Merge branch 'connection-lifetime' into 'master'

thread_local connections

See merge request famedly/conduit!175

Cargo.lock

@@ -267,6 +267,7 @@ dependencies = [
  "serde_yaml",
  "sled",
  "thiserror",
+ "thread_local",
  "threadpool",
  "tokio",
  "tracing",

Cargo.toml

@@ -80,6 +80,7 @@ crossbeam = { version = "0.8.1", optional = true }
 num_cpus = "1.13.0"
 threadpool = "1.8.1"
 heed = { git = "https://github.com/timokoesters/heed.git", rev = "f6f825da7fb2c758867e05ad973ef800a6fe1d5d", optional = true }
+thread_local = "1.1.3"
 
 [features]
 default = ["conduit_bin", "backend_sqlite"]

src/database/abstraction/sqlite.rs

@@ -10,6 +10,7 @@ use std::{
     pin::Pin,
     sync::Arc,
 };
+use thread_local::ThreadLocal;
 use tokio::sync::oneshot::Sender;
 use tracing::debug;
 
@@ -40,6 +41,8 @@ impl<T> Drop for NonAliasingBox<T> {
 
 pub struct Engine {
     writer: Mutex<Connection>,
+    read_conn_tls: ThreadLocal<Connection>,
+    read_iterator_conn_tls: ThreadLocal<Connection>,
 
     path: PathBuf,
     cache_size_per_thread: u32,
@@ -62,34 +65,14 @@ impl Engine {
         self.writer.lock()
     }
 
-    fn read_lock(&self) -> &'static Connection {
-        READ_CONNECTION.with(|cell| {
-            let connection = &mut cell.borrow_mut();
-
-            if (*connection).is_none() {
-                let c = Box::leak(Box::new(
-                    Self::prepare_conn(&self.path, self.cache_size_per_thread).unwrap(),
-                ));
-                **connection = Some(c);
-            }
-
-            connection.unwrap()
-        })
+    fn read_lock<'a>(&'a self) -> &'a Connection {
+        self.read_conn_tls
+            .get_or(|| Self::prepare_conn(&self.path, self.cache_size_per_thread).unwrap())
     }
 
-    fn read_lock_iterator(&self) -> &'static Connection {
-        READ_CONNECTION_ITERATOR.with(|cell| {
-            let connection = &mut cell.borrow_mut();
-
-            if (*connection).is_none() {
-                let c = Box::leak(Box::new(
-                    Self::prepare_conn(&self.path, self.cache_size_per_thread).unwrap(),
-                ));
-                **connection = Some(c);
-            }
-
-            connection.unwrap()
-        })
+    fn read_lock_iterator<'a>(&'a self) -> &'a Connection {
+        self.read_iterator_conn_tls
+            .get_or(|| Self::prepare_conn(&self.path, self.cache_size_per_thread).unwrap())
     }
 
     pub fn flush_wal(self: &Arc<Self>) -> Result<()> {
@@ -105,15 +88,18 @@ impl DatabaseEngine for Engine {
 
         // calculates cache-size per permanent connection
         // 1. convert MB to KiB
-        // 2. divide by permanent connections
+        // 2. divide by permanent connections + permanent iter connections + write connection
         // 3. round down to nearest integer
-        let cache_size_per_thread: u32 =
-            ((config.db_cache_capacity_mb * 1024.0) / (num_cpus::get().max(1) + 1) as f64) as u32;
+        let cache_size_per_thread: u32 = ((config.db_cache_capacity_mb * 1024.0)
+            / ((num_cpus::get().max(1) * 2) + 1) as f64)
+            as u32;
 
         let writer = Mutex::new(Self::prepare_conn(&path, cache_size_per_thread)?);
 
         let arc = Arc::new(Engine {
             writer,
+            read_conn_tls: ThreadLocal::new(),
+            read_iterator_conn_tls: ThreadLocal::new(),
             path,
             cache_size_per_thread,
         });