Enforce nonzero connections in PoolBuilder

Author: ryanfowler

src/pool.rs

@@ -37,7 +37,7 @@ pub struct PoolBuilder {
     flags: OpenFlags,
     journal_mode: Option<JournalMode>,
     vfs: Option<String>,
-    num_conns: Option<usize>,
+    num_conns: Option<NonZeroUsize>,
 }
 
 impl PoolBuilder {
@@ -79,7 +79,20 @@ impl PoolBuilder {
     /// Specify the number of sqlite connections to open as part of the pool.
     ///
     /// Defaults to the number of logical CPUs of the current system.
-    pub fn num_conns(mut self, num_conns: usize) -> Self {
+    ///
+    /// ```
+    /// use async_sqlite::PoolBuilder;
+    /// use std::num::NonZeroUsize;
+    ///
+    /// let builder = PoolBuilder::new().num_conns(NonZeroUsize::new(2).unwrap());
+    /// ```
+    ///
+    /// ```compile_fail
+    /// use async_sqlite::PoolBuilder;
+    ///
+    /// PoolBuilder::new().num_conns(0);
+    /// ```
+    pub fn num_conns(mut self, num_conns: NonZeroUsize) -> Self {
         self.num_conns = Some(num_conns);
         self
     }
@@ -97,7 +110,7 @@ impl PoolBuilder {
     /// ```
     pub async fn open(self) -> Result<Pool, Error> {
         let num_conns = self.get_num_conns();
-        let opens = (0..num_conns).map(|_| {
+        let opens = (0..num_conns.get()).map(|_| {
             ClientBuilder {
                 path: self.path.clone(),
                 flags: self.flags,
@@ -132,7 +145,7 @@ impl PoolBuilder {
     /// ```
     pub fn open_blocking(self) -> Result<Pool, Error> {
         let num_conns = self.get_num_conns();
-        let clients = (0..num_conns)
+        let clients = (0..num_conns.get())
             .map(|_| {
                 ClientBuilder {
                     path: self.path.clone(),
@@ -151,11 +164,10 @@ impl PoolBuilder {
         })
     }
 
-    fn get_num_conns(&self) -> usize {
+    fn get_num_conns(&self) -> NonZeroUsize {
         self.num_conns.unwrap_or_else(|| {
             available_parallelism()
                 .unwrap_or_else(|_| NonZeroUsize::new(1).unwrap())
-                .into()
         })
     }
 }

tests/tests.rs

@@ -1,4 +1,5 @@
 use async_sqlite::{ClientBuilder, Error, JournalMode, PoolBuilder};
+use std::num::NonZeroUsize;
 
 #[test]
 fn test_blocking_client() {
@@ -138,7 +139,7 @@ async fn test_pool() {
     let tmp_dir = tempfile::tempdir().unwrap();
     let pool = PoolBuilder::new()
         .path(tmp_dir.path().join("sqlite.db"))
-        .num_conns(2)
+        .num_conns(NonZeroUsize::new(2).unwrap())
         .open()
         .await
         .expect("client unable to be opened");
@@ -191,7 +192,7 @@ async fn test_pool_conn_for_each() {
 
     let pool = PoolBuilder::new()
         .path(tmp_dir.path().join("another-sqlite.db"))
-        .num_conns(2)
+        .num_conns(NonZeroUsize::new(2).unwrap())
         .open()
         .await
         .expect("pool unable to be opened");