Lib.rs

As an attribute macro, log_function will

1. Automatically log the name, input and return value of current function at debug level before it returns by trying to recognize return stmt and inserting a debug! stmt.
2. Set the name of current function as a key in mdc at the beginning of the function and remove it before the function returns.

Note:

1. Input and return type need to implement Debug.
2. When dealing with async function, using #![feature(async_fn_in_trait)] is recommended. Also this is compatible with #[async_trait].
3. To protect secrets, input and return values are ignored by default. You can specify whether to print all values, or a subset of them with semantic literal options. For example:

   use arpa_log::*;
   
   #[log_function("show-input", "except foo bar", "show-return")]
   fn show_subset_of_input_and_return_value(foo: usize, bar: usize, baz: usize) -> usize {
      foo + bar + baz
   }
   

   Then the log should be: {"message":"LogModel { fn_name: "show_subset_of_input_and_return_value", fn_args: ["foo: ignored", "bar: ignored", "baz: 3"], fn_return: "6" }","level":"DEBUG", "target":"show_subset_of_input_and_return_value","mdc":{"fn_name":"show_subset_of_input_and_return_value"}} with test logger.

Note: Logging result can be different with different logger implementation.