qorb 0.4.1

Connection Pooling
Documentation 
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

//! Utilities to help with testing qorb

use crate::backend::{self, Backend, Connector};
use async_trait::async_trait;
use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};

/// A test-only connector which can slow down connection access
/// to mimic high-latency connection issues.
pub struct SlowConnector {
    delay_ms: AtomicU64,
    panic_on_access: AtomicBool,
}

impl SlowConnector {
    /// Creates a new connector, which only takes 1ms per operation
    pub fn new() -> Self {
        Self {
            delay_ms: AtomicU64::new(1),
            panic_on_access: AtomicBool::new(false),
        }
    }

    /// Stalls all new operations through the connector, forcing them to
    /// take an unrealistically long time.
    pub fn stall(&self) {
        self.delay_ms.store(9999999, Ordering::SeqCst);
    }

    /// Mark that any future access through the connector should panic.
    ///
    /// Although "stall" prevents connections from getting through the
    /// Connector APIs, this ensures that new connection operations
    /// aren't even starting.
    pub fn panic_on_access(&self) {
        self.panic_on_access.store(true, Ordering::SeqCst);
    }

    // Internal shared logic for each of the connector APIs
    async fn react_to_connection_operation(&self) {
        if self.panic_on_access.load(Ordering::SeqCst) {
            panic!("Should not be making new requests through this connector!");
        }

        let delay_ms = self.delay_ms.load(Ordering::SeqCst);
        tokio::time::sleep(tokio::time::Duration::from_millis(delay_ms)).await;
    }
}

#[async_trait]
impl Connector for SlowConnector {
    type Connection = ();

    async fn connect(&self, _backend: &Backend) -> Result<Self::Connection, backend::Error> {
        self.react_to_connection_operation().await;
        Ok(())
    }

    async fn is_valid(&self, _: &mut Self::Connection) -> Result<(), backend::Error> {
        self.react_to_connection_operation().await;
        Ok(())
    }

    async fn on_acquire(&self, _: &mut Self::Connection) -> Result<(), backend::Error> {
        self.react_to_connection_operation().await;
        Ok(())
    }

    async fn on_recycle(&self, _: &mut Self::Connection) -> Result<(), backend::Error> {
        self.react_to_connection_operation().await;
        Ok(())
    }
}

/// A test-only connector which can throw errors on connection access
pub struct FaultyConnector {
    fail_on_access: AtomicBool,
}

impl FaultyConnector {
    pub fn new() -> Self {
        Self {
            fail_on_access: AtomicBool::new(false),
        }
    }

    pub fn start_failing(&self) {
        self.fail_on_access.store(true, Ordering::SeqCst);
    }

    // Internal shared logic for each of the connector APIs
    async fn react_to_connection_operation(&self) -> Result<(), backend::Error> {
        if self.fail_on_access.load(Ordering::SeqCst) {
            return Err(backend::Error::Other(anyhow::anyhow!(
                "Connector failing intentionally"
            )));
        }
        Ok(())
    }
}

#[async_trait]
impl Connector for FaultyConnector {
    type Connection = ();

    async fn connect(&self, _backend: &Backend) -> Result<Self::Connection, backend::Error> {
        self.react_to_connection_operation().await?;
        Ok(())
    }

    async fn is_valid(&self, _: &mut Self::Connection) -> Result<(), backend::Error> {
        self.react_to_connection_operation().await?;
        Ok(())
    }

    async fn on_acquire(&self, _: &mut Self::Connection) -> Result<(), backend::Error> {
        self.react_to_connection_operation().await?;
        Ok(())
    }

    async fn on_recycle(&self, _: &mut Self::Connection) -> Result<(), backend::Error> {
        self.react_to_connection_operation().await?;
        Ok(())
    }
}