elfo-telemeter 0.2.0-alpha.16

Collects and exposes metrics of the elfo 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

use std::{sync::Arc, time::Duration};

use tracing::{error, info};

use elfo_core::{
    message, messages::ConfigUpdated, msg, stream::Stream, time::Interval, ActorGroup, Blueprint,
    Context, RestartParams, RestartPolicy, SourceHandle,
};

use crate::{
    config::{Config, Retention, Sink},
    hyper,
    protocol::{GetSnapshot, Render, Rendered, ServerFailed, Snapshot},
    render::Renderer,
    storage::Storage,
};

struct Telemeter {
    ctx: Context<Config>,
    interval: Interval<CompactionTick>,
    server: Option<Stream<ServerFailed>>,
    storage: Arc<Storage>,
    snapshot: Arc<Snapshot>,
    renderer: Renderer,
}

#[message]
struct CompactionTick;

pub(crate) fn new(storage: Arc<Storage>) -> Blueprint {
    ActorGroup::new()
        .config::<Config>()
        .restart_policy(RestartPolicy::on_failure(RestartParams::new(
            Duration::from_secs(5),
            Duration::from_secs(30),
        )))
        .stop_order(100)
        .exec(move |ctx| Telemeter::new(ctx, storage.clone()).main())
}

impl Telemeter {
    pub(crate) fn new(mut ctx: Context<Config>, storage: Arc<Storage>) -> Self {
        let mut renderer = Renderer::default();
        renderer.configure(ctx.config());

        Self {
            interval: ctx.attach(Interval::new(CompactionTick)),
            server: None,
            storage,
            snapshot: Default::default(),
            renderer,
            ctx,
        }
    }

    async fn main(mut self) {
        // Now only OpenMetrics is supported.
        assert_eq!(self.ctx.config().sink, Sink::OpenMetrics);

        let mut listen = self.ctx.config().listen;
        self.start_server();

        self.interval.start(self.ctx.config().compaction_interval);

        while let Some(envelope) = self.ctx.recv().await {
            msg!(match envelope {
                ConfigUpdated => {
                    let config = self.ctx.config();

                    self.renderer.configure(config);

                    if config.listen != listen {
                        info!(
                            message = "listen address changed, rerun the server",
                            old = %listen,
                            new = %config.listen,
                        );
                        listen = config.listen;
                        self.start_server();
                    }
                }
                (GetSnapshot, token) => {
                    // Rendering includes compaction, skip extra compaction tick.
                    self.interval.start(self.ctx.config().compaction_interval);

                    self.update_snapshot(/* only_compact = */ false).await;
                    self.ctx.respond(token, self.snapshot.clone().into());
                }
                (Render, token) => {
                    // Rendering includes compaction, skip extra compaction tick.
                    self.interval.start(self.ctx.config().compaction_interval);

                    self.update_snapshot(/* only_compact = */ false).await;
                    let descriptions = self.storage.descriptions();
                    let output = self.renderer.render(&self.snapshot, &descriptions);
                    drop(descriptions);

                    self.ctx.respond(token, Rendered(output));

                    if self.ctx.config().retention == Retention::ResetOnScrape {
                        self.reset_distributions();
                    }
                }
                CompactionTick => {
                    self.update_snapshot(/* only_compact = */ true).await;
                }
                ServerFailed(err) => {
                    error!(error = %err, "server failed");
                    panic!("server failed, cannot continue");
                }
            });
        }
    }

    async fn update_snapshot(&mut self, only_compact: bool) {
        // Reuse the latest snapshot if possible.
        let snapshot = Arc::make_mut(&mut self.snapshot);

        // Run the preemtive merge process.
        self.storage.merge(snapshot, only_compact).await;

        if !only_compact {
            snapshot.emit_stats();
        }
    }

    fn reset_distributions(&mut self) {
        // Reuse the latest snapshot if possible.
        let snapshot = Arc::make_mut(&mut self.snapshot);

        snapshot.reset_distributions();
    }

    fn start_server(&mut self) {
        // Terminate a running server.
        if let Some(source) = self.server.take() {
            source.terminate();
        }

        // Start a new one.
        let listen = self.ctx.config().listen;
        let pruned_ctx = self.ctx.pruned();
        let source = Stream::once(hyper::server(listen, pruned_ctx));

        self.server = Some(self.ctx.attach(source));
    }
}