imported duplicate check speed

openlp/plugins/songs/forms/duplicatesongremovalform.py

@@ -31,6 +31,7 @@ The duplicate song removal logic for OpenLP.
 """
 
 import logging
+import multiprocessing
 import os
 
 from PyQt4 import QtCore, QtGui
@@ -45,6 +46,17 @@ from openlp.plugins.songs.lib.songcompare import songs_probably_equal
 log = logging.getLogger(__name__)
 
 
+class SongIterator(object):
+    def __init__(self, songs):
+        self.songs = songs
+
+    def __iter__(self):
+        for outer_song_counter in range(len(self.songs) - 1):
+            for inner_song_counter in range(outer_song_counter + 1, len(self.songs)):
+                yield (self.songs[outer_song_counter], self.songs[inner_song_counter])
+
+
+
 class DuplicateSongRemovalForm(OpenLPWizard):
     """
     This is the Duplicate Song Removal Wizard. It provides functionality to search for and remove duplicate songs
@@ -167,24 +179,32 @@ class DuplicateSongRemovalForm(OpenLPWizard):
                 max_progress_count = max_songs * (max_songs - 1) // 2
                 self.duplicate_search_progress_bar.setMaximum(max_progress_count)
                 songs = self.plugin.manager.get_all_objects(Song)
-                for outer_song_counter in range(max_songs - 1):
-                    for inner_song_counter in range(outer_song_counter + 1, max_songs):
-                        if songs_probably_equal(songs[outer_song_counter], songs[inner_song_counter]):
-                            duplicate_added = self.add_duplicates_to_song_list(
-                                songs[outer_song_counter], songs[inner_song_counter])
-                            if duplicate_added:
-                                self.found_duplicates_edit.appendPlainText(
-                                    songs[outer_song_counter].title + "  =  " + songs[inner_song_counter].title)
+                # Create a worker/process pool to check the songs.
+                process_number = max(1, multiprocessing.cpu_count() - 1)
+                pool = multiprocessing.Pool(process_number)
+                song_list = SongIterator(songs)
+                #song_list = [(songs[outer_song_counter], songs[inner_song_counter]) for outer_song_counter in range(max_songs - 1) for inner_song_counter in range(outer_song_counter + 1, max_songs)]
+                result = pool.imap_unordered(songs_probably_equal, song_list, 30)
+                # Do not accept any further tasks. Also this closes the processes if all tasks are done.
+                pool.close()
+                # While the processes are still working, start to look at the results.
+                for song_tuple in result:
                     self.duplicate_search_progress_bar.setValue(self.duplicate_search_progress_bar.value() + 1)
                     # The call to process_events() will keep the GUI responsive.
                     self.application.process_events()
                     if self.break_search:
+                        pool.terminate()
                         return
-                self.review_total_count = len(self.duplicate_song_list)
-                if self.review_total_count == 0:
-                    self.notify_no_duplicates()
-                else:
+                    if song_tuple is None:
+                        continue
+                    song1, song2 = song_tuple
+                    duplicate_added = self.add_duplicates_to_song_list(song1, song2)
+                    if duplicate_added:
+                        self.found_duplicates_edit.appendPlainText(song1.title + "  =  " + song2.title)
+                if self.duplicate_song_list:
                     self.button(QtGui.QWizard.NextButton).show()
+                else:
+                    self.notify_no_duplicates()
             finally:
                 self.application.set_normal_cursor()
         elif page_id == self.review_page_id:

openlp/plugins/songs/lib/songcompare.py

@@ -52,13 +52,15 @@ MIN_BLOCK_SIZE = 70
 MAX_TYPO_SIZE = 3
 
 
-def songs_probably_equal(song1, song2):
+def songs_probably_equal(song1, song2=None):
     """
     Calculate and return whether two songs are probably equal.
 
     :param song1: The first song to compare.
     :param song2:  The second song to compare.
     """
+    if song2 is None:
+        song1, song2 = song1
     if len(song1.search_lyrics) < len(song2.search_lyrics):
         small = song1.search_lyrics
         large = song2.search_lyrics
@@ -75,8 +77,9 @@ def songs_probably_equal(song1, song2):
     for element in diff_no_typos:
         if element[0] == "equal" and _op_length(element) >= MIN_BLOCK_SIZE:
             length_of_equal_blocks += _op_length(element)
+
     if length_of_equal_blocks >= MIN_BLOCK_SIZE:
-        return True
+        return song1, song2
     # Check 2: Similarity based on the relative length of the longest equal block.
     # Calculate the length of the largest equal block of the diff set.
     length_of_longest_equal_block = 0
@@ -84,9 +87,9 @@ def songs_probably_equal(song1, song2):
         if element[0] == "equal" and _op_length(element) > length_of_longest_equal_block:
             length_of_longest_equal_block = _op_length(element)
     if length_of_equal_blocks >= MIN_BLOCK_SIZE or length_of_longest_equal_block > len(small) * 2 // 3:
-        return True
+        return song1, song2
     # Both checks failed. We assume the songs are not equal.
-    return False
+    return None
 
 
 def _op_length(opcode):