Feature: add feature flag "tracing-log" to emit log record for tracin…

…g event

Cargo.toml

@@ -34,7 +34,7 @@ serde_json = "1.0.57"
 tempfile = { version = "3.4.0" }
 thiserror = "1.0.33"
 tokio = { version="1.8", default-features=false, features=["fs", "io-util", "macros", "rt", "rt-multi-thread", "sync", "time"] }
-tracing = "0.1.29"
+tracing = { version = "0.1.29" }
 tracing-appender = "0.2.0"
 tracing-futures = "0.2.4"
 tracing-subscriber = { version = "0.3.3",  features=["env-filter"] }

openraft/Cargo.toml

@@ -93,6 +93,11 @@ singlethreaded = ["macros/singlethreaded"]
 # For instance, in an even number nodes cluster, erasing a node's data and then rebooting it(log reverts to empty) will not result in data loss.
 loosen-follower-log-revert = []
 
+# Enables "log" feature in `tracing` crate, to let tracing events emit log
+# record.
+# See: https://docs.rs/tracing/latest/tracing/#emitting-log-records
+tracing-log = [ "tracing/log" ]
+
 # default = ["single-term-leader"]
 
 [package.metadata.docs.rs]

openraft/src/docs/feature_flags/feature-flags.md

@@ -37,9 +37,13 @@ By default openraft enables no features.
   This feature disables `Adapter`, which is for v1 storage to be used as v2.
   V2 storage separates log store and state machine store so that log IO and state machine IO can be parallelized naturally.
   <br/><br/>
-  
+
 - `singlethreaded`: removes `Send` bounds from `AppData`, `AppDataResponse`, `RaftEntry`, and `SnapshotData` to force the
   asynchronous runtime to spawn any tasks in the current thread.
   This is for any single-threaded application that never allows a raft instance to be shared among multiple threads.
   In order to use the feature, `AsyncRuntime::spawn` should invoke `tokio::task::spawn_local` or equivalents.
   <br/><br/>
+
+- `tracing-log`: enables "log" feature in `tracing` crate, to let tracing events
+  emit log record.
+  See: [tracing doc: emitting-log-records](https://docs.rs/tracing/latest/tracing/#emitting-log-records)