urlfetcher: Drop explicit prepare/cleanup calls

We can do this automatically easily enough. The downsides of
not cleaning up are pretty minor these days anyways without
the 'mount' handling

tests/test_urls.py

@@ -198,11 +198,7 @@ def _testURL(fetcher, testdata):
 
 def _fetchWrapper(url, cb):
     fetcher = urlfetcher.fetcherForURI(url, "/tmp", meter)
-    try:
-        fetcher.prepareLocation()
-        return cb(fetcher)
-    finally:
-        fetcher.cleanupLocation()
+    return cb(fetcher)
 
 
 def _testURLWrapper(testdata):

virtManager/create.py

@@ -217,6 +217,8 @@ class vmmCreate(vmmGObjectUI):
         if self._storage_browser:
             self._storage_browser.close()
         self._set_conn(None)
+        self._failed_guest = None
+        self._guest = None
 
     def _cleanup(self):
         if self._storage_browser:
@@ -331,8 +333,6 @@ class vmmCreate(vmmGObjectUI):
         Reset all UI state to default values. Conn specific state is
         populated in _populate_conn_state
         """
-        self._failed_guest = None
-        self._guest = None
         self.reset_finish_cursor()
 
         self.widget("create-pages").set_current_page(PAGE_NAME)

virtinst/installertreemedia.py

@@ -106,7 +106,6 @@ class InstallerTreeMedia(object):
         return self._cached_fetcher
 
     def _get_store(self, guest, fetcher):
-        # Caller is responsible for calling fetcher prepare/cleanup if needed
         if not self._cached_store:
             self._cached_store = urldetect.getDistroStore(guest, fetcher)
         return self._cached_store
@@ -143,17 +142,7 @@ class InstallerTreeMedia(object):
 
     def prepare(self, guest, meter):
         fetcher = self._get_fetcher(guest, meter)
-        try:
-            try:
-                fetcher.prepareLocation()
-            except ValueError as e:
-                logging.debug("Error preparing install location",
-                    exc_info=True)
-                raise ValueError(_("Invalid install location: ") + str(e))
-
-            return self._prepare_kernel_url(guest, fetcher)
-        finally:
-            fetcher.cleanupLocation()
+        return self._prepare_kernel_url(guest, fetcher)
 
     def cleanup(self, guest):
         ignore = guest
@@ -176,25 +165,15 @@ class InstallerTreeMedia(object):
         if self._media_type not in [MEDIA_URL]:
             return True
 
-        try:
-            fetcher = self._get_fetcher(guest, None)
-            fetcher.prepareLocation()
-
-            # This will throw an error for us
-            ignore = self._get_store(guest, fetcher)
-        finally:
-            fetcher.cleanupLocation()
+        fetcher = self._get_fetcher(guest, None)
+        # This will throw an error for us
+        ignore = self._get_store(guest, fetcher)
         return True
 
     def detect_distro(self, guest):
         if self._media_type in [MEDIA_ISO]:
             return InstallerTreeMedia.detect_iso_distro(guest, self.location)
 
-        try:
-            fetcher = self._get_fetcher(guest, None)
-            fetcher.prepareLocation()
-
-            store = self._get_store(guest, fetcher)
-            return store.get_osdict_info()
-        finally:
-            fetcher.cleanupLocation()
+        fetcher = self._get_fetcher(guest, None)
+        store = self._get_store(guest, fetcher)
+        return store.get_osdict_info()

virtinst/urlfetcher.py

@@ -33,6 +33,7 @@ class _URLFetcher(object):
         self.meter = meter
 
         logging.debug("Using scratchdir=%s", scratchdir)
+        self._prepare()
 
 
     ####################
@@ -103,18 +104,21 @@ class _URLFetcher(object):
         """
         return self._is_iso
 
-    def prepareLocation(self):
+    def _prepare(self):
         """
         Perform any necessary setup
         """
         pass
 
-    def cleanupLocation(self):
+    def _cleanup(self):
         """
         Perform any necessary cleanup
         """
         pass
 
+    def __del__(self):
+        self._cleanup()
+
     def can_access(self):
         """
         Return True if the location URL seems to be valid
@@ -165,10 +169,10 @@ class _URLFetcher(object):
 class _HTTPURLFetcher(_URLFetcher):
     _session = None
 
-    def prepareLocation(self):
+    def _prepare(self):
         self._session = requests.Session()
 
-    def cleanupLocation(self):
+    def _cleanup(self):
         if self._session:
             try:
                 self._session.close()
@@ -219,7 +223,7 @@ class _HTTPURLFetcher(_URLFetcher):
 class _FTPURLFetcher(_URLFetcher):
     _ftp = None
 
-    def prepareLocation(self):
+    def _prepare(self):
         if self._ftp:
             return
 
@@ -246,7 +250,7 @@ class _FTPURLFetcher(_URLFetcher):
         return urlobj, size
 
 
-    def cleanupLocation(self):
+    def _cleanup(self):
         if not self._ftp:
             return