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
169
170
171
172
173
174
175
176
177

// Copyright 2017 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::thread::{self, Builder as ThreadBuilder, JoinHandle};

use grpc_sys;

use async::CallTag;
use cq::{CompletionQueue, CompletionQueueHandle, EventType};

// event loop
fn poll_queue(cq: Arc<CompletionQueueHandle>) {
    let id = thread::current().id();
    let cq = CompletionQueue::new(cq, id);
    loop {
        let e = cq.next();
        match e.event_type {
            EventType::QueueShutdown => break,
            // timeout should not happen in theory.
            EventType::QueueTimeout => continue,
            EventType::OpComplete => {}
        }

        let tag: Box<CallTag> = unsafe { Box::from_raw(e.tag as _) };

        tag.resolve(&cq, e.success != 0);
    }
}

/// [`Environment`] factory in order to configure the properties.
pub struct EnvBuilder {
    cq_count: usize,
    name_prefix: Option<String>,
}

impl EnvBuilder {
    /// Initialize a new [`EnvBuilder`].
    pub fn new() -> EnvBuilder {
        EnvBuilder {
            cq_count: unsafe { grpc_sys::gpr_cpu_num_cores() as usize },
            name_prefix: None,
        }
    }

    /// Set the number of completion queues and polling threads. Each thread polls
    /// one completion queue.
    ///
    /// # Panics
    ///
    /// This method will panic if `count` is 0.
    pub fn cq_count(mut self, count: usize) -> EnvBuilder {
        assert!(count > 0);
        self.cq_count = count;
        self
    }

    /// Set the thread name prefix of each polling thread.
    pub fn name_prefix<S: Into<String>>(mut self, prefix: S) -> EnvBuilder {
        self.name_prefix = Some(prefix.into());
        self
    }

    /// Finalize the [`EnvBuilder`], build the [`Environment`] and initialize the gRPC library.
    pub fn build(self) -> Environment {
        unsafe {
            grpc_sys::grpc_init();
        }
        let mut cqs = Vec::with_capacity(self.cq_count);
        let mut handles = Vec::with_capacity(self.cq_count);
        for i in 0..self.cq_count {
            let cq = Arc::new(CompletionQueueHandle::new());
            let cq_ = cq.clone();
            let mut builder = ThreadBuilder::new();
            if let Some(ref prefix) = self.name_prefix {
                builder = builder.name(format!("{}-{}", prefix, i));
            }
            let handle = builder.spawn(move || poll_queue(cq_)).unwrap();
            cqs.push(CompletionQueue::new(cq, handle.thread().id()));
            handles.push(handle);
        }

        Environment {
            cqs,
            idx: AtomicUsize::new(0),
            _handles: handles,
        }
    }
}

/// An object that used to control concurrency and start gRPC event loop.
pub struct Environment {
    cqs: Vec<CompletionQueue>,
    idx: AtomicUsize,
    _handles: Vec<JoinHandle<()>>,
}

impl Environment {
    /// Initialize gRPC and create a thread pool to poll completion queue. The thread pool size
    /// and the number of completion queue is specified by `cq_count`. Each thread polls one
    /// completion queue.
    ///
    /// # Panics
    ///
    /// This method will panic if `cq_count` is 0.
    pub fn new(cq_count: usize) -> Environment {
        assert!(cq_count > 0);
        EnvBuilder::new()
            .name_prefix("grpc-poll")
            .cq_count(cq_count)
            .build()
    }

    /// Get all the created completion queues.
    pub fn completion_queues(&self) -> &[CompletionQueue] {
        self.cqs.as_slice()
    }

    /// Pick an arbitrary completion queue.
    pub fn pick_cq(&self) -> CompletionQueue {
        let idx = self.idx.fetch_add(1, Ordering::Relaxed);
        self.cqs[idx % self.cqs.len()].clone()
    }
}

impl Drop for Environment {
    fn drop(&mut self) {
        for cq in self.completion_queues() {
            // it's safe to shutdown more than once.
            cq.shutdown()
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_basic_loop() {
        let mut env = Environment::new(2);

        let q1 = env.pick_cq();
        let q2 = env.pick_cq();
        let q3 = env.pick_cq();
        let cases = vec![(&q1, &q3, true), (&q1, &q2, false)];
        for (lq, rq, is_eq) in cases {
            let lq_ref = lq.borrow().unwrap();
            let rq_ref = rq.borrow().unwrap();
            if is_eq {
                assert_eq!(lq_ref.as_ptr(), rq_ref.as_ptr());
            } else {
                assert_ne!(lq_ref.as_ptr(), rq_ref.as_ptr());
            }
        }

        assert_eq!(env.completion_queues().len(), 2);
        for cq in env.completion_queues() {
            cq.shutdown();
        }

        for handle in env._handles.drain(..) {
            handle.join().unwrap();
        }
    }
}