[#11585] Fix unnecessary data read in expected submission count

src/main/java/teammates/logic/core/FeedbackQuestionsLogic.java

@@ -122,6 +122,31 @@ public List<FeedbackQuestionAttributes> getFeedbackQuestionsForSession(
         return questions;
     }
 
+    /**
+     * Gets the number of questions for student to answer from a map of giver type to question counts.
+     */
+    public int getFeedbackQuestionForStudentCountFrom(Map<FeedbackParticipantType, Integer> giverTypeCounts) {
+        return giverTypeCounts.getOrDefault(FeedbackParticipantType.STUDENTS, 0)
+                + giverTypeCounts.getOrDefault(FeedbackParticipantType.TEAMS, 0);
+    }
+
+    /**
+     * Gets the number of questions for instructor to answer from a map of giver type to question counts.
+     */
+    public int getFeedbackQuestionForInstructorCountFrom(
+            Map<FeedbackParticipantType, Integer> giverTypeCounts, boolean isCreator) {
+        return giverTypeCounts.getOrDefault(FeedbackParticipantType.INSTRUCTORS, 0)
+                + (isCreator ? giverTypeCounts.getOrDefault(FeedbackParticipantType.SELF, 0) : 0);
+    }
+
+    /**
+     * Gets a {@link Map} of FeedbackQuestion giver types to count in the given session.
+     */
+    public Map<FeedbackParticipantType, Integer> getFeedbackQuestionGiverCountForSession(
+            String feedbackSessionName, String courseId) {
+        return fqDb.getFeedbackQuestionGiverTypeCountForSession(feedbackSessionName, courseId);
+    }
+
     // TODO can be removed once we are sure that question numbers will be consistent
     private boolean areQuestionNumbersConsistent(List<FeedbackQuestionAttributes> questions) {
         Set<Integer> questionNumbersInSession = new HashSet<>();

src/main/java/teammates/logic/core/FeedbackSessionsLogic.java

@@ -3,14 +3,14 @@
 import java.time.Instant;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 import java.util.stream.Collectors;
 
 import teammates.common.datatransfer.AttributesDeletionQuery;
 import teammates.common.datatransfer.FeedbackParticipantType;
 import teammates.common.datatransfer.attributes.FeedbackQuestionAttributes;
 import teammates.common.datatransfer.attributes.FeedbackSessionAttributes;
 import teammates.common.datatransfer.attributes.InstructorAttributes;
-import teammates.common.datatransfer.attributes.StudentAttributes;
 import teammates.common.exception.EntityAlreadyExistsException;
 import teammates.common.exception.EntityDoesNotExistException;
 import teammates.common.exception.InvalidParametersException;
@@ -492,22 +492,18 @@ public void restoreFeedbackSessionFromRecycleBin(String feedbackSessionName, Str
      * Gets the expected number of submissions for a feedback session.
      */
     public int getExpectedTotalSubmission(FeedbackSessionAttributes fsa) {
-        List<StudentAttributes> students = studentsLogic.getStudentsForCourse(fsa.getCourseId());
-        List<InstructorAttributes> instructors = instructorsLogic.getInstructorsForCourse(fsa.getCourseId());
-        List<FeedbackQuestionAttributes> questions =
-                fqLogic.getFeedbackQuestionsForSession(fsa.getFeedbackSessionName(), fsa.getCourseId());
-        List<FeedbackQuestionAttributes> studentQns = fqLogic.getFeedbackQuestionsForStudents(questions);
+        int numOfStudents = studentsLogic.getNumberOfStudentsForCourse(fsa.getCourseId());
+        List<String> instructorEmails = instructorsLogic.getInstructorEmailsForCourse(fsa.getCourseId());
+        Map<FeedbackParticipantType, Integer> giverTypeCounts = fqLogic.getFeedbackQuestionGiverCountForSession(
+                fsa.getFeedbackSessionName(), fsa.getCourseId());
 
         int expectedTotal = 0;
-
-        if (!studentQns.isEmpty()) {
-            expectedTotal += students.size();
+        if (fqLogic.getFeedbackQuestionForStudentCountFrom(giverTypeCounts) > 0) {
+            expectedTotal += numOfStudents;
         }
 
-        for (InstructorAttributes instructor : instructors) {
-            List<FeedbackQuestionAttributes> instructorQns =
-                    fqLogic.getFeedbackQuestionsForInstructors(questions, fsa.isCreator(instructor.getEmail()));
-            if (!instructorQns.isEmpty()) {
+        for (String instructorEmail : instructorEmails) {
+            if (fqLogic.getFeedbackQuestionForInstructorCountFrom(giverTypeCounts, fsa.isCreator(instructorEmail)) > 0) {
                 expectedTotal += 1;
             }
         }

src/main/java/teammates/logic/core/InstructorsLogic.java

@@ -1,6 +1,7 @@
 package teammates.logic.core;
 
