Repository: unum-cloud/usearch (language: rust)

Issue:
Feature parity between GoLang and C
Our GoLang binding for USearch is missing several APIs that are available in the C version. Let's add these to make the GoLang version just as powerful!

Missing APIs:

1. `SerializedLength`: Get file size after serialization.
2. `SaveBuffer`: Save index to an in-memory buffer.
3. `LoadBuffer`: Load index from an in-memory buffer.
4. `ViewBuffer`: View index from an in-memory buffer without copying.
5. `Metadata`: Load index metadata from a file.
6. `MetadataBuffer`: Load index metadata from a buffer.
7. `ExpansionAdd`: Get expansion value for index creation.
8. `ExpansionSearch`: Get expansion value for search.
9. `ChangeExpansionAdd`: Set new expansion value for index creation.
10. `ChangeExpansionSearch`: Set new expansion value for search.
11. `HardwareAcceleration`: Get SIMD capabilities.
12. `MemoryUsage`: Get memory usage of the index.
13. `Distance`: Compute distance between two vectors.
14. `ExactSearch`: Multi-threaded exact nearest neighbors search.
15. `Rename`: Rename a vector to a different key.


### Can you contribute to the implementation?

- [X] I can contribute

### Is your feature request specific to a certain interface?

Other bindings

### Contact Details

_No response_

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct


Discussion / hints:
Working on this

Fix patch:
diff --git a/.gitignore b/.gitignore
index 5e7a197b..ea441b31 100644
--- a/.gitignore
+++ b/.gitignore
@@ -56,6 +56,9 @@ target/
 .build
 .swiftpm
 
+# Golang builds
+golang/usearch.h
+
 # C# builds
 csharp/**/[Bb]in/
 csharp/**/[Oo]bj/
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index adbc0719..072f3340 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -335,10 +335,10 @@ So one should first compile the C library, link it with GoLang, and only then ru
 cmake -B build_release -DUSEARCH_BUILD_LIB_C=1 -DUSEARCH_BUILD_TEST_C=1 -DUSEARCH_USE_OPENMP=1 -DUSEARCH_USE_SIMSIMD=1 
 cmake --build build_release --config Release -j
 
-mv c/libusearch_c.so golang/ # or .dylib to install the library on MacOS
-cp c/usearch.h golang/ # to make the header available to GoLang
+cp build_release/libusearch_c.so golang/ # or .dylib to install the library on MacOS
+cp c/usearch.h golang/                   # to make the header available to GoLang
 
