Implement course-wide asset paging methods.

Add SortedCollection class to help sort lists efficiently.
https://openedx.atlassian.net/browse/PLAT-74

common/lib/xmodule/xmodule/assetstore/__init__.py

@@ -5,6 +5,7 @@ Classes representing asset & asset thumbnail metadata.
 from datetime import datetime
 import pytz
 from contracts import contract, new_contract
+from bisect import bisect_left, bisect_right
 from opaque_keys.edx.keys import CourseKey, AssetKey
 
 new_contract('AssetKey', AssetKey)
@@ -33,8 +34,8 @@ class AssetMetadata(object):
     # All AssetMetadata objects should have AssetLocators with this type.
     ASSET_TYPE = 'asset'
 
-    @contract(asset_id='AssetKey', basename='basestring | None', internal_name='str | None', locked='bool | None', contenttype='basestring | None',
-              md5='str | None', curr_version='str | None', prev_version='str | None', edited_by='int | None', edited_on='datetime | None')
+    @contract(asset_id='AssetKey', basename='basestring|None', internal_name='basestring|None', locked='bool|None', contenttype='basestring|None',
+              md5='basestring|None', curr_version='basestring|None', prev_version='basestring|None', edited_by='int|None', edited_on='datetime|None')
     def __init__(self, asset_id,
                  basename=None, internal_name=None,
                  locked=None, contenttype=None, md5=None,
@@ -99,12 +100,10 @@ class AssetMetadata(object):
             'locked': self.locked,
             'contenttype': self.contenttype,
             'md5': self.md5,
-            'edit_info': {
-                'curr_version': self.curr_version,
-                'prev_version': self.prev_version,
-                'edited_by': self.edited_by,
-                'edited_on': self.edited_on
-            }
+            'curr_version': self.curr_version,
+            'prev_version': self.prev_version,
+            'edited_by': self.edited_by,
+            'edited_on': self.edited_on
         }
 
     @contract(asset_doc='dict | None')
@@ -121,11 +120,10 @@ class AssetMetadata(object):
         self.locked = asset_doc['locked']
         self.contenttype = asset_doc['contenttype']
         self.md5 = asset_doc['md5']
-        edit_info = asset_doc['edit_info']
-        self.curr_version = edit_info['curr_version']
-        self.prev_version = edit_info['prev_version']
-        self.edited_by = edit_info['edited_by']
-        self.edited_on = edit_info['edited_on']
+        self.curr_version = asset_doc['curr_version']
+        self.prev_version = asset_doc['prev_version']
+        self.edited_by = asset_doc['edited_by']
+        self.edited_on = asset_doc['edited_on']
 
 
 class AssetThumbnailMetadata(object):

common/lib/xmodule/xmodule/modulestore/__init__.py

@@ -14,6 +14,8 @@ import collections
 from contextlib import contextmanager
 import functools
 import threading
+from operator import itemgetter
+from sortedcontainers import SortedListWithKey
 
 from abc import ABCMeta, abstractmethod
 from contracts import contract, new_contract
@@ -292,19 +294,23 @@ class ModuleStoreAssetInterface(object):
         if course_assets is None:
             return None, None
 
-        if get_thumbnail:
-            all_assets = course_assets['thumbnails']
-        else:
-            all_assets = course_assets['assets']
+        info = 'thumbnails' if get_thumbnail else 'assets'
+        all_assets = SortedListWithKey([], key=itemgetter('filename'))
+        # Assets should be pre-sorted, so add them efficiently without sorting.
+        # extend() will raise a ValueError if the passed-in list is not sorted.
+        all_assets.extend(course_assets.get(info, []))
 
         # See if this asset already exists by checking the external_filename.
         # Studio doesn't currently support using multiple course assets with the same filename.
         # So use the filename as the unique identifier.
-        for idx, asset in enumerate(all_assets):
-            if asset['filename'] == filename:
-                return course_assets, idx
+        idx = None
+        idx_left = all_assets.bisect_left({'filename': filename})
+        idx_right = all_assets.bisect_right({'filename': filename})
+        if idx_left != idx_right:
+            # Asset was found in the list.
+            idx = idx_left
 
