From 4463d03ecbe98b00eb8000b399a13d36e26dfa85 Mon Sep 17 00:00:00 2001
From: jiacai2050 <dev@liujiacai.net>
Date: Thu, 29 Aug 2024 15:03:51 +0800
Subject: [PATCH] fix: use iter to avoid reallocate

---
 rust/fury-core/src/resolver/meta_resolver.rs |  2 +-
 rust/fury-core/src/serializer/list.rs        | 11 ++++-------
 rust/fury-core/src/serializer/map.rs         | 17 +++++++----------
 rust/fury-core/src/serializer/mod.rs         |  4 ++--
 rust/fury-core/src/serializer/set.rs         |  9 +++------
 5 files changed, 17 insertions(+), 26 deletions(-)

diff --git a/rust/fury-core/src/resolver/meta_resolver.rs b/rust/fury-core/src/resolver/meta_resolver.rs
index b9a442c54e..1e177423d8 100644
--- a/rust/fury-core/src/resolver/meta_resolver.rs
+++ b/rust/fury-core/src/resolver/meta_resolver.rs
@@ -69,7 +69,7 @@ impl<'a> MetaWriterResolver<'a> {
 
     pub fn to_bytes(&self, writer: &mut Writer) -> Result<(), Error> {
         writer.var_int32(self.type_defs.len() as i32);
-        for item in self.type_defs.iter() {
+        for item in &self.type_defs {
             writer.bytes(item)
         }
         Ok(())
diff --git a/rust/fury-core/src/serializer/list.rs b/rust/fury-core/src/serializer/list.rs
index 0b147f4379..46e76ff013 100644
--- a/rust/fury-core/src/serializer/list.rs
+++ b/rust/fury-core/src/serializer/list.rs
@@ -38,14 +38,11 @@ where
     }
 
     fn read(context: &mut ReadContext) -> Result<Self, Error> {
-        // length
+        // vec length
         let len = context.reader.var_int32();
-        // value
-        let mut result = Vec::new();
-        for _ in 0..len {
-            result.push(T::deserialize(context)?);
-        }
-        Ok(result)
+        (0..len)
+            .map(|_| T::deserialize(context))
+            .collect::<Result<Vec<_>, Error>>()
     }
 
     fn reserved_space() -> usize {
diff --git a/rust/fury-core/src/serializer/map.rs b/rust/fury-core/src/serializer/map.rs
index e79740f403..837e3ab61b 100644
--- a/rust/fury-core/src/serializer/map.rs
+++ b/rust/fury-core/src/serializer/map.rs
@@ -42,17 +42,14 @@ impl<T1: Serializer + Eq + std::hash::Hash, T2: Serializer> Serializer for HashM
     }
 
     fn read(context: &mut ReadContext) -> Result<Self, Error> {
-        // length
+        // map length
         let len = context.reader.var_int32();
-        let mut result = HashMap::new();
-        // key-value
-        for _ in 0..len {
-            result.insert(
-                <T1 as Serializer>::deserialize(context)?,
-                <T2 as Serializer>::deserialize(context)?,
-            );
-        }
-        Ok(result)
+        (0..len)
+            .map(|_| {
+                <T1 as Serializer>::deserialize(context)
+                    .and_then(|k| <T2 as Serializer>::deserialize(context).map(|v| (k, v)))
+            })
+            .collect::<Result<HashMap<_, _>, Error>>()
     }
 
     fn reserved_space() -> usize {
diff --git a/rust/fury-core/src/serializer/mod.rs b/rust/fury-core/src/serializer/mod.rs
index 1803bdfb54..20f02093c5 100644
--- a/rust/fury-core/src/serializer/mod.rs
+++ b/rust/fury-core/src/serializer/mod.rs
@@ -67,8 +67,8 @@ pub trait Serializer
 where
     Self: Sized,
 {
-    /// The fixed memory size of the Type.
-    /// Avoid the memory check, which would hurt performance.
+    /// The possible max memory size of the type.
+    /// Used to reserve the buffer space to avoid reallocation, which may hurt performance.
     fn reserved_space() -> usize;
 
     /// Write the data into the buffer.
diff --git a/rust/fury-core/src/serializer/set.rs b/rust/fury-core/src/serializer/set.rs
index 4b8b84dba4..fd4eb51415 100644
--- a/rust/fury-core/src/serializer/set.rs
+++ b/rust/fury-core/src/serializer/set.rs
@@ -42,12 +42,9 @@ impl<T: Serializer + Eq + std::hash::Hash> Serializer for HashSet<T> {
     fn read(context: &mut ReadContext) -> Result<Self, Error> {
         // length
         let len = context.reader.var_int32();
-        let mut result = HashSet::new();
-        // key-value
-        for _ in 0..len {
-            result.insert(<T as Serializer>::deserialize(context)?);
-        }
-        Ok(result)
+        (0..len)
+            .map(|_| T::deserialize(context))
+            .collect::<Result<HashSet<_>, Error>>()
     }
 
     fn reserved_space() -> usize {