widget: Add wait support

Widgets can now specify that they wish to wait on an fd or for a target
time to be reached.

This can be used to save a few worker threads.

Cargo.lock

@@ -586,6 +586,14 @@ dependencies = [
  "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "timerfd"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "typenum"
 version = "1.11.2"
@@ -723,6 +731,7 @@ dependencies = [
  "serde_yaml 0.8.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "shlex 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "smithay-client-toolkit 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "timerfd 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "wayland-client 0.23.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "wayland-protocols 0.23.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -818,6 +827,7 @@ dependencies = [
 "checksum syn 0.15.44 (registry+https://github.com/rust-lang/crates.io-index)" = "9ca4b3b69a77cbe1ffc9e198781b7acb0c7365a883670e8f1c1bc66fba79a5c5"
 "checksum syn 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)" = "66850e97125af79138385e9b88339cbcd037e3f28ceab8c5ad98e64f0f1f80bf"
 "checksum time 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)" = "db8dcfca086c1143c9270ac42a2bbd8a7ee477b78ac8e45b19abfb0cbede4b6f"
+"checksum timerfd 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "6c9a7822e546fa39d0b5ae14a93a33903975b62af6597288aea77f0580a6abbe"
 "checksum typenum 1.11.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6d2783fe2d6b8c1101136184eb41be8b1ad379e4657050b8aaff0c79ee7575f9"
 "checksum ucd-trie 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "8f00ed7be0c1ff1e24f46c3d2af4859f7e863672ba3a6e92e7cff702bf9f06c2"
 "checksum unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fc72304796d0818e357ead4e000d19c9c174ab23dc11093ac919054d20a6a7fc"

Cargo.toml

@@ -33,6 +33,7 @@ lazy_static = "1.4"
 rcalc_lib = { version = "0.9" }
 rust-ini = "0.13"
 shlex = "0.1"
+timerfd = "1.0.0"
 
 serde = { version = "1.0", features = ["derive"] }
 serde_json = { version = "1.0", optional = true }

src/config.rs

@@ -91,7 +91,7 @@ impl Widget {
                     .map(|x| x.unwrap())
                     .collect(),
             )),
-            Widget::Clock { font_size } => Some(widgets::clock::Clock::new(font_size, tx.clone())),
+            Widget::Clock { font_size } => Some(widgets::clock::Clock::new(font_size)),
             Widget::Date { font_size } => Some(widgets::date::Date::new(font_size)),
             Widget::Calendar {
                 font_size,

src/main.rs

@@ -5,8 +5,10 @@ use std::os::unix::io::AsRawFd;
 use std::os::unix::net::{UnixListener, UnixStream};
 use std::sync::mpsc::channel;
 
+use timerfd::{TimerFd, TimerState, SetTimeFlags};
 use nix::poll::{poll, PollFd, PollFlags};
 use os_pipe::pipe;
+use chrono::{Local, Duration};
 
 mod app;
 mod buffer;
@@ -24,6 +26,7 @@ use app::{App, OutputMode};
 use cmd::Cmd;
 use config::Config;
 use configfmt::ConfigFmt;
+use widget::WaitContext;
 
 enum Mode {
     Start,
@@ -222,14 +225,19 @@ fn main() {
             }
         });
 
-    let mut fds = [
-        PollFd::new(app.event_queue().get_connection_fd(), PollFlags::POLLIN),
-        PollFd::new(rx_pipe.as_raw_fd(), PollFlags::POLLIN),
-    ];
+    let mut timer = TimerFd::new().unwrap();
+    let ev_fd = PollFd::new(app.event_queue().get_connection_fd(), PollFlags::POLLIN);
+    let rx_fd = PollFd::new(rx_pipe.as_raw_fd(), PollFlags::POLLIN);
+    let tm_fd = PollFd::new(timer.as_raw_fd(), PollFlags::POLLIN);
 
     app.cmd_queue().lock().unwrap().push_back(Cmd::Draw);
 
     let mut visible = !daemon;
+    let mut wait_ctx = WaitContext{
+        fds: Vec::new(),
+        target_time: None,
+    };
+
     let q = app.cmd_queue();
     loop {
         let cmd = q.lock().unwrap().pop_front();
@@ -287,9 +295,27 @@ fn main() {
             None => {
                 app.flush_display();
 
