CancellationToken;
try {
for (int i = index; i < stopIndex; range.Actual = ++i)
{
if (infos.IsStopped)
{
return;
}
token.ThrowIfCancellationRequested();
if (infos.LowestBreakIteration != null && infos.LowestBreakIteration > i)
{
return;
}
state.CurrentIteration = i;
local = action(i, state, local);
if (i >= stopIndex - range.Stolen)
{
break;
}
}
// Try to steal from our right neighbor (cyclic)
int len = num + localWorker;
for (int sIndex = localWorker + 1; sIndex < len; ++sIndex)
{
int extWorker = sIndex % num;
range = ranges[extWorker];
stopIndex = extWorker + 1 == num ? to : Math.Min(to, from + (extWorker + 1) * step);
int stolen;
do
{
stolen = range.Stolen;
if (stopIndex - stolen > range.Actual)
{
goto next;
}
} while (Interlocked.CompareExchange(ref range.Stolen, stolen + 1, stolen) != stolen);
stolen = stopIndex - stolen - 1;
if (stolen > range.Actual)
{
local = action(stolen, state, local);
}
next:
continue;
}
} finally {
destruct(local);
}
};
InitTasks(tasks, num, workerMethod, options);
try {
Task.WaitAll(tasks);
} catch {
HandleExceptions(tasks, infos);
}
return(new ParallelLoopResult(infos.LowestBreakIteration, !(infos.IsStopped || infos.IsExceptional)));
}
