reduced the lag when filtering is on and typing or pressing Backspace quickly, by killing the database query and providing basic 'a,b,c' suggestions

app/src/main/java/io/github/sspanak/tt9/db/DataStore.java

@@ -1,22 +1,35 @@
 package io.github.sspanak.tt9.db;
 
 import android.content.Context;
+import android.os.CancellationSignal;
 import android.os.Handler;
 
 import androidx.annotation.NonNull;
 
 import java.util.ArrayList;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
 
 import io.github.sspanak.tt9.db.entities.AddWordResult;
 import io.github.sspanak.tt9.db.wordPairs.WordPairStore;
 import io.github.sspanak.tt9.db.words.DictionaryLoader;
 import io.github.sspanak.tt9.db.words.WordStore;
 import io.github.sspanak.tt9.languages.Language;
+import io.github.sspanak.tt9.preferences.settings.SettingsStore;
 import io.github.sspanak.tt9.util.ConsumerCompat;
 import io.github.sspanak.tt9.util.Logger;
 
 public class DataStore {
-	private static final Handler asyncHandler = new Handler();
+	private final static String LOG_TAG = DataStore.class.getSimpleName();
+
+	private static final Handler asyncReturn = new Handler();
+	private static final ExecutorService executor = Executors.newCachedThreadPool();
+
+	private static Future<?> getWordsTask;
+	private static CancellationSignal getWordsCancellationSignal = new CancellationSignal();
+
 	private static WordPairStore pairs;
 	private static WordStore words;
 
@@ -28,7 +41,7 @@ public class DataStore {
 
 
 	private static void runInThread(@NonNull Runnable action) {
-		new Thread(action).start();
+		executor.submit(action);
 	}
 
 
@@ -40,7 +53,7 @@ public class DataStore {
 				words.finishTransaction();
 			} catch (Exception e) {
 				words.failTransaction();
-				Logger.e(DataStore.class.getSimpleName(), errorMessagePrefix + " " + e.getMessage());
+				Logger.e(LOG_TAG, errorMessagePrefix + " " + e.getMessage());
 			}
 			onFinish.run();
 		});
@@ -85,17 +98,42 @@ public class DataStore {
 
 
 	public static void getWords(ConsumerCompat<ArrayList<String>> dataHandler, Language language, String sequence, String filter, int minWords, int maxWords) {
-		runInThread(() -> {
+		if (getWordsTask != null && !getWordsTask.isDone()) {
-			ArrayList<String> data = words.getSimilar(language, sequence, filter, minWords, maxWords);
+			dataHandler.accept(new ArrayList<>());
-			asyncHandler.post(() -> dataHandler.accept(data));
+			getWordsCancellationSignal.cancel();
-		});
+			return;
+		}
+
+		getWordsCancellationSignal = new CancellationSignal();
+		getWordsTask = executor.submit(() -> getWordsSync(dataHandler, language, sequence, filter, minWords, maxWords));
+		executor.submit(DataStore::setGetWordsTimeout);
+	}
+
+
+	private static void getWordsSync(ConsumerCompat<ArrayList<String>> dataHandler, Language language, String sequence, String filter, int minWords, int maxWords) {
+		try {
+			ArrayList<String> data = words.getSimilar(getWordsCancellationSignal, language, sequence, filter, minWords, maxWords);
+			asyncReturn.post(() -> dataHandler.accept(data));
+		} catch (Exception e) {
+			Logger.e(LOG_TAG, "Error fetching words: " + e.getMessage());
+		}
+	}
+
+
+	private static void setGetWordsTimeout() {
+		try {
+			getWordsTask.get(SettingsStore.SLOW_QUERY_TIMEOUT, TimeUnit.MILLISECONDS);
+		} catch (Exception e) {
+			getWordsCancellationSignal.cancel();
+			Logger.e(LOG_TAG, "Word loading timed out after " + SettingsStore.SLOW_QUERY_TIMEOUT + " ms.");
+		}
 	}
 
 
 	public static void getCustomWords(ConsumerCompat<ArrayList<String>> dataHandler, String wordFilter, int maxWords) {
 		runInThread(() -> {
 			ArrayList<String> data = words.getSimilarCustom(wordFilter, maxWords);
-			asyncHandler.post(() -> dataHandler.accept(data));
+			asyncReturn.post(() -> dataHandler.accept(data));
 		});
 	}
 
@@ -103,7 +141,7 @@ public class DataStore {
 	public static void countCustomWords(ConsumerCompat<Long> dataHandler) {
 		runInThread(() -> {
 			long data = words.countCustom();
-			asyncHandler.post(() -> dataHandler.accept(data));
+			asyncReturn.post(() -> dataHandler.accept(data));
 		});
 	}
 
