Question

我想用sdl2-rs crate启动计时器来执行绘制调用。我想通过做这样的事情来启动它：

extern crate sdl2;

use std::sync::mpsc;

enum Event {
    Draw,
}

fn main() {
    let sdl_context = sdl2::init().unwrap();
    let video_subsystem = sdl_context.video().unwrap();
    video_subsystem.gl_attr().set_context_version(4, 5);
    println!(
        "Current gl version: {:?}",
        video_subsystem.gl_attr().context_version()
    );
    let timer_subsystem = sdl_context.timer().unwrap();

    let window = video_subsystem
        .window("rust-sdl2 demo: Video", 800, 600)
        .position_centered()
        .opengl()
        .build()
        .unwrap();

    let context = window.gl_create_context().unwrap();

    let (tx, rx) = mpsc::channel();
    {
        let timer_tx = tx.clone();
        timer_subsystem.add_timer(
            1000u32 / 120u32,
            Box::new(move || {
                timer_tx.send(Event::Draw);
                1000u32 / 120u32
            }),
        );
    }
}

然而，我收到此错误：

error[E0277]: the trait bound `std::sync::mpsc::Sender<Event>: std::marker::Sync` is not satisfied in `[closure@src/main.rs:33:22: 36:14 timer_tx:std::sync::mpsc::Sender<Event>]`
  --> src/main.rs:33:13
   |
33 | /             Box::new(move || {
34 | |                 timer_tx.send(Event::Draw);
35 | |                 1000u32 / 120u32
36 | |             }),
   | |______________^ `std::sync::mpsc::Sender<Event>` cannot be shared between threads safely
   |
   = help: within `[closure@src/main.rs:33:22: 36:14 timer_tx:std::sync::mpsc::Sender<Event>]`, the trait `std::marker::Sync` is not implemented for `std::sync::mpsc::Sender<Event>`
   = note: required because it appears within the type `[closure@src/main.rs:33:22: 36:14 timer_tx:std::sync::mpsc::Sender<Event>]`
   = note: required for the cast to the object type `std::ops::FnMut() -> u32 + std::marker::Sync`

我理解发件人不是Sync所以我克隆它并将克隆的对象移动到FnMut闭包中但是它无论如何都不起作用。我怎样才能做到这一点？根据我的理解，通过将对象移动到闭包中，我们不共享它，因此它必须以这种方式工作。此外，文档中的示例也是如此。

Answer 1

克隆的发件人与原始发件人的类型相同，因此它仍然不是add_timer。 Sync函数需要一个Mutex的闭包，因此您需要将发件人包装在let timer_tx = Mutex::new(tx.clone()); timer_subsystem.add_timer( 1000u32 / 120u32, Box::new(move || { timer_tx.lock().unwrap().send(Event::Draw); 1000u32 / 120u32 }), );中，这样可以让发件人在线程之间共享。

input: "data"
input_shape {
  dim: 1
  dim: 1
  dim: 28
  dim: 28
}
layer {
  name: "conv1"
  type: "Convolution"
  bottom: "data"
  top: "conv1"
  param {
    lr_mult: 1.0
    decay_mult: 1.0
  }
  param {
    lr_mult: 2.0
    decay_mult: 0.0
  }
  convolution_param {
    num_output: 5
    kernel_size: 3
    stride: 1
    weight_filler {
      type: "gaussian"
      std: 0.01
    }
    bias_filler {
      type: "constant"
      value: 0.0
    }
  }
}
layer {
  name: "relu1"
  type: "ReLU"
  bottom: "conv1"
  top: "conv1"
}
layer {
  name: "pool1"
  type: "Pooling"
  bottom: "conv1"
  top: "pool1"
  pooling_param {
    pool: MAX
    kernel_size: 3
    stride: 2
  }
}
layer {
  name: "conv2"
  type: "Convolution"
  bottom: "pool1"
  top: "conv2"
  param {
    lr_mult: 1.0
    decay_mult: 1.0
  }
  param {
    lr_mult: 2.0
    decay_mult: 0.0
  }
  convolution_param {
    num_output: 5
    kernel_size: 3
    stride: 1
    weight_filler {
      type: "gaussian"
      std: 0.01
    }
    bias_filler {
      type: "constant"
      value: 0.1
    }
  }
}
layer {
  name: "relu2"
  type: "ReLU"
  bottom: "conv2"
  top: "conv2"
}
layer {
  name: "pool2"
  type: "Pooling"
  bottom: "conv2"
  top: "pool2"
  pooling_param {
    pool: MAX
    kernel_size: 3
    stride: 2
  }
}
layer {
  name: "fc3"
  type: "InnerProduct"
  bottom: "pool2"
  top: "fc3"
  param {
    lr_mult: 1.0
    decay_mult: 1.0
  }
  param {
    lr_mult: 2.0
    decay_mult: 0.0
  }
  inner_product_param {
    num_output: 20
    weight_filler {
      type: "gaussian"
      std: 0.005
    }
    bias_filler {
      type: "constant"
      value: 0.1
    }
  }
}
layer {
  name: "relu3"
  type: "ReLU"
  bottom: "fc3"
  top: "fc3"
}
layer {
  name: "drop3"
  type: "Dropout"
  bottom: "fc3"
  top: "fc3"
  dropout_param {
    dropout_ratio: 0.5
  }
}
layer {
  name: "fc4"
  type: "InnerProduct"
  bottom: "fc3"
  top: "fc4"
  param {
    lr_mult: 1.0
    decay_mult: 1.0
  }
  param {
    lr_mult: 2.0
    decay_mult: 0.0
  }
  inner_product_param {
    num_output: 10
    weight_filler {
      type: "gaussian"
      std: 0.01
    }
    bias_filler {
      type: "constant"
      value: 0.0
    }
  }
}
layer {
  name: "softmax"
  type: "Softmax"
  bottom: "fc4"
  top: "softmax"
}

SDL2，FnMut和mpsc，发送方不能在线程之间安全共享

1 个答案: