Make init/shutdown thread safe

Author: mthrok

torchaudio/csrc/sox_effects.cpp

@@ -1,41 +1,48 @@
 #include <sox.h>
 #include <torchaudio/csrc/sox_effects.h>
 
-using namespace torch::indexing;
-
 namespace torchaudio {
 namespace sox_effects {
 
 namespace {
 
 enum SoxEffectsResourceState { NotInitialized, Initialized, ShutDown };
 SoxEffectsResourceState SOX_RESOURCE_STATE = NotInitialized;
+std::mutex SOX_RESOUCE_STATE_MUTEX;
 
 } // namespace
 
 void initialize_sox_effects() {
-  if (SOX_RESOURCE_STATE == ShutDown) {
-    throw std::runtime_error(
-        "SoX Effects has been shut down. Cannot initialize again.");
-  }
-  if (SOX_RESOURCE_STATE == NotInitialized) {
-    if (sox_init() != SOX_SUCCESS) {
-      throw std::runtime_error("Failed to initialize sox effects.");
-    };
-    SOX_RESOURCE_STATE = Initialized;
+  const std::lock_guard<std::mutex> lock(SOX_RESOUCE_STATE_MUTEX);
+
+  switch (SOX_RESOURCE_STATE) {
+    case NotInitialized:
+      if (sox_init() != SOX_SUCCESS) {
+        throw std::runtime_error("Failed to initialize sox effects.");
+      };
+      SOX_RESOURCE_STATE = Initialized;
+    case Initialized:
+      break;
+    case ShutDown:
+      throw std::runtime_error(
+          "SoX Effects has been shut down. Cannot initialize again.");
   }
 };
 
 void shutdown_sox_effects() {
-  if (SOX_RESOURCE_STATE == NotInitialized) {
-    throw std::runtime_error(
-        "SoX Effects is not initialized. Cannot shutdown.");
-  }
-  if (SOX_RESOURCE_STATE == Initialized) {
-    if (sox_quit() != SOX_SUCCESS) {
-      throw std::runtime_error("Failed to initialize sox effects.");
-    };
-    SOX_RESOURCE_STATE = ShutDown;
+  const std::lock_guard<std::mutex> lock(SOX_RESOUCE_STATE_MUTEX);
+
+  switch (SOX_RESOURCE_STATE) {
+    case NotInitialized:
+      throw std::runtime_error(
+          "SoX Effects is not initialized. Cannot shutdown.");
+    case Initialized:
+      if (sox_quit() != SOX_SUCCESS) {
+        throw std::runtime_error("Failed to initialize sox effects.");
+      };
+      SOX_RESOURCE_STATE = ShutDown;
+    case ShutDown:
+      break;
   }
 }