Bump default read ahead size to 4MiB and make it configurable

src/main/java/org/cryptomator/fusecloudaccess/CloudAccessFSConfig.java

@@ -12,6 +12,7 @@ public class CloudAccessFSConfig {
 	private static final long DEFAULT_TOTAL_QUOTA = 1_000_000_000; // 1 GB
 	private static final long DEFAULT_AVAILABLE_QUOTA = 500_000_000; // 500 MB
 	private static final int DEFAULT_IDLE_FILE_TIMEOUT = 20;
+	public static final int DEFAULT_READAHEAD_SIZE = 1024 * 1024 * 4; // 4 MiB
 	private static final String DEFAULT_CACHE_DIR = System.getProperty("java.io.tmpdir") + "/fcaCache";
 	private static final String DEFAULT_LOST_AND_FOUND_DIR = "lostAndFound";
 	private static final String DEFAULT_UPLOAD_DIR = "/58a230a40ae05cee64dfc0680d920e1e";
@@ -20,6 +21,7 @@ public class CloudAccessFSConfig {
 	private final long totalQuota;
 	private final long availableQuota;
 	private final int idleFileTimeoutSeconds;
+	private final int readAheadBytes;
 	private final String cacheDir;
 	private final String lostAndFoundDir;
 	private final String uploadDir;
@@ -28,6 +30,7 @@ public class CloudAccessFSConfig {
 	CloudAccessFSConfig() {
 		this.pendingUploadTimeoutSeconds = Integer.getInteger("org.cryptomator.fusecloudaccess.pendingUploadsTimeoutSeconds", DEFAULT_PENDING_UPLOAD_TIMEOUT);
 		this.idleFileTimeoutSeconds = Integer.getInteger("org.cryptomator.fusecloudaccess.idleFileTimeoutSeconds", DEFAULT_IDLE_FILE_TIMEOUT);
+		this.readAheadBytes = Integer.getInteger("org.cryptomator.fusecloudaccess.readAheadBytes", DEFAULT_READAHEAD_SIZE);
 		this.totalQuota = Long.getLong("org.cryptomator.fusecloudaccess.totalQuota", DEFAULT_TOTAL_QUOTA);
 		this.availableQuota = Long.getLong("org.cryptomator.fusecloudaccess.availableQuota", DEFAULT_AVAILABLE_QUOTA);
 		this.cacheDir = System.getProperty("org.cryptomator.fusecloudaccess.cacheDir", DEFAULT_CACHE_DIR);
@@ -43,6 +46,10 @@ public int getIdleFileTimeoutSeconds() {
 		return idleFileTimeoutSeconds;
 	}
 
+	public int getReadAheadBytes() {
+		return readAheadBytes;
+	}
+
 	public long getTotalQuota() {
 		return totalQuota;
 	}

src/main/java/org/cryptomator/fusecloudaccess/OpenFile.java

@@ -41,21 +41,21 @@
 class OpenFile implements Closeable {
 
 	private static final Logger LOG = LoggerFactory.getLogger(OpenFile.class);
-	private static final int READAHEAD_SIZE = 1024 * 1024; // 1 MiB TODO: should this be configurable?
 
 	private final CompletableAsynchronousFileChannel fc;
 	private final CloudProvider provider;
 	private final RangeSet<Long> populatedRanges;
 	private final RangeMap<Long, CompletionStage<Void>> activeRequests;
 	private final AtomicInteger openFileHandleCount;
 	private final AtomicReference<OpenFile.State> state;
+	private final int readAheadBytes;
 	private volatile CloudPath path;
 	private Instant lastModified;
 
 	public enum State {UNMODIFIED, NEEDS_UPLOAD, UPLOADING, NEEDS_REUPLOAD}
 
 	// visible for testing
-	OpenFile(CloudPath path, CompletableAsynchronousFileChannel fc, CloudProvider provider, RangeSet<Long> populatedRanges, RangeMap<Long, CompletionStage<Void>> activeRequests, Instant initialLastModified) {
+	OpenFile(CloudPath path, CompletableAsynchronousFileChannel fc, CloudProvider provider, RangeSet<Long> populatedRanges, RangeMap<Long, CompletionStage<Void>> activeRequests, Instant initialLastModified, int readAheadBytes) {
 		this.path = path;
 		this.fc = fc;
 		this.provider = provider;
@@ -64,6 +64,7 @@ public enum State {UNMODIFIED, NEEDS_UPLOAD, UPLOADING, NEEDS_REUPLOAD}
 		this.openFileHandleCount = new AtomicInteger();
 		this.state = new AtomicReference<>(State.UNMODIFIED);
 		this.lastModified = initialLastModified;
+		this.readAheadBytes = readAheadBytes;
 	}
 
 	/**
@@ -76,7 +77,7 @@ public enum State {UNMODIFIED, NEEDS_UPLOAD, UPLOADING, NEEDS_REUPLOAD}
 	 * @return The created file
 	 * @throws IOException I/O errors during creation of the cache file located at <code>tmpFilePath</code>
 	 */
-	public static OpenFile create(CloudPath path, Path tmpFilePath, CloudProvider provider, long initialSize) throws IOException {
+	public static OpenFile create(CloudPath path, Path tmpFilePath, CloudProvider provider, long initialSize, int readAheadBytes) throws IOException {
 		var fc = AsynchronousFileChannel.open(tmpFilePath, READ, WRITE, CREATE_NEW, SPARSE, DELETE_ON_CLOSE);
 		if (initialSize > 0) {
 			try {
@@ -88,7 +89,7 @@ public static OpenFile create(CloudPath path, Path tmpFilePath, CloudProvider pr
 				throw new IOException("Failed to create file", e);
 			}
 		}
-		return new OpenFile(path, new CompletableAsynchronousFileChannel(fc), provider, TreeRangeSet.create(), TreeRangeMap.create(), Instant.now());
+		return new OpenFile(path, new CompletableAsynchronousFileChannel(fc), provider, TreeRangeSet.create(), TreeRangeMap.create(), Instant.now(), readAheadBytes);
 	}
 