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.List;
 
 import teammates.common.datatransfer.AttributesDeletionQuery;
@@ -122,6 +123,16 @@ public InstructorAttributes getInstructorForRegistrationKey(String registrationK
         return instructorsDb.getInstructorForRegistrationKey(registrationKey);
     }
 
+    /**
+     * Gets emails of all instructors of a course.
+     */
+    public List<String> getInstructorEmailsForCourse(String courseId) {
+        List<String> instructorEmails = instructorsDb.getInstructorEmailsForCourse(courseId);
+        instructorEmails.sort(Comparator.naturalOrder());
+
+        return instructorEmails;
+    }
+
     /**
      * Gets all instructors of a course.
      */

src/main/java/teammates/logic/core/StudentsLogic.java

@@ -98,6 +98,13 @@ public List<StudentAttributes> getStudentsForGoogleId(String googleId) {
         return studentsDb.getStudentsForGoogleId(googleId);
     }
 
+    /**
+     * Gets the total number of students of a course.
+     */
+    public int getNumberOfStudentsForCourse(String courseId) {
+        return studentsDb.getNumberOfStudentsForCourse(courseId);
+    }
+
     /**
      * Gets all students of a course.
      */

src/main/java/teammates/storage/api/FeedbackQuestionsDb.java

@@ -3,6 +3,8 @@
 import static com.googlecode.objectify.ObjectifyService.ofy;
 
 import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
 
 import com.googlecode.objectify.cmd.LoadType;
 import com.googlecode.objectify.cmd.Query;
@@ -52,6 +54,22 @@ public FeedbackQuestionAttributes getFeedbackQuestion(
         return makeAttributesOrNull(getFeedbackQuestionEntity(feedbackSessionName, courseId, questionNumber));
     }
 
+    /**
+     * Gets feedback question count grouped by giver types of a session.
+     */
+    public Map<FeedbackParticipantType, Integer> getFeedbackQuestionGiverTypeCountForSession(
+            String feedbackSessionName, String courseId) {
+        assert feedbackSessionName != null;
+        assert courseId != null;
+
+        return load()
+                .filter("feedbackSessionName =", feedbackSessionName)
+                .filter("courseId =", courseId)
+                .list()
+                .stream()
+                .collect(Collectors.groupingBy(FeedbackQuestion::getGiverType, Collectors.summingInt(x -> 1)));
+    }
+
     /**
      * Gets all feedback questions of a session.
      */

src/main/java/teammates/storage/api/InstructorsDb.java

@@ -146,6 +146,21 @@ public List<InstructorAttributes> getInstructorsForGoogleId(String googleId, boo
         return makeAttributes(getInstructorEntitiesForGoogleId(googleId, omitArchived));
     }
 
+    /**
+     * Gets the emails of all instructors of a course.
+     */
+    public List<String> getInstructorEmailsForCourse(String courseId) {
+        assert courseId != null;
+
+        return load()
+                .filter("courseId =", courseId)
+                .project("email")
+                .list()
+                .stream()
+                .map(Instructor::getEmail)
+                .collect(Collectors.toList());
+    }
+
     /**
      * Gets all instructors of a course.
      */

src/main/java/teammates/storage/api/StudentsDb.java

@@ -166,6 +166,15 @@ public List<StudentAttributes> getStudentsForGoogleId(String googleId) {
         return makeAttributes(getCourseStudentEntitiesForGoogleId(googleId));
     }
 
+    /**
+     * Gets the total number of students of a course.
+     */
+    public int getNumberOfStudentsForCourse(String courseId) {
+        assert courseId != null;
+
+        return getCourseStudentsForCourseQuery(courseId).count();
+    }
+
     /**
      * Gets all students of a course.
      */

src/test/java/teammates/logic/core/FeedbackQuestionsLogicTest.java

@@ -77,6 +77,7 @@ public void testDeleteFeedbackQuestions_byCourseIdAndSessionName_shouldDeleteQue
 
     @Test
     public void allTests() throws Exception {
+        testGetFeedbackQuestionGiverCount();
         testHasFeedbackQuestionsForInstructor();
         testGetFeedbackQuestionsForInstructor();
         testHasFeedbackQuestionsForStudents();
@@ -907,6 +908,41 @@ public void testBuildCompleteGiverRecipientMap_teamQuestion_shouldBuildMapCorrec
         assertTrue(completeGiverRecipientMap.get("Team 1.2").contains("Team 1.1</td></div>'\""));
     }
 
