Merge pull request #11088 from edx/ormsbee/seq_new_relic_tagging

Add New Relic instrumentation to SequenceModule.

common/lib/xmodule/xmodule/seq_module.py

@@ -3,7 +3,7 @@ xModule implementation of a learning sequence
 """
 
 # pylint: disable=abstract-method
-
+import collections
 import json
 import logging
 from pkg_resources import resource_string
@@ -13,6 +13,7 @@ from lxml import etree
 from xblock.core import XBlock
 from xblock.fields import Integer, Scope, Boolean, String
 from xblock.fragment import Fragment
+import newrelic.agent
 
 from .exceptions import NotFoundError
 from .fields import Date
@@ -191,6 +192,11 @@ class SequenceModule(SequenceFields, ProctoringFields, XModule):
         context["username"] = self.runtime.service(self, "user").get_current_user().opt_attrs['edx-platform.username']
 
         display_names = [self.get_parent().display_name or '', self.display_name or '']
+
+        # We do this up here because proctored exam functionality could bypass
+        # rendering after this section.
+        self._capture_basic_metrics()
+
         # Is this sequential part of a timed or proctored exam?
         if self.is_time_limited:
             view_html = self._time_limited_student_view(context)
@@ -201,7 +207,8 @@ class SequenceModule(SequenceFields, ProctoringFields, XModule):
                 fragment.add_content(view_html)
                 return fragment
 
-        for child in self.get_display_items():
+        display_items = self.get_display_items()
+        for child in display_items:
             is_bookmarked = bookmarks_service.is_bookmarked(usage_key=child.scope_ids.usage_id)
             context["bookmarked"] = is_bookmarked
 
@@ -238,8 +245,78 @@ class SequenceModule(SequenceFields, ProctoringFields, XModule):
 
         fragment.add_content(self.system.render_template("seq_module.html", params))
 
+        self._capture_full_seq_item_metrics(display_items)
+        self._capture_current_unit_metrics(display_items)
+
+        # Get all descendant XBlock types and counts
         return fragment
 
+    def _locations_in_subtree(self, node):
+        """
+        The usage keys for all descendants of an XBlock/XModule as a flat list.
+
+        Includes the location of the node passed in.
+        """
+        stack = [node]
+        locations = []
+
+        while stack:
+            curr = stack.pop()
+            locations.append(curr.location)
+            if curr.has_children:
+                stack.extend(curr.get_children())
+
+        return locations
+
+    def _capture_basic_metrics(self):
+        """
+        Capture basic information about this sequence in New Relic.
+        """
+        newrelic.agent.add_custom_parameter('seq.block_id', unicode(self.location))
+        newrelic.agent.add_custom_parameter('seq.display_name', self.display_name or '')
+        newrelic.agent.add_custom_parameter('seq.position', self.position)
+        newrelic.agent.add_custom_parameter('seq.is_time_limited', self.is_time_limited)
+
+    def _capture_full_seq_item_metrics(self, display_items):
+        """
+        Capture information about the number and types of XBlock content in
+        the sequence as a whole. We send this information to New Relic so that
+        we can do better performance analysis of courseware.
+        """
+        # Basic count of the number of Units (a.k.a. VerticalBlocks) we have in
+        # this learning sequence
+        newrelic.agent.add_custom_parameter('seq.num_units', len(display_items))
+
+        # Count of all modules (leaf nodes) in this sequence (e.g. videos,
+        # problems, etc.) The units (verticals) themselves are not counted.
+        all_item_keys = self._locations_in_subtree(self)
+        newrelic.agent.add_custom_parameter('seq.num_items', len(all_item_keys))
+
+        # Count of all modules by block_type (e.g. "video": 2, "discussion": 4)
+        block_counts = collections.Counter(usage_key.block_type for usage_key in all_item_keys)
+        for block_type, count in block_counts.items():
+            newrelic.agent.add_custom_parameter('seq.block_counts.{}'.format(block_type), count)
+
+    def _capture_current_unit_metrics(self, display_items):
+        """
+        Capture information about the current selected Unit within the Sequence.
+        """
+        # Positions are stored with indexing starting at 1. If we get into a
+        # weird state where the saved position is out of bounds (e.g. the
+        # content was changed), avoid going into any details about this unit.
+        if 1 <= self.position <= len(display_items):
+            # Basic info about the Unit...
+            current = display_items[self.position - 1]
+            newrelic.agent.add_custom_parameter('seq.current.block_id', unicode(current.location))
+            newrelic.agent.add_custom_parameter('seq.current.display_name', current.display_name or '')
+
+            # Examining all items inside the Unit (or split_test, conditional, etc.)
+            child_locs = self._locations_in_subtree(current)
+            newrelic.agent.add_custom_parameter('seq.current.num_items', len(child_locs))
+            curr_block_counts = collections.Counter(usage_key.block_type for usage_key in child_locs)
+            for block_type, count in curr_block_counts.items():
+                newrelic.agent.add_custom_parameter('seq.current.block_counts.{}'.format(block_type), count)
+
     def _time_limited_student_view(self, context):
         """
         Delegated rendering of a student view when in a time