Simplify connection pool

It's going to just be fixed size for now

Author: sfackler

README.md

@@ -171,6 +171,23 @@ match conn.try_update(query, params) {
 }
 ```
 
+Connection Pooling
+------------------
+A very basic fixed-size connection pool is provided in the `pool` module. A
+single pool can be shared across tasks and `get_connection` will block until a
+connection is available.
+```rust
+let pool = PostgresConnectionPool::new("postgres://postgres@localhost", 5)
+        .unwrap();
+
+for _ in range(0, 10) {
+    do task::spawn_with(pool.clone()) |pool| {
+        let conn = pool.get_connection();
+        conn.query(...);
+    }
+}
+```
+
 Type Correspondence
 -------------------
 Rust-Postgres enforces a strict correspondence between Rust types and Postgres

src/pool/mod.rs

@@ -9,39 +9,16 @@ use super::{PostgresConnection,
             PostgresTransaction};
 use super::types::ToSql;
 
-pub struct PostgresConnectionPoolConfig {
-    initial_size: uint,
-    min_size: uint,
-    max_size: uint
-}
-
-impl PostgresConnectionPoolConfig {
-    fn validate(&self) {
-        assert!(self.initial_size >= self.min_size);
-        assert!(self.initial_size <= self.max_size);
-    }
-}
-
-pub static DEFAULT_CONFIG: PostgresConnectionPoolConfig =
-    PostgresConnectionPoolConfig {
-        initial_size: 3,
-        min_size: 3,
-        max_size: 15
-    };
-
 struct InnerConnectionPool {
     url: ~str,
-    config: PostgresConnectionPoolConfig,
     pool: ~[PostgresConnection],
-    size: uint,
 }
 
 impl InnerConnectionPool {
     fn new_connection(&mut self) -> Option<PostgresConnectError> {
         match PostgresConnection::try_connect(self.url) {
             Ok(conn) => {
                 self.pool.push(conn);
-                self.size += 1;
                 None
             }
             Err(err) => Some(err)
@@ -56,18 +33,14 @@ pub struct PostgresConnectionPool {
 }
 
 impl PostgresConnectionPool {
-    pub fn new(url: &str, config: PostgresConnectionPoolConfig)
+    pub fn try_new(url: &str, pool_size: uint)
             -> Result<PostgresConnectionPool, PostgresConnectError> {
-        config.validate();
-
         let mut pool = InnerConnectionPool {
             url: url.to_owned(),
-            config: config,
             pool: ~[],
-            size: 0,
         };
 
-        while pool.size < pool.config.initial_size {
+        while pool.pool.len() < pool_size {
             match pool.new_connection() {
                 None => (),
                 Some(err) => return Err(err)
@@ -79,6 +52,13 @@ impl PostgresConnectionPool {
         })
     }
 
+    pub fn new(url: &str, pool_size: uint) -> PostgresConnectionPool {
+        match PostgresConnectionPool::try_new(url, pool_size) {
+            Ok(pool) => pool,
+            Err(err) => fail!("Unable to initialize pool: %s", err.to_str())
+        }
+    }
+
     pub fn try_get_connection(&self) -> Result<PooledPostgresConnection,
                                                PostgresConnectError> {
         let conn = unsafe {
@@ -108,7 +88,7 @@ impl PostgresConnectionPool {
 // Should be a newtype
 pub struct PooledPostgresConnection {
     priv pool: PostgresConnectionPool,
-    // Todo remove the Option wrapper when drop takes self by value
+    // TODO remove the Option wrapper when drop takes self by value
     priv conn: Option<PostgresConnection>
 }
 

src/pool/test.rs

@@ -5,18 +5,12 @@ use std::cell::Cell;
 use extra::comm::DuplexStream;
 use extra::future;
 
-use postgres::pool::{PostgresConnectionPool, PostgresConnectionPoolConfig};
+use postgres::pool::PostgresConnectionPool;
 
 #[test]
 // Make sure we can take both connections at once and can still get one after
 fn test_pool() {
-    let config = PostgresConnectionPoolConfig {
-        initial_size: 2,
-        min_size: 2,
-        max_size: 2
-    };
-    let pool = PostgresConnectionPool::new("postgres://postgres@localhost",
-                                           config).unwrap();
+    let pool = PostgresConnectionPool::new("postgres://postgres@localhost", 2);
 
     let (stream1, stream2) = DuplexStream::<(), ()>();