+    private void testGetFeedbackQuestionGiverCount() {
+        ______TS("Valid session valid course should give correct counts");
+        Map<FeedbackParticipantType, Integer> giverTypeCounts = fqLogic.getFeedbackQuestionGiverCountForSession(
+                "First feedback session", "idOfTypicalCourse1");
+        int studentTypeCount = giverTypeCounts.get(FeedbackParticipantType.STUDENTS);
+        int instructorTypeCount = giverTypeCounts.get(FeedbackParticipantType.INSTRUCTORS);
+        int selfTypeCount = giverTypeCounts.get(FeedbackParticipantType.SELF);
+        assertEquals(2, studentTypeCount);
+        assertEquals(1, instructorTypeCount);
+        assertEquals(2, selfTypeCount);
+
+        assertEquals(studentTypeCount, fqLogic.getFeedbackQuestionForStudentCountFrom(giverTypeCounts));
+
+        assertEquals(instructorTypeCount,
+                fqLogic.getFeedbackQuestionForInstructorCountFrom(giverTypeCounts, false));
+        assertEquals(instructorTypeCount + selfTypeCount,
+                fqLogic.getFeedbackQuestionForInstructorCountFrom(giverTypeCounts, true));
+
+        ______TS("Invalid session valid course should give no count");
+        giverTypeCounts = fqLogic.getFeedbackQuestionGiverCountForSession("invalid session", "idOfTypicalCourse1");
+        assertEquals(0, giverTypeCounts.size());
+
+        assertEquals(0, fqLogic.getFeedbackQuestionForStudentCountFrom(giverTypeCounts));
+        assertEquals(0, fqLogic.getFeedbackQuestionForInstructorCountFrom(giverTypeCounts, false));
+        assertEquals(0, fqLogic.getFeedbackQuestionForInstructorCountFrom(giverTypeCounts, true));
+
+        ______TS("Invalid session invalid course should give no count");
+        giverTypeCounts = fqLogic.getFeedbackQuestionGiverCountForSession("invalid session", "invalid course");
+        assertEquals(0, giverTypeCounts.size());
+
+        assertEquals(0, fqLogic.getFeedbackQuestionForStudentCountFrom(giverTypeCounts));
+        assertEquals(0, fqLogic.getFeedbackQuestionForInstructorCountFrom(giverTypeCounts, false));
+        assertEquals(0, fqLogic.getFeedbackQuestionForInstructorCountFrom(giverTypeCounts, true));
+    }
+
     private void testHasFeedbackQuestionsForInstructor() {
         ______TS("Valid session valid instructor should have questions");
         assertTrue(fqLogic.hasFeedbackQuestionsForInstructors(

src/test/java/teammates/logic/core/StudentsLogicTest.java

@@ -51,6 +51,7 @@ public void testAll() throws Exception {
         testGetStudentForRegistrationKey();
         testGetStudentsForGoogleId();
         testGetStudentForCourseIdAndGoogleId();
+        testGetNumberOfStudentsForCourse();
         testGetStudentsForCourse();
         testIsStudentInAnyCourse();
         testIsStudentInTeam();
@@ -411,6 +412,31 @@ private void testGetStudentForCourseIdAndGoogleId() {
                 () -> studentsLogic.getStudentForCourseIdAndGoogleId("valid.course", null));
     }
 
+    private void testGetNumberOfStudentsForCourse() {
+
+        ______TS("course with multiple students");
+
+        CourseAttributes course1OfInstructor1 = dataBundle.courses.get("typicalCourse1");
+        int numOfStudents = studentsLogic.getNumberOfStudentsForCourse(course1OfInstructor1.getId());
+        assertEquals(5, numOfStudents);
+
+        ______TS("course with 0 students");
+
+        CourseAttributes course2OfInstructor1 = dataBundle.courses.get("courseNoEvals");
+        numOfStudents = studentsLogic.getNumberOfStudentsForCourse(course2OfInstructor1.getId());
+        assertEquals(0, numOfStudents);
+
+        ______TS("null parameter");
+
+        assertThrows(AssertionError.class, () -> studentsLogic.getNumberOfStudentsForCourse(null));
+
+        ______TS("non-existent course");
+
+        numOfStudents = studentsLogic.getNumberOfStudentsForCourse("non-existent");
+        assertEquals(0, numOfStudents);
+
+    }
+
     private void testGetStudentsForCourse() {
 
