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MurmurHash : Add std::hash specialization, for use in std::unordered_map
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‎include/IECore/MurmurHash.inl‎

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@@ -461,4 +461,13 @@ inline void murmurHashAppend( MurmurHash &h, const T *data, size_t numElements )
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} // namespace IECore
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template <>
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struct std::hash<IECore::MurmurHash>
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{
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std::size_t operator()( const IECore::MurmurHash& h ) const
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{
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return h.h1() ^ h.h2();
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}
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};
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#endif // IECORE_MURMURHASH_INL

‎test/IECore/IECoreTest.cpp‎

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@@ -69,6 +69,7 @@ IECORE_POP_DEFAULT_VISIBILITY
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#include "CompoundDataTest.h"
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#include "CompoundObjectTest.h"
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#include "ComputationCacheTest.h"
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#include "MurmurHashTest.h"
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using namespace boost::unit_test;
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@@ -102,6 +103,7 @@ bool init()
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addCompoundDataTest(test);
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addCompoundObjectTest(test);
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addComputationCacheTest(test);
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addMurmurHashTest(test);
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}
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catch (std::exception &ex)
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{

‎test/IECore/MurmurHashTest.cpp‎

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//////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2023, Image Engine Design Inc. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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//
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// * Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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//
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// * Neither the name of Image Engine Design nor the names of any
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// other contributors to this software may be used to endorse or
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// promote products derived from this software without specific prior
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// written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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//////////////////////////////////////////////////////////////////////////
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#include "MurmurHashTest.h"
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#include "IECore/MurmurHash.h"
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#include <unordered_set>
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using namespace boost;
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using namespace boost::unit_test;
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namespace IECore
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{
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struct MurmurHashTest
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{
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void testUnorderedSet()
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{
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std::unordered_set< IECore::MurmurHash > set;
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for( size_t i = 0; i < 1000000; i++ )
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{
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IECore::MurmurHash h;
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h.append( i );
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set.insert( h );
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}
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BOOST_CHECK( set.size() == 1000000 );
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size_t maxBucketOccupancy = 0;
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for( size_t i = 0; i < set.bucket_count(); i++ )
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{
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maxBucketOccupancy = std::max( maxBucketOccupancy, set.bucket_size( i ) );
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}
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// If our hash function is good, then there shouldn't be any bucket that gets way too
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// many elements in it - currently, I'm seeing a max occupancy of 8.
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BOOST_CHECK( maxBucketOccupancy < 16 );
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}
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};
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struct MurmurHashTestSuite : public boost::unit_test::test_suite
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{
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MurmurHashTestSuite() : boost::unit_test::test_suite( "MurmurHashTestSuite" )
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{
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boost::shared_ptr<MurmurHashTest> instance( new MurmurHashTest() );
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add( BOOST_CLASS_TEST_CASE( &MurmurHashTest::testUnorderedSet, instance ) );
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}
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};
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void addMurmurHashTest(boost::unit_test::test_suite* test)
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{
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test->add( new MurmurHashTestSuite( ) );
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}
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} // namespace IECore

‎test/IECore/MurmurHashTest.h‎

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//////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2023, Image Engine Design Inc. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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//
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// * Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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//
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// * Neither the name of Image Engine Design nor the names of any
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// other contributors to this software may be used to endorse or
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// promote products derived from this software without specific prior
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// written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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//////////////////////////////////////////////////////////////////////////
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#ifndef IECORE_MURMURHASHTEST_H
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#define IECORE_MURMURHASHTEST_H
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#include "IECore/Export.h"
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IECORE_PUSH_DEFAULT_VISIBILITY
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#include "boost/test/unit_test.hpp"
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IECORE_POP_DEFAULT_VISIBILITY
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namespace IECore
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{
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void addMurmurHashTest( boost::unit_test::test_suite *test );
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}
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#endif // IECORE_MURMURHASHTEST_H
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