-        return course_assets, None
+        return course_assets, idx
 
     @contract(asset_key='AssetKey')
     def _find_asset_info(self, asset_key, thumbnail=False, **kwargs):
@@ -358,14 +364,14 @@ class ModuleStoreAssetInterface(object):
         """
         return self._find_asset_info(asset_key, thumbnail=True, **kwargs)
 
-    @contract(course_key='CourseKey', start='int | None', maxresults='int | None', sort='list | None', get_thumbnails='bool')
+    @contract(course_key='CourseKey', start='int|None', maxresults='int|None', sort='tuple(str,str)|None', get_thumbnails='bool')
     def _get_all_asset_metadata(self, course_key, start=0, maxresults=-1, sort=None, get_thumbnails=False, **kwargs):
         """
         Returns a list of static asset (or thumbnail) metadata for a course.
 
         Args:
             course_key (CourseKey): course identifier
-            start (int): optional - start at this asset number
+            start (int): optional - start at this asset number. Zero-based!
             maxresults (int): optional - return at most this many, -1 means no limit
             sort (array): optional - None means no sort
                 (sort_by (str), sort_order (str))
@@ -382,35 +388,60 @@ class ModuleStoreAssetInterface(object):
             # to distinguish zero assets from "not able to retrieve assets".
             return None
 
-        if get_thumbnails:
-            all_assets = course_assets.get('thumbnails', [])
-        else:
-            all_assets = course_assets.get('assets', [])
-
-        # DO_NEXT: Add start/maxresults/sort functionality as part of https://openedx.atlassian.net/browse/PLAT-74
-        if start and maxresults and sort:
-            pass
+        # Determine the proper sort - with defaults of ('displayname', 'ascending').
+        sort_field = 'filename'
+        sort_order = 'ascending'
+        if sort:
+            if sort[0] == 'uploadDate':
+                sort_field = 'edited_on'
+            if sort[1] == 'descending':
+                sort_order = 'descending'
+
+        info = 'thumbnails' if get_thumbnails else 'assets'
+        all_assets = SortedListWithKey(course_assets.get(info, []), key=itemgetter(sort_field))
+        num_assets = len(all_assets)
+
+        start_idx = start
+        end_idx = min(num_assets, start + maxresults)
+        if maxresults < 0:
+            # No limit on the results.
+            end_idx = num_assets
+
+        step_incr = 1
+        if sort_order == 'descending':
+            # Flip the indices and iterate backwards.
+            step_incr = -1
+            start_idx = (num_assets - 1) - start_idx
+            end_idx = (num_assets - 1) - end_idx
 
         ret_assets = []
-        for asset in all_assets:
+        for idx in range(start_idx, end_idx, step_incr):
+            asset = all_assets[idx]
             if get_thumbnails:
                 thumb = AssetThumbnailMetadata(
                     course_key.make_asset_key('thumbnail', asset['filename']),
-                    internal_name=asset['filename'], **kwargs
+                    internal_name=asset['filename'],
+                    **kwargs
                 )
                 ret_assets.append(thumb)
             else:
-                asset = AssetMetadata(
+                new_asset = AssetMetadata(
                     course_key.make_asset_key('asset', asset['filename']),
                     basename=asset['filename'],
-                    edited_on=asset['edit_info']['edited_on'],
+                    internal_name=asset['internal_name'],
+                    locked=asset['locked'],
                     contenttype=asset['contenttype'],
-                    md5=str(asset['md5']), **kwargs
+                    md5=asset['md5'],
+                    curr_version=asset['curr_version'],
+                    prev_version=asset['prev_version'],
+                    edited_on=asset['edited_on'],
+                    edited_by=asset['edited_by'],
+                    **kwargs
                 )
-                ret_assets.append(asset)
+                ret_assets.append(new_asset)
         return ret_assets
 
