Introduce db connection pool. Derive Clone for State

Cargo.lock

@@ -14,6 +14,8 @@ dependencies = [
  "num 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)",
  "pulldown-cmark 0.0.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "r2d2 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "r2d2-diesel 0.16.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 1.0.11 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -37,6 +39,11 @@ name = "ansi_term"
 version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "antidote"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "atty"
 version = "0.2.2"
@@ -451,6 +458,25 @@ name = "quote"
 version = "0.3.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "r2d2"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "antidote 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "scheduled-thread-pool 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "r2d2-diesel"
+version = "0.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "diesel 0.15.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "r2d2 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "rand"
 version = "0.3.16"
@@ -504,6 +530,14 @@ dependencies = [
  "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "scheduled-thread-pool"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "antidote 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "scoped-tls"
 version = "0.1.0"
@@ -791,6 +825,7 @@ dependencies = [
 [metadata]
 "checksum aho-corasick 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)" = "500909c4f87a9e52355b26626d890833e9e1d53ac566db76c36faa984b889699"
 "checksum ansi_term 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "23ac7c30002a5accbf7e8987d0632fa6de155b7c3d39d0067317a391e00a2ef6"
+"checksum antidote 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "34fde25430d87a9388dadbe6e34d7f72a462c8b43ac8d309b42b0a8505d7e2a5"
 "checksum atty 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "d912da0db7fa85514874458ca3651fe2cddace8d0b0505571dbdcd41ab490159"
 "checksum bart 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "f0f9d52a5c46e2abe28ae1c2ecdaa320c01e424c29a56acb7a6222141c78bae7"
 "checksum bart_derive 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "39fdc9035ac29aeb14993e2cdae217de7ccc9f9960eae0c5a12d541ca11c6af1"
@@ -843,6 +878,8 @@ dependencies = [
 "checksum pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "3a8b4c6b8165cd1a1cd4b9b120978131389f64bdaf456435caa41e630edba903"
 "checksum pulldown-cmark 0.0.11 (registry+https://github.com/rust-lang/crates.io-index)" = "4c7c04a8bb38f80717527edea39c82378c2ef13ecdbc914cbd90653a2e24afdf"
 "checksum quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e920b65c65f10b2ae65c831a81a073a89edd28c7cce89475bff467ab4167a"
+"checksum r2d2 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)" = "6c665a538b218e1620093be6643b375d3321837bfc1b30aa18757b7c6546d2ca"
+"checksum r2d2-diesel 0.16.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f6b921696a6c45991296d21b52ed973b9fb56f6c47524fda1f99458c2d6c0478"
 "checksum rand 0.3.16 (registry+https://github.com/rust-lang/crates.io-index)" = "eb250fd207a4729c976794d03db689c9be1d634ab5a1c9da9492a13d8fecbcdf"
 "checksum redox_syscall 0.1.30 (registry+https://github.com/rust-lang/crates.io-index)" = "8312fba776a49cf390b7b62f3135f9b294d8617f7a7592cfd0ac2492b658cd7b"
 "checksum regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "1731164734096285ec2a5ec7fea5248ae2f5485b3feeb0115af4fda2183b2d1b"
@@ -850,6 +887,7 @@ dependencies = [
 "checksum rustc_version 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "c5f5376ea5e30ce23c03eb77cbe4962b988deead10910c372b226388b594c084"
 "checksum safemem 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e27a8b19b835f7aea908818e871f5cc3a5a186550c30773be987e155e8163d8f"
 "checksum same-file 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "d931a44fdaa43b8637009e7632a02adc4f2b2e0733c08caa4cf00e8da4a117a7"
+"checksum scheduled-thread-pool 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "2d9fbe48ead32343b76f544c85953bf260ed39219a8bbbb62cd85f6a00f9644f"
 "checksum scoped-tls 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f417c22df063e9450888a7561788e9bd46d3bb3c1466435b4eccb903807f147d"
 "checksum semver 0.1.20 (registry+https://github.com/rust-lang/crates.io-index)" = "d4f410fedcf71af0345d7607d246e7ad15faaadd49d240ee3b24e5dc21a820ac"
 "checksum serde 1.0.11 (registry+https://github.com/rust-lang/crates.io-index)" = "f7726f29ddf9731b17ff113c461e362c381d9d69433f79de4f3dd572488823e9"

Cargo.toml

@@ -12,6 +12,8 @@ tokio-service = "0.1"
 serde_derive = "1.0.0"
 serde = "1.0.0"
 serde_urlencoded = "0.5.0"
+r2d2 = "0.7"
+r2d2-diesel = "0.16"
 regex = "0.2"
 lazy_static = "0.2"
 chrono = "0.4"

src/db.rs

@@ -1,23 +1,33 @@
-use diesel::Connection;
 use diesel::sqlite::SqliteConnection;
 use diesel::prelude::*;
 use diesel::expression::sql_literal::sql;
 use diesel::types::*;
+use r2d2::{Config, CustomizeConnection, Pool};
+use r2d2_diesel::{self, ConnectionManager};
 
 embed_migrations!();
 
