Develop Reference

How to implement fault tolerant file upload with akka remote and steam

I'm an Akka beginner. (I am using Java)
I'm making a file transfer system using Akka.
Currently, I have completed sending the Actor1(Local) -> Actor2(Remote) file.
Now,
When I have a problem transferring files, I'm thinking about how to solve it.
Then I had a question. The questions are as follows.
If I lost my network connection while I was transferring files, the file transfer failed (90 percent complete).
I will recover my network connection a few minutes later.
Is it possible to transfer the rest of the file data? (10% Remaining)
If that's possible, Please give me some advice.
here is my simple code.
thanks :)
Actor1 (Local)
private Behavior<Event> onTick() {
....
String fileName = "test.zip";
Source<ByteString, CompletionStage<IOResult>> logs = FileIO.fromPath(Paths.get(fileName));
logs.runForeach(f -> originalSize += f.size(), mat).thenRun(() -> System.out.println("originalSize : " + originalSize));
SourceRef<ByteString> logsRef = logs.runWith(StreamRefs.sourceRef(), mat);
getContext().ask(
Receiver.FileTransfered.class,
selectedReceiver,
timeout,
responseRef -> new Receiver.TransferFile(logsRef, responseRef, fileName),
(response, failure) -> {
if (response != null) {
return new TransferCompleted(fileName, response.transferedSize);
} else {
return new JobFailed("Processing timed out", fileName);
}
}
);
}
Actor2 (Remote)
public static Behavior<Command> create() {
return Behaviors.setup(context -> {
...
Materializer mat = Materializer.createMaterializer(context);
return Behaviors.receive(Command.class)
.onMessage(TransferFile.class, command -> {
command.sourceRef.getSource().runWith(FileIO.toPath(Paths.get("test.zip")), mat);
command.replyTo.tell(new FileTransfered("filename", 1024));
return Behaviors.same();
}).build();
});
}

You need to think about following for a proper implementation of file transfer with fault tolerance:
How to identify that a transfer has to be resumed for a given file.
How to find the point from which to resume the transfer.
Following implementation makes very simple assumptions about 1 and 2.
The file name is unique and thus can be used for such identification. Strictly speaking, this is not true, for example you can transfer files with the same name from different folders. Or from different nodes, etc. You will have to readjust this based on your use case.
It is assumed that the last/all writes on the receiver side wrote all bytes correctly and total number of written bytes indicate the point to resume the transfer. If this cannot be guaranteed, you need to logically split the original file into chunks and transfer hashes of each chunk, its size and position to the receiver, which has to validate chunks on its side and find correct pointer for resuming the transfer.
(That's a bit more than 2 :) ) This implementation ignores identification of transfer problem and focuses on 1 and 2 instead.
The code:
object Sender {
sealed trait Command
case class Upload(file: String) extends Command
case class StartWithIndex(file: String, index: Long) extends Sender.Command
def behavior(receiver: ActorRef[Receiver.Command]): Behavior[Sender.Command] = Behaviors.setup[Sender.Command] { ctx =>
implicit val materializer: Materializer = SystemMaterializer(ctx.system).materializer
Behaviors.receiveMessage {
case Upload(file) =>
receiver.tell(Receiver.InitUpload(file, ctx.self.narrow[StartWithIndex]))
ctx.log.info(s"Initiating upload of $file")
Behaviors.same
case StartWithIndex(file, starWith) =>
val source = FileIO.fromPath(Paths.get(file), chunkSize = 8192, starWith)
val ref = source.runWith(StreamRefs.sourceRef())
ctx.log.info(s"Starting upload of $file")
receiver.tell(Receiver.Upload(file, ref))
Behaviors.same
}
}
}
object Receiver {
sealed trait Command
case class InitUpload(file: String, replyTo: ActorRef[Sender.StartWithIndex]) extends Command
case class Upload(file: String, fileSource: SourceRef[ByteString]) extends Command
val behavior: Behavior[Receiver.Command] = Behaviors.setup[Receiver.Command] { ctx =>
implicit val materializer: Materializer = SystemMaterializer(ctx.system).materializer
Behaviors.receiveMessage {
case InitUpload(path, replyTo) =>
val file = fileAtDestination(path)
val index = if (file.exists()) file.length else 0
ctx.log.info(s"Got init command for $file at pointer $index")
replyTo.tell(Sender.StartWithIndex(path, index.toLong))
Behaviors.same
case Upload(path, fileSource) =>
val file = fileAtDestination(path)
val sink = if (file.exists()) {
FileIO.toPath(file.toPath, Set(StandardOpenOption.APPEND, StandardOpenOption.WRITE))
} else {
FileIO.toPath(file.toPath, Set(StandardOpenOption.CREATE_NEW, StandardOpenOption.WRITE))
}
ctx.log.info(s"Saving file into ${file.toPath}")
fileSource.runWith(sink)
Behaviors.same
}
}
}
Some auxiliary methods
val destination: File = Files.createTempDirectory("destination").toFile
def fileAtDestination(file: String) = {
val name = new File(file).getName
new File(destination, name)
}
def writeRandomToFile(file: File, size: Int): Unit = {
val out = new FileOutputStream(file, true)
(0 until size).foreach { _ =>
out.write(Random.nextPrintableChar())
}
out.close()
}
And finally some test code
// sender and receiver bootstrapping is omitted
//Create some dummy file to upload
val file: Path = Files.createTempFile("test", "test")
writeRandomToFile(file.toFile, 1000)
//Initiate a new upload
sender.tell(Sender.Upload(file.toAbsolutePath.toString))
// Sleep to allow file upload to finish
Thread.sleep(1000)
//Write more data to the file to emulate a failure
writeRandomToFile(file.toFile, 1000)
//Initiate a new upload that will "recover" from the previous upload
sender.tell(Sender.Upload(file.toAbsolutePath.toString))
Finally, the whole process can be defined as

