Implement Drain::flush for Json

Requires slog-rs/slog#349 to be accepted first.

Author: Techcable

CHANGELOG.md

@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+* Implement `Drain::flush` method added in [slog-rs/slog#349]
+
+[slog-rs/slog#349]: https://github.com/slog-rs/slog/pull/349
 
 ## 2.6.0 - 2022-02-20
 ### Changed

Cargo.toml

@@ -25,7 +25,7 @@ dynamic-keys = ["slog/dynamic-keys"]
 default = []
 
 [dependencies]
-slog = { version = "2.1.1" }
+slog = { git = "https://github.com/Techcable/slog.git", branch = "feature/simple-flush-method" }
 serde_json = "1"
 serde = "1"
 erased-serde = {version = "0.3", optional = true }

src/lib.rs

@@ -254,6 +254,11 @@ where
         }
         Ok(())
     }
+
+    fn flush(&self) -> Result<(), slog::FlushError> {
+        let mut io = self.io.borrow_mut();
+        io.flush().map_err(slog::FlushError::from)
+    }
 }
 
 // }}}