@@ -111,7 +149,7 @@ public class DataStore {
 	public static void exists(ConsumerCompat<ArrayList<Integer>> dataHandler, ArrayList<Language> languages) {
 		runInThread(() -> {
 			ArrayList<Integer> data = words.exists(languages);
-			asyncHandler.post(() -> dataHandler.accept(data));
+			asyncReturn.post(() -> dataHandler.accept(data));
 		});
 	}
 

app/src/main/java/io/github/sspanak/tt9/db/sqlite/ReadOps.java

@@ -4,6 +4,8 @@ import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteDoneException;
 import android.database.sqlite.SQLiteStatement;
+import android.os.CancellationSignal;
+import android.os.OperationCanceledException;
 
 import androidx.annotation.NonNull;
 
@@ -118,19 +120,19 @@ public class ReadOps {
 
 
 	@NonNull
-	public WordList getWords(@NonNull SQLiteDatabase db, @NonNull Language language, @NonNull String positions, String filter, int maximumWords, boolean fullOutput) {
+	public WordList getWords(@NonNull SQLiteDatabase db, CancellationSignal cancel, @NonNull Language language, @NonNull String positions, String filter, int maximumWords, boolean fullOutput) {
 		if (positions.isEmpty()) {
 			Logger.d(LOG_TAG, "No word positions. Not searching words.");
 			return new WordList();
 		}
 
 		String wordsQuery = getWordsQuery(language, positions, filter, maximumWords, fullOutput);
-		if (wordsQuery.isEmpty()) {
+		if (wordsQuery.isEmpty() || cancel.isCanceled()) {
 			return new WordList();
 		}
 
 		WordList words = new WordList();
-		try (Cursor cursor = db.rawQuery(wordsQuery, null)) {
+		try (Cursor cursor = db.rawQuery(wordsQuery, null, cancel)) {
 			while (cursor.moveToNext()) {
 					words.add(
 						cursor.getString(0),
@@ -138,26 +140,29 @@ public class ReadOps {
 						fullOutput ? cursor.getInt(2) : 0
 					);
 			}
+		} catch (OperationCanceledException e) {
+			Logger.d(LOG_TAG, "Words query cancelled!");
+			return words;
 		}
 
 		return words;
 	}
 
 
-	public String getSimilarWordPositions(@NonNull SQLiteDatabase db, @NonNull Language language, @NonNull String sequence, String wordFilter, int minPositions) {
+	public String getSimilarWordPositions(@NonNull SQLiteDatabase db, @NonNull CancellationSignal cancel, @NonNull Language language, @NonNull String sequence, String wordFilter, int minPositions) {
 		int generations = switch (sequence.length()) {
 			case 2 -> wordFilter.isEmpty() ? 1 : 10;
 			case 3, 4 -> wordFilter.isEmpty() ? 2 : 10;
 			default -> 10;
 		};
 
-		return getWordPositions(db, language, sequence, generations, minPositions, wordFilter);
+		return getWordPositions(db, cancel, language, sequence, generations, minPositions, wordFilter);
 	}
 
 
 	@NonNull
-	public String getWordPositions(@NonNull SQLiteDatabase db, @NonNull Language language, @NonNull String sequence, int generations, int minPositions, String wordFilter) {
+	public String getWordPositions(@NonNull SQLiteDatabase db, CancellationSignal cancel, @NonNull Language language, @NonNull String sequence, int generations, int minPositions, String wordFilter) {
-		if (sequence.length() == 1) {
+		if (sequence.length() == 1 || cancel.isCanceled()) {
 			return sequence;
 		}
 
@@ -165,18 +170,24 @@ public class ReadOps {
 
 		String cachedFactoryPositions = SlowQueryStats.getCachedIfSlow(SlowQueryStats.generateKey(language, sequence, wordFilter, minPositions));
 		if (cachedFactoryPositions != null) {
-			String customWordPositions = getCustomWordPositions(db, language, sequence, generations);
+			String customWordPositions = getCustomWordPositions(db, cancel, language, sequence, generations);
 			return customWordPositions.isEmpty() ? cachedFactoryPositions : customWordPositions + "," + cachedFactoryPositions;
 		}
 
-		try (Cursor cursor = db.rawQuery(getPositionsQuery(language, sequence, generations), null)) {
+		try (Cursor cursor = db.rawQuery(getPositionsQuery(language, sequence, generations), null, cancel)) {
 			positions.appendFromDbRanges(cursor);
+		} catch (OperationCanceledException ignored) {
+			Logger.d(LOG_TAG, "Word positions query cancelled!");
+			return sequence;
 		}
 
 		if (positions.size < minPositions && generations < Integer.MAX_VALUE) {
 			Logger.d(LOG_TAG, "Not enough positions: " + positions.size + " < " + minPositions + ". Searching for more.");
-			try (Cursor cursor = db.rawQuery(getFactoryWordPositionsQuery(language, sequence, Integer.MAX_VALUE), null)) {
+			try (Cursor cursor = db.rawQuery(getFactoryWordPositionsQuery(language, sequence, Integer.MAX_VALUE), null, cancel)) {
 				positions.appendFromDbRanges(cursor);
+			} catch (OperationCanceledException ignored) {
+				Logger.d(LOG_TAG, "Word positions query cancelled!");
+				return sequence;
 			}
 		}
 