Changing a File's content does not change the file lastModified

I am writing a simple test to change a File's content. As you can see the printed content is what's expected. But the lastModified() descriptor is not modified. Eventually, what I'm just trying to get to is a Boolean field representing whether or not my file has changed.
I need to make my thread sleep for 1 sec to pass the test... I don't like this it's not reliable.
Error I'm getting:
[header1,header2, before,before]
[header1,header2, after,after]
false was not equal to true
ScalaTestFailureLocation: NonSense at (NonSense.scala:38)
Expected :true
Actual :false
Code Snippet below:
import java.io.File
import java.nio.file.{Files, Path, Paths}
import org.apache.commons.io.FileUtils
import org.scalatest.{FlatSpec, Matchers}
class NonSense extends FlatSpec with Matchers {
val classLoader: ClassLoader = getClass.getClassLoader
val testAclsPath: Path = Paths.get(classLoader.getResource("file/test.csv").getPath)
def withTempConfigFile(block: (Path) => Unit) {
val tempDir: Path = Files.createTempDirectory("test")
val tempCsv = new File(tempDir.toFile, "test.csv")
val path = tempCsv.toPath.toAbsolutePath
Files.copy(testAclsPath, path)
block(path)
}
"changing a file" should "change last modified timestamp" in {
withTempConfigFile { (path) =>
// refresh and get current Acls
val lastModified = path.toFile.lastModified
// read CSV
val file = path.toFile
val lines = FileUtils.readLines(file, "UTF-8")
System.out.println(lines)
// delete the last line
val deletedLine = lines.remove(lines.size() - 1)
// add a line
lines.add("after,after")
// write to file
// Thread.sleep(10) doesn't change anything, but Thread.sleep(1000) does
FileUtils.writeLines(path.toFile, "UTF-8", lines, false)
val linesChanged = FileUtils.readLines(file, "UTF-8")
System.out.println(linesChanged)
// assert the obvious - not working
path.toFile.lastModified() > lastModified shouldBe true
}
}
}

Scala vs Java Streaming: Scala prints nothing, Java works

I'm doing a comparison between Scala vs Java Reactive Spec implementations using akka-stream and RxJava, respectively. My use case is a simplistic grep: Given a directory, a file filter and a search text, I look in that directory for all matching files that have the text. I then stream the (filename -> matching line) pair.
This works fine for Java but for Scala, nothing is printed. There's no exception but no output either.
The data for the test is downloaded from the internet but as you can see, the code can easily be tested with any local directory as well.
Scala:
object Transformer {
implicit val system = ActorSystem("transformer")
implicit val materializer = ActorMaterializer()
implicit val executionContext: ExecutionContext = {
implicitly
}
import collection.JavaConverters._
def run(path: String, text: String, fileFilter: String) = {
Source.fromIterator { () =>
Files.newDirectoryStream(Paths.get(path), fileFilter).iterator().asScala
}.map(p => {
val lines = io.Source.fromFile(p.toFile).getLines().filter(_.contains(text)).map(_.trim).to[ImmutableList]
(p, lines)
})
.runWith(Sink.foreach(e => println(s"${e._1} -> ${e._2}")))
}
}
Java:
public class Transformer {
public static void run(String path, String text, String fileFilter) {
Observable.from(files(path, fileFilter)).flatMap(p -> {
try {
return Observable.from((Iterable<Map.Entry<String, List<String>>>) Files.lines(p)
.filter(line -> line.contains(text))
.map(String::trim)
.collect(collectingAndThen(groupingBy(pp -> p.toAbsolutePath().toString()), Map::entrySet)));
} catch (IOException e) {
throw new UncheckedIOException(e);
}
}).toBlocking().forEach(e -> System.out.printf("%s -> %s.%n", e.getKey(), e.getValue()));
}
private static Iterable<Path> files(String path, String fileFilter) {
try {
return Files.newDirectoryStream(Paths.get(path), fileFilter);
} catch (IOException e) {
throw new UncheckedIOException(e);
}
}
}
Unit test using Scala Test:
class TransformerSpec extends FlatSpec with Matchers {
"Transformer" should "extract temperature" in {
Transformer.run(NoaaClient.currentConditionsPath(), "temp_f", "*.xml")
}
"Java Transformer" should "extract temperature" in {
JavaTransformer.run(JavaNoaaClient.currentConditionsPath(false), "temp_f", "*.xml")
}
}

