remove non-thread multigrid and sep. thread for io

sbp/examples/multigrid/bin.rs

@@ -87,89 +87,7 @@ impl<T: operators::UpwindOperator> System<T> {
         }
     }
 
-    fn advance(&mut self, dt: Float) {
-        for i in 0.. {
-            let time;
-            let fnext;
-            match i {
-                0 => {
-                    for (prev, fut) in self.fnow.iter().zip(self.fnext.iter_mut()) {
-                        fut.assign(prev);
-                    }
-                    fnext = &mut self.k[i];
-                    time = self.time;
-                }
-                1 | 2 => {
-                    for ((prev, fut), k) in self
-                        .fnow
-                        .iter()
-                        .zip(self.fnext.iter_mut())
-                        .zip(&self.k[i - 1])
-                    {
-                        fut.assign(prev);
-                        fut.scaled_add(1.0 / 2.0 * dt, k);
-                    }
-                    fnext = &mut self.k[i];
-                    time = self.time + dt / 2.0;
-                }
-                3 => {
-                    for ((prev, fut), k) in self
-                        .fnow
-                        .iter()
-                        .zip(self.fnext.iter_mut())
-                        .zip(&self.k[i - 1])
-                    {
-                        fut.assign(prev);
-                        fut.scaled_add(dt, k);
-                    }
-                    fnext = &mut self.k[i];
-                    time = self.time + dt;
-                }
-                4 => {
-                    for (((((prev, fut), k0), k1), k2), k3) in self
-                        .fnow
-                        .iter()
-                        .zip(self.fnext.iter_mut())
-                        .zip(&self.k[0])
-                        .zip(&self.k[1])
-                        .zip(&self.k[2])
-                        .zip(&self.k[3])
-                    {
-                        ndarray::Zip::from(&mut **fut)
-                            .and(&**prev)
-                            .and(&**k0)
-                            .and(&**k1)
-                            .and(&**k2)
-                            .and(&**k3)
-                            .apply(|y1, &y0, &k1, &k2, &k3, &k4| {
-                                *y1 = y0 + dt / 6.0 * (k1 + 2.0 * k2 + 2.0 * k3 + k4)
-                            });
-                    }
-                    std::mem::swap(&mut self.fnext, &mut self.fnow);
-                    self.time += dt;
-                    return;
-                }
-                _ => {
-                    unreachable!();
-                }
-            }
-
-            let fields = &self.fnext;
-            let bt = extract_boundaries(&fields, &mut self.bt, &mut self.eb, &self.grids, time);
-
-            for ((((prev, fut), metrics), wb), bt) in fields
-                .iter()
-                .zip(fnext)
-                .zip(&self.metrics)
-                .zip(&mut self.wb)
-                .zip(bt)
-            {
-                euler::RHS_upwind(fut, prev, metrics, &bt, wb)
-            }
-        }
-    }
-
-    fn advance_parallel(&mut self, dt: Float, s: &rayon::ThreadPool) {
+    fn advance(&mut self, dt: Float, s: &rayon::ThreadPool) {
         for i in 0.. {
             let time;
             match i {
@@ -404,33 +322,69 @@ fn main() {
 
     let ntime = (integration_time / dt).round() as u64;
 
-    let pool = if let Some(j) = opt.jobs {
+    let pool = {
         let builder = rayon::ThreadPoolBuilder::new();
-        let builder = if let Some(j) = j {
-            builder.num_threads(j)
+        if let Some(j) = opt.jobs {
+            if let Some(j) = j {
+                builder.num_threads(j)
+            } else {
+                builder
+            }
         } else {
-            builder
-        };
-        Some(builder.build().unwrap())
-    } else {
-        None
+            builder.num_threads(1)
+        }
+        .build()
+        .unwrap()
     };
 
     let output = File::create(&opt.output, sys.grids.as_slice()).unwrap();
-    output.add_timestep(0, sys.fnow.as_slice()).unwrap();
+
+    // Pingpong back and forth a number of Vec<Field> to be used for the
+    // output. The sync_channel applies some backpressure
+    let (tx_thread, rx) = std::sync::mpsc::channel::<Vec<euler::Field>>();
+    let (tx, rx_thread) = std::sync::mpsc::sync_channel::<(u64, Vec<euler::Field>)>(3);
+    let outputthread = std::thread::Builder::new()
+        .name("multigrid_output".to_owned())
+        .spawn(move || {
+            let mut times = Vec::<u64>::new();
+
+            for (ntime, fields) in rx_thread.iter() {
+                if !times.contains(&ntime) {
+                    output.add_timestep(ntime, fields.as_slice()).unwrap();
+                    times.push(ntime);
+                }
+                tx_thread.send(fields).unwrap();
+            }
+        })
+        .unwrap();
+
+    let output = |ntime: u64, nowfield: &[euler::Field]| match rx.try_recv() {
+        Ok(mut fields) => {
+            for (from, to) in nowfield.iter().zip(fields.iter_mut()) {
+                to.assign(&from);
+            }
+            tx.send((ntime, fields)).unwrap();
+        }
+        Err(std::sync::mpsc::TryRecvError::Empty) => {
+            let fields = nowfield.to_vec();
+            tx.send((ntime, fields)).unwrap();
+        }
+        Err(e) => panic!("{:?}", e),
+    };
+
+    output(0, &sys.fnow);
 
     let bar = progressbar(opt.no_progressbar, ntime);
     for _ in 0..ntime {
         bar.inc(1);
-        if let Some(pool) = pool.as_ref() {
-            sys.advance_parallel(dt, &pool);
-        } else {
-            sys.advance(dt);
-        }
+        sys.advance(dt, &pool);
     }
     bar.finish();
 
-    output.add_timestep(ntime, sys.fnow.as_slice()).unwrap();
+    output(ntime, &sys.fnow);
+
+    std::mem::drop(tx);
+    outputthread.join().unwrap();
 }
 
 fn progressbar(dummy: bool, ntime: u64) -> indicatif::ProgressBar {