-cd golang && go test -v ; cd ..
+cd golang && LD_LIBRARY_PATH=. go test -v ; cd ..
 ```
 
 ## Java
diff --git a/golang/lib.go b/golang/lib.go
index 6b61b1f1..35099626 100644
--- a/golang/lib.go
+++ b/golang/lib.go
@@ -56,6 +56,27 @@ func (m Metric) String() string {
 		panic("Unknown metric")
 	}
 }
+func (m Metric) CValue() C.usearch_metric_kind_t {
+	switch m {
+	case L2sq:
+		return C.usearch_metric_l2sq_k
+	case InnerProduct:
+		return C.usearch_metric_ip_k
+	case Cosine:
+		return C.usearch_metric_cos_k
+	case Haversine:
+		return C.usearch_metric_haversine_k
+	case Pearson:
+		return C.usearch_metric_pearson_k
+	case Hamming:
+		return C.usearch_metric_hamming_k
+	case Tanimoto:
+		return C.usearch_metric_tanimoto_k
+	case Sorensen:
+		return C.usearch_metric_sorensen_k
+	}
+    return C.usearch_metric_l2sq_k
+}
 
 // Quantization represents the type for different scalar kinds used in quantization.
 type Quantization uint8
@@ -137,28 +158,7 @@ func NewIndex(conf IndexConfig) (index *Index, err error) {
 	options.expansion_add = expansion_add
 	options.expansion_search = expansion_search
 	options.multi = multi
-
-	// Map the metric kind to a C enum
-	switch conf.Metric {
-	case L2sq:
-		options.metric_kind = C.usearch_metric_l2sq_k
-	case InnerProduct:
-		options.metric_kind = C.usearch_metric_ip_k
-	case Cosine:
-		options.metric_kind = C.usearch_metric_cos_k
-	case Haversine:
-		options.metric_kind = C.usearch_metric_haversine_k
-	case Pearson:
-		options.metric_kind = C.usearch_metric_pearson_k
-	case Hamming:
-		options.metric_kind = C.usearch_metric_hamming_k
-	case Tanimoto:
-		options.metric_kind = C.usearch_metric_tanimoto_k
-	case Sorensen:
-		options.metric_kind = C.usearch_metric_sorensen_k
-	default:
-		options.metric_kind = C.usearch_metric_unknown_k
-	}
+    options.metric_kind = conf.Metric.CValue()
 
 	// Map the quantization method
 	switch conf.Quantization {
@@ -196,6 +196,66 @@ func (index *Index) Len() (len uint, err error) {
 	return len, err
 }
 
+// SerializedLength reports the expected file size after serialization.
+func (index *Index) SerializedLength() (len uint, err error) {
+	var errorMessage *C.char
+	len = uint(C.usearch_serialized_length((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), (*C.usearch_error_t)(&errorMessage)))
+	if errorMessage != nil {
+		err = errors.New(C.GoString(errorMessage))
+	}
+	return len, err
+}
+
+// MemoryUsage reports the memory usage of the index
+func (index *Index) MemoryUsage() (len uint, err error) {
+	var errorMessage *C.char
+	len = uint(C.usearch_memory_usage((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), (*C.usearch_error_t)(&errorMessage)))
+	if errorMessage != nil {
+		err = errors.New(C.GoString(errorMessage))
+	}
+	return len, err
+}
+
+// ExpansionAdd returns the expansion value used during index creation
+func (index *Index) ExpansionAdd() (val uint, err error) {
+	var errorMessage *C.char
+	val = uint(C.usearch_expansion_add((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), (*C.usearch_error_t)(&errorMessage)))
+	if errorMessage != nil {
+		err = errors.New(C.GoString(errorMessage))
+	}
+	return val, err
+}
+
+// ExpansionSearch returns the expansion value used during search
+func (index *Index) ExpansionSearch() (val uint, err error) {
+	var errorMessage *C.char
+	val = uint(C.usearch_expansion_search((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), (*C.usearch_error_t)(&errorMessage)))
+	if errorMessage != nil {
+		err = errors.New(C.GoString(errorMessage))
+	}
+	return val, err
+}
+
+// ChangeExpansionAdd sets the expansion value used during index creation
+func (index *Index) ChangeExpansionAdd(val uint) error {
+	var errorMessage *C.char
+	C.usearch_change_expansion_add((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), C.size_t(val), (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return errors.New(C.GoString(errorMessage))
+	}
+	return nil
+}
+
+// ChangeExpansionSearch sets the expansion value used during search
+func (index *Index) ChangeExpansionSearch(val uint) error {
+	var errorMessage *C.char
