make it much faster and use boolean default values where possible

src/main/java/de/tum/cit/aet/artemis/communication/domain/conversation/Channel.java

@@ -57,25 +57,22 @@ public class Channel extends Conversation {
      * A channel is either public or private. Users need an invitation to join a private channel. Every user can join a public channel.
      */
     @Column(name = "is_public")
-    @NotNull
-    private Boolean isPublic;
+    private boolean isPublic = false;
 
     /**
      * An announcement channel is a special type of channel where only channel moderators and instructors can start new posts.
      * Answer posts are still possible so that students can ask questions concerning the announcement.
      */
     @Column(name = "is_announcement")
-    @NotNull
-    private Boolean isAnnouncementChannel;
+    private boolean isAnnouncementChannel = false;
 
     /**
      * A channel that is no longer needed can be archived or deleted.
      * Archived channels are closed to new activity, but the message history is retained and searchable.
      * The channel can be unarchived at any time.
      */
     @Column(name = "is_archived")
-    @NotNull
-    private Boolean isArchived;
+    private boolean isArchived = false;
 
     /**
      * Channels, that are meant to be seen by all course members by default, even if they haven't joined the channel yet, can be flagged with is_course_wide=true.
@@ -101,7 +98,7 @@ public class Channel extends Conversation {
     private Exam exam;
 
     public Channel(Long id, User creator, Set<ConversationParticipant> conversationParticipants, Set<Post> posts, Course course, ZonedDateTime creationDate,
-            ZonedDateTime lastMessageDate, String name, @Nullable String description, @Nullable String topic, Boolean isPublic, Boolean isAnnouncementChannel, Boolean isArchived,
+            ZonedDateTime lastMessageDate, String name, @Nullable String description, @Nullable String topic, boolean isPublic, boolean isAnnouncementChannel, boolean isArchived,
             boolean isCourseWide, Lecture lecture, Exercise exercise, Exam exam) {
         super(id, creator, conversationParticipants, posts, course, creationDate, lastMessageDate);
         this.name = name;
@@ -138,11 +135,11 @@ public void setDescription(@Nullable String description) {
     }
 
     @Nullable
-    public Boolean getIsPublic() {
+    public boolean getIsPublic() {
         return isPublic;
     }
 
-    public void setIsPublic(@Nullable Boolean isPublic) {
+    public void setIsPublic(boolean isPublic) {
         this.isPublic = isPublic;
     }
 
@@ -155,19 +152,19 @@ public void setTopic(@Nullable String topic) {
         this.topic = topic;
     }
 
-    public Boolean getIsArchived() {
+    public boolean getIsArchived() {
         return isArchived;
     }
 
-    public void setIsArchived(Boolean archived) {
+    public void setIsArchived(boolean archived) {
         isArchived = archived;
     }
 
-    public Boolean getIsAnnouncementChannel() {
+    public boolean getIsAnnouncementChannel() {
         return isAnnouncementChannel;
     }
 
-    public void setIsAnnouncementChannel(Boolean announcementChannel) {
+    public void setIsAnnouncementChannel(boolean announcementChannel) {
         isAnnouncementChannel = announcementChannel;
     }
 

src/main/java/de/tum/cit/aet/artemis/communication/dto/ChannelDTO.java

@@ -6,6 +6,7 @@
 import de.tum.cit.aet.artemis.communication.domain.conversation.ChannelSubType;
 
 @JsonInclude(JsonInclude.Include.NON_EMPTY)
+// TODO: use record in the future
 public class ChannelDTO extends ConversationDTO {
 
     private String name;
@@ -14,25 +15,25 @@ public class ChannelDTO extends ConversationDTO {
 
     private String topic;
 
-    private Boolean isPublic;
+    private boolean isPublic = false; // default value
 
-    private Boolean isAnnouncementChannel;
+    private boolean isAnnouncementChannel = false; // default value
 
-    private Boolean isArchived;
+    private boolean isArchived = false; // default value
 
-    private Boolean isCourseWide;
+    private boolean isCourseWide = false; // default value
 
     // property not taken from entity
     /**
      * A course instructor has channel moderation rights but is not necessarily a moderator of the channel
      */
-    private Boolean hasChannelModerationRights;
+    private boolean hasChannelModerationRights = false; // default value
 
     // property not taken from entity
     /**
      * Member of the channel that is also a moderator of the channel
      */
-    private Boolean isChannelModerator;
+    private boolean isChannelModerator = false; // default value
 
     // property not taken from entity
     /**
@@ -98,43 +99,43 @@ public void setTopic(String topic) {
         this.topic = topic;
     }
 
-    public Boolean getIsPublic() {
+    public boolean getIsPublic() {
         return isPublic;
     }
 
-    public void setIsPublic(Boolean isPublic) {
+    public void setIsPublic(boolean isPublic) {
         this.isPublic = isPublic;
     }
 
-    public Boolean getIsAnnouncementChannel() {
+    public boolean getIsAnnouncementChannel() {
         return isAnnouncementChannel;
     }
 
