From d69bdd281083c66b2c21b5fce5da4512f39b97e6 Mon Sep 17 00:00:00 2001
From: Vesna Tanko <tankovesna@hotmail.com>
Date: Wed, 11 Sep 2019 08:43:48 +0200
Subject: [PATCH] VizRankDialog: Restrict frequency of signal emitting

---
 .../visualize/tests/test_vizrankdialog.py       |  6 +++---
 Orange/widgets/visualize/utils/__init__.py      | 17 ++++++++++++++++-
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/Orange/widgets/visualize/tests/test_vizrankdialog.py b/Orange/widgets/visualize/tests/test_vizrankdialog.py
index fb3f11f9889..343bb6e41ca 100644
--- a/Orange/widgets/visualize/tests/test_vizrankdialog.py
+++ b/Orange/widgets/visualize/tests/test_vizrankdialog.py
@@ -41,7 +41,7 @@ def test_run_vizrank(self):
         res_scores = sorted([compute_score(x) for x in states])
         self.assertListEqual(res.scores, res_scores)
         self.assertIsNot(scores, res.scores)
-        self.assertEqual(task.set_partial_result.call_count, 6)
+        self.assertEqual(task.set_partial_result.call_count, 2)
         self.assertEqual(task.set_progress_value.call_count, 7)
 
     def test_run_vizrank_interrupt(self):
@@ -59,7 +59,7 @@ def test_run_vizrank_interrupt(self):
         res_scores = sorted([compute_score(x) for x in states[:2]])
         self.assertListEqual(res.scores, res_scores)
         self.assertIsNot(scores, res.scores)
-        self.assertEqual(task.set_partial_result.call_count, 2)
+        self.assertEqual(task.set_partial_result.call_count, 1)
         self.assertEqual(task.set_progress_value.call_count, 3)
         task.set_progress_value.assert_called_with(int(1 / 6 * 100))
 
@@ -76,7 +76,7 @@ def test_run_vizrank_interrupt(self):
         res_scores = sorted([compute_score(x) for x in states])
         self.assertListEqual(res.scores, res_scores)
         self.assertIsNot(scores, res.scores)
-        self.assertEqual(task.set_partial_result.call_count, 6)
+        self.assertEqual(task.set_partial_result.call_count, 3)
         self.assertEqual(task.set_progress_value.call_count, 8)
         task.set_progress_value.assert_called_with(int(5 / 6 * 100))
 
diff --git a/Orange/widgets/visualize/utils/__init__.py b/Orange/widgets/visualize/utils/__init__.py
index 99c0b6c5f94..4d03d73f4c2 100644
--- a/Orange/widgets/visualize/utils/__init__.py
+++ b/Orange/widgets/visualize/utils/__init__.py
@@ -7,6 +7,7 @@
 from queue import Queue, Empty
 from types import SimpleNamespace as namespace
 from typing import Optional, Iterable, List, Callable
+from threading import Timer
 
 from AnyQt.QtCore import Qt, QSize, pyqtSignal as Signal, QSortFilterProxyModel
 from AnyQt.QtGui import QStandardItemModel, QStandardItem, QColor, QBrush, QPen
@@ -393,6 +394,7 @@ def run_vizrank(compute_score: Callable, iterate_states: Callable,
     task.set_status("Getting scores...")
     res = Result(queue=Queue(), scores=None)
     scores = scores.copy()
+    can_set_partial_result = True
 
     def do_work(st, next_st):
         try:
@@ -405,7 +407,10 @@ def do_work(st, next_st):
         except Exception:  # ignore current state in case of any problem
             pass
         res.scores = scores.copy()
-        task.set_partial_result(res)
+
+    def reset_flag():
+        nonlocal can_set_partial_result
+        can_set_partial_result = True
 
     state = None
     next_state = next(states)
@@ -419,8 +424,18 @@ def do_work(st, next_st):
             state = copy.copy(next_state)
             next_state = copy.copy(next(states))
             do_work(state, next_state)
+            # for simple scores (e.g. correlations widget) and many feature
+            # combinations, the 'partial_result_ready' signal (emitted by
+            # invoking 'task.set_partial_result') was emitted too frequently
+            # for a longer period of time and therefore causing the widget
+            # being unresponsive
+            if can_set_partial_result:
+                task.set_partial_result(res)
+                can_set_partial_result = False
+                Timer(0.01, reset_flag).start()
     except StopIteration:
         do_work(state, None)
+        task.set_partial_result(res)
     return res