Multiple logging improvements

* JSON logging fails to encode functions/cdata/udata, it now uses tostring to
  encode some objects

closes gh-2899
closes gh-2900

src/box/error.cc

@@ -131,7 +131,8 @@ BuildClientError(const char *file, unsigned line, uint32_t errcode, ...)
 void
 ClientError::log() const
 {
-	_say(S_ERROR, file, line, errmsg, "%s", tnt_errcode_str(m_errcode));
+	say_file_line(S_ERROR, file, line, errmsg, "%s",
+		      tnt_errcode_str(m_errcode));
 }
 
 

src/exception.cc

@@ -126,7 +126,7 @@ Exception::Exception(const struct type_info *type_arg, const char *file,
 void
 Exception::log() const
 {
-	_say(S_ERROR, file, line, errmsg, "%s", type->name);
+	say_file_line(S_ERROR, file, line, errmsg, "%s", type->name);
 }
 
 static const struct method_info systemerror_methods[] = {
@@ -159,8 +159,8 @@ SystemError::SystemError(const char *file, unsigned line,
 void
 SystemError::log() const
 {
-	_say(S_SYSERROR, file, line, strerror(m_errno), "SystemError %s",
-	     errmsg);
+	say_file_line(S_SYSERROR, file, line, strerror(m_errno),
+		      "SystemError %s", errmsg);
 }
 
 const struct type_info type_OutOfMemory =

src/lua/log.lua

@@ -39,7 +39,13 @@ local S_VERBOSE = ffi.C.S_VERBOSE
 local S_DEBUG = ffi.C.S_DEBUG
 local S_ERROR = ffi.C.S_ERROR
 
-local json = require("json")
+local json = require("json").new()
+json.cfg{
+    encode_invalid_numbers = true,
+    encode_load_metatables = true,
+    encode_use_tostring    = true,
+    encode_invalid_as_nil  = true,
+}
 
 local special_fields = {
     "file",

src/say.h

@@ -123,14 +123,28 @@ CFORMAT(printf, 5, 0) extern sayfunc_t _say;
  * Format and print a message to Tarantool log file.
  *
  * \param level (int) - log level (see enum \link say_level \endlink)
+ * \param file (const char * ) - file name to print
+ * \param line (int) - line number to print
  * \param format (const char * ) - printf()-like format string
  * \param ... - format arguments
  * \sa printf()
  * \sa enum say_level
  */
-#define say(level, format, ...) ({ \
+#define say_file_line(level, file, line, format, ...) ({ \
 	if (say_log_level_is_enabled(level)) \
-		_say(level, __FILE__, __LINE__, format, ##__VA_ARGS__); })
+		_say(level, file, line, format, ##__VA_ARGS__); })
+
+/**
+ * Format and print a message to Tarantool log file.
+ *
+ * \param level (int) - log level (see enum \link say_level \endlink)
+ * \param format (const char * ) - printf()-like format string
+ * \param ... - format arguments
+ * \sa printf()
+ * \sa enum say_level
+ */
+#define say(level, format, ...) ({ \
+	say_file_line(level, __FILE__, __LINE__, format, ##__VA_ARGS__); })
 
 /**
  * Format and print a message to Tarantool log file.