+	C.usearch_change_expansion_search((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), C.size_t(val), (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return errors.New(C.GoString(errorMessage))
+	}
+	return nil
+}
+
 // Connectivity returns the connectivity parameter of the index.
 func (index *Index) Connectivity() (con uint, err error) {
 	var errorMessage *C.char
@@ -226,6 +286,17 @@ func (index *Index) Capacity() (cap uint, err error) {
 	return cap, err
 }
 
+// HardwareAcceleration returns a string showing the SIMD capability for the index
+func (index *Index) HardwareAcceleration() (string, error) {
+	var str *C.char
+	var errorMessage *C.char
+	str = C.usearch_hardware_acceleration((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return C.GoString(nil), errors.New(C.GoString(errorMessage))
+	}
+	return C.GoString(str), nil
+}
+
 // Destroy frees the resources associated with the index.
 func (index *Index) Destroy() error {
 	if index.opaque_handle == nil {
@@ -316,6 +387,27 @@ func (index *Index) Get(key Key, count uint) (vectors []float32, err error) {
 	return vectors, nil
 }
 
+// Rename the vector at key from to key to
+func (index *Index) Rename(from Key, to Key) error {
+	var errorMessage *C.char
+	C.usearch_rename((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), C.usearch_key_t(from), C.usearch_key_t(to), (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return errors.New(C.GoString(errorMessage))
+	}
+	return nil
+}
+
+// Distance computes the distance between two vectors
+func Distance(vec1 []float32, vec2 []float32, dims uint, metric Metric) (float32, error) {
+
+	var errorMessage *C.char
+	dist := C.usearch_distance(unsafe.Pointer(&vec1[0]), unsafe.Pointer(&vec2[0]), C.usearch_scalar_f32_k, C.size_t(dims), metric.CValue(), (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return 0, errors.New(C.GoString(errorMessage))
+	}
+	return float32(dist), nil
+}
+
 // Search performs k-Approximate Nearest Neighbors Search for the closest vectors to the query vector.
 func (index *Index) Search(query []float32, limit uint) (keys []Key, distances []float32, err error) {
 	if index.opaque_handle == nil {
@@ -338,6 +430,189 @@ func (index *Index) Search(query []float32, limit uint) (keys []Key, distances [
 	return keys, distances, nil
 }
 
+// ExactSearch is a multithreaded exact nearest neighbors search
+func ExactSearch(dataset []float32, queries []float32, dataset_size uint, queries_size uint,
+                dataset_stride uint, queries_stride uint, dims uint, metric Metric, 
+                count uint, threads uint, keys_stride uint, distances_stride uint) (keys []Key, distances []float32, err error) {
+	if (len(dataset) % int(dims)) != 0 {
+		return nil, nil, errors.New("Dataset length must be a multiple of the dimensions")
+	}
+	if (len(queries) % int(dims)) != 0 {
+		return nil, nil, errors.New("Queries length must be a multiple of the dimensions")
+	}
+
+	keys = make([]Key, count)
+	distances = make([]float32, count)
+	var errorMessage *C.char
+	C.usearch_exact_search(unsafe.Pointer(&dataset[0]), C.size_t(dataset_size), C.size_t(dataset_stride), unsafe.Pointer(&queries[0]), C.size_t(queries_size), C.size_t(queries_stride), 
+            C.usearch_scalar_f32_k, C.size_t(dims), metric.CValue(), C.size_t(count), C.size_t(threads),
+            (*C.usearch_key_t)(&keys[0]), C.size_t(keys_stride), (*C.usearch_distance_t)(&distances[0]), C.size_t(distances_stride), (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return nil, nil, errors.New(C.GoString(errorMessage))
+	}
+
+	keys = keys[:count]
+	distances = distances[:count]
+	return keys, distances, nil
+}
+
+// Save saves the index to a specified buffer.
+func (index *Index) SaveBuffer(buf []byte, buffer_size uint) error {
+	if index.opaque_handle == nil {
+		panic("Index is uninitialized")
+	}
+
+	var errorMessage *C.char
+	C.usearch_save_buffer((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), unsafe.Pointer(&buf[0]), C.size_t(buffer_size), (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return errors.New(C.GoString(errorMessage))
