rstango 0.4.0

Implementation of the Tango distributed control system
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
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231

//! The polling of the devices of a server: where its periods come from, what it records
//! and sends, and how a client changes it through the admin device.

mod common;

use std::sync::atomic::{AtomicI32, Ordering};
use std::time::{Duration, Instant};
use std::thread;

use tango::dev::{AttrValueEvent, DevProxy, DevSource};
use tango::server::{AttrDef, ClassDef, CommandDef, Dev};
use tango::error::Result;
use tango::testing::TestContext;

use common::{local_and_wire, test_context, test_server};


/// A motor counting how many times it is read.
struct Motor {
    reads: AtomicI32,
}

impl Motor {

    fn init(_dev: &Dev<Self>) -> Result<Self> {
        Ok(Self { reads: AtomicI32::new(0) })
    }

    fn count(&self, _dev: &Dev<Self>) -> Result<i32> {
        Ok(self.reads.fetch_add(1, Ordering::Relaxed) + 1)
    }

    fn position(&self, _dev: &Dev<Self>) -> Result<f64> {
        Ok(1.5)
    }

    fn set_target(&self, _dev: &Dev<Self>, _target: f64) -> Result<()> {
        Ok(())
    }

    fn get_speed(&self, _dev: &Dev<Self>, _: ()) -> Result<i32> {
        Ok(7)
    }

    fn move_by(&self, _dev: &Dev<Self>, _delta: f64) -> Result<()> {
        Ok(())
    }

}

/// The motor class, which asks for its `Position` and its `GetSpeed` to be polled.
fn motor_def() -> ClassDef<Motor> {
    ClassDef::new("Motor", Motor::init)
        .attr(AttrDef::new("Count")
            .read(Motor::count)
            .periodic_event(Duration::from_millis(50)))
        .attr(AttrDef::new("Position")
            .read(Motor::position)
            .polled(Duration::from_millis(500)))
        .attr(AttrDef::new("Target")
            .write(Motor::set_target))
        .command(CommandDef::new("GetSpeed")
            .exec(Motor::get_speed)
            .polled(Duration::from_millis(500)))
        .command(CommandDef::new("MoveBy")
            .exec(Motor::move_by))
}

/// A context serving the motor `motor/dev/1`, its database holding those properties of it.
fn serve(local: bool, props: &[(&str, &[&str])]) -> TestContext {

    let ctx = test_context(&[("motor/dev/1", "Motor")]);
    for &(name, values) in props {
        let values = values.iter().map(|value| value.to_string()).collect::<Vec<_>>();
        ctx.database().set_dev_prop("motor/dev/1", (name, values)).unwrap();
    }

    ctx.serve(test_server(local)
        .class(motor_def()))
        .unwrap();

    ctx

}

/// Wait for that to hold, failing after a few seconds.
fn wait_until(what: &str, mut cond: impl FnMut() -> bool) {
    let deadline = Instant::now() + Duration::from_secs(5);
    while !cond() {
        assert!(Instant::now() < deadline, "timed out waiting for {what}");
        thread::sleep(Duration::from_millis(10));
    }
}

/// What the database holds of that property of the motor.
fn prop(ctx: &TestContext, name: &str) -> Vec<String> {
    ctx.database().get_dev_prop::<Vec<String>, _>("motor/dev/1", name).unwrap()
}

fn ms(ms: u64) -> Duration {
    Duration::from_millis(ms)
}


local_and_wire! {
    /// The periods a device is polled at: the database first, then its definitions, what
    /// is polled being recorded in its history and read from the cache.
    fn periods(local: bool) {

        let ctx = serve(local, &[
            ("polled_attr", &["count", "20", "Position", "300", "Missing", "100"]),
            ("poll_ring_depth", &["3"]),
        ]);

        let client = ctx.dev("motor/dev/1");
        assert_eq!(client.attr_poll_period("Count").unwrap(), Some(ms(20)));
        assert_eq!(client.attr_poll_period("Position").unwrap(), Some(ms(300)));
        assert_eq!(client.command_poll_period("GetSpeed").unwrap(), Some(ms(500)));
        assert_eq!(client.attr_poll_period("Target").unwrap(), None);
        assert_eq!(client.attr_poll_period("Missing").unwrap(), None);

        wait_until("the history to fill", || client.attr_history::<i32>("Count", 10).is_ok_and(|history| history.len() == 3));
        assert!(client.command_history::<i32>("GetSpeed", 10).is_ok());

        let mut cached = client.clone();
        cached.set_source(DevSource::Cache);
        assert!(cached.read_attr::<i32, _>("Count").unwrap().value.unwrap() >= 3);
        assert_eq!(cached.command::<_, i32>("GetSpeed", ()).unwrap(), 7);
        assert_eq!(cached.read_attr::<f64, _>("Target").unwrap_err().reason(), "API_AttrNotPolled");

        let status = client.polling_status().unwrap();
        assert_eq!(status.len(), 3);
        assert!(status[0].starts_with("Polled command name = GetSpeed"));
        assert!(status.iter().any(|status| status.contains("Polling ring buffer depth = 3")));