-                poll(&mut fds, -1).unwrap();
+                wait_ctx.fds.clear();
+                wait_ctx.fds.push(ev_fd);
+                wait_ctx.fds.push(rx_fd);
+                wait_ctx.target_time = None;
 
-                if fds[0].revents().unwrap().contains(PollFlags::POLLIN) {
+                app.get_widget().wait(&mut wait_ctx);
+
+                if let Some(target_time) = wait_ctx.target_time {
+                    let n = Local::now();
+                    let sleep = if target_time > n {
+                        target_time - n
+                    } else {
+                        Duration::seconds(0)
+                    };
+                    timer.set_state(TimerState::Oneshot(sleep.to_std().unwrap()), SetTimeFlags::Default);
+                    wait_ctx.fds.push(tm_fd);
+                }
+
+                poll(&mut wait_ctx.fds, -1).unwrap();
+
+                if wait_ctx.fds[0].revents().unwrap().contains(PollFlags::POLLIN) {
                     if let Some(guard) = app.event_queue().prepare_read() {
                         if let Err(e) = guard.read_events() {
                             if e.kind() != ::std::io::ErrorKind::WouldBlock {
@@ -306,10 +332,16 @@ fn main() {
                         .expect("Failed to dispatch all messages.");
                 }
 
-                if fds[1].revents().unwrap().contains(PollFlags::POLLIN) {
+                if wait_ctx.fds[1].revents().unwrap().contains(PollFlags::POLLIN) {
                     let mut v = [0x00];
                     rx_pipe.read_exact(&mut v).unwrap();
                 }
+
+                if wait_ctx.target_time.is_some() &&
+                    wait_ctx.fds[wait_ctx.fds.len()-1].revents().unwrap().contains(PollFlags::POLLIN) {
+                    timer.read();
+                    q.lock().unwrap().push_back(Cmd::Draw);
+                }
             }
         }
     }

src/widget.rs

@@ -1,3 +1,4 @@
+use nix::poll::{PollFd};
 use crate::buffer::Buffer;
 use crate::color::Color;
 use chrono::{DateTime, Local};
@@ -29,7 +30,25 @@ impl DrawReport {
     }
 }
 
+pub struct WaitContext {
+    pub fds: Vec<PollFd>,
+    pub target_time: Option<DateTime<Local>>,
+}
+
+impl WaitContext {
+    pub fn set_time(&mut self, new_time: DateTime<Local>) {
+        if let Some(ot) = self.target_time {
+            if new_time < ot {
+                self.target_time = Some(new_time);
+            }
+        } else {
+            self.target_time = Some(new_time);
+        }
+    }
+}
+
 pub trait Widget {
+    fn wait(&self, ctx: &mut WaitContext);
     fn enter(&mut self);
     fn leave(&mut self);
     fn size(&self) -> (u32, u32);
@@ -62,6 +81,11 @@ impl VerticalLayout {
 }
 
 impl Widget for VerticalLayout {
+    fn wait(&self, ctx: &mut WaitContext) {
+        for child in &self.children {
+            child.wait(ctx);
+        }
+    }
     fn enter(&mut self) {
         for child in &mut self.children {
             child.enter();
@@ -168,6 +192,11 @@ impl HorizontalLayout {
 }
 
 impl Widget for HorizontalLayout {
+    fn wait(&self, ctx: &mut WaitContext) {
+        for child in &self.children {
+            child.wait(ctx);
+        }
+    }
     fn enter(&mut self) {
         for child in &mut self.children {
             child.enter();
@@ -280,6 +309,9 @@ impl Margin {
 }
 
 impl Widget for Margin {
+    fn wait(&self, ctx: &mut WaitContext) {
+        self.child.wait(ctx)
+    }
     fn enter(&mut self) {
         self.child.enter()
     }
@@ -354,6 +386,9 @@ impl Fixed {
 }
 
 impl Widget for Fixed {
+    fn wait(&self, ctx: &mut WaitContext) {
+        self.child.wait(ctx)
+    }
     fn enter(&mut self) {
         self.child.enter()
     }

src/widgets/bar_widget.rs

@@ -1,6 +1,6 @@
 use crate::color::Color;
 use crate::draw::{draw_bar, draw_box, Font, ROBOTO_REGULAR};
-use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget};
+use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget, WaitContext};
 
 use std::sync::{Arc, Mutex};
 
