added gpu_bindings.go to enable transferring index to GPU

In addition added a test for the bindings which show how to use the
functionality.

Author: orihabAnyvision

gpu_bindings.go

@@ -0,0 +1,26 @@
+package faiss
+
+/*
+#include <faiss/c_api/gpu/StandardGpuResources_c.h>
+#include <faiss/c_api/gpu/GpuAutoTune_c.h>
+*/
+import "C"
+import (
+	"errors"
+)
+
+func TransferToGpu(index Index) (Index, error) {
+	var gpuResources *C.FaissStandardGpuResources
+	var gpuIndex *C.FaissGpuIndex
+	c := C.faiss_StandardGpuResources_new(&gpuResources)
+	if c != 0 {
+		return nil, errors.New("error on init gpu %v")
+	}
+
+	exitCode := C.faiss_index_cpu_to_gpu(gpuResources, 0, index.cPtr(), &gpuIndex)
+	if exitCode != 0 {
+		return nil, errors.New("error transferring to gpu")
+	}
+
+	return &faissIndex{idx: gpuIndex}, nil
+}

gpu_bindings_test.go

@@ -0,0 +1,57 @@
+package faiss
+
+import (
+	"fmt"
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+func TestFlatIndexOnGpu(t *testing.T) {
+	index, err := NewIndexFlatL2(1)
+	require.Nil(t, err)
+
+	gpuIdx, err := TransferToGpu(index)
+	require.Nil(t, err)
+
+	vectorsToAdd := []float32{1,2,3,4,5}
+	err = gpuIdx.Add(vectorsToAdd)
+	require.Nil(t, err)
+
+	distances, resultIds, err := gpuIdx.Search(vectorsToAdd, 5)
+	require.Nil(t, err)
+
+	fmt.Println(distances, resultIds, err)
+	for i := range vectorsToAdd {
+		require.Equal(t, int64(i), resultIds[len(vectorsToAdd)*i])
+		require.Zero(t, distances[len(vectorsToAdd)*i])
+	}
+}
+
+func TestIndexIDMapOnGPU(t *testing.T) {
+	index, err := NewIndexFlatL2(1)
+	require.Nil(t, err)
+
+	indexMap, err := NewIndexIDMap(index)
+	require.Nil(t, err)
+
+	gpuIndex, err := TransferToGpu(indexMap)
+	require.Nil(t, err)
+
+	vectorsToAdd := []float32{1,2,3,4,5}
+	ids := make([]int64, len(vectorsToAdd))
+	for i := 0; i < len(vectorsToAdd); i++ {
+		ids[i] = int64(i)
+	}
+
+	err = gpuIndex.AddWithIDs(vectorsToAdd, ids)
+	require.Nil(t, err)
+
+	distances, resultIds, err := gpuIndex.Search(vectorsToAdd, 5)
+	require.Nil(t, err)
+	fmt.Println(gpuIndex.D(), gpuIndex.Ntotal())
+	fmt.Println(distances, resultIds, err)
+	for i := range vectorsToAdd {
+		require.Equal(t, ids[i], resultIds[len(vectorsToAdd)*i])
+		require.Zero(t, distances[len(vectorsToAdd)*i])
+	}
+}