1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153

use std::sync::Arc;

use super::{
    backend::{r#trait::Backend, Error},
    conn_pool::{ReusableConnectionPool as ReusableConnectionPoolInner, SingleUseConnectionPool},
    object_pool::{ObjectPool, Reusable},
};

/// Wrapper for a reusable connection pool wrapped in a reusable object wrapper
pub type ReusableConnectionPool<'a, B> = Reusable<'a, ReusableConnectionPoolInner<B>>;

/// Database pool
pub struct DatabasePool<B: Backend> {
    backend: Arc<B>,
    object_pool: ObjectPool<ReusableConnectionPoolInner<B>>,
}

impl<B: Backend> DatabasePool<B> {
    /// Pulls a reusable connection pool
    ///
    /// Privileges are granted only for ``SELECT``, ``INSERT``, ``UPDATE``, and ``DELETE`` operations.
    /// # Example
    /// ```
    /// use db_pool::{
    ///     sync::{DatabasePoolBuilderTrait, DieselPostgresBackend},
    ///     PrivilegedPostgresConfig,
    /// };
    /// use diesel::{sql_query, RunQueryDsl};
    /// use dotenvy::dotenv;
    /// use r2d2::Pool;
    ///
    /// dotenv().ok();
    ///
    /// let config = PrivilegedPostgresConfig::from_env().unwrap();
    ///
    /// let backend = DieselPostgresBackend::new(
    ///     config,
    ///     || Pool::builder().max_size(10),
    ///     || Pool::builder().max_size(2),
    ///     move |conn| {
    ///         sql_query("CREATE TABLE book(id SERIAL PRIMARY KEY, title TEXT NOT NULL)")
    ///             .execute(conn)
    ///             .unwrap();
    ///     },
    /// )
    /// .unwrap();
    ///
    /// let db_pool = backend.create_database_pool().unwrap();
    /// let conn_pool = db_pool.pull_immutable();
    /// ```
    #[must_use]
    pub fn pull_immutable(&self) -> Reusable<ReusableConnectionPoolInner<B>> {
        self.object_pool.pull()
    }

    /// Creates a single-use connection pool
    ///
    /// All privileges are granted.
    /// # Example
    /// ```
    /// use db_pool::{
    ///     sync::{DatabasePoolBuilderTrait, DieselPostgresBackend},
    ///     PrivilegedPostgresConfig,
    /// };
    /// use diesel::{sql_query, RunQueryDsl};
    /// use dotenvy::dotenv;
    /// use r2d2::Pool;
    ///
    /// dotenv().ok();
    ///
    /// let config = PrivilegedPostgresConfig::from_env().unwrap();
    ///
    /// let backend = DieselPostgresBackend::new(
    ///     config,
    ///     || Pool::builder().max_size(10),
    ///     || Pool::builder().max_size(2),
    ///     move |conn| {
    ///         sql_query("CREATE TABLE book(id SERIAL PRIMARY KEY, title TEXT NOT NULL)")
    ///             .execute(conn)
    ///             .unwrap();
    ///     },
    /// )
    /// .unwrap();
    ///
    /// let db_pool = backend.create_database_pool().unwrap();
    /// let conn_pool = db_pool.create_mutable();
    /// ```
    pub fn create_mutable(
        &self,
    ) -> Result<SingleUseConnectionPool<B>, Error<B::ConnectionError, B::QueryError>> {
        SingleUseConnectionPool::new(self.backend.clone())
    }
}

/// Database pool builder trait implemented for all sync backends
pub trait DatabasePoolBuilder: Backend {
    /// Creates a database pool
    /// # Example
    /// ```
    /// use db_pool::{
    ///     sync::{DatabasePoolBuilderTrait, DieselPostgresBackend},
    ///     PrivilegedPostgresConfig,
    /// };
    /// use diesel::{sql_query, RunQueryDsl};
    /// use dotenvy::dotenv;
    /// use r2d2::Pool;
    ///
    /// dotenv().ok();
    ///
    /// let config = PrivilegedPostgresConfig::from_env().unwrap();
    ///
    /// let backend = DieselPostgresBackend::new(
    ///     config,
    ///     || Pool::builder().max_size(10),
    ///     || Pool::builder().max_size(2),
    ///     move |conn| {
    ///         sql_query("CREATE TABLE book(id SERIAL PRIMARY KEY, title TEXT NOT NULL)")
    ///             .execute(conn)
    ///             .unwrap();
    ///     },
    /// )
    /// .unwrap();
    ///
    /// let db_pool = backend.create_database_pool().unwrap();
    /// ```
    fn create_database_pool(
        self,
    ) -> Result<DatabasePool<Self>, Error<Self::ConnectionError, Self::QueryError>> {
        self.init()?;
        let backend = Arc::new(self);
        let object_pool = {
            let backend = backend.clone();
            ObjectPool::new(
                move || {
                    let backend = backend.clone();
                    ReusableConnectionPoolInner::new(backend)
                        .expect("connection pool creation must succeed")
                },
                |conn_pool| {
                    conn_pool
                        .clean()
                        .expect("connection pool cleaning must succeed");
                },
            )
        };
        Ok(DatabasePool {
            backend,
            object_pool,
        })
    }
}

impl<B> DatabasePoolBuilder for B where B: Backend + Sized {}