-pub fn connect_database(connection_string: &str, run_migrations: bool) -> SqliteConnection {
+#[derive(Debug)]
-    let connection = SqliteConnection::establish(connection_string)
+struct SqliteInitializer;
-        .expect(&format!("Error connecting to database at {}", connection_string));
 
-    // Integer is a dummy placeholder. Compiling fails when passing ().
+impl CustomizeConnection<SqliteConnection, r2d2_diesel::Error> for SqliteInitializer {
+    fn on_acquire(&self, conn: &mut SqliteConnection) -> Result<(), r2d2_diesel::Error> {
         sql::<(Integer)>("PRAGMA foreign_keys = ON")
-        .execute(&connection)
+            .execute(conn)
-        .expect("Should be able to enable foreign_keys");
+            .and(Ok(()))
-
+            .map_err(|x| r2d2_diesel::Error::QueryError(x))
-    if run_migrations {
-        embedded_migrations::run(&connection).unwrap();
     }
-
+}
-    connection
+
+pub fn create_pool(connection_string: String) -> Result<Pool<ConnectionManager<SqliteConnection>>, Box<::std::error::Error>> {
+    let config = Config::builder()
+        .connection_customizer(Box::new(SqliteInitializer {}))
+        .build();
+    let manager = ConnectionManager::<SqliteConnection>::new(connection_string);
+
+    let pool = Pool::new(config, manager)?;
+
+    embedded_migrations::run(&*pool.get()?)?;
+
+    Ok(pool)
 }

src/main.rs

@@ -2,13 +2,16 @@
 #[macro_use] extern crate diesel;
 #[macro_use] extern crate diesel_codegen;
 #[macro_use] extern crate lazy_static;
+#[macro_use] extern crate serde_derive;
 
-extern crate bart;
 extern crate chrono;
 extern crate clap;
 extern crate futures;
 extern crate hyper;
 extern crate pulldown_cmark;
+extern crate r2d2;
+extern crate r2d2_diesel;
+extern crate serde_urlencoded;
 
 use std::net::SocketAddr;
 
@@ -48,14 +51,14 @@ fn core_main() -> Result<(), Box<std::error::Error>> {
         .map(|p| p.parse().expect("Guaranteed by validator"))
         .unwrap_or(8080);
 
-    // Connect to the database and run migrations up front:
+    let db_pool = db::create_pool(db_file)?;
-    db::connect_database(&db_file, true);
+    let state = state::State::new(db_pool);
 
     let server =
         hyper::server::Http::new()
             .bind(
                 &SocketAddr::new(bind_host, bind_port),
-                move || Ok(site::Site::new(state::State::new(db::connect_database(&db_file, false))))
+                move || Ok(site::Site::new(state.clone()))
             )?;
 
     println!("Listening on http://{}", server.local_addr().unwrap());

src/state.rs

@@ -3,19 +3,30 @@ use std;
 use chrono;
 use diesel::sqlite::SqliteConnection;
 use diesel::prelude::*;
+use r2d2::Pool;
+use r2d2_diesel::ConnectionManager;
 
 use models;
 
+#[derive(Clone)]
 pub struct State {
-    db_connection: SqliteConnection
+    connection_pool: Pool<ConnectionManager<SqliteConnection>>
 }
 
+#[derive(Deserialize)]
+pub struct UpdateArticle {
+    base_revision: i32,
+    body: String,
+}
+
+pub type Error = Box<std::error::Error + Send + Sync>;
+
 impl State {
-    pub fn new(db_connection: SqliteConnection) -> State {
+    pub fn new(connection_pool: Pool<ConnectionManager<SqliteConnection>>) -> State {
-        State { db_connection }
+        State { connection_pool }
     }
 
-    pub fn get_article_revision_by_slug(&self, slug: &str) -> Result<Option<models::ArticleRevision>, Box<std::error::Error + Send + Sync>> {
+    pub fn get_article_revision_by_slug(&self, slug: &str) -> Result<Option<models::ArticleRevision>, Error> {
         Ok(Some(models::ArticleRevision {
             article_id: 0,
             revision: 0,
@@ -25,14 +36,14 @@ impl State {
         }))
     }
 
-    pub fn get_article_revision_by_id(&self, article_id: i32) -> Result<Option<models::ArticleRevision>, Box<std::error::Error + Send + Sync>> {
+    pub fn get_article_revision_by_id(&self, article_id: i32) -> Result<Option<models::ArticleRevision>, Error> {
         use schema::article_revisions;
 
         Ok(article_revisions::table
             .filter(article_revisions::article_id.eq(article_id))
             .order(article_revisions::revision.desc())
             .limit(1)
-            .load::<models::ArticleRevision>(&self.db_connection)?
+            .load::<models::ArticleRevision>(&*self.connection_pool.get()?)?
             .pop())
     }
 }