+	}
+	return nil
+}
+
+// Loads the index from a specified buffer.
+func (index *Index) LoadBuffer(buf []byte, buffer_size uint) error {
+	if index.opaque_handle == nil {
+		panic("Index is uninitialized")
+	}
+
+	var errorMessage *C.char
+	C.usearch_load_buffer((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), unsafe.Pointer(&buf[0]), C.size_t(buffer_size), (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return errors.New(C.GoString(errorMessage))
+	}
+	return nil
+}
+
+// Loads the index from a specified buffer without copying the data.
+func (index *Index) ViewBuffer(buf []byte, buffer_size uint) error {
+	if index.opaque_handle == nil {
+		panic("Index is uninitialized")
+	}
+
+	var errorMessage *C.char
+	C.usearch_view_buffer((C.usearch_index_t)(unsafe.Pointer(index.opaque_handle)), unsafe.Pointer(&buf[0]), C.size_t(buffer_size), (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return errors.New(C.GoString(errorMessage))
+	}
+	return nil
+}
+
+// Loads the metadata from a specified buffer.
+func MetadataBuffer(buf []byte, buffer_size uint) (c IndexConfig, err error) {
+	if buf == nil {
+		panic("Buffer is uninitialized")
+	}
+	c = IndexConfig{}
+
+	options := C.struct_usearch_init_options_t{}
+
+	var errorMessage *C.char
+	C.usearch_metadata_buffer(unsafe.Pointer(&buf[0]), C.size_t(buffer_size), &options, (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return c, errors.New(C.GoString(errorMessage))
+	}
+
+	c.Dimensions = uint(options.dimensions)
+	c.Connectivity = uint(options.connectivity)
+	c.ExpansionAdd = uint(options.expansion_add)
+	c.ExpansionSearch = uint(options.expansion_search)
+	c.Multi = bool(options.multi)
+
+	// Map the metric kind
+	switch options.metric_kind {
+    case C.usearch_metric_l2sq_k:
+	    c.Metric = L2sq
+	case C.usearch_metric_ip_k:
+	    c.Metric = InnerProduct
+    case C.usearch_metric_cos_k:
+	    c.Metric = Cosine
+    case C.usearch_metric_haversine_k:
+	    c.Metric = Haversine
+    case C.usearch_metric_pearson_k:
+	    c.Metric = Pearson
+    case C.usearch_metric_hamming_k:
+	    c.Metric = Hamming
+    case C.usearch_metric_tanimoto_k:
+	    c.Metric = Tanimoto
+    case C.usearch_metric_sorensen_k:
+	    c.Metric = Sorensen
+    }
+
+	// Map the quantization method
+	switch options.quantization {
+    case C.usearch_scalar_f16_k:
+	    c.Quantization = F16
+    case C.usearch_scalar_f32_k:
+	    c.Quantization = F32
+	case C.usearch_scalar_f64_k:
+	    c.Quantization = F64
+	case C.usearch_scalar_i8_k:
+	    c.Quantization = I8
+	case C.usearch_scalar_b1_k:
+	    c.Quantization = B1
+	}
+
+	return c, nil
+}
+
+// Metadata loads the metadata from a specified file.
+func Metadata(path string) (c IndexConfig, err error)  {
+
+	c_path := C.CString(path)
+	defer C.free(unsafe.Pointer(c_path))
+
+	options := C.struct_usearch_init_options_t{}
+
+	var errorMessage *C.char
+	C.usearch_metadata(c_path, &options, (*C.usearch_error_t)(&errorMessage))
+	if errorMessage != nil {
+		return c, errors.New(C.GoString(errorMessage))
+	}
+
+	c.Dimensions = uint(options.dimensions)
+	c.Connectivity = uint(options.connectivity)
+	c.ExpansionAdd = uint(options.expansion_add)
+	c.ExpansionSearch = uint(options.expansion_search)
+	c.Multi = bool(options.multi)
+
+	// Map the metric kind
+	switch options.metric_kind {
+    case C.usearch_metric_l2sq_k:
+	    c.Metric = L2sq
+	case C.usearch_metric_ip_k:
+	    c.Metric = InnerProduct
+    case C.usearch_metric_cos_k:
+	    c.Metric = Cosine
+    case C.usearch_metric_haversine_k:
+	    c.Metric = Haversine
+    case C.usearch_metric_pearson_k:
+	    c.Metric = Pearson
+    case C.usearch_metric_hamming_k:
+	    c.Metric = Hamming
+    case C.usearch_metric_tanimoto_k:
+	    c.Metric = Tanimoto
+    case C.usearch_metric_sorensen_k:
+	    c.Metric = Sorensen
+    }
+
+	// Map the quantization method
+	switch options.quantization {
+    case C.usearch_scalar_f16_k:
+	    c.Quantization = F16
+    case C.usearch_scalar_f32_k:
+	    c.Quantization = F32
+	case C.usearch_scalar_f64_k:
