Migrate conversation rendering to the paging library.

app/build.gradle

@@ -278,6 +278,9 @@ dependencies {
     implementation "androidx.camera:camera-lifecycle:1.0.0-beta01"
     implementation "androidx.concurrent:concurrent-futures:1.0.0"
     implementation "androidx.autofill:autofill:1.0.0"
+    implementation "androidx.paging:paging-common:2.1.2"
+    implementation "androidx.paging:paging-runtime:2.1.2"
+
 
     implementation('com.google.firebase:firebase-messaging:17.3.4') {
         exclude group: 'com.google.firebase', module: 'firebase-core'

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java

@@ -596,7 +596,6 @@ public void onActivityResult(final int reqCode, int resultCode, Intent data) {
       break;
     case ADD_CONTACT:
       onRecipientChanged(recipient.get());
-      fragment.reloadList();
       break;
     case PICK_LOCATION:
       SignalPlace place = new SignalPlace(PlacePickerActivity.addressFromData(data));

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationData.java

@@ -1,82 +1,49 @@
 package org.thoughtcrime.securesms.conversation;
 
-import android.database.Cursor;
-
-import androidx.annotation.NonNull;
-
-public final class ConversationData {
-  private final Cursor  cursor;
-  private final int     offset;
-  private final int     limit;
+/**
+ * Represents metadata about a conversation.
+ */
+final class ConversationData {
   private final long    lastSeen;
-  private final int     previousOffset;
-  private final boolean firstLoad;
   private final boolean hasSent;
   private final boolean isMessageRequestAccepted;
   private final boolean hasPreMessageRequestMessages;
+  private final int     jumpToPosition;
 
-  public ConversationData(Cursor cursor,
-                          int offset,
-                          int limit,
-                          long lastSeen,
-                          int previousOffset,
-                          boolean firstLoad,
-                          boolean hasSent,
-                          boolean isMessageRequestAccepted,
-                          boolean hasPreMessageRequestMessages)
+  ConversationData(long lastSeen,
+                   boolean hasSent,
+                   boolean isMessageRequestAccepted,
+                   boolean hasPreMessageRequestMessages,
+                   int jumpToPosition)
   {
-     this.cursor                       = cursor;
-     this.offset                       = offset;
-     this.limit                        = limit;
      this.lastSeen                     = lastSeen;
-     this.previousOffset               = previousOffset;
-     this.firstLoad                    = firstLoad;
      this.hasSent                      = hasSent;
      this.isMessageRequestAccepted     = isMessageRequestAccepted;
      this.hasPreMessageRequestMessages = hasPreMessageRequestMessages;
+     this.jumpToPosition               = jumpToPosition;
   }
 
-  public @NonNull Cursor getCursor() {
-    return cursor;
-  }
-
-  public boolean hasLimit() {
-    return limit > 0;
-  }
-
-  public int getLimit() {
-    return limit;
-  }
-
-  public boolean hasOffset() {
-        return offset > 0;
-    }
-
-  public int getOffset() {
-    return offset;
-  }
-
-  public int getPreviousOffset() {
-    return previousOffset;
-  }
-
-  public long getLastSeen() {
+  long getLastSeen() {
         return lastSeen;
     }
 
-  public boolean isFirstLoad() {
-    return firstLoad;
-  }
-
-  public boolean hasSent() {
+  boolean hasSent() {
     return hasSent;
   }
 
-  public boolean isMessageRequestAccepted() {
+  boolean isMessageRequestAccepted() {
     return isMessageRequestAccepted;
   }
 
-  public boolean hasPreMessageRequestMessages() {
+  boolean hasPreMessageRequestMessages() {
     return hasPreMessageRequestMessages;
   }
+
+  boolean shouldJumpToMessage() {
+    return jumpToPosition >= 0;
+  }
+
+  int getJumpToPosition() {
+    return jumpToPosition;
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationDataSource.java

@@ -0,0 +1,95 @@
+package org.thoughtcrime.securesms.conversation;
+
+import android.content.Context;
+import android.database.ContentObserver;
+
+import androidx.annotation.NonNull;
+import androidx.paging.DataSource;
+import androidx.paging.PositionalDataSource;
+
+import org.thoughtcrime.securesms.database.DatabaseContentProviders;
+import org.thoughtcrime.securesms.database.DatabaseFactory;
+import org.thoughtcrime.securesms.database.MmsSmsDatabase;
+import org.thoughtcrime.securesms.database.model.MessageRecord;
+import org.thoughtcrime.securesms.logging.Log;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Core data source for loading an individual conversation.
+ */
+class ConversationDataSource extends PositionalDataSource<MessageRecord> {
+
+  private static final String TAG = Log.tag(ConversationDataSource.class);
+
+  private final Context context;
+  private final long    threadId;
+
+  private ConversationDataSource(@NonNull Context context, long threadId) {
+    this.context  = context;
+    this.threadId = threadId;
+
+    ContentObserver contentObserver = new ContentObserver(null) {
+      @Override
+      public void onChange(boolean selfChange) {
+        invalidate();
+        context.getContentResolver().unregisterContentObserver(this);
+      }
+    };
+
+    context.getContentResolver().registerContentObserver(DatabaseContentProviders.Conversation.getUriForThread(threadId), true, contentObserver);
+  }
+
+  @Override
+  public void loadInitial(@NonNull LoadInitialParams params, @NonNull LoadInitialCallback<MessageRecord> callback) {
+    long start = System.currentTimeMillis();
+
+    MmsSmsDatabase      db      = DatabaseFactory.getMmsSmsDatabase(context);
+    List<MessageRecord> records = new ArrayList<>(params.requestedLoadSize);
+
+    try (MmsSmsDatabase.Reader reader = db.readerFor(db.getConversation(threadId, params.requestedStartPosition, params.requestedLoadSize))) {
+      MessageRecord record;
+      while ((record = reader.getNext()) != null && !isInvalid()) {
+        records.add(record);
+      }
+    }
+
+    callback.onResult(records, params.requestedStartPosition, db.getConversationCount(threadId));
+    Log.d(TAG, "[Initial Load] " + (System.currentTimeMillis() - start) + " ms" + (isInvalid() ? " -- invalidated" : ""));
+  }
+
+  @Override
+  public void loadRange(@NonNull LoadRangeParams params, @NonNull LoadRangeCallback<MessageRecord> callback) {
+    long start = System.currentTimeMillis();
+
+    MmsSmsDatabase      db      = DatabaseFactory.getMmsSmsDatabase(context);
+    List<MessageRecord> records = new ArrayList<>(params.loadSize);
+
+    try (MmsSmsDatabase.Reader reader = db.readerFor(db.getConversation(threadId, params.startPosition, params.loadSize))) {
+      MessageRecord record;
+      while ((record = reader.getNext()) != null && !isInvalid()) {
+        records.add(record);
+      }
+    }
+
+    callback.onResult(records);
+    Log.d(TAG, "[Update] " + (System.currentTimeMillis() - start) + " ms" + (isInvalid() ? " -- invalidated" : ""));
+  }
+
+  static class Factory extends DataSource.Factory<Integer, MessageRecord> {
+
+    private final Context context;
+    private final long    threadId;
+
+    Factory(Context context, long threadId) {
+      this.context  = context;
+      this.threadId = threadId;
+    }
+
+    @Override
+    public @NonNull DataSource<Integer, MessageRecord> create() {
+      return new ConversationDataSource(context, threadId);
+    }
+  }
+}