feat: adds trace events to server

src/cmd/get.rs

@@ -1,6 +1,7 @@
 use crate::{Connection, Frame, Kv, Parse, ParseError};
 
 use std::io;
+use tracing::{debug, instrument};
 
 #[derive(Debug)]
 pub struct Get {
@@ -8,18 +9,31 @@ pub struct Get {
 }
 
 impl Get {
+    // instrumenting functions will log all of the arguments passed to the function
+    // with their debug implementations
+    // see https://docs.rs/tracing/0.1.13/tracing/attr.instrument.html
+    #[instrument]
     pub(crate) fn parse(parse: &mut Parse) -> Result<Get, ParseError> {
         let key = parse.next_string()?;
+
+        // adding this debug event allows us to see what key is parsed
+        // the ? sigil tells `tracing` to use the `Debug` implementation
+        // get parse events can be filtered by running
+        // RUST_LOG=mini_redis::cmd::get[parse]=debug cargo run --bin server
+        // see https://docs.rs/tracing/0.1.13/tracing/#recording-fields
+        debug!(?key);
+
         Ok(Get { key })
     }
 
+    #[instrument]
     pub(crate) async fn apply(self, kv: &Kv, dst: &mut Connection) -> io::Result<()> {
         let response = if let Some(value) = kv.get(&self.key) {
             Frame::Bulk(value)
         } else {
             Frame::Null
         };
-
+        debug!(?response);
         dst.write_frame(&response).await
     }
 }

src/cmd/set.rs

@@ -4,6 +4,7 @@ use crate::{Connection, Frame, Kv};
 use bytes::Bytes;
 use std::io;
 use std::time::Duration;
+use tracing::{debug, instrument};
 
 #[derive(Debug)]
 pub struct Set {
@@ -13,6 +14,7 @@ pub struct Set {
 }
 
 impl Set {
+    #[instrument]
     pub(crate) fn parse(parse: &mut Parse) -> Result<Set, ParseError> {
         use ParseError::EndOfStream;
 
@@ -34,14 +36,18 @@ impl Set {
             Err(err) => return Err(err),
         }
 
+        debug!(?key, ?value, ?expire);
+
         Ok(Set { key, value, expire })
     }
 
+    #[instrument]
     pub(crate) async fn apply(self, kv: &Kv, dst: &mut Connection) -> io::Result<()> {
         // Set the value
         kv.set(self.key, self.value, self.expire);
 
         let response = Frame::Simple("OK".to_string());
+        debug!(?response);
         dst.write_frame(&response).await
     }
 }