+	    c.Quantization = F64
+	case C.usearch_scalar_i8_k:
+	    c.Quantization = I8
+	case C.usearch_scalar_b1_k:
+	    c.Quantization = B1
+	}
+
+	return c, nil
+}
+
 // Save saves the index to a specified file.
 func (index *Index) Save(path string) error {
 	if index.opaque_handle == nil {


Test patch:
diff --git a/golang/lib_test.go b/golang/lib_test.go
index 4203640a..acb35cd5 100644
--- a/golang/lib_test.go
+++ b/golang/lib_test.go
@@ -1,9 +1,9 @@
 package usearch
 
 import (
+	"math"
 	"runtime"
 	"testing"
-	"math"
 )
 
 func TestUSearch(t *testing.T) {
@@ -34,10 +34,35 @@ func TestUSearch(t *testing.T) {
 			t.Fatalf("Expected size to be 0, got %d", found_len)
 		}
 
+		found_len, err = ind.SerializedLength()
+		if err != nil {
+			t.Fatalf("Failed to retrieve serialized length: %s", err)
+		}
+		if found_len != 112 {
+			t.Fatalf("Expected serialized length to be 112, got %d", found_len)
+		}
+
 		err = ind.Reserve(100)
 		if err != nil {
 			t.Fatalf("Failed to reserve capacity: %s", err)
 		}
+
+		mem, err := ind.MemoryUsage()
+		if err != nil {
+			t.Fatalf("Failed to retrieve serialized length: %s", err)
+		}
+		if mem == 0 {
+			t.Fatalf("Expected the empty index memory usage to be positive, got zero")
+		}
+
+		s, err := ind.HardwareAcceleration()
+		if err != nil {
+			t.Fatalf("Failed to retrieve hardware acceleration: %s", err)
+		}
+		if s == "" {
+			t.Fatalf("An empty string was returned from HardwareAcceleration")
+		}
+
 	})
 
 	t.Run("Test Insertion", func(t *testing.T) {
@@ -104,5 +129,91 @@ func TestUSearch(t *testing.T) {
 		if keys[0] != 42 || math.Abs(float64(distances[0])) > tolerance {
 			t.Fatalf("Expected result 42 with distance 0, got key %d with distance %f", keys[0], distances[0])
 		}
+
+        // TODO: Add exact search
+	})
+
+	t.Run("Test Save and Load", func(t *testing.T) {
+		dim := uint(128)
+		conf := DefaultConfig(dim)
+		ind, err := NewIndex(conf)
+		if err != nil {
+			t.Fatalf("Failed to construct the index: %s", err)
+		}
+		defer ind.Destroy()
+		ind2, err := NewIndex(conf)
+		if err != nil {
+			t.Fatalf("Failed to construct the index: %s", err)
+		}
+		defer ind2.Destroy()
+		indView, err := NewIndex(conf)
+		if err != nil {
+			t.Fatalf("Failed to construct the index: %s", err)
+		}
+		defer indView.Destroy()
+
+		err = ind.Reserve(100)
+		if err != nil {
+			t.Fatalf("Failed to reserve capacity: %s", err)
+		}
+
+		vec := make([]float32, dim)
+        for i := uint(0); i < dim; i++ {
+		    vec[i] = float32(i) + 0.2
+		    err = ind.Add(uint64(i), vec)
+		    if err != nil {
+			    t.Fatalf("Failed to insert: %s", err)
+		    }
+        }
+
+		ind_length, err := ind.Len()
+		if err != nil {
+			t.Fatalf("Failed to retrieve size: %s", err)
+		}
+
+        // TODO: Add invalid save and loads?
+        buffer_size := uint(1*1024*1024)
+        buf := make([]byte, buffer_size)
+		err = ind.SaveBuffer(buf, buffer_size)
+		if err != nil {
+			t.Fatalf("Failed to save the index to a buffer: %s", err)
+		}
+
+		err = ind2.LoadBuffer(buf, buffer_size)
+		if err != nil {
+			t.Fatalf("Failed to load the index from a buffer: %s", err)
+		}
+
+		ind2_length, err := ind2.Len()
+		if err != nil {
+			t.Fatalf("Failed to retrieve size: %s", err)
+		}
+		if ind_length != ind2_length {
+			t.Fatalf("Loaded index length %d doesn't match original of %d ", ind2_length, ind_length)
+		}
+        // TODO: Check some values
+
+		err = indView.ViewBuffer(buf, buffer_size)
+		if err != nil {
+			t.Fatalf("Failed to load the view from a buffer: %s", err)
+		}
+
+		indView_length, err := indView.Len()
+		if err != nil {
+			t.Fatalf("Failed to retrieve size: %s", err)
+		}
+		if ind_length != indView_length {
+			t.Fatalf("Loaded view length %d doesn't match original of %d ", indView_length, ind_length)
+		}
+
+		conf, err = MetadataBuffer(buf, buffer_size)
+		if err != nil {
+			t.Fatalf("Failed to load the metadata from a buffer: %s", err)
+		}
+		if conf != ind.config {
+			t.Fatalf("Loaded metadata doesn't match the index metadata")
+		}
+
+        // TODO: Check file save/load/metadata
 	})
 }