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diff --git a/parser/README.md b/parser/README.md new file mode 100644 index 000000000..50d55e3d6 --- /dev/null +++ b/parser/README.md @@ -0,0 +1,149 @@ +#### Introduction + +The parser will be used to process streaming and plugins input as well as metadata + +Usage + +1. Define a structure that will be used to share user state across calls +1. Initialize the parser using `parser_init` +2. Register keywords and associated callback function using `parser_add_keyword` +3. Register actions on the keywords +4. Start a loop until EOF + 1. Fetch the next line using `parser_next` + 2. Process the line using `parser_action` + 1. The registered callbacks are executed to parse the input + 2. The registered action for the callback is called for processing +4. Release the parser using `parser_destroy` +5. Release the user structure + +#### Functions + +---- +##### parse_init(RRDHOST *host, void *user, void *input, int flags) + +Initialize an internal parser with the specified user defined data structure that will be shared across calls. + +Input +- Host + - The host this parser will be dealing with. For streaming with SSL enabled for this host +- user + - User defined structure that is passed in all the calls +- input + - Where the parser will get the input from +- flags + - flags to define processing on the input + +Output +- A parser structure + + + +---- +##### parse_push(PARSER *parser, char *line) + +Push a new line for processing + +Input + +- parser + - The parser object as returned by the `parser_init` +- line + - The new line to process + + +Output +- The line will be injected into the stream and will be the next one to be processed + +Returns +- 0 line added +- 1 error detected + +---- +##### parse_add_keyword(PARSER *parser, char *keyword, keyword_function callback_function) + +The function will add callbacks for keywords. The callback function is defined as + +`typedef PARSER_RC (*keyword_function)(char **, void *);` + +Input + +- parser + - The parser object as returned by the `parser_init` +- keyword + - The keyword to register +- keyword_function + - The callback that will handle the keyword processing + * The callback function should return one of the following + * PARSER_RC_OK -- Callback was successful (continue with other callbacks) + * PARSER_RC_STOP -- Stop processing callbacks (return OK) + * PARSER_RC_ERROR -- Callback failed, exit + +Output +- The corresponding keyword and callback will be registered + +Returns +- 0 maximum callbacks already registered for this keyword +- > 0 which is the number of callbacks associated with this keyword. + + +---- +##### parser_next(PARSER *parser) +Return the next item to parse + +Input +- parser + - The parser object as returned by the `parser_init` + +Output +- The parser will store internally the next item to parse + +Returns +- 0 Next item fetched successfully +- 1 No more items to parse + +---- +##### parser_action(PARSER *parser, char *input) +Return the next item to parse + +Input +- parser + - The parser object as returned by the `parser_init` +- input + - Process the input specified instead of using the internal buffer + +Output +- The current keyword will be processed by calling all the registered callbacks + +Returns +- 0 Callbacks called successfully +- 1 Failed + +---- +##### parser_destroy(PARSER *parser) +Cleanup a previously allocated parser + +Input +- parser + - The parser object as returned by the `parser_init` + +Output +- The parser is deallocated + +Returns +- none + +---- +##### parser_recover_input(PARSER *parser) +Cleanup a previously allocated parser + +Input +- parser + - The parser object as returned by the `parser_init` + +Output +- The parser is deallocated + +Returns +- none + +[]() |