From 52c41b24ad71b5323af79de837f0198737813d45 Mon Sep 17 00:00:00 2001
From: alessandro90 <alessandro.ceccato.3@gmail.com>
Date: Sun, 9 Jun 2019 12:39:26 +0200
Subject: [PATCH] Avoid using 'terminate' on the download thread

---
 download_window.py | 17 +++++++++-----
 threads.py         | 58 +++++++++++++++++++++++++---------------------
 2 files changed, 42 insertions(+), 33 deletions(-)

diff --git a/download_window.py b/download_window.py
index 252675e..f089ede 100644
--- a/download_window.py
+++ b/download_window.py
@@ -5,6 +5,7 @@ from threads import DownloadThread, ThreadStatus
 from utilities import pop_up, resource_path
 from constants import Constants, Messages
 
+
 Ui_Download_window, _ = uic.loadUiType(
     resource_path("download_db_window.ui")
 )
@@ -14,6 +15,7 @@ class DownloadWindow(QWidget, Ui_Download_window):
     """Subclass QWidget and Ui_Download_window. It is the window displayed during the database download."""
 
     complete = pyqtSignal()
+    closed = pyqtSignal()
 
     def __init__(self):
         """Initialize the window."""
@@ -38,6 +40,7 @@ class DownloadWindow(QWidget, Ui_Download_window):
         self._download_thread = DownloadThread()
         self._download_thread.finished.connect(self._wait_close)
         self._download_thread.progress.connect(self._display_progress)
+        self.closed.connect(self._download_thread.set_exit)
         self.cancel_btn.clicked.connect(self._terminate_process)
 
     def start_download(self):
@@ -61,12 +64,16 @@ class DownloadWindow(QWidget, Ui_Download_window):
         elif progress == Constants.EXTRACTING_CODE:
             self.status_lbl.setText(Constants.EXTRACTING_MSG + '\n')
 
+    def _stop_thread(self):
+        """Ask the download thread to stop."""
+        if self._download_thread.isRunning():
+            self.closed.emit()
+            self._download_thread.wait()
+
     @pyqtSlot()
     def _terminate_process(self):
         """Terminate the download thread and close."""
-        if self._download_thread.isRunning():
-            self._download_thread.terminate()
-            self._download_thread.wait()
+        self._stop_thread()
         self.close()
 
     @pyqtSlot()
@@ -84,7 +91,5 @@ class DownloadWindow(QWidget, Ui_Download_window):
 
     def reject(self):
         """Extends QWidget.reject. Terminate the download thread."""
-        if self._download_thread.isRunning():
-            self._download_thread.terminate()
-            self._download_thread.wait()
+        self._stop_thread()
         super().reject()
diff --git a/threads.py b/threads.py
index 04904d2..2c6764a 100644
--- a/threads.py
+++ b/threads.py
@@ -41,16 +41,17 @@ class DownloadThread(BaseDownloadThread):
     """Subclass BaseDownloadThread. Download the database, images and audio samples."""
 
     progress = pyqtSignal(int, float)
-    CHUNK = 1024**2
+    _CHUNK = 1024**2
 
     def __init__(self):
         """Just call super().__init__."""
-        self.db = None
+        self._db = None
+        self._exit_call = False
         super().__init__()
 
     def _pretty_len(self, byte_obj):
         """Return a well-formatted number of downloaded MB."""
-        mega = len(byte_obj) / self.CHUNK
+        mega = len(byte_obj) / self._CHUNK
         if mega.is_integer():
             return int(mega)
         else:
@@ -59,40 +60,51 @@ class DownloadThread(BaseDownloadThread):
     def _get_download_speed(self, data, delta):
         """Return the download speed in MB/s."""
         return round(
-            (len(data) / self.CHUNK) / delta, 2
+            (len(data) / self._CHUNK) / delta, 2
         )
 
+    def set_exit(self):
+        self._exit_call = True
+
     def run(self):
         """Override QThread.run. Download the database, images and audio samples.
 
         Handle all possible exceptions. Also extract the files
         in the local folder."""
         self.status = ThreadStatus.UNDEFINED
-        self.db = None
+        self._db = None
         raw_data = bytes(0)
         try:
-            self.db = urllib3.PoolManager().request(
+            self._db = urllib3.PoolManager().request(
                 'GET',
                 Database.LINK_LOC,
-                preload_content=False
+                preload_content=False,
+                timeout=4.0
             )
             while True:
                 start = time()
-                data = self.db.read(self.CHUNK)
-                delta = time() - start
-                if not data:
-                    break
-                raw_data += data
-                self.progress.emit(
-                    self._pretty_len(raw_data),
-                    self._get_download_speed(data, delta)
-                )
-            self.db.release_conn()
+                try:
+                    data = self._db.read(self._CHUNK)
+                except Exception:
+                    raise
+                else:
+                    delta = time() - start
+                    if not data:
+                        break
+                    raw_data += data
+                    self.progress.emit(
+                        self._pretty_len(raw_data),
+                        self._get_download_speed(data, delta)
+                    )
+                    if self._exit_call:
+                        self._exit_call = False
+                        self._db.release_conn()
+                        return
         except Exception:  # No internet connection.
-            self.db.release_conn()
+            self._db.release_conn()
             self.status = ThreadStatus.NO_CONNECTION_ERR
             return
-        if self.db.status != 200:
+        if self._db.status != 200:
             self.status = ThreadStatus.BAD_DOWNLOAD_ERR
             return
         try:
@@ -115,14 +127,6 @@ class DownloadThread(BaseDownloadThread):
         else:
             self.status = ThreadStatus.OK
 
-    def terminate(self):
-        """Extend QThread.terminate.
-
-        Release the connection in case of termination."""
-        if self.db is not None:
-            self.db.release_conn()
-        super().terminate()
-
 
 class _AsyncDownloader:
     """Mixin class for asynchronous threads."""