[backend] add debug flag

Author: botbw

csrc/backend.cpp

@@ -127,22 +127,38 @@ std::string get_default_backend() {
     return std::string(env);
 }
 
+bool get_debug_flag() {
+    const char* env_ = getenv("TENSORNVME_DEBUG");
+    if (env_ == nullptr) {
+        return false;
+    }
+    std::string env(env_);
+    std::transform(env.begin(), env.end(), env.begin(),
+                   [](unsigned char c) { return std::tolower(c); });
+    return env == "1" || env == "true";
+}
+
 AsyncIO *create_asyncio(unsigned int n_entries, std::string backend)
 {
     std::unordered_set<std::string> backends = get_backends();
     std::string default_backend = get_default_backend();
+    bool is_debugging = get_debug_flag();
 
     if (backends.empty())
         throw std::runtime_error("No asyncio backend is installed");
 
     if (default_backend.size() > 0) {  // priority 1: environ is set
-        std::cout << "[backend] backend is overwritten by environ TENSORNVME_BACKEND from " << backend << " to " << default_backend << std::endl;
+        if (is_debugging) {
+            std::cout << "[backend] backend is overwritten by environ TENSORNVME_BACKEND from " << backend << " to " << default_backend << std::endl;
+        }
         backend = default_backend;
     } else if (backend.size() > 0) {  // priority 2: backend is set
         if (backends.find(backend) == backends.end())
             throw std::runtime_error("Unsupported backend: " + backend);
     }
-    std::cout << "[backend] using backend: " << backend << std::endl;
+    if (is_debugging) {
+        std::cout << "[backend] using backend: " << backend << std::endl;
+    }
 
     if (!probe_backend(backend))
         throw std::runtime_error("Backend \"" + backend + "\" is not install correctly");

include/backend.h

@@ -1,5 +1,7 @@
 #include "asyncio.h"
 #include <string>
+#include <algorithm>
+#include <cctype>
 #include <unordered_set>
 #include <cstdlib>
 #include <iostream>
@@ -10,4 +12,6 @@ bool probe_backend(const std::string &backend);
 
 std::string get_default_backend();
 
+bool get_debug_flag();
+
 AsyncIO *create_asyncio(unsigned int n_entries, std::string backend);