-    public void setIsAnnouncementChannel(Boolean announcementChannel) {
+    public void setIsAnnouncementChannel(boolean announcementChannel) {
         isAnnouncementChannel = announcementChannel;
     }
 
-    public Boolean getIsArchived() {
+    public boolean getIsArchived() {
         return isArchived;
     }
 
-    public void setIsArchived(Boolean archived) {
+    public void setIsArchived(boolean archived) {
         isArchived = archived;
     }
 
-    public Boolean getHasChannelModerationRights() {
+    public boolean getHasChannelModerationRights() {
         return hasChannelModerationRights;
     }
 
-    public void setHasChannelModerationRights(Boolean hasChannelModerationRights) {
+    public void setHasChannelModerationRights(boolean hasChannelModerationRights) {
         this.hasChannelModerationRights = hasChannelModerationRights;
     }
 
-    public Boolean getIsChannelModerator() {
+    public boolean getIsChannelModerator() {
         return isChannelModerator;
     }
 
-    public void setIsChannelModerator(Boolean isChannelModerator) {
+    public void setIsChannelModerator(boolean isChannelModerator) {
         this.isChannelModerator = isChannelModerator;
     }
 
@@ -162,11 +163,11 @@ public Long getSubTypeReferenceId() {
         return subTypeReferenceId;
     }
 
-    public Boolean getIsCourseWide() {
+    public boolean getIsCourseWide() {
         return isCourseWide;
     }
 
-    public void setIsCourseWide(Boolean courseWide) {
+    public void setIsCourseWide(boolean courseWide) {
         isCourseWide = courseWide;
     }
 
@@ -195,4 +196,16 @@ else if (channel.getExam() != null) {
             this.subType = ChannelSubType.GENERAL;
         }
     }
+
+    public Channel toChannel() {
+        Channel channel = new Channel();
+        channel.setName(this.name);
+        channel.setDescription(this.description);
+        channel.setTopic(this.topic);
+        channel.setIsPublic(this.isPublic);
+        channel.setIsArchived(this.isArchived);
+        channel.setIsAnnouncementChannel(this.isAnnouncementChannel);
+        channel.setIsCourseWide(this.isCourseWide);
+        return channel;
+    }
 }

src/main/java/de/tum/cit/aet/artemis/communication/dto/ConversationDTO.java

@@ -39,6 +39,8 @@ public class ConversationDTO {
     // property not taken from entity
     private Long unreadMessagesCount;
 
+    // TODO: use boolean where possible
+
     // property not taken from entity
     private Boolean isFavorite;
 

src/main/java/de/tum/cit/aet/artemis/communication/repository/ConversationParticipantRepository.java

@@ -3,6 +3,7 @@
 import static de.tum.cit.aet.artemis.core.config.Constants.PROFILE_CORE;
 
 import java.time.ZonedDateTime;
+import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 
@@ -60,8 +61,27 @@ public interface ConversationParticipantRepository extends ArtemisJpaRepository<
             """)
     void updateLastReadAsync(@Param("userId") Long userId, @Param("conversationId") Long conversationId, @Param("now") ZonedDateTime now);
 
+    @Async
+    @Transactional // ok because of modifying query
+    @Modifying
+    @Query("""
+            UPDATE ConversationParticipant p
+            SET p.lastRead = :now, p.unreadMessagesCount = 0
+            WHERE p.user.id = :userId
+                AND p.conversation.id IN :conversationIds
+            """)
+    void updateMultipleLastReadAsync(@Param("userId") Long userId, @Param("conversationIds") List<Long> conversationIds, @Param("now") ZonedDateTime now);
+
     boolean existsByConversationIdAndUserId(Long conversationId, Long userId);
 
+    @Query("""
+            SELECT DISTINCT conversationParticipant.conversation.id
+            FROM ConversationParticipant conversationParticipant
+            WHERE conversationParticipant.user.id = :userId
+                AND conversationParticipant.conversation.course.id = :courseId
+            """)
+    List<Long> findConversationIdsByUserIdAndCourseId(@Param("userId") Long userId, @Param("courseId") Long courseId);
+
     Optional<ConversationParticipant> findConversationParticipantByConversationIdAndUserId(Long conversationId, Long userId);
 
     @Query("""

src/main/java/de/tum/cit/aet/artemis/communication/repository/conversation/ConversationRepository.java

@@ -14,6 +14,7 @@
 import org.springframework.stereotype.Repository;
 import org.springframework.transaction.annotation.Transactional;
 
+import de.tum.cit.aet.artemis.communication.domain.conversation.Channel;
 import de.tum.cit.aet.artemis.communication.domain.conversation.Conversation;
 import de.tum.cit.aet.artemis.communication.dto.GeneralConversationInfo;
 import de.tum.cit.aet.artemis.communication.dto.UserConversationInfo;
@@ -90,11 +91,17 @@ SELECT COUNT(p.id) > 0
             """)
     boolean userHasUnreadMessageInCourse(@Param("courseId") Long courseId, @Param("userId") Long userId);
 