@@ -61,6 +61,7 @@ impl BarWidget {
 }
 
 impl Widget for BarWidget {
+    fn wait(&self, _: &mut WaitContext) {}
     fn enter(&mut self) {}
     fn leave(&mut self) {}
     fn size(&self) -> (u32, u32) {

src/widgets/calendar.rs

@@ -1,7 +1,7 @@
 use crate::buffer::Buffer;
 use crate::color::Color;
 use crate::draw::{Font, DEJAVUSANS_MONO, ROBOTO_REGULAR};
-use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget};
+use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget, WaitContext};
 
 use chrono::{Date, Datelike, Local};
 
@@ -177,6 +177,7 @@ impl Calendar {
 }
 
 impl Widget for Calendar {
+    fn wait(&self, _: &mut WaitContext) {}
     fn enter(&mut self) {}
     fn leave(&mut self) {}
 

src/widgets/clock.rs

@@ -1,9 +1,6 @@
-use crate::cmd::Cmd;
 use crate::color::Color;
 use crate::draw::{Font, ROBOTO_REGULAR};
-use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget};
-
-use std::sync::mpsc::Sender;
+use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget, WaitContext};
 
 use chrono::{DateTime, Datelike, Duration, Local, Timelike};
 
@@ -14,23 +11,7 @@ pub struct Clock {
 }
 
 impl Clock {
-    pub fn new(size: f32, ch: Sender<Cmd>) -> Box<Clock> {
-        let _ = std::thread::Builder::new()
-            .name("clock_ticker".to_string())
-            .spawn(move || loop {
-                let n = Local::now();
-                let target = (n + Duration::seconds(60))
-                    .with_second(0)
-                    .unwrap()
-                    .with_nanosecond(0)
-                    .unwrap();
-
-                let d = target - n;
-
-                std::thread::sleep(d.to_std().unwrap());
-                ch.send(Cmd::Draw).unwrap();
-            });
-
+    pub fn new(size: f32) -> Box<Clock> {
         let mut clock_cache = Font::new(&ROBOTO_REGULAR, size);
         clock_cache.add_str_to_cache("0123456789:");
 
@@ -45,6 +26,14 @@ impl Clock {
 }
 
 impl Widget for Clock {
+    fn wait(&self, ctx: &mut WaitContext) {
+        let target = (self.cur_time + Duration::seconds(60))
+            .with_second(0)
+            .unwrap()
+            .with_nanosecond(0)
+            .unwrap();
+        ctx.set_time(target);
+    }
     fn enter(&mut self) {}
     fn leave(&mut self) {}
     fn size(&self) -> (u32, u32) {

src/widgets/date.rs

@@ -1,6 +1,6 @@
 use crate::color::Color;
 use crate::draw::{Font, ROBOTO_REGULAR};
-use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget};
+use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget, WaitContext};
 
 use chrono::{DateTime, Datelike, Local};
 
@@ -27,6 +27,7 @@ impl Date {
 }
 
 impl Widget for Date {
+    fn wait(&self, _: &mut WaitContext) {}
     fn enter(&mut self) {}
     fn leave(&mut self) {}
     fn size(&self) -> (u32, u32) {

src/widgets/launcher.rs

@@ -3,7 +3,7 @@ use crate::cmd::Cmd;
 use crate::color::Color;
 use crate::desktop::{load_desktop_files, Desktop};
 use crate::draw::{Font, ROBOTO_REGULAR};
-use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget};
+use crate::widget::{DrawContext, DrawReport, KeyState, ModifiersState, Widget, WaitContext};
 
 use std::cell::RefCell;
 use std::cmp::Ordering;
@@ -192,6 +192,7 @@ fn wlcopy(s: &str) -> Result<(), String> {
 }
 
 impl Widget for Launcher {
+    fn wait(&self, _: &mut WaitContext) {}
     fn enter(&mut self) {}
     fn leave(&mut self) {
         self.input = "".to_string();