-    @contract(course_key='CourseKey', start='int | None', maxresults='int | None', sort='list | None')
+    @contract(course_key='CourseKey', start='int|None', maxresults='int|None', sort='tuple(str,str)|None')
     def get_all_asset_metadata(self, course_key, start=0, maxresults=-1, sort=None, **kwargs):
         """
         Returns a list of static assets for a course.

common/lib/xmodule/xmodule/modulestore/mixed.py

@@ -370,7 +370,7 @@ class MixedModuleStore(ModuleStoreDraftAndPublished, ModuleStoreWriteBase):
         return store.find_asset_thumbnail_metadata(asset_key, **kwargs)
 
     @strip_key
-    @contract(course_key='CourseKey', start=int, maxresults=int, sort='list | None')
+    @contract(course_key='CourseKey', start=int, maxresults=int, sort='tuple|None')
     def get_all_asset_metadata(self, course_key, start=0, maxresults=-1, sort=None, **kwargs):
         """
         Returns a list of static assets for a course.

common/lib/xmodule/xmodule/modulestore/mongo/base.py

@@ -25,6 +25,8 @@ from path import path
 from datetime import datetime
 from pytz import UTC
 from contracts import contract, new_contract
+from operator import itemgetter
+from sortedcontainers import SortedListWithKey
 
 from importlib import import_module
 from xmodule.errortracker import null_error_tracker, exc_info_to_str
@@ -1493,7 +1495,10 @@ class MongoModuleStore(ModuleStoreDraftAndPublished, ModuleStoreWriteBase, Mongo
 
         course_assets, asset_idx = self._find_course_asset(course_key, asset_metadata.asset_id.path, thumbnail)
         info = 'thumbnails' if thumbnail else 'assets'
-        all_assets = course_assets[info]
+        all_assets = SortedListWithKey([], key=itemgetter('filename'))
+        # Assets should be pre-sorted, so add them efficiently without sorting.
+        # extend() will raise a ValueError if the passed-in list is not sorted.
+        all_assets.extend(course_assets[info])
 
         # Set the edited information for assets only - not thumbnails.
         if not thumbnail:
@@ -1502,15 +1507,15 @@ class MongoModuleStore(ModuleStoreDraftAndPublished, ModuleStoreWriteBase, Mongo
         # Translate metadata to Mongo format.
         metadata_to_insert = asset_metadata.to_mongo()
         if asset_idx is None:
-            # Append new metadata.
-            # Future optimization: Insert in order & binary search to retrieve.
-            all_assets.append(metadata_to_insert)
+            # Add new metadata sorted into the list.
+            all_assets.add(metadata_to_insert)
         else:
             # Replace existing metadata.
-            all_assets[asset_idx] = metadata_to_insert
+            all_assets.pop(asset_idx)
+            all_assets.insert(asset_idx, metadata_to_insert)
 
         # Update the document.
-        self.asset_collection.update({'_id': course_assets['_id']}, {'$set': {info: all_assets}})
+        self.asset_collection.update({'_id': course_assets['_id']}, {'$set': {info: all_assets.as_list()}})
         return True
 
     @contract(asset_key='AssetKey', attr_dict=dict)

common/lib/xmodule/xmodule/modulestore/tests/test_assetstore.py

@@ -6,6 +6,7 @@ from datetime import datetime, timedelta
 import pytz
 import unittest
 import ddt
+from time import sleep
 
 from xmodule.assetstore import AssetMetadata, AssetThumbnailMetadata
 from xmodule.modulestore import ModuleStoreEnum
@@ -79,12 +80,23 @@ class TestMongoAssetMetadataStorage(unittest.TestCase):
         asset6_vals = ('asset.txt', 'JJJCCC747858', '/dev/null', False, ModuleStoreEnum.UserID.test * 4, datetime.now(pytz.utc), '50', '49')
         asset6 = dict(zip(asset_fields[1:], asset6_vals[1:]))
 