    }
}

local_and_wire! {
    /// The polling a client changes through the admin device, which writes it to the
    /// database along, so that a restarted device is polled the same.
    fn admin(local: bool) {

        let ctx = serve(local, &[]);
        let client = ctx.dev("motor/dev/1");
        let admin = client.admin_dev().unwrap();

        client.poll_attr("Count", ms(100)).unwrap();
        assert_eq!(client.attr_poll_period("Count").unwrap(), Some(ms(100)));
        assert_eq!(prop(&ctx, "polled_attr"), ["Count", "100"]);

        // Polled already, which is its period updated.
        client.poll_attr("count", ms(200)).unwrap();
        assert_eq!(client.attr_poll_period("Count").unwrap(), Some(ms(200)));
        assert_eq!(prop(&ctx, "polled_attr"), ["Count", "200"]);

        // A period the definition asks for, written once changed.
        client.poll_command("GetSpeed", ms(250)).unwrap();
        assert_eq!(prop(&ctx, "polled_cmd"), ["GetSpeed", "250"]);

        assert_eq!(admin.command::<_, Vec<String>>("PolledDevice", ()).unwrap(), ["motor/dev/1"]);

        // A restart reads the database again, the device restarted being another one,
        // which a client reaching it directly has to reach anew.
        admin.command::<_, ()>("DevRestart", "motor/dev/1").unwrap();
        let client = ctx.dev("motor/dev/1");
        assert_eq!(client.attr_poll_period("Count").unwrap(), Some(ms(200)));
        assert_eq!(client.command_poll_period("GetSpeed").unwrap(), Some(ms(250)));

        client.stop_poll_attr("Count").unwrap();
        assert_eq!(client.attr_poll_period("Count").unwrap(), None);
        assert!(prop(&ctx, "polled_attr").is_empty());
        assert_eq!(client.stop_poll_attr("Count").unwrap_err().reason(), "API_PollObjNotFound");

        // Neither a write-only attribute nor a command taking an argument can be polled,
        // nor what the device does not have.
        assert_eq!(client.poll_attr("Target", ms(100)).unwrap_err().reason(), "API_NotSupported");
        assert_eq!(client.poll_command("MoveBy", ms(100)).unwrap_err().reason(), "API_NotSupported");
        assert!(client.poll_attr("Missing", ms(100)).is_err());
        assert_eq!(client.poll_attr("Count", Duration::ZERO).unwrap_err().reason(), "API_NotSupported");

    }
}

local_and_wire! {
    /// The periodic events of a polled attribute, sent at the period of the event rather
    /// than at the one of the polling, and refused once it is not polled.
    #[cfg_attr(miri, ignore = "Miri is too slow: the wire variant times out subscribing, before even reaching ZMQ")]
    fn periodic_event(local: bool) {

        let ctx = serve(local, &[("polled_attr", &["Count", "10"])]);
        let client = ctx.dev("motor/dev/1");

        let mut periodic = client.subscribe_attr_value::<i32>("Count", AttrValueEvent::Periodic);
        periodic.ensure_subscribed().unwrap();

        let first = periodic.wait(Duration::from_secs(5)).unwrap().value.unwrap();
        let second = periodic.wait(Duration::from_secs(5)).unwrap().value.unwrap();
        assert!(second > first + 1, "polled at 10 ms, sent at 50 ms: {first} then {second}");

        client.stop_poll_attr("Count").unwrap();
        let refused = client.subscribe_attr_value::<i32>("Count", AttrValueEvent::Periodic).ensure_subscribed();
        assert_eq!(refused.unwrap_err().reason(), "API_AttributePollingNotStarted");

    }
}

local_and_wire! {
    /// Nothing is polled between the `StopPolling` and the `StartPolling` of the admin
    /// device, what is polled being kept.
    fn stop_start(local: bool) {

        let ctx = serve(local, &[("polled_attr", &["Count", "10"])]);
        let client = ctx.dev("motor/dev/1");
        let admin = client.admin_dev().unwrap();

        wait_until("a first poll", || client.attr_history::<i32>("Count", 1).is_ok());
        admin.command::<_, ()>("StopPolling", ()).unwrap();
        thread::sleep(ms(50));

        let latest = |client: &DevProxy| client.attr_history::<i32>("Count", 1).unwrap()[0].value.as_ref().unwrap().value.unwrap();
        let stopped = latest(&client);
        thread::sleep(ms(100));
        assert_eq!(latest(&client), stopped);
        assert_eq!(client.attr_poll_period("Count").unwrap(), Some(ms(10)));

        admin.command::<_, ()>("StartPolling", ()).unwrap();
        wait_until("the polling to start again", || latest(&client) > stopped);

    }
}