From 8c4603c73675958efc960fbd4bb599a2909d106a Mon Sep 17 00:00:00 2001
From: Konstantin <const@const.me>
Date: Mon, 16 Jan 2023 14:52:43 +0100
Subject: Source codes

---
 Whisper/CPU/ParallelForRunner.cpp | 149 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 149 insertions(+)
 create mode 100644 Whisper/CPU/ParallelForRunner.cpp

(limited to 'Whisper/CPU/ParallelForRunner.cpp')

diff --git a/Whisper/CPU/ParallelForRunner.cpp b/Whisper/CPU/ParallelForRunner.cpp
new file mode 100644
index 0000000..7151a23
--- /dev/null
+++ b/Whisper/CPU/ParallelForRunner.cpp
@@ -0,0 +1,149 @@
+#include "stdafx.h"
+#include "ParallelForRunner.h"
+using namespace CpuCompute;
+
+ParallelForRunner::ParallelForRunner( int threads ) :
+	maxThreads( threads )
+{
+	if( maxThreads <= 1 )
+	{
+		threadBuffers.resize( 1 );
+		return;
+	}
+
+	work = CreateThreadpoolWork( &workCallbackStatic, this, nullptr );
+	if( nullptr == work )
+		throw getLastHr();
+	threadBuffers.resize( maxThreads );
+}
+
+HRESULT ParallelForRunner::setThreadsCount( int threads )
+{
+	maxThreads = threads;
+	if( threads <= 1 )
+	{
+		threadBuffers.resize( 1 );
+		return S_OK;
+	}
+
+	threadBuffers.resize( maxThreads );
+	if( nullptr == work )
+	{
+		work = CreateThreadpoolWork( &workCallbackStatic, this, nullptr );
+		if( nullptr == work )
+			return getLastHr();
+	}
+	return S_OK;
+}
+
+ParallelForRunner::~ParallelForRunner()
+{
+	if( nullptr != work )
+	{
+		if( S_FALSE == status )
+			WaitForThreadpoolWorkCallbacks( work, FALSE );
+		CloseThreadpoolWork( work );
+	}
+}
+
+namespace
+{
+	thread_local uint32_t currentThreadIndex = UINT_MAX;
+}
+
+void ParallelForRunner::runBatch( size_t ith ) noexcept
+{
+	currentThreadIndex = (uint32_t)ith;
+	const size_t begin = ( ith * countItems ) / countThreads;
+	const size_t end = ( ( ith + 1 ) * countItems ) / countThreads;
+
+	HRESULT hr = E_UNEXPECTED;
+	try
+	{
+		hr = computeRange->compute( begin, end );
+	}
+	catch( HRESULT code )
+	{
+		hr = code;
+	}
+	catch( const std::bad_alloc& )
+	{
+		hr = E_OUTOFMEMORY;
+	}
+	catch( const std::exception& )
+	{
+		hr = E_FAIL;
+	}
+	currentThreadIndex = UINT_MAX;
+	if( SUCCEEDED( hr ) )
+		return;
+	InterlockedCompareExchange( &status, hr, S_FALSE );
+}
+
+void* ParallelForRunner::threadLocalBuffer( size_t cb )
+{
+	const uint32_t idx = currentThreadIndex;
+	if( idx < threadBuffers.size() )
+	{
+		ThreadBuffer& tb = threadBuffers[ idx ];
+		if( tb.cb >= cb )
+		{
+			// We already have large enough buffer for the current thread
+			return tb.memory.pointer();
+		}
+		tb.memory.deallocate();
+		check( tb.memory.allocate( cb ) );
+		tb.cb = cb;
+		return tb.memory.pointer();
+	}
+	if( idx != UINT_MAX )
+		throw E_BOUNDS;
+	else
+	{
+		logError( u8"threadLocalBuffer() method only works from inside a pool callback" );
+		throw E_UNEXPECTED;
+	}
+}
+
+void __stdcall ParallelForRunner::workCallbackStatic( PTP_CALLBACK_INSTANCE Instance, void* pv, PTP_WORK Work ) noexcept
+{
+	ParallelForRunner& context = *(ParallelForRunner*)pv;
+	const size_t ith = (uint32_t)( InterlockedIncrement( &context.threadIndex ) );
+	context.runBatch( ith );
+}
+
+HRESULT ParallelForRunner::parallelFor( iComputeRange& compute, size_t length, size_t minBatch )
+{
+	if( maxThreads <= 1 )
+	{
+		currentThreadIndex = 0;
+		const HRESULT hr1 = compute.compute( 0, length );
+		currentThreadIndex = UINT_MAX;
+		return hr1;
+	}
+	assert( minBatch > 0 );
+
+	size_t nth = length / minBatch;
+	nth = std::min( nth, (size_t)(uint32_t)maxThreads );
+
+	computeRange = &compute;
+	countItems = length;
+	countThreads = nth;
+	threadIndex = 0;
+	status = S_FALSE;
+
+	for( size_t i = 1; i < nth; i++ )
+		SubmitThreadpoolWork( work );
+	runBatch( 0 );
+
+	if( nth > 1 )
+		WaitForThreadpoolWorkCallbacks( work, FALSE );
+
+	computeRange = nullptr;
+	const HRESULT hr = status;
+	status = S_OK;
+	if( SUCCEEDED( hr ) )
+		return S_OK;
+
+	return hr;
+}
\ No newline at end of file
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