+        # More assets.
+        asset7_vals = ('roman_history.pdf', 'JASDUNSADK', 'texts/italy', True, ModuleStoreEnum.UserID.test * 7, datetime.now(pytz.utc), '1.1', '1.01')
+        asset8_vals = ('weather_patterns.bmp', '928SJXX2EB', 'science', False, ModuleStoreEnum.UserID.test * 8, datetime.now(pytz.utc), '52', '51')
+        asset9_vals = ('demo.swf', 'DFDFGGGG14', 'demos/easy', False, ModuleStoreEnum.UserID.test * 9, datetime.now(pytz.utc), '5', '4')
+        asset7 = dict(zip(asset_fields[1:], asset7_vals[1:]))
+        asset8 = dict(zip(asset_fields[1:], asset8_vals[1:]))
+        asset9 = dict(zip(asset_fields[1:], asset9_vals[1:]))
+
         asset1_key = course1_key.make_asset_key('asset', asset1_vals[0])
         asset2_key = course1_key.make_asset_key('asset', asset2_vals[0])
         asset3_key = course2_key.make_asset_key('asset', asset3_vals[0])
         asset4_key = course2_key.make_asset_key('asset', asset4_vals[0])
         asset5_key = course2_key.make_asset_key('asset', asset5_vals[0])
         asset6_key = course2_key.make_asset_key('asset', asset6_vals[0])
+        asset7_key = course2_key.make_asset_key('asset', asset7_vals[0])
+        asset8_key = course2_key.make_asset_key('asset', asset8_vals[0])
+        asset9_key = course2_key.make_asset_key('asset', asset9_vals[0])
 
         asset1_md = AssetMetadata(asset1_key, **asset1)
         asset2_md = AssetMetadata(asset2_key, **asset2)
@@ -92,13 +104,26 @@ class TestMongoAssetMetadataStorage(unittest.TestCase):
         asset4_md = AssetMetadata(asset4_key, **asset4)
         asset5_md = AssetMetadata(asset5_key, **non_existent_asset)
         asset6_md = AssetMetadata(asset6_key, **asset6)
+        asset7_md = AssetMetadata(asset7_key, **asset7)
+        asset8_md = AssetMetadata(asset8_key, **asset8)
+        asset9_md = AssetMetadata(asset9_key, **asset9)
 
         if store is not None:
+            # Sleeps are to ensure that edited_on order is correct.
             store.save_asset_metadata(course1_key, asset1_md, ModuleStoreEnum.UserID.test)
-            store.save_asset_metadata(course1_key, asset2_md, ModuleStoreEnum.UserID.test)
-            store.save_asset_metadata(course2_key, asset3_md, ModuleStoreEnum.UserID.test)
-            store.save_asset_metadata(course2_key, asset4_md, ModuleStoreEnum.UserID.test)
+            sleep(0.0001)
+            store.save_asset_metadata(course1_key, asset2_md, ModuleStoreEnum.UserID.test * 2)
+            sleep(0.0001)
+            store.save_asset_metadata(course2_key, asset3_md, ModuleStoreEnum.UserID.test * 3)
+            sleep(0.0001)
+            store.save_asset_metadata(course2_key, asset4_md, ModuleStoreEnum.UserID.test * 4)
+            sleep(0.0001)
             # 5 & 6 are not saved on purpose!
+            store.save_asset_metadata(course2_key, asset7_md, ModuleStoreEnum.UserID.test * 7)
+            sleep(0.0001)
+            store.save_asset_metadata(course2_key, asset8_md, ModuleStoreEnum.UserID.test * 8)
+            sleep(0.0001)
+            store.save_asset_metadata(course2_key, asset9_md, ModuleStoreEnum.UserID.test * 9)
 
         return (asset1_md, asset2_md, asset3_md, asset4_md, asset5_md, asset6_md)
 
@@ -387,8 +412,67 @@ class TestMongoAssetMetadataStorage(unittest.TestCase):
                 store.delete_all_asset_metadata(course.id, ModuleStoreEnum.UserID.test)
                 self.assertEquals(len(store.get_all_asset_thumbnail_metadata(course.id)), 0)
 
