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/*
This file is part of TALER
Copyright (C) 2022 Taler Systems SA
TALER is free software; you can redistribute it and/or modify it under the
terms of the GNU Affero General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
TALER is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License along with
TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
*/
use std::time::Duration;
use log::error;
use postgres::{Client, NoTls};
const RECONNECT_DELAY: Duration = Duration::from_secs(5);
pub struct AutoReconnect<S, C> {
config: S,
client: C,
connect: fn(&S) -> Option<C>,
check: fn(&mut C) -> bool,
}
impl<S, C> AutoReconnect<S, C> {
pub fn new(config: S, connect: fn(&S) -> Option<C>, check: fn(&mut C) -> bool) -> Self {
Self {
client: Self::connect(&config, connect),
connect,
check,
config,
}
}
/// Create a new client, loop on error
fn connect(config: &S, connect: fn(&S) -> Option<C>) -> C {
loop {
match connect(config) {
Some(new) => return new,
None => std::thread::sleep(RECONNECT_DELAY),
}
}
}
/// Get a mutable connection, block until a connection can be established
pub fn client(&mut self) -> &mut C {
if (self.check)(&mut self.client) {
self.client = Self::connect(&self.config, self.connect);
}
&mut self.client
}
}
pub type AutoReconnectDb = AutoReconnect<postgres::Config, Client>;
pub fn auto_reconnect_db(config: postgres::Config) -> AutoReconnectDb {
AutoReconnect::new(
config,
|config| {
config
.connect(NoTls)
.map_err(|err| error!("connect DB: {}", err))
.ok()
},
|client| client.is_valid(RECONNECT_DELAY).is_err(),
)
}
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