#166 Diesel connection pooling example

r2d2_firebird/Cargo.toml

@@ -17,5 +17,12 @@ rsfbclient = { version = "0.25.2", path = "../", default-features = false }
 rsfbclient-core = { version = "0.25.2", path = "../rsfbclient-core" }
 r2d2 = "0.8.9"
 
+diesel = { version = "2.0.0", optional = true }
+rsfbclient-diesel = { version = "0.25.1", path = "../rsfbclient-diesel", optional = true }
+
+[features]
+default=[]
+diesel_pool=["diesel", "rsfbclient-diesel"]
+
 [dev-dependencies]
 rsfbclient = { version = "0.25.2", path = "../", features = ["pure_rust"], default-features = false }

r2d2_firebird/src/lib.rs

@@ -47,3 +47,48 @@ where
         false
     }
 }
+
+// Implementation for Diesel
+#[cfg(feature = "diesel_pool")]
+mod diesel_manager {
+    use diesel::prelude::*;
+    use diesel::{sql_query, Connection, ConnectionError};
+    use rsfbclient_diesel::FbConnection;
+
+    pub struct DieselConnectionManager {
+        connection_string: String,
+    }
+
+    impl DieselConnectionManager {
+        pub fn new(database_url: &str) -> Self {
+            Self {
+                connection_string: database_url.to_string(),
+            }
+        }
+    }
+
+    impl r2d2::ManageConnection for DieselConnectionManager {
+        type Connection = FbConnection;
+        type Error = ConnectionError;
+
+        fn connect(&self) -> Result<Self::Connection, Self::Error> {
+            FbConnection::establish(&self.connection_string)
+        }
+
+        fn is_valid(&self, conn: &mut Self::Connection) -> Result<(), Self::Error> {
+            sql_query("SELECT 1 FROM RDB$DATABASE")
+                .execute(conn)
+                .map(|_| ())
+                .map_err(|_| {
+                    ConnectionError::BadConnection("Diesel pooled connection check failed.".into())
+                })
+        }
+
+        fn has_broken(&self, _conn: &mut Self::Connection) -> bool {
+            false
+        }
+    }
+}
+
+#[cfg(feature = "diesel_pool")]
+pub use diesel_manager::DieselConnectionManager;

rsfbclient-diesel/examples/employee_pool/.gitignore

@@ -0,0 +1,19 @@
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+lcov.info
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+tests/use
+
+# firebird lib
+fbclient.lib
+
+# vscode conf folder
+.vscode

rsfbclient-diesel/examples/employee_pool/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "employee-pool"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+diesel = "2.0.0"
+rsfbclient-diesel = "0.25.0"
+r2d2 = "0.8.10"
+rsfbclient = "0.25.2"
+r2d2_firebird = {version="0.25.2", path="../../../r2d2_firebird", features=["diesel_pool"]}
+rsfbclient-core = "0.25.2"
+
+[workspace]

rsfbclient-diesel/examples/employee_pool/README.md

@@ -0,0 +1,4 @@
+
+# Diesel with connection pooling example.
+
+This example use the `employee.fdb` database, present in your Firebird instalation. You also can get this database in `examples/empbuild` folder from the [official instalation files](https://firebirdsql.org/en/firebird-4-0/)

rsfbclient-diesel/examples/employee_pool/src/main.rs

@@ -0,0 +1,51 @@
+use diesel::{QueryDsl, RunQueryDsl};
+use r2d2::Pool;
+use r2d2_firebird::DieselConnectionManager;
+use std::{env, sync::Arc, thread, time::Duration};
+
+use schema::{job::dsl::*, Job};
+
+mod schema;
+
+fn main() {
+
+    let connecton_string = env::var("DIESELFDB_CONN").expect("DIESELFDB_CONN env not found");
+
+    let manager = DieselConnectionManager::new(&connecton_string);
+    let pool = Arc::new(
+        Pool::builder()
+            .max_size(4)
+            .build(manager)
+            .expect("Failed to build connection pooling."),
+    );
+
+    let mut tasks = vec![];
+
+    for n in 0..3 {
+        let pool = pool.clone();
+        let th = thread::spawn(move || loop {
+
+            match pool.get() {
+                Ok(mut conn) => match job.offset(n).limit(1).first::<Job>(&mut *conn) {
+                    Ok(model) => {
+                        println!("Thread {}: {}", n, model.title)
+                    }
+
+                    Err(e) => println!("Execute query error in line:{} ! error: {:?}", line!(), e),
+                },
+                Err(e) => println!(
+                    "Get connection from pool error in line:{} ! error: {:?}",
+                    line!(),
+                    e
+                ),
+            }
+
+            thread::sleep(Duration::from_secs(1));
+        });
+        tasks.push(th);
+    }
+
+    for th in tasks {
+        let _ = th.join();
+    }
+}

rsfbclient-diesel/examples/employee_pool/src/schema.rs

@@ -0,0 +1,28 @@
+use diesel::{ Queryable };
+
+#[allow(dead_code)]
+#[derive(Queryable)]
+#[diesel(table_name = job)]
+pub struct Job {
+    #[diesel(column_name = job_code)]
+    pub code: String,
+    #[diesel(column_name = job_title)]
+    pub title: String,
+    #[diesel(column_name = job_country)]
+    pub country: String,
+    #[diesel(column_name = job_grade)]
+    pub grade: i16,
+    pub min_salary: f32,
+    pub max_salary: f32,
+}
+
+diesel::table! {
+    job(job_code) {
+        job_code -> Text,
+        job_title -> Text,
+        job_country -> Text,
+        job_grade -> Smallint,
+        min_salary -> Float,
+        max_salary -> Float,
+    }
+}