Implement SQL connection pool

server/Cargo.lock

@@ -694,6 +694,7 @@ dependencies = [
  "chrono 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "diesel_derives 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "pq-sys 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "r2d2 0.8.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1514,6 +1515,15 @@ dependencies = [
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "parking_lot"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "lock_api 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot_core 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "parking_lot_core"
 version = "0.4.0"
@@ -1555,6 +1565,19 @@ dependencies = [
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "parking_lot_core"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "redox_syscall 0.1.56 (registry+https://github.com/rust-lang/crates.io-index)",
+ "smallvec 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "percent-encoding"
 version = "1.0.1"
@@ -1667,6 +1690,16 @@ dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "r2d2"
+version = "0.8.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parking_lot 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "scheduled-thread-pool 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "rand"
 version = "0.3.23"
@@ -1966,6 +1999,14 @@ dependencies = [
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "scheduled-thread-pool"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "parking_lot 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "scopeguard"
 version = "0.3.3"
@@ -2122,6 +2163,11 @@ name = "smallvec"
 version = "0.6.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "smallvec"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "socket2"
 version = "0.3.9"
@@ -2824,12 +2870,14 @@ dependencies = [
 "checksum openssl-probe 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "77af24da69f9d9341038eba93a073b1fdaaa1b788221b00a69bce9e762cb32de"
 "checksum openssl-sys 0.9.52 (registry+https://github.com/rust-lang/crates.io-index)" = "c977d08e1312e2f7e4b86f9ebaa0ed3b19d1daff75fae88bbb88108afbd801fc"
 "checksum owning_ref 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "49a4b8ea2179e6a2e27411d3bca09ca6dd630821cf6894c6c7c8467a8ee7ef13"
+"checksum parking_lot 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "92e98c49ab0b7ce5b222f2cc9193fc4efe11c6d0bd4f648e374684a6857b1cfc"
 "checksum parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ab41b4aed082705d1056416ae4468b6ea99d52599ecf3169b00088d43113e337"
 "checksum parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fa7767817701cce701d5585b9c4db3cdd02086398322c1d7e8bf5094a96a2ce7"
 "checksum parking_lot 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f842b1982eb6c2fe34036a4fbfb06dd185a3f5c8edfaacdf7d1ea10b07de6252"
 "checksum parking_lot_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "94c8c7923936b28d546dfd14d4472eaf34c99b14e1c973a32b3e6d4eb04298c9"
 "checksum parking_lot_core 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "cb88cb1cb3790baa6776844f968fea3be44956cf184fa1be5a03341f5491278c"
 "checksum parking_lot_core 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)" = "b876b1b9e7ac6e1a74a6da34d25c42e17e8862aa409cbbbdcfc8d86c6f3bc62b"
+"checksum parking_lot_core 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7582838484df45743c8434fbff785e8edf260c28748353d44bc0da32e0ceabf1"
 "checksum percent-encoding 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "31010dd2e1ac33d5b46a5b413495239882813e0369f8ed8a5e266f173602f831"
 "checksum phf 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)" = "b3da44b85f8e8dfaec21adae67f95d93244b2ecf6ad2a692320598dcc8e6dd18"
 "checksum phf_codegen 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)" = "b03e85129e324ad4166b06b2c7491ae27fe3ec353af72e72cd1654c7225d517e"
@@ -2845,6 +2893,7 @@ dependencies = [
 "checksum quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e920b65c65f10b2ae65c831a81a073a89edd28c7cce89475bff467ab4167a"
 "checksum quote 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9949cfe66888ffe1d53e6ec9d9f3b70714083854be20fd5e271b232a017401e8"
 "checksum quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)" = "6ce23b6b870e8f94f81fb0a363d65d86675884b34a09043c81e5562f11c1f8e1"
+"checksum r2d2 0.8.7 (registry+https://github.com/rust-lang/crates.io-index)" = "22b5c5fc5fba064373f03887337b412e0e1562d63023393db77251146cb75553"
 "checksum rand 0.3.23 (registry+https://github.com/rust-lang/crates.io-index)" = "64ac302d8f83c0c1974bf758f6b041c6c8ada916fbb44a609158ca8b064cc76c"
 "checksum rand 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "552840b97013b1a26992c11eac34bdd778e464601a4c2054b5f0bff7c6761293"
 "checksum rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)" = "6d71dacdc3c88c1fde3885a3be3fbab9f35724e6ce99467f7d9c5026132184ca"
@@ -2879,6 +2928,7 @@ dependencies = [
 "checksum ryu 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c92464b447c0ee8c4fb3824ecc8383b81717b9f1e74ba2e72540aef7b9f82997"
 "checksum safemem 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ef703b7cb59335eae2eb93ceb664c0eb7ea6bf567079d843e09420219668e072"
 "checksum schannel 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)" = "87f550b06b6cba9c8b8be3ee73f391990116bf527450d2556e9b9ce263b9a021"
+"checksum scheduled-thread-pool 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "f5de7bc31f28f8e6c28df5e1bf3d10610f5fdc14cc95f272853512c70a2bd779"
 "checksum scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "94258f53601af11e6a49f722422f6e3425c52b06245a5cf9bc09908b174f5e27"
 "checksum scopeguard 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b42e15e59b18a828bbf5c58ea01debb36b9b096346de35d941dcb89009f24a0d"
 "checksum security-framework 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "eee63d0f4a9ec776eeb30e220f0bc1e092c3ad744b2a379e3993070364d3adc2"
@@ -2899,6 +2949,7 @@ dependencies = [
 "checksum siphasher 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "0b8de496cf83d4ed58b6be86c3a275b8602f6ffe98d3024a869e124147a9a3ac"
 "checksum slab 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "c111b5bd5695e56cffe5129854aa230b39c93a305372fdbb2668ca2394eea9f8"
 "checksum smallvec 0.6.10 (registry+https://github.com/rust-lang/crates.io-index)" = "ab606a9c5e214920bb66c458cd7be8ef094f813f20fe77a54cc7dbfff220d4b7"
+"checksum smallvec 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "4ecf3b85f68e8abaa7555aa5abdb1153079387e60b718283d732f03897fcfc86"
 "checksum socket2 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "4e626972d3593207547f14bf5fc9efa4d0e7283deb73fef1dff313dae9ab8878"
 "checksum spin 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "44363f6f51401c34e7be73db0db371c04705d35efbe9f7d6082e03a921a32c55"
 "checksum stable_deref_trait 1.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "dba1a27d3efae4351c8051072d619e3ade2820635c3958d826bfea39d59b54c8"

