Initial QSfera import

Server/vendor/github.com/blevesearch/go-faiss/index_ivf.go

@@ -0,0 +1,61 @@
+package faiss
+
+/*
+#include <faiss/c_api/IndexIVFFlat_c.h>
+#include <faiss/c_api/MetaIndexes_c.h>
+#include <faiss/c_api/Index_c.h>
+#include <faiss/c_api/IndexIVF_c.h>
+#include <faiss/c_api/IndexIVF_c_ex.h>
+*/
+import "C"
+import (
+	"fmt"
+)
+
+func (idx *IndexImpl) SetDirectMap(mapType int) (err error) {
+
+	ivfPtr := C.faiss_IndexIVF_cast(idx.cPtr())
+	if ivfPtr == nil {
+		return fmt.Errorf("index is not of ivf type")
+	}
+	if c := C.faiss_IndexIVF_set_direct_map(
+		ivfPtr,
+		C.int(mapType),
+	); c != 0 {
+		err = getLastError()
+	}
+	return err
+}
+
+func (idx *IndexImpl) GetSubIndex() (*IndexImpl, error) {
+
+	ptr := C.faiss_IndexIDMap2_cast(idx.cPtr())
+	if ptr == nil {
+		return nil, fmt.Errorf("index is not a id map")
+	}
+
+	subIdx := C.faiss_IndexIDMap2_sub_index(ptr)
+	if subIdx == nil {
+		return nil, fmt.Errorf("couldn't retrieve the sub index")
+	}
+
+	return &IndexImpl{&faissIndex{subIdx}}, nil
+}
+
+// pass nprobe to be set as index time option for IVF indexes only.
+// varying nprobe impacts recall but with an increase in latency.
+func (idx *IndexImpl) SetNProbe(nprobe int32) {
+	ivfPtr := C.faiss_IndexIVF_cast(idx.cPtr())
+	if ivfPtr == nil {
+		return
+	}
+	C.faiss_IndexIVF_set_nprobe(ivfPtr, C.size_t(nprobe))
+}
+
+func (idx *IndexImpl) GetNProbe() int32 {
+	ivfPtr := C.faiss_IndexIVF_cast(idx.cPtr())
+	if ivfPtr == nil {
+		return 0
+	}
+	return int32(C.faiss_IndexIVF_nprobe(ivfPtr))
+}