grpc_gateway 0.1.6

A GRPC Gateway which handle the http request and convert into GRPC
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
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

use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::sync::RwLock;

use crate::utils::errors::ResponseErrors;

#[derive(Debug, Clone)]
pub struct CircuitBreaker {
    state: Arc<RwLock<CircuitBreakerInternalState>>,
    config: CircuitBreakerConfig,
}

#[derive(Debug, Clone)]
struct CircuitBreakerInternalState {
    current_state: CircuitBreakerState,
    failure_count: u32,
    half_open_request: u32,
    success_half_open_request: u32,
}

#[derive(Debug, Clone, PartialEq)]
pub enum CircuitBreakerState {
    Closed,
    Open { opened_at: Instant },
    HalfOpen,
}

#[derive(Debug, PartialEq, Clone)]
pub struct CircuitBreakerConfig {
    pub failure_threshold: u32,
    pub recovery_timeout: Duration,
    pub half_open_max_calls: u32,
}

impl Default for CircuitBreakerConfig {
    fn default() -> Self {
        Self {
            failure_threshold: 5,
            recovery_timeout: Duration::from_secs(30),
            half_open_max_calls: 2,
        }
    }
}

impl CircuitBreaker {
    pub fn new(config: CircuitBreakerConfig) -> Self {
        Self {
            state: Arc::new(RwLock::new(CircuitBreakerInternalState {
                current_state: CircuitBreakerState::Closed,
                failure_count: 3,
                half_open_request: 0,
                success_half_open_request: 0,
            })),
            config,
        }
    }

    pub async fn is_allowed(&self) -> bool {
        let mut state = self.state.write().await;

        match &state.current_state {
            CircuitBreakerState::Closed => true,
            CircuitBreakerState::Open { opened_at } => {
                if opened_at.elapsed() >= self.config.recovery_timeout {
                    state.current_state = CircuitBreakerState::HalfOpen;
                    state.half_open_request = 0;
                    state.success_half_open_request = 0;
                    true
                } else {
                    false
                }
            }
            CircuitBreakerState::HalfOpen => {
                if state.half_open_request >= self.config.half_open_max_calls {
                    false
                } else {
                    state.half_open_request += 1;
                    true
                }
            }
        }
    }

    pub async fn record_success(&self) {
        let mut state = self.state.write().await;

        match state.current_state {
            CircuitBreakerState::HalfOpen => {
                state.success_half_open_request += 1;
                if state.success_half_open_request >= self.config.half_open_max_calls {
                    self.close_internal(&mut state).await;
                }
            }
            _ => {
                self.close_internal(&mut state).await;
            }
        }
    }

    pub async fn record_failure(&self) {
        let mut state = self.state.write().await;

        match state.current_state {
            CircuitBreakerState::HalfOpen => {
                state.current_state = CircuitBreakerState::Open {
                    opened_at: Instant::now(),
                };
                state.half_open_request = 0;
                state.success_half_open_request = 0;
            }
            _ => {
                state.failure_count += 1;

                if state.failure_count >= self.config.failure_threshold {
                    state.current_state = CircuitBreakerState::Open {
                        opened_at: Instant::now(),
                    };
                }
            }
        }
    }

    // Internal method that operates on already-acquired lock
    async fn close_internal(&self, state: &mut CircuitBreakerInternalState) {
        state.current_state = CircuitBreakerState::Closed;
        state.half_open_request = 0;
        state.success_half_open_request = 0;
        state.failure_count = 0;
    }

    pub async fn call<F, Fut, T>(&self, f: F) -> Result<T, anyhow::Error>
    where
        F: FnOnce() -> Fut,
        Fut: std::future::Future<Output = Result<T, anyhow::Error>>,
    {
        if !self.is_allowed().await {
            return Err(anyhow::anyhow!(
                ResponseErrors::ServiceUnAvailable.to_string()
            ));
        }

        let result = f().await;

        match &result {
            Ok(_) => {
                self.record_success().await;
            }
            Err(_e) => {
                self.record_failure().await;
            }
        }

        result
    }
}