server/Cargo.toml

@@ -5,7 +5,7 @@ authors = ["Dessalines <happydooby@gmail.com>"]
 edition = "2018"
 
 [dependencies]
-diesel = { version = "1.4.2", features = ["postgres","chrono"] }
+diesel = { version = "1.4.2", features = ["postgres","chrono", "r2d2"] }
 diesel_migrations = "1.4.0"
 dotenv = "0.14.1"
 bcrypt = "0.5.0"

server/config/defaults.hjson

@@ -5,6 +5,7 @@
       host: "localhost"
       port: 5432
       database: "lemmy"
+      pool_size: 5
     }
   hostname: "rrr"
   bind: "0.0.0.0"

server/src/db/mod.rs

@@ -1,5 +1,7 @@
+extern crate lazy_static;
 use crate::settings::Settings;
 use diesel::dsl::*;
+use diesel::r2d2::*;
 use diesel::result::Error;
 use diesel::*;
 use serde::{Deserialize, Serialize};
@@ -109,9 +111,19 @@ impl<T> MaybeOptional<T> for Option<T> {
   }
 }
 
-pub fn establish_connection() -> PgConnection {
+lazy_static! {
+  static ref PG_POOL: Pool<ConnectionManager<PgConnection>> = {
     let db_url = Settings::get().get_database_url();
-  PgConnection::establish(&db_url).expect(&format!("Error connecting to {}", db_url))
+    let manager = ConnectionManager::<PgConnection>::new(&db_url);
+    Pool::builder()
+      .max_size(Settings::get().database.pool_size)
+      .build(manager)
+      .expect(&format!("Error connecting to {}", db_url))
+  };
+}
+
+pub fn establish_connection() -> PooledConnection<ConnectionManager<PgConnection>> {
+  return PG_POOL.get().unwrap();
 }
 
 #[derive(EnumString, ToString, Debug, Serialize, Deserialize)]

server/src/settings.rs

@@ -43,6 +43,7 @@ pub struct Database {
   pub host: String,
   pub port: i32,
   pub database: String,
+  pub pool_size: u32,
 }
 
 lazy_static! {