-    def test_get_all_assets_with_paging(self):
-        pass
+    @ddt.data(*MODULESTORE_SETUPS)
+    def test_get_all_assets_with_paging(self, storebuilder):
+        """
+        Save multiple metadata in each store and retrieve it singularly, as all assets, and after deleting all.
+        """
+        # Temporarily only perform this test for Old Mongo - not Split.
+        if not isinstance(storebuilder, MongoModulestoreBuilder):
+            raise unittest.SkipTest
+        with MongoContentstoreBuilder().build() as contentstore:
+            with storebuilder.build(contentstore) as store:
+                course1 = CourseFactory.create(modulestore=store)
+                course2 = CourseFactory.create(modulestore=store)
+                self.setup_assets(course1.id, course2.id, store)
+
+                expected_sorts_by_2 = (
+                    (
+                        ('displayname', 'ascending'),
+                        ('code.tgz', 'demo.swf', 'dog.png', 'roman_history.pdf', 'weather_patterns.bmp'),
+                        (2, 2, 1)
+                    ),
+                    (
+                        ('displayname', 'descending'),
+                        ('weather_patterns.bmp', 'roman_history.pdf', 'dog.png', 'demo.swf', 'code.tgz'),
+                        (2, 2, 1)
+                    ),
+                    (
+                        ('uploadDate', 'ascending'),
+                        ('code.tgz', 'dog.png', 'roman_history.pdf', 'weather_patterns.bmp', 'demo.swf'),
+                        (2, 2, 1)
+                    ),
+                    (
+                        ('uploadDate', 'descending'),
+                        ('demo.swf', 'weather_patterns.bmp', 'roman_history.pdf', 'dog.png', 'code.tgz'),
+                        (2, 2, 1)
+                    ),
+                )
+                # First, with paging across all sorts.
+                for sort_test in expected_sorts_by_2:
+                    for i in xrange(3):
+                        asset_page = store.get_all_asset_metadata(course2.id, start=2 * i, maxresults=2, sort=sort_test[0])
+                        self.assertEquals(len(asset_page), sort_test[2][i])
+                        self.assertEquals(asset_page[0].asset_id.path, sort_test[1][2 * i])
+                        if sort_test[2][i] == 2:
+                            self.assertEquals(asset_page[1].asset_id.path, sort_test[1][(2 * i) + 1])
+
+                # Now fetch everything.
+                asset_page = store.get_all_asset_metadata(course2.id, start=0, sort=('displayname', 'ascending'))
+                self.assertEquals(len(asset_page), 5)
+                self.assertEquals(asset_page[0].asset_id.path, 'code.tgz')
+                self.assertEquals(asset_page[1].asset_id.path, 'demo.swf')
+                self.assertEquals(asset_page[2].asset_id.path, 'dog.png')
+                self.assertEquals(asset_page[3].asset_id.path, 'roman_history.pdf')
+                self.assertEquals(asset_page[4].asset_id.path, 'weather_patterns.bmp')
+
+                # Some odd conditions.
+                asset_page = store.get_all_asset_metadata(course2.id, start=100, sort=('displayname', 'ascending'))
+                self.assertEquals(len(asset_page), 0)
+                asset_page = store.get_all_asset_metadata(course2.id, start=3, maxresults=0, sort=('displayname', 'ascending'))
+                self.assertEquals(len(asset_page), 0)
+                asset_page = store.get_all_asset_metadata(course2.id, start=3, maxresults=-12345, sort=('displayname', 'descending'))
+                self.assertEquals(len(asset_page), 2)
 
     def test_copy_all_assets(self):
         pass

docs/shared/requirements.txt

@@ -56,6 +56,7 @@ PyYAML==3.10
 requests==2.3.0
 Shapely==1.2.16
 sorl-thumbnail==11.12
+sortedcontainers==0.9.2
 South==0.7.6
 sympy==0.7.1
 xmltodict==0.4.1