Fixed TSan report in base64 library

dbms/src/Functions/FunctionBase64Conversion.h

@@ -166,4 +166,14 @@ private:
     }
 };
 }
+
+/** We must call it in advance from a single thread
+  *  to avoid thread sanitizer report about data race in "codec_choose" function.
+  */
+inline void initializeBase64()
+{
+    size_t outlen = 0;
+    base64_encode(nullptr, 0, nullptr, &outlen, 0);
+}
+
 #endif

dbms/src/Functions/base64Decode.cpp

@@ -8,6 +8,7 @@ namespace DB
 {
 void registerFunctionBase64Decode(FunctionFactory & factory)
 {
+    initializeBase64();
     factory.registerFunction<FunctionBase64Conversion<Base64Decode>>();
 }
 }

dbms/src/Functions/base64Encode.cpp

@@ -9,6 +9,7 @@ namespace DB
 {
 void registerFunctionBase64Encode(FunctionFactory & factory)
 {
+    initializeBase64();
     factory.registerFunction<FunctionBase64Conversion<Base64Encode>>();
 }
 }