Add log library

Cargo.toml

@@ -13,4 +13,6 @@ tokio-util={version="^0.6", features = ["full"] }
 futures = { version = "0.3.0", features = ["thread-pool"]}
 tokio-stream="0.1"
 seahash = "4"
+log="0.4"
+env_logger = "0.8.4"
 bytes = "1"

src/commands/string.rs → src/cmd/string.rs

@@ -5,10 +5,14 @@ pub fn incr(db: &Db, args: &[Bytes]) -> Result<Value, Error> {
     db.incr(&args[1], 1)
 }
 
+pub fn decr(db: &Db, args: &[Bytes]) -> Result<Value, Error> {
+    db.incr(&args[1], -1)
+}
+
 pub fn get(db: &Db, args: &[Bytes]) -> Result<Value, Error> {
     db.get(&args[1])
 }
 
 pub fn set(db: &Db, args: &[Bytes]) -> Result<Value, Error> {
-    db.set(&args[1], &Value::Blob(args[2].clone()))
+    db.set(&args[1], &Value::Blob(args[2].to_owned()))
 }

src/db/mod.rs

@@ -1,4 +1,5 @@
 use crate::{error::Error, value::Value};
+use log::trace;
 use bytes::Bytes;
 use seahash::hash;
 use std::collections::{BTreeMap, HashMap};
@@ -29,7 +30,9 @@ impl Db {
     }
 
     fn get_slot(&self, key: &Bytes) -> usize {
-        (hash(key) as usize) % self.entries.len()
+        let id = (hash(key) as usize) % self.entries.len();
+        trace!("selected slot {} for key {:?}", id, key);
+        id
     }
 
     pub fn incr(&self, key: &Bytes, incr_by: i64) -> Result<Value, Error> {

src/dispatcher.rs

@@ -1,4 +1,4 @@
-use crate::{commands, db::Db, dispatcher, error::Error, value::Value};
+use crate::{cmd, db::Db, dispatcher, error::Error, value::Value};
 use bytes::Bytes;
 use std::convert::TryInto;
 use std::time::SystemTime;
@@ -28,17 +28,22 @@ dispatcher! {
         1,
     },
     incr {
-        commands::string::incr,
+        cmd::string::incr,
+        ["write" "denyoom" "fast"],
+        2,
+    },
+    decr {
+        cmd::string::decr,
         ["write" "denyoom" "fast"],
         2,
     },
     get {
-        commands::string::get,
+        cmd::string::get,
         ["random" "loading" "stale"],
         2,
     },
     set {
-        commands::string::set,
+        cmd::string::set,
         ["random" "loading" "stale"],
         -3,
     },

src/error.rs

@@ -0,0 +1,30 @@
+use crate::value::Value;
+
+pub enum Error {
+    CommandNotFound(String),
+    InvalidArgsCount(String),
+    ProtocolError(String, String),
+    NotANumber,
+    WrongType,
+}
+
+impl From<Error> for Value {
+    fn from(value: Error) -> Value {
+        let err_type = match value {
+            Error::WrongType => "WRONGTYPE",
+            _ => "ERR",
+        };
+
+        let err_msg = match value {
+            Error::CommandNotFound(x) => format!("unknown command `{}`", x),
+            Error::InvalidArgsCount(x) => format!("wrong number of arguments for '{}' command", x),
+            Error::ProtocolError(x, y) => format!("Protocol error: expected '{}', got '{}'", x, y),
+            Error::NotANumber => "value is not an integer or out of range".to_string(),
+            Error::WrongType => {
+                "Operation against a key holding the wrong kind of value".to_string()
+            }
+        };
+
+        Value::Err(err_type.to_string(), err_msg)
+    }
+}

src/main.rs

@@ -1,4 +1,4 @@
-mod commands;
+mod cmd;
 mod db;
 mod dispatcher;
 mod error;
@@ -9,6 +9,7 @@ use bytes::{Buf, Bytes, BytesMut};
 use dispatcher::Dispatcher;
 use futures::SinkExt;
 use redis_zero_parser::{parse_server, Error as RedisError};
+use log::info;
 use std::env;
 use std::error::Error;
 use std::ops::Deref;
@@ -24,10 +25,13 @@ async fn main() -> Result<(), Box<dyn Error>> {
         .nth(1)
         .unwrap_or_else(|| "127.0.0.1:8080".to_string());
 
+    env_logger::init();
+
+
     let listener = TcpListener::bind(&addr).await?;
-    println!("Listening on: {}", addr);
+    info!("Listening on: {}", addr);
 
-    let db = Arc::new(db::Db::new(12));
+    let db = Arc::new(db::Db::new(1000));
 
     loop {
         match listener.accept().await {