Improve sync performance with more caching and wrapping things in Arcs to avoid copies

src/database/key_value/rooms/state_accessor.rs

@@ -16,7 +16,7 @@ impl service::rooms::state_accessor::Data for KeyValueDatabase {
             .1;
         let mut result = HashMap::new();
         let mut i = 0;
-        for compressed in full_state.into_iter() {
+        for compressed in full_state.iter() {
             let parsed = services()
                 .rooms
                 .state_compressor
@@ -45,7 +45,7 @@ impl service::rooms::state_accessor::Data for KeyValueDatabase {
 
         let mut result = HashMap::new();
         let mut i = 0;
-        for compressed in full_state {
+        for compressed in full_state.iter() {
             let (_, eventid) = services()
                 .rooms
                 .state_compressor
@@ -95,7 +95,7 @@ impl service::rooms::state_accessor::Data for KeyValueDatabase {
             .expect("there is always one layer")
             .1;
         Ok(full_state
-            .into_iter()
+            .iter()
             .find(|bytes| bytes.starts_with(&shortstatekey.to_be_bytes()))
             .and_then(|compressed| {
                 services()

src/database/key_value/rooms/state_compressor.rs

@@ -1,4 +1,4 @@
-use std::{collections::HashSet, mem::size_of};
+use std::{collections::HashSet, mem::size_of, sync::Arc};
 
 use crate::{
     database::KeyValueDatabase,
@@ -37,20 +37,20 @@ impl service::rooms::state_compressor::Data for KeyValueDatabase {
 
         Ok(StateDiff {
             parent,
-            added,
-            removed,
+            added: Arc::new(added),
+            removed: Arc::new(removed),
         })
     }
 
     fn save_statediff(&self, shortstatehash: u64, diff: StateDiff) -> Result<()> {
         let mut value = diff.parent.unwrap_or(0).to_be_bytes().to_vec();
-        for new in &diff.added {
+        for new in diff.added.iter() {
             value.extend_from_slice(&new[..]);
         }
 
         if !diff.removed.is_empty() {
             value.extend_from_slice(&0_u64.to_be_bytes());
-            for removed in &diff.removed {
+            for removed in diff.removed.iter() {
                 value.extend_from_slice(&removed[..]);
             }
         }

src/database/mod.rs

@@ -587,8 +587,8 @@ impl KeyValueDatabase {
 
                         services().rooms.state_compressor.save_state_from_diff(
                             current_sstatehash,
-                            statediffnew,
-                            statediffremoved,
+                            Arc::new(statediffnew),
+                            Arc::new(statediffremoved),
                             2, // every state change is 2 event changes on average
                             states_parents,
                         )?;