From 88fa163c95231969a0898470a11c72dc65d4ca2e Mon Sep 17 00:00:00 2001
From: ylxdzsw <ylxdzsw@gmail.com>
Date: Fri, 21 Jul 2017 16:31:12 +0800
Subject: [PATCH] throttle

---
 src/training.jl | 45 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/src/training.jl b/src/training.jl
index 62a34c46..3632eb82 100644
--- a/src/training.jl
+++ b/src/training.jl
@@ -25,18 +25,59 @@ macro cb(ex, t, f)
   end)
 end
 
+"""
+Returns a function that when invoked, will only be triggered at most once
+during `timeout` seconds. Normally, the throttled function will run
+as much as it can, without ever going more than once per `wait` duration;
+but if you'd like to disable the execution on the leading edge, pass
+`leading=false`. To enable execution on the trailing edge, ditto.
+"""
+function throttle(f, timeout; leading=true, trailing=false)
+  cooldown = true
+  later = nothing
+
+  function throttled(args...; kwargs...)
+    yield()
+
+    if cooldown
+      if leading
+        f(args...; kwargs...)
+      else
+        later = () -> f(args...; kwargs...)
+      end
+
+      cooldown = false
+      @schedule try
+        while (sleep(timeout); later != nothing)
+          later()
+          later = nothing
+        end
+      finally
+        cooldown = true
+      end
+    elseif trailing
+      later = () -> f(args...; kwargs...)
+    end
+
+    nothing
+  end
+end
+
 function train!(m, train; cb = [],
                 epoch = 1, η = 0.1, loss = mse)
+    callback = throttle(()->foreach(f -> f(), cb), 5)
+
     @progress for e in 1:epoch
       info("Epoch $e")
-      @cb for (x, y) in train
+      for (x, y) in train
         x, y = mapt(tobatch, (x, y))
         ŷ = m(x)
         any(isnan, ŷ) && error("NaN")
         Δ = back!(loss, 1, ŷ, y)
         back!(m, Δ, x)
         update!(m, η)
-      end 5 foreach(f -> f(), cb)
+        callback()
+      end
     end
     return m
 end