From b10761d456672f94c72e261df816e4c6c1cf0bae Mon Sep 17 00:00:00 2001
From: Zhihao Yuan <zhihao.yuan@rackspace.com>
Date: Tue, 23 Apr 2013 10:54:54 -0400
Subject: [PATCH] Support list queue pagination in storage.

Change-Id: Ifc87f84518593ce25a9b18fd62dbe4d5cd39006f
Implements: blueprint storage-reference
Implements: blueprint storage-mongodb
---
 marconi/storage/mongodb/controllers.py | 30 ++++++++++++++++-----
 marconi/storage/sqlite/controllers.py  | 37 +++++++++++++++++++++-----
 marconi/tests/storage/base.py          | 26 +++++++++++-------
 marconi/transport/wsgi/queues.py       |  4 +--
 4 files changed, 74 insertions(+), 23 deletions(-)

diff --git a/marconi/storage/mongodb/controllers.py b/marconi/storage/mongodb/controllers.py
index ff9c17ea5..5d943ab92 100644
--- a/marconi/storage/mongodb/controllers.py
+++ b/marconi/storage/mongodb/controllers.py
@@ -55,12 +55,30 @@ class QueueController(storage.QueueBase):
         # as specific tenant, for example. Order Matters!
         self._col.ensure_index([("t", 1), ("n", 1)], unique=True)
 
-    def list(self, tenant=None):
-        cursor = self._col.find({"t": tenant}, fields=dict(n=1, m=1, _id=0))
-        for queue in cursor:
-            queue["name"] = queue.pop("n")
-            queue["metadata"] = queue.pop("m", {})
-            yield queue
+    def list(self, tenant=None, marker=None,
+             limit=10, detailed=False):
+        query = {"t": tenant}
+        if marker:
+            query["n"] = {"$gt": marker}
+
+        fields = {"n": 1, "_id": 0}
+        if detailed:
+            fields["m"] = 1
+
+        cursor = self._col.find(query, fields=fields)
+        cursor = cursor.limit(limit).sort("n")
+        marker_name = {}
+
+        def normalizer(records):
+            for rec in records:
+                queue = {"name": rec["n"]}
+                marker_name["next"] = queue["name"]
+                if detailed:
+                    queue["metadata"] = rec["m"]
+                yield queue
+
+        yield normalizer(cursor)
+        yield marker_name["next"]
 
     def _get(self, name, tenant=None, fields={"m": 1, "_id": 0}):
         queue = self._col.find_one({"t": tenant, "n": name}, fields=fields)
diff --git a/marconi/storage/sqlite/controllers.py b/marconi/storage/sqlite/controllers.py
index cbefd5327..aa82c8099 100644
--- a/marconi/storage/sqlite/controllers.py
+++ b/marconi/storage/sqlite/controllers.py
@@ -34,13 +34,38 @@ class Queue(base.QueueBase):
             )
         ''')
 
-    def list(self, tenant):
-        records = self.driver.run('''
-            select name, metadata from Queues
-             where tenant = ?''', tenant)
+    def list(self, tenant, marker=None,
+             limit=10, detailed=False):
+        sql = (('''
+            select name from Queues''' if not detailed
+                else '''
+            select name, metadata from Queues''') +
+               '''
+             where tenant = ?''')
+        args = [tenant]
 
-        for k, v in records:
-            yield {'name': k, 'metadata': v}
+        if marker:
+            sql += '''
+               and name > ?'''
+            args += [marker]
+
+        sql += '''
+             order by name
+             limit ?'''
+        args += [limit]
+
+        records = self.driver.run(sql, *args)
+        marker_name = {}
+
+        def it():
+            for rec in records:
+                marker_name['next'] = rec[0]
+                yield ({'name': rec[0]} if not detailed
+                       else
+                       {'name': rec[0], 'metadata': rec[1]})
+
+        yield it()
+        yield marker_name['next']
 
     def get(self, name, tenant):
         try:
diff --git a/marconi/tests/storage/base.py b/marconi/tests/storage/base.py
index f7a54712e..64eb4872f 100644
--- a/marconi/tests/storage/base.py
+++ b/marconi/tests/storage/base.py
@@ -50,19 +50,27 @@ class QueueControllerTest(ControllerBaseTest):
         self.claim_controller = self.driver.claim_controller
 
     def test_list(self):
-        num = 4
+        num = 15
         for queue in xrange(num):
             self.controller.upsert(queue, {}, tenant=self.tenant)
 
-        queues = self.controller.list(tenant=self.tenant)
+        interaction = self.controller.list(tenant=self.tenant,
+                                           detailed=True)
+        queues = list(interaction.next())
 
-        counter = 0
-        for queue in queues:
-            self.assertEqual(len(queue), 2)
-            self.assertIn("name", queue)
-            self.assertIn("metadata", queue)
-            counter += 1
-        self.assertEqual(counter, num)
+        self.assertEquals(all(map(lambda queue:
+                                  'name' in queue and
+                                  'metadata' in queue, queues)), True)
+        self.assertEquals(len(queues), 10)
+
+        interaction = self.controller.list(tenant=self.tenant,
+                                           marker=interaction.next())
+        queues = list(interaction.next())
+
+        self.assertEquals(all(map(lambda queue:
+                                  'name' in queue and
+                                  'metadata' not in queue, queues)), True)
+        self.assertEquals(len(queues), 5)
 
     def test_queue_lifecycle(self):
         # Test Queue Creation
diff --git a/marconi/transport/wsgi/queues.py b/marconi/transport/wsgi/queues.py
index 931e5d6cd..a36bcbc5a 100644
--- a/marconi/transport/wsgi/queues.py
+++ b/marconi/transport/wsgi/queues.py
@@ -100,9 +100,9 @@ class CollectionResource(object):
     def on_get(self, req, resp, tenant_id):
         resp_dict = {}
         try:
-            queues = self.queue_ctrl.list(tenant_id)
+            interaction = self.queue_ctrl.list(tenant_id, detailed=True)
 
-            resp_dict['queues'] = list(queues)
+            resp_dict['queues'] = list(interaction.next())
             for queue in resp_dict['queues']:
                 queue['href'] = req.path + '/' + queue['name']