From b3885f80ddc997006068b1972c5196011c40ffa1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Moritz=20B=C3=B6hme?= <mail@moritzboeh.me>
Date: Sat, 29 Jul 2023 10:15:46 +0200
Subject: [PATCH] perf: make daemon more memory efficient

Use Box<str> instead of String in daemon. Because we don't need to
change names of timers in the daemon this is way more memory efficient.
---
 src/daemon.rs | 42 ++++++++++++++++--------------------------
 src/main.rs   |  4 ++--
 src/timer.rs  |  4 ++--
 3 files changed, 20 insertions(+), 30 deletions(-)

diff --git a/src/daemon.rs b/src/daemon.rs
index 5bba1a2..7032698 100644
--- a/src/daemon.rs
+++ b/src/daemon.rs
@@ -11,8 +11,8 @@ use std::{
 
 #[derive(Debug, Serialize, Deserialize)]
 pub enum Command {
-    Add(String, Duration),
-    Remove(String),
+    Add(Box<str>, Duration),
+    Remove(Box<str>),
     List,
 }
 
@@ -42,12 +42,11 @@ impl Display for Answer {
 #[derive(Debug, thiserror::Error, Serialize, Deserialize)]
 pub enum AnswerErr {
     #[error("Timer with name '{}' already exists", .0)]
-    TimerAlreadyExist(String),
+    TimerAlreadyExist(Box<str>),
     #[error("No timer with the name '{}' exists", .0)]
-    NoSuchTimer(String),
+    NoSuchTimer(Box<str>),
 }
 
-
 pub struct Daemon {
     listener: UnixListener,
     timers: Vec<Timer>,
@@ -68,14 +67,14 @@ impl Daemon {
         })
     }
 
-    fn has_timer(&mut self, name: &String) -> bool {
-        self.timers.iter().any(|other| &other.name == name)
+    fn has_timer(&mut self, name: &str) -> bool {
+        self.timers.iter().any(|other| other.name.as_ref() == name)
     }
 
     fn handle_command(&mut self, command: Command) -> Result<Answer, AnswerErr> {
         println!("Received command {:?}", command);
         match command {
-            Command::List => Ok(Answer::Timers(self.timers.to_vec())),
+            Command::List => Ok(Answer::Timers(self.timers.clone())),
             Command::Add(name, duration) => {
                 if self.has_timer(&name) {
                     return Err(AnswerErr::TimerAlreadyExist(name));
@@ -88,12 +87,8 @@ impl Daemon {
                 if !self.has_timer(&name) {
                     return Err(AnswerErr::NoSuchTimer(name));
                 }
-                self.timers = self
-                    .timers
-                    .iter()
-                    .cloned()
-                    .filter(|other| other.name != name)
-                    .collect();
+                self.timers
+                    .retain(|other| other.name.as_ref() != name.as_ref());
                 Ok(Answer::Ok)
             }
         }
@@ -108,18 +103,13 @@ impl Daemon {
     }
 
     fn check_timers(&mut self) {
-        self.timers = self
-            .timers
-            .iter()
-            .cloned()
-            .filter(|timer| {
-                let expired = timer.is_expired();
-                if expired {
-                    println!("Timer {} is expired!", timer.name);
-                }
-                !expired
-            })
-            .collect();
+        self.timers.retain(|timer| {
+            let expired = timer.is_expired();
+            if expired {
+                println!("Timer {} is expired!", timer.name);
+            }
+            !expired
+        });
     }
 
     pub fn run(&mut self) -> anyhow::Result<()> {
diff --git a/src/main.rs b/src/main.rs
index aa44d10..96b77f4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -16,9 +16,9 @@ fn main() -> Result<()> {
         CliCommand::Add {
             name,
             duration_seconds,
-        } => DaemonCommand::Add(name, Duration::from_secs(duration_seconds)),
+        } => DaemonCommand::Add(name.into_boxed_str(), Duration::from_secs(duration_seconds)),
         CliCommand::List => DaemonCommand::List,
-        CliCommand::Remove { name } => DaemonCommand::Remove(name),
+        CliCommand::Remove { name } => DaemonCommand::Remove(name.into_boxed_str()),
     };
     send_command(&args.socket, daemon_command)
 }
diff --git a/src/timer.rs b/src/timer.rs
index 262f41c..291fe5e 100644
--- a/src/timer.rs
+++ b/src/timer.rs
@@ -33,7 +33,7 @@ mod approx_instant {
 
 #[derive(Debug, Serialize, Deserialize, PartialEq, Eq, Clone)]
 pub struct Timer {
-    pub name: String,
+    pub name: Box<str>,
     #[serde(with = "approx_instant")]
     start: Instant,
     duration: Duration,
@@ -51,7 +51,7 @@ impl Display for Timer {
 }
 
 impl Timer {
-    pub fn new(name: String, duration: Duration) -> Timer {
+    pub fn new(name: Box<str>, duration: Duration) -> Timer {
         Timer {
             name,
             start: Instant::now(),