         ______TS("course with multiple students");

src/test/java/teammates/storage/api/FeedbackQuestionsDbTest.java

@@ -4,6 +4,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 
 import org.testng.annotations.Test;
 import org.testng.collections.Lists;
@@ -286,6 +287,47 @@ public void testGetFeedbackQuestions() throws Exception {
         assertNull(actual);
     }
 
+    @Test
+    public void testGetFeedbackQuestionGiverTypeCountsForSession() throws Exception {
+        ______TS("standard success case");
+        FeedbackQuestionAttributes fqa = getNewFeedbackQuestionAttributes();
+
+        // remove possibly conflicting entity from the database
+        deleteFeedbackQuestion(fqa);
+
+        int[] numOfQuestions = createNewQuestionsForDifferentRecipientTypes();
+
+        Map<FeedbackParticipantType, Integer> giverTypeCounts =
+                fqDb.getFeedbackQuestionGiverTypeCountForSession(
+                        fqa.getFeedbackSessionName(),
+                        fqa.getCourseId());
+
+        assertEquals(Integer.valueOf(numOfQuestions[0]), giverTypeCounts.get(FeedbackParticipantType.INSTRUCTORS));
+        assertEquals(Integer.valueOf(numOfQuestions[1]), giverTypeCounts.get(FeedbackParticipantType.STUDENTS));
+        assertEquals(Integer.valueOf(numOfQuestions[2]), giverTypeCounts.get(FeedbackParticipantType.SELF));
+        assertEquals(Integer.valueOf(numOfQuestions[3]), giverTypeCounts.get(FeedbackParticipantType.TEAMS));
+
+        ______TS("null params");
+
+        assertThrows(AssertionError.class,
+                () -> fqDb.getFeedbackQuestionGiverTypeCountForSession(null, fqa.getCourseId()));
+
+        assertThrows(AssertionError.class,
+                () -> fqDb.getFeedbackQuestionGiverTypeCountForSession(fqa.getFeedbackSessionName(), null));
+
+        ______TS("non-existent session");
+
+        assertTrue(fqDb.getFeedbackQuestionGiverTypeCountForSession(
+                "non-existant session", fqa.getCourseId()).isEmpty());
+
+        ______TS("no questions in session");
+
+        assertTrue(fqDb.getFeedbackQuestionGiverTypeCountForSession(
+                "Empty session", fqa.getCourseId()).isEmpty());
+
+        deleteFeedbackQuestions(numOfQuestions[0] + numOfQuestions[1] + numOfQuestions[2] + numOfQuestions[3]);
+    }
+
     @Test
     public void testGetFeedbackQuestionsForSession() throws Exception {
 
@@ -364,7 +406,7 @@ public void testGetFeedbackQuestionsForGiverType() throws Exception {
         assertThrows(AssertionError.class,
                 () -> fqDb.getFeedbackQuestionsForGiverType(fqa.getFeedbackSessionName(), fqa.getCourseId(), null));
 
-        ______TS("non-existant session");
+        ______TS("non-existent session");
 
         assertTrue(fqDb.getFeedbackQuestionsForGiverType("non-existant session", fqa.getCourseId(),
                                                          FeedbackParticipantType.STUDENTS).isEmpty());

src/test/java/teammates/storage/api/FeedbackSessionsDbTest.java

@@ -199,7 +199,7 @@ private void testGetFeedbackSessions() {
 
         assertEquals(expected.toString(), actual.toString());
 
-        ______TS("non-existant session");
+        ______TS("non-existent session");
 
         assertNull(fsDb.getFeedbackSession("non-course", "Non-existant feedback session"));
 

src/test/java/teammates/storage/api/InstructorsDbTest.java

@@ -210,6 +210,31 @@ public void testGetInstructorsForGoogleId() throws Exception {
 
     }
 
+    @Test
+    public void testGetInstructorEmailsForCourse() {
+
+        ______TS("Success: get instructors of a specific course");
+
+        String courseId = "idOfTypicalCourse1";
+
+        List<String> emails = instructorsDb.getInstructorEmailsForCourse(courseId);
+        List<InstructorAttributes> instructors = instructorsDb.getInstructorsForCourse(courseId);
+        assertEquals(5, emails.size());
+        assertEquals(5, instructors.size());
+        for (var instructor : instructors) {
+            assertTrue(emails.contains(instructor.getEmail()));
+        }
+
+        ______TS("Failure: no instructors for a course");
+
+        emails = instructorsDb.getInstructorEmailsForCourse("non-exist-course");
+        assertEquals(0, emails.size());
+
+        ______TS("Failure: null parameters");
+
+        assertThrows(AssertionError.class, () -> instructorsDb.getInstructorEmailsForCourse(null));
+    }
+
     @Test
     public void testGetInstructorsForCourse() {