scanner: Create a TaskQueue

For running tasks with a GLib idle callback

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

scanner/__init__.py

@@ -1,3 +1,4 @@
 # Copyright 2021 (c) Anna Schumaker.
 from . import metadata
+from . import queue
 from . import task

scanner/queue.py

@@ -0,0 +1,53 @@
+# Copyright 2021 (c) Anna Schumaker.
+from gi.repository import GLib
+from gi.repository import GObject
+from . import task
+
+class TaskQueue(GObject.GObject):
+    def __init__(self):
+        GObject.GObject.__init__(self)
+        self.tasks  = [ ]
+        self.total  = 0
+        self.idleid = None
+
+    def __del__(self):
+        if self.idleid != None:
+            GLib.source_remove(self.idleid)
+
+    def push(self, task):
+        self.emit("task-pushed", task)
+
+    def run(self):
+        self.emit("run-task", self.tasks.pop(0))
+        if len(self.tasks) > 0:
+            return GLib.SOURCE_CONTINUE
+
+        self.emit("tasks-finished")
+        return GLib.SOURCE_REMOVE
+
+    @GObject.Property
+    def progress(self):
+        if len(self.tasks) == 0:
+            return 0
+        return (self.total - len(self.tasks)) / self.total
+
+    @GObject.Signal(arg_types=(task.Task,))
+    def task_pushed(self, task):
+        self.tasks.append(task)
+        self.total += 1
+        if self.idleid == None:
+            self.idleid = GLib.idle_add(self.run)
+
+    @GObject.Signal(arg_types=(task.Task,))
+    def run_task(self, task):
+        if tasks := task.run_task():
+            self.tasks += tasks
+            self.total += len(tasks)
+
+    @GObject.Signal
+    def tasks_finished(self):
+        if self.idleid:
+            GLib.source_remove(self.idleid)
+            self.tasks.clear()
+            self.total  = 0
+            self.idleid = None

scanner/test_queue.py

@@ -0,0 +1,78 @@
+# Copyright 2021 (c) Anna Schumaker.
+import unittest
+from gi.repository import GObject
+from . import queue
+from . import task
+
+class FakeTask(task.Task):
+    def __init__(self, res=None):
+        task.Task.__init__(self)
+        self.res = res
+    def run_task(self): return self.res
+
+class TestScannerTaskQueue(unittest.TestCase):
+    def setUp(self):
+        self.idle_start = None
+
+    def on_task_pushed(self, queue, task):
+        self.pushed_task = task
+
+    def on_run_task(self, queue, task):
+        self.run_task = task
+
+    def on_tasks_finished(self, queue):
+        self.tasks_finished = True
+
+    def test_scanner_queue_init(self):
+        q = queue.TaskQueue()
+
+        self.assertIsInstance(q, GObject.GObject)
+        self.assertEqual(q.tasks, [ ])
+        self.assertEqual(q.total, 0)
+        self.assertEqual(q.idleid, None)
+        self.assertEqual(q.progress, 0)
+
+    def test_scanner_queue_push(self):
+        q = queue.TaskQueue()
+        fake = FakeTask()
+        q.connect("task-pushed", self.on_task_pushed)
+
+        q.push(fake)
+        self.assertEqual(q.tasks, [ fake ])
+        self.assertIsNotNone(q.idleid)
+        self.assertEqual(self.pushed_task, fake)
+
+    def test_scanner_queue_run(self):
+        q = queue.TaskQueue()
+        fake3 = FakeTask()
+        fake2 = FakeTask()
+        fake1 = FakeTask([ fake2, fake3 ])
+        q.connect("run-task", self.on_run_task)
+        q.connect("tasks-finished", self.on_tasks_finished)
+
+        q.push(fake1)
+        self.assertEqual(q.tasks, [ fake1 ])
+        self.assertEqual(q.total, 1)
+        self.assertEqual(q.progress, 0/1)
+
+        q.run()
+        self.assertEqual(self.run_task, fake1)
+        self.assertEqual(q.tasks, [ fake2, fake3 ])
+        self.assertEqual(q.total, 3)
+        self.assertEqual(q.progress, 1/3)
+        self.assertIsNotNone(q.idleid)
+
+        q.run()
+        self.assertEqual(self.run_task, fake2)
+        self.assertEqual(q.tasks, [ fake3 ])
+        self.assertEqual(q.progress, 2/3)
+        self.assertIsNotNone(q.idleid)
+
+        q.run()
+        self.assertEqual(self.run_task, fake3)
+        self.assertEqual(q.tasks, [ ])
+
+        self.assertTrue(self.tasks_finished)
+        self.assertEqual(q.total, 0)
+        self.assertEqual(q.progress, 0)
+        self.assertIsNone(q.idleid)