 	public AtomicInteger getOpenFileHandleCount() {
@@ -233,7 +234,7 @@ CompletionStage<Void> load(long offset, long count) {
 				if (requiredRange.isEmpty() || populatedRanges.encloses(requiredRange)) {
 					return CompletableFuture.completedFuture(null);
 				} else {
-					var desiredCount = Math.max(count, READAHEAD_SIZE); // reads at least the readahead
+					var desiredCount = Math.max(count, readAheadBytes); // reads at least the readahead
 					var desiredLastByte = Math.min(size, offset + desiredCount); // reads not behind eof (lastByte is exclusive!)
 					var desiredRange = Range.closedOpen(offset, desiredLastByte);
 

src/main/java/org/cryptomator/fusecloudaccess/OpenFileFactory.java

@@ -44,6 +44,7 @@ class OpenFileFactory {
 	private final Path cacheDir;
 	private final ScheduledExecutorService scheduler;
 	private final int keepIdleFileSeconds;
+	private final int readAheadBytes;
 
 	@Inject
 	OpenFileFactory(@Named("openFiles") ConcurrentMap<CloudPath, OpenFile> openFiles, CloudProvider provider, CloudAccessFSConfig config, OpenFileUploader uploader, ScheduledExecutorService scheduler) {
@@ -52,6 +53,7 @@ class OpenFileFactory {
 		this.provider = provider;
 		this.uploader = uploader;
 		this.cacheDir = config.getCacheDir();
+		this.readAheadBytes = config.getReadAheadBytes();
 		this.scheduler = scheduler;
 		this.keepIdleFileSeconds = config.getIdleFileTimeoutSeconds();
 	}
@@ -86,7 +88,7 @@ public long open(CloudPath path, Set<OpenFlags> flags, long initialSize, Instant
 	OpenFile createOpenFile(CloudPath path, long initialSize) {
 		try {
 			var tmpFile = cacheDir.resolve(UUID.randomUUID().toString());
-			return OpenFile.create(path, tmpFile, provider, initialSize);
+			return OpenFile.create(path, tmpFile, provider, initialSize, readAheadBytes);
 		} catch (IOException e) {
 			throw new UncheckedIOException(e);
 		}

src/test/java/org/cryptomator/fusecloudaccess/OpenFileTest.java

@@ -43,14 +43,16 @@ public class OpenFileTest {
 	private RangeSet<Long> populatedRanges;
 	private RangeMap<Long, CompletionStage<Void>> activeRequests;
 
+	public static final int DEFAULT_READAHEAD_SIZE = 1024 * 1024 * 4; // 4 MiB
+
 	@BeforeEach
 	public void setup() throws IOException {
 		this.file = Mockito.mock(CloudPath.class, "/path/to/file");
 		this.provider = Mockito.mock(CloudProvider.class);
 		this.fileChannel = Mockito.mock(CompletableAsynchronousFileChannel.class);
 		this.populatedRanges = Mockito.spy(TreeRangeSet.create());
 		this.activeRequests = Mockito.spy(TreeRangeMap.create());
-		this.openFile = new OpenFile(file, fileChannel, provider, populatedRanges, activeRequests, Instant.EPOCH);
+		this.openFile = new OpenFile(file, fileChannel, provider, populatedRanges, activeRequests, Instant.EPOCH, DEFAULT_READAHEAD_SIZE);
 		Mockito.when(fileChannel.size()).thenReturn(100l);
 		Mockito.when(fileChannel.isOpen()).thenReturn(true);
 	}
@@ -60,7 +62,7 @@ public void setup() throws IOException {
 	@ValueSource(longs = {0l, 1l, 42l})
 	public void testCreate(long size, @TempDir Path tmpDir) throws IOException {
 		Path tmpFile = tmpDir.resolve("cache.file");
-		try (var cachedFile = OpenFile.create(file, tmpFile, provider, size)) {
+		try (var cachedFile = OpenFile.create(file, tmpFile, provider, size, DEFAULT_READAHEAD_SIZE)) {
 			Assertions.assertNotNull(cachedFile);
 			Assertions.assertEquals(size, cachedFile.getSize());
 		}
@@ -73,7 +75,7 @@ public void testPersist(@TempDir Path tmpDir) throws IOException {
 		Path tmpFile = tmpDir.resolve("cache.file");
 		Path persistentFile = tmpDir.resolve("persistent.file");
 
-		try (var cachedFile = OpenFile.create(file, tmpFile, provider, 0)) {
+		try (var cachedFile = OpenFile.create(file, tmpFile, provider, 0, DEFAULT_READAHEAD_SIZE)) {
 			cachedFile.truncate(100l);
 			Assertions.assertTimeoutPreemptively(Duration.ofMillis(100), () -> cachedFile.persistTo(persistentFile).toCompletableFuture().get());
 		}
@@ -453,7 +455,7 @@ public class Merge {
 		public void setup() {
 			var prePopulatedRanges = ImmutableRangeSet.of(Range.closedOpen(0l, 50l));
 			populatedRanges = Mockito.spy(TreeRangeSet.create(prePopulatedRanges));
-			openFile = new OpenFile(file, fileChannel, provider, populatedRanges, activeRequests, Instant.EPOCH);
+			openFile = new OpenFile(file, fileChannel, provider, populatedRanges, activeRequests, Instant.EPOCH, DEFAULT_READAHEAD_SIZE);
 			this.fileSpy = Mockito.spy(openFile);
 		}