common: Add ECC_Context RAII wrapper for ECC_Start/ECC_Stop

src/key.cpp

@@ -457,3 +457,13 @@ void ECC_Stop() {
         secp256k1_context_destroy(ctx);
     }
 }
+
+ECC_Context::ECC_Context()
+{
+    ECC_Start();
+}
+
+ECC_Context::~ECC_Context()
+{
+    ECC_Stop();
+}

src/key.h

@@ -245,4 +245,18 @@ void ECC_Stop();
 /** Check that required EC support is available at runtime. */
 bool ECC_InitSanityCheck();
 
+/**
+ * RAII class initializing and deinitializing global state for elliptic curve support.
+ * Only one instance may be initialized at a time.
+ *
+ * In the future global ECC state could be removed, and this class could contain
+ * state and be passed as an argument to ECC key functions.
+ */
+class ECC_Context
+{
+public:
+    ECC_Context();
+    ~ECC_Context();
+};
+
 #endif // BITCOIN_KEY_H