@@ -184,9 +195,12 @@ public class ReadOps {
 	}
 
 
-	@NonNull private String getCustomWordPositions(@NonNull SQLiteDatabase db, Language language, String sequence, int generations) {
+	@NonNull private String getCustomWordPositions(@NonNull SQLiteDatabase db, CancellationSignal cancel, Language language, String sequence, int generations) {
-		try (Cursor cursor = db.rawQuery(getCustomWordPositionsQuery(language, sequence, generations), null)) {
+		try (Cursor cursor = db.rawQuery(getCustomWordPositionsQuery(language, sequence, generations), null, cancel)) {
 			return new WordPositionsStringBuilder().appendFromDbRanges(cursor).toString();
+		} catch (OperationCanceledException e) {
+			Logger.d(LOG_TAG, "Custom word positions query cancelled.");
+			return "";
 		}
 	}
 

app/src/main/java/io/github/sspanak/tt9/db/words/WordStore.java

@@ -1,6 +1,7 @@
 package io.github.sspanak.tt9.db.words;
 
 import android.content.Context;
+import android.os.CancellationSignal;
 
 import androidx.annotation.NonNull;
 
@@ -60,7 +61,7 @@ public class WordStore extends BaseSyncStore {
 	 * For example: "7655" -> "roll" (exact match), but also: "rolled", "roller", "rolling", ...
 	 * and other similar.
 	 */
-	public ArrayList<String> getSimilar(Language language, String sequence, String wordFilter, int minimumWords, int maximumWords) {
+	public ArrayList<String> getSimilar(@NonNull CancellationSignal cancel, Language language, String sequence, String wordFilter, int minimumWords, int maximumWords) {
 		if (!checkOrNotify()) {
 			return new ArrayList<>();
 		}
@@ -80,15 +81,17 @@ public class WordStore extends BaseSyncStore {
 		final String filter = wordFilter == null ? "" : wordFilter;
 
 		Timer.start("get_positions");
-		String positions = readOps.getSimilarWordPositions(sqlite.getDb(), language, sequence, filter, minWords);
+		String positions = readOps.getSimilarWordPositions(sqlite.getDb(), cancel, language, sequence, filter, minWords);
 		long positionsTime = Timer.stop("get_positions");
 
 		Timer.start("get_words");
-		ArrayList<String> words = readOps.getWords(sqlite.getDb(), language, positions, filter, maxWords, false).toStringList();
+		ArrayList<String> words = readOps.getWords(sqlite.getDb(), cancel, language, positions, filter, maxWords, false).toStringList();
 		long wordsTime = Timer.stop("get_words");
 
 		printLoadingSummary(sequence, words, positionsTime, wordsTime);
-		SlowQueryStats.add(SlowQueryStats.generateKey(language, sequence, wordFilter, minWords), (int) (positionsTime + wordsTime), positions);
+		if (!cancel.isCanceled()) { // do not store empty results from aborted queries in the cache
+			SlowQueryStats.add(SlowQueryStats.generateKey(language, sequence, wordFilter, minWords), (int) (positionsTime + wordsTime), positions);
+		}
 
 		return words;
 	}
@@ -188,8 +191,8 @@ public class WordStore extends BaseSyncStore {
 		try {
 			Timer.start(LOG_TAG);
 
-			String topWordPositions = readOps.getWordPositions(sqlite.getDb(), language, sequence, 0, 0, "");
+			String topWordPositions = readOps.getWordPositions(sqlite.getDb(), null, language, sequence, 0, 0, "");
-			WordList topWords = readOps.getWords(sqlite.getDb(), language, topWordPositions, "", 9999, true);
+			WordList topWords = readOps.getWords(sqlite.getDb(), null, language, topWordPositions, "", 9999, true);
 			if (topWords.isEmpty()) {
 				throw new Exception("No such word");
 			}

app/src/main/java/io/github/sspanak/tt9/preferences/settings/SettingsStore.java

@@ -20,6 +20,7 @@ public class SettingsStore extends SettingsUI {
 	public final static int DICTIONARY_IMPORT_PROGRESS_UPDATE_TIME = 250; // ms
 	public final static int RESIZE_THROTTLING_TIME = 60; // ms
 	public final static byte SLOW_QUERY_TIME = 50; // ms
+	public final static int SLOW_QUERY_TIMEOUT = 3000; // ms
 	public final static int SOFT_KEY_DOUBLE_CLICK_DELAY = 500; // ms
 	public final static int SOFT_KEY_REPEAT_DELAY = 40; // ms
 	public final static int SOFT_KEY_TITLE_MAX_CHARS = 5;