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
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168

use std::ops::{Deref, DerefMut};

use futures_core::future::BoxFuture;
use futures_core::stream::BoxStream;

use crate::connection::Connection;
use crate::database::Database;
use crate::describe::Describe;
use crate::executor::Executor;
use crate::runtime::spawn;

pub struct Transaction<T>
where
    T: Connection + Send + 'static,
{
    inner: Option<T>,
    depth: u32,
}

impl<T> Transaction<T>
where
    T: Connection + Send + 'static,
{
    pub(crate) async fn new(depth: u32, mut inner: T) -> crate::Result<Self> {
        if depth == 0 {
            inner.send("BEGIN").await?;
        } else {
            let stmt = format!("SAVEPOINT _sqlx_savepoint_{}", depth);

            inner.send(&stmt).await?;
        }

        Ok(Self {
            inner: Some(inner),
            depth: depth + 1,
        })
    }

    pub async fn begin(mut self) -> crate::Result<Transaction<T>> {
        Transaction::new(self.depth, self.inner.take().expect(ERR_FINALIZED)).await
    }

    pub async fn commit(mut self) -> crate::Result<T> {
        let mut inner = self.inner.take().expect(ERR_FINALIZED);
        let depth = self.depth;

        if depth == 1 {
            inner.send("COMMIT").await?;
        } else {
            let stmt = format!("RELEASE SAVEPOINT _sqlx_savepoint_{}", depth - 1);

            inner.send(&stmt).await?;
        }

        Ok(inner)
    }

    pub async fn rollback(mut self) -> crate::Result<T> {
        let mut inner = self.inner.take().expect(ERR_FINALIZED);
        let depth = self.depth;

        if depth == 1 {
            inner.send("ROLLBACK").await?;
        } else {
            let stmt = format!("ROLLBACK TO SAVEPOINT _sqlx_savepoint_{}", depth - 1);

            inner.send(&stmt).await?;
        }

        Ok(inner)
    }
}

const ERR_FINALIZED: &str = "(bug) transaction already finalized";

impl<Conn> Deref for Transaction<Conn>
where
    Conn: Connection,
{
    type Target = Conn;

    fn deref(&self) -> &Self::Target {
        self.inner.as_ref().expect(ERR_FINALIZED)
    }
}

impl<Conn> DerefMut for Transaction<Conn>
where
    Conn: Connection,
{
    fn deref_mut(&mut self) -> &mut Self::Target {
        self.inner.as_mut().expect(ERR_FINALIZED)
    }
}

impl<T> Connection for Transaction<T>
where
    T: Connection,
{
    // Close is equivalent to ROLLBACK followed by CLOSE
    fn close(self) -> BoxFuture<'static, crate::Result<()>> {
        Box::pin(async move { self.rollback().await?.close().await })
    }
}

impl<T> Executor for Transaction<T>
where
    T: Connection,
{
    type Database = T::Database;

    fn send<'e, 'q: 'e>(&'e mut self, commands: &'q str) -> BoxFuture<'e, crate::Result<()>> {
        self.deref_mut().send(commands)
    }

    fn execute<'e, 'q: 'e>(
        &'e mut self,
        query: &'q str,
        args: <Self::Database as Database>::Arguments,
    ) -> BoxFuture<'e, crate::Result<u64>> {
        self.deref_mut().execute(query, args)
    }

    fn fetch<'e, 'q: 'e>(
        &'e mut self,
        query: &'q str,
        args: <Self::Database as Database>::Arguments,
    ) -> BoxStream<'e, crate::Result<<Self::Database as Database>::Row>> {
        self.deref_mut().fetch(query, args)
    }

    fn fetch_optional<'e, 'q: 'e>(
        &'e mut self,
        query: &'q str,
        args: <Self::Database as Database>::Arguments,
    ) -> BoxFuture<'e, crate::Result<Option<<Self::Database as Database>::Row>>> {
        self.deref_mut().fetch_optional(query, args)
    }

    fn describe<'e, 'q: 'e>(
        &'e mut self,
        query: &'q str,
    ) -> BoxFuture<'e, crate::Result<Describe<Self::Database>>> {
        self.deref_mut().describe(query)
    }
}

impl<Conn> Drop for Transaction<Conn>
where
    Conn: Connection,
{
    fn drop(&mut self) {
        if self.depth > 0 {
            if let Some(mut inner) = self.inner.take() {
                spawn(async move {
                    let res = inner.send("ROLLBACK").await;

                    // If the rollback failed we need to close the inner connection
                    if res.is_err() {
                        // This will explicitly forget the connection so it will not
                        // return to the pool
                        let _ = inner.close().await;
                    }
                });
            }
        }
    }
}