Add a refcount to dl load() and close() calls

Signed-off-by: Kevin Klues <[email protected]>

gen/nvml/lib.go

@@ -38,9 +38,10 @@ var errLibraryAlreadyLoaded = errors.New("library already loaded")
 // This includes a reference to the underlying DynamicLibrary
 type library struct {
 	sync.Mutex
-	path  string
-	flags int
-	dl    dynamicLibrary
+	path     string
+	flags    int
+	refcount refcount
+	dl       dynamicLibrary
 }
 
 // libnvml is a global instance of the nvml library.
@@ -77,10 +78,14 @@ var newDynamicLibrary = func(path string, flags int) dynamicLibrary {
 
 // load initializes the library and updates the versioned symbols.
 // Multiple calls to an already loaded library will return without error.
-func (l *library) load() error {
+func (l *library) load() (rerr error) {
 	l.Lock()
 	defer l.Unlock()
-	if l.dl != nil {
+
+	l.refcount.Inc()
+	defer l.refcount.DecOnError(rerr)
+
+	if l.refcount > 1 {
 		return nil
 	}
 
@@ -99,10 +104,17 @@ func (l *library) load() error {
 // close the underlying library and ensure that the global pointer to the
 // library is set to nil to ensure that subsequent calls to open will reinitialize it.
 // Multiple calls to an already closed nvml library will return without error.
-func (l *library) close() error {
+func (l *library) close() (rerr error) {
 	l.Lock()
 	defer l.Unlock()
 
+	l.refcount.Dec()
+	defer l.refcount.IncOnError(rerr)
+
+	if l.refcount > 0 {
+		return nil
+	}
+
 	if l.dl == nil {
 		return nil
 	}
@@ -111,7 +123,6 @@ func (l *library) close() error {
 	if err != nil {
 		return fmt.Errorf("error closing %s: %w", l.path, err)
 	}
-
 	l.dl = nil
 
 	return nil

gen/nvml/refcount.go

@@ -0,0 +1,43 @@
+/**
+# Copyright 2024 NVIDIA CORPORATION
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package nvml
+
+import ()
+
+type refcount int
+
+func (r *refcount) Inc() {
+	(*r)++
+}
+
+func (r *refcount) Dec() {
+	if *r > 0 {
+		(*r)--
+	}
+}
+
+func (r *refcount) IncOnError(err error) {
+	if err != nil {
+		r.Inc()
+	}
+}
+
+func (r *refcount) DecOnError(err error) {
+	if err != nil {
+		r.Dec()
+	}
+}

pkg/nvml/lib.go

@@ -38,9 +38,10 @@ var errLibraryAlreadyLoaded = errors.New("library already loaded")
 // This includes a reference to the underlying DynamicLibrary
 type library struct {
 	sync.Mutex
-	path  string
-	flags int
-	dl    dynamicLibrary
+	path     string
+	flags    int
+	refcount refcount
+	dl       dynamicLibrary
 }
 
 // libnvml is a global instance of the nvml library.
@@ -77,10 +78,14 @@ var newDynamicLibrary = func(path string, flags int) dynamicLibrary {
 
 // load initializes the library and updates the versioned symbols.
 // Multiple calls to an already loaded library will return without error.
-func (l *library) load() error {
+func (l *library) load() (rerr error) {
 	l.Lock()
 	defer l.Unlock()
-	if l.dl != nil {
+
+	l.refcount.Inc()
+	defer l.refcount.DecOnError(rerr)
+
+	if l.refcount > 1 {
 		return nil
 	}
 
@@ -99,10 +104,17 @@ func (l *library) load() error {
 // close the underlying library and ensure that the global pointer to the
 // library is set to nil to ensure that subsequent calls to open will reinitialize it.
 // Multiple calls to an already closed nvml library will return without error.
-func (l *library) close() error {
+func (l *library) close() (rerr error) {
 	l.Lock()
 	defer l.Unlock()
 
+	l.refcount.Dec()
+	defer l.refcount.IncOnError(rerr)
+
+	if l.refcount > 0 {
+		return nil
+	}
+
 	if l.dl == nil {
 		return nil
 	}
@@ -111,7 +123,6 @@ func (l *library) close() error {
 	if err != nil {
 		return fmt.Errorf("error closing %s: %w", l.path, err)
 	}
-
 	l.dl = nil
 
 	return nil

pkg/nvml/refcount.go

@@ -0,0 +1,43 @@
+/**
+# Copyright 2024 NVIDIA CORPORATION
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package nvml
+
+import ()
+
+type refcount int
+
+func (r *refcount) Inc() {
+	(*r)++
+}
+
+func (r *refcount) Dec() {
+	if *r > 0 {
+		(*r)--
+	}
+}
+
+func (r *refcount) IncOnError(err error) {
+	if err != nil {
+		r.Inc()
+	}
+}
+
+func (r *refcount) DecOnError(err error) {
+	if err != nil {
+		r.Dec()
+	}
+}