refactor: use with_capacity to improve allocate performance

Author: pan93412

engine-base/src/executor.rs

@@ -51,7 +51,7 @@ impl Executor {
         info!("Searching {song} with engines {engines:?}");
         self.validate_engines(engines)?;
 
-        let mut futures = Vec::new();
+        let mut futures = Vec::with_capacity(engines.len());
 
         for engine_id in engines {
             let engine = self.resolve_engine(engine_id)?;
@@ -107,7 +107,7 @@ impl Executor {
     /// Validate engines to check if the engines specified are all registered.
     fn validate_engines(&self, engines: &[EngineId]) -> ExecutorResult<()> {
         debug!("Validating if all the engines ({engines:?}) are registered…");
-        let mut missing_engines = Vec::new();
+        let mut missing_engines = Vec::with_capacity(engines.len());
 
         for engine_id in engines {
             trace!("Validating: {engine_id}");

engines/kugou/src/lib.rs

@@ -64,7 +64,7 @@ impl From<KugouSongContext> for HashMap<String, String> {
     fn from(ctx: KugouSongContext) -> Self {
         debug!("Constructing the context HashMap from KugouSongContext…");
 
-        let mut map = HashMap::new();
+        let mut map = HashMap::with_capacity(3);
 
         [
             (KugouFormat::Hash, ctx.id),

engines/migu/src/types.rs

@@ -239,7 +239,7 @@ mod tests {
         .into_iter();
 
         let expected = {
-            let mut hm = HashMap::new();
+            let mut hm = HashMap::with_capacity(3);
 
             hm.insert(
                 "LQ".to_string(),

engines/ytdl/src/lib.rs

@@ -167,7 +167,7 @@ mod tests {
         let config = ConfigManager::new(config);
         assert_eq!(decide_ytdl_exe(&Some(config)), DEFAULT_EXECUTABLE);
 
-        let mut config = HashMap::new();
+        let mut config = HashMap::with_capacity(1);
         config.insert(Cow::Borrowed("ytdl:exe"), "youtube-dl".to_string());
         let config = ConfigManager::new(config);
         assert_eq!(decide_ytdl_exe(&Some(config)), "youtube-dl");

request/src/lib.rs

@@ -170,7 +170,7 @@ mod tests {
     use std::collections::HashMap;
 
     static TRANSLATE_MAP: Lazy<HashMap<&str, &str>> = Lazy::new(|| {
-        let mut map = HashMap::new();
+        let mut map = HashMap::with_capacity(2);
         map.insert("www.cloudflare.com", "1.1.1.1");
         map.insert("www.google.com", "www.bing.com");