kernel: Only setup kernel context globals once

The globals setup by the function calls when creating a new kernel
context only need to be setup once. Calling them multiple times may be
wasteful and has no apparent benefit.

Besides kernel users potentially creating multiple contexts, this change
may also be useful for tests creating multiple setups.

Co-authored-by: stickies-v <stickies-v@protonmail.com>

src/kernel/context.cpp

@@ -8,15 +8,18 @@
 #include <logging.h>
 #include <random.h>
 
+#include <mutex>
 #include <string>
 
-
 namespace kernel {
 Context::Context()
 {
-    std::string sha256_algo = SHA256AutoDetect();
-    LogPrintf("Using the '%s' SHA256 implementation\n", sha256_algo);
-    RandomInit();
+    static std::once_flag globals_initialized{};
+    std::call_once(globals_initialized, []() {
+        std::string sha256_algo = SHA256AutoDetect();
+        LogInfo("Using the '%s' SHA256 implementation\n", sha256_algo);
+        RandomInit();
+    });
 }