Add debouncing to superzip

Author: cpsievert

Diff for: examples/superzip/app.py

@@ -4,6 +4,7 @@
 import ipywidgets
 import pandas as pd
 from faicons import icon_svg
+from ratelimit import debounce
 from shiny import App, Inputs, Outputs, Session, reactive, render, req, ui
 from utils import col_numeric, create_map, density_plot, heatmap_gradient
 
@@ -173,6 +174,7 @@ def _():
         with reactive.isolate():
             current_bounds.set(bb)
 
+    @debounce(0.3)
     @reactive.calc
     def zips_in_bounds():
         bb = req(current_bounds())
@@ -326,4 +328,4 @@ def _on_click(**kwargs):
         return m
 
 
-app = App(app_ui, server)
+app = App(app_ui, server, static_assets=app_dir / "www")

Diff for: examples/superzip/ratelimit.py

@@ -0,0 +1,103 @@
+# From https://gist.github.com/jcheng5/427de09573816c4ce3a8c6ec1839e7c0
+import functools
+import time
+
+from shiny import reactive
+
+
+def debounce(delay_secs):
+    def wrapper(f):
+        when = reactive.Value(None)
+        trigger = reactive.Value(0)
+
+        @reactive.Calc
+        def cached():
+            """
+            Just in case f isn't a reactive calc already, wrap it in one. This ensures
+            that f() won't execute any more than it needs to.
+            """
+            return f()
+
+        @reactive.Effect(priority=102)
+        def primer():
+            """
+            Whenever cached() is invalidated, set a new deadline for when to let
+            downstream know--unless cached() invalidates again
+            """
+            try:
+                cached()
+            except Exception:
+                ...
+            finally:
+                when.set(time.time() + delay_secs)
+
+        @reactive.Effect(priority=101)
+        def timer():
+            """
+            Watches changes to the deadline and triggers downstream if it's expired; if
+            not, use invalidate_later to wait the necessary time and then try again.
+            """
+            deadline = when()
+            if deadline is None:
+                return
+            time_left = deadline - time.time()
+            if time_left <= 0:
+                # The timer expired
+                with reactive.isolate():
+                    when.set(None)
+                    trigger.set(trigger() + 1)
+            else:
+                reactive.invalidate_later(time_left)
+
+        @reactive.Calc
+        @reactive.event(trigger, ignore_none=False)
+        @functools.wraps(f)
+        def debounced():
+            return cached()
+
+        return debounced
+
+    return wrapper
+
+
+def throttle(delay_secs):
+    def wrapper(f):
+        last_signaled = reactive.Value(None)
+        last_triggered = reactive.Value(None)
+        trigger = reactive.Value(0)
+
+        @reactive.Calc
+        def cached():
+            return f()
+
+        @reactive.Effect(priority=102)
+        def primer():
+            try:
+                cached()
+            except Exception:
+                ...
+            finally:
+                last_signaled.set(time.time())
+
+        @reactive.Effect(priority=101)
+        def timer():
+            if last_triggered() is not None and last_signaled() < last_triggered():
+                return
+
+            now = time.time()
+            if last_triggered() is None or (now - last_triggered()) >= delay_secs:
+                last_triggered.set(now)
+                with reactive.isolate():
+                    trigger.set(trigger() + 1)
+            else:
+                reactive.invalidate_later(delay_secs - (now - last_triggered()))
+
+        @reactive.Calc
+        @reactive.event(trigger, ignore_none=False)
+        @functools.wraps(f)
+        def throttled():
+            return cached()
+
+        return throttled
+
+    return wrapper