-    /**
-     * Retrieves a list of conversations for the given course
-     *
-     * @param courseId the course id
-     * @return a list of conversations for the given course
-     */
-    List<Conversation> findAllByCourseId(Long courseId);
+    @Query("""
+            SELECT DISTINCT c
+            FROM Conversation c
+            WHERE c.course.id = :courseId
+                AND TYPE(c) = Channel
+                AND c.isCourseWide = TRUE
+                AND c.id NOT IN (
+                    SELECT cp.conversation.id
+                    FROM ConversationParticipant cp
+                    WHERE cp.user.id = :userId
+                )
+            """)
+    List<Channel> findAllCourseWideChannelsByUserIdAndCourseIdWithoutConversationParticipant(@Param("courseId") Long courseId, @Param("userId") Long userId);
 }

src/main/java/de/tum/cit/aet/artemis/communication/service/conversation/ChannelService.java

@@ -256,14 +256,12 @@ public void unarchiveChannel(Long channelId) {
      *
      * @param lecture     the lecture to create the channel for
      * @param channelName the name of the channel
-     * @return the created channel
      */
-    public Channel createLectureChannel(Lecture lecture, Optional<String> channelName) {
+    public void createLectureChannel(Lecture lecture, Optional<String> channelName) {
         Channel channelToCreate = createDefaultChannel(channelName, "lecture-", lecture.getTitle());
         channelToCreate.setLecture(lecture);
         Channel createdChannel = createChannel(lecture.getCourse(), channelToCreate, Optional.of(userRepository.getUserWithGroupsAndAuthorities()));
         lecture.setChannelName(createdChannel.getName());
-        return createdChannel;
     }
 
     /**
@@ -287,32 +285,29 @@ public Channel createExerciseChannel(Exercise exercise, Optional<String> channel
      *
      * @param exam        the exam to create the channel for
      * @param channelName the name of the channel
-     * @return the created channel
      */
-    public Channel createExamChannel(Exam exam, Optional<String> channelName) {
+    public void createExamChannel(Exam exam, Optional<String> channelName) {
         Channel channelToCreate = createDefaultChannel(channelName, "exam-", exam.getTitle());
         channelToCreate.setExam(exam);
         Channel createdChannel = createChannel(exam.getCourse(), channelToCreate, Optional.of(userRepository.getUserWithGroupsAndAuthorities()));
         exam.setChannelName(createdChannel.getName());
-        return createdChannel;
     }
 
     /**
      * Update the channel of a lecture
      *
      * @param originalLecture the original lecture
      * @param channelName     the new channel name
-     * @return the updated channel
      */
-    public Channel updateLectureChannel(Lecture originalLecture, String channelName) {
+    public void updateLectureChannel(Lecture originalLecture, String channelName) {
         if (channelName == null) {
-            return null;
+            return;
         }
         Channel channel = channelRepository.findChannelByLectureId(originalLecture.getId());
         if (channel == null) {
-            return null;
+            return;
         }
-        return updateChannelName(channel, channelName);
+        updateChannelName(channel, channelName);
     }
 
     /**
@@ -428,18 +423,11 @@ private static String generateChannelNameFromTitle(@NotNull String prefix, Optio
      * @throws BadRequestAlertException if the channel name starts with an invalid prefix (e.g., "$").
      */
     public Channel createFeedbackChannel(Course course, Long exerciseId, ChannelDTO channelDTO, List<String> feedbackDetailTexts, String testCaseName, User requestingUser) {
-        Channel channelToCreate = new Channel();
-        channelToCreate.setName(channelDTO.getName());
-        channelToCreate.setIsPublic(channelDTO.getIsPublic());
-        channelToCreate.setIsAnnouncementChannel(channelDTO.getIsAnnouncementChannel());
-        channelToCreate.setIsArchived(false);
-        channelToCreate.setDescription(channelDTO.getDescription());
-
-        if (channelToCreate.getName() != null && channelToCreate.getName().trim().startsWith("$")) {
+        if (channelDTO.getName() != null && channelDTO.getName().trim().startsWith("$")) {
             throw new BadRequestAlertException("User generated channels cannot start with $", "channel", "channelNameInvalid");
         }
 
-        Channel createdChannel = createChannel(course, channelToCreate, Optional.of(requestingUser));
+        Channel createdChannel = createChannel(course, channelDTO.toChannel(), Optional.of(requestingUser));
 
         List<String> userLogins = studentParticipationRepository.findAffectedLoginsByFeedbackDetailText(exerciseId, feedbackDetailTexts, testCaseName);
 
@@ -451,14 +439,4 @@ public Channel createFeedbackChannel(Course course, Long exerciseId, ChannelDTO
 
         return createdChannel;
     }
-
-    /**
-     * Marks all channels of a course as read for the requesting user.
-     *
-     * @param course         the course for which all channels should be marked as read.
-     * @param requestingUser the user requesting the marking of all channels as read.
-     */
-    public void markAllChannelsOfCourseAsRead(Course course, User requestingUser) {
-        conversationService.markAllConversationOfAUserAsRead(course.getId(), requestingUser);
-    }
 }