Background loading, initially implemented for search window

[jamaendo] / jamaui / fetcher.py

diff --git a/jamaui/fetcher.py b/jamaui/fetcher.py
new file mode 100644 (file)
index 0000000..d6f5ff0
--- /dev/null
+++ b/jamaui/fetcher.py
@@ -0,0 +1,71 @@
+# Background fetcher:
+# Takes a generator and a notification identifier as parameter,
+# starts a thread, and post a notification whenever data arrives.
+# Posts a completion notification when done.
+# Terminates if generator fails or encounters an error.
+
+import threading
+from postoffice import postoffice
+import jamaendo
+import logging
+
+import hildon
+
+log = logging.getLogger(__name__)
+
+class _Worker(threading.Thread):
+    def __init__(self, generator, owner):
+        threading.Thread.__init__(self)
+        self.setDaemon(True)
+        self.generator = generator
+        self.owner = owner
+
+    def _post(self, item):
+        postoffice.notify("fetch", self.owner, item)
+
+    def _post_ok(self):
+        postoffice.notify("fetch-ok", self.owner)
+
+    def _post_fail(self, e):
+        postoffice.notify("fetch-fail", self.owner, e)
+
+    def run(self):
+        try:
+            for item in self.generator():
+                self._post(item)
+            self._post_ok()
+        except jamaendo.JamendoAPIError, e:
+            log.exception("Failed to fetch, id %s" % (self.owner))
+            self._post_fail(e)
+
+class Fetcher(object):
+    def __init__(self, generator, owner, on_item = None, on_ok = None, on_fail = None):
+        self.generator = generator
+        self.owner = owner
+        self.worker = None
+
+        self.on_item = on_item
+        self.on_ok = on_ok
+        self.on_fail = on_fail
+
+    def _on_item_cb(self, i, x):
+        self.on_item(i, x)
+
+    def _on_ok_cb(self, i):
+        self.on_ok(i)
+        hildon.hildon_gtk_window_set_progress_indicator(self.owner, 0)
+
+    def _on_fail_cb(self, i, e):
+        self.on_fail(i, e)
+        hildon.hildon_gtk_window_set_progress_indicator(self.owner, 0)
+
+    def start(self):
+        postoffice.connect('fetch', self, self._on_item_cb)
+        postoffice.connect('fetch-ok', self, self._on_ok_cb)
+        postoffice.connect('fetch-fail', self, self._on_fail_cb)
+        hildon.hildon_gtk_window_set_progress_indicator(self.owner, 1)
+        self.worker = _Worker(self.generator, self.owner)
+        self.worker.start()
+
+    def stop(self):
+        postoffice.disconnect(['fetch', 'fetch-ok', 'fetch-fail'], self)