Dang, I forgot that Source returns a Future, which means the flow never ran. #MrWiggles' comment gave me a hint. The following Scala code produces equivalent result as the Java version.
Note: The code in my question didn't close the DirectoryStreamwhich, for directories with a large number of files, caused a java.io.IOException: Too many open files in system. The code below closes the resources up properly.
def run(path: String, text: String, fileFilter: String) = {
val files = Files.newDirectoryStream(Paths.get(path), fileFilter)
val future = Source(files.asScala.toList).map(p => {
val lines = io.Source.fromFile(p.toFile).getLines().filter(_.contains(text)).map(_.trim).to[ImmutableList]
(p, lines)
})
.filter(!_._2.isEmpty)
.runWith(Sink.foreach(e => println(s"${e._1} -> ${e._2}")))
Await.result(future, 10.seconds)
files.close
true // for testing
}

android code to merge two videos side by side and make it as one video(want only one audio)

Any one can help me!
I have two videos.
I want to merge as one video(side by side) and i need to display side by side and also i don't want to merge two audio.
I want only one audio.So now i want sample codes or reference for video merging code

I don't have enough reputation to comment so I am writing this as answer.
Muting one video is a good idea as dbilz suggested.
For merging videos use ffmpeg. If both the files you want to concatenate are using similar encoding try mp4parser
Look this question for more merging two or more video files

Gradle Dependency
implementation "com.writingminds:FFmpegAndroid:0.3.2"
Code
Command to concate two video side by side into one
val cmd : arrayOf("-y", "-i", videoFile!!.path, "-i", videoFileTwo!!.path, "-filter_complex", "hstack", outputFile.path)
Note :
"videoFile" is your first video path.
"videoFileTwo" is your second video path.
"outputFile" is your combined video path which is our final output path
To create output path of video
fun createVideoPath(context: Context): File {
val timeStamp: String = SimpleDateFormat(Constant.DATE_FORMAT, Locale.getDefault()).format(Date())
val imageFileName: String = "APP_NAME_"+ timeStamp + "_"
val storageDir: File? = context.getExternalFilesDir(Environment.DIRECTORY_MOVIES)
if (storageDir != null) {
if (!storageDir.exists()) storageDir.mkdirs()
}
return File.createTempFile(imageFileName, Constant.VIDEO_FORMAT, storageDir)
}
Code to execute command
try {
FFmpeg.getInstance(context).execute(cmd, object : ExecuteBinaryResponseHandler() {
override fun onStart() {
}
override fun onProgress(message: String?) {
callback!!.onProgress(message!!)
}
override fun onSuccess(message: String?) {
callback!!.onSuccess(outputFile)
}
override fun onFailure(message: String?) {
if (outputFile.exists()) {
outputFile.delete()
}
callback!!.onFailure(IOException(message))
}
override fun onFinish() {
callback!!.onFinish()
}
})
} catch (e: Exception) {
} catch (e2: FFmpegCommandAlreadyRunningException) {
}

Is there a workaround for Java's poor performance on walking huge directories?

I am trying to process files one at a time that are stored over a network. Reading the files is fast due to buffering is not the issue. The problem I have is just listing the directories in a folder. I have at least 10k files per folder over many folders.
Performance is super slow since File.list() returns an array instead of an iterable. Java goes off and collects all the names in a folder and packs it into an array before returning.
The bug entry for this is http://bugs.sun.com/view_bug.do;jsessionid=db7fcf25bcce13541c4289edeb4?bug_id=4285834 and doesn't have a work around. They just say this has been fixed for JDK7.
A few questions:
Does anybody have a workaround to this performance bottleneck?
Am I trying to achieve the impossible? Is performance still going to be poor even if it just iterates over the directories?
Could I use the beta JDK7 builds that have this functionality without having to build my entire project on it?

Although it's not pretty, I solved this kind of problem once by piping the output of dir/ls to a file before starting my app, and passing in the filename.
If you needed to do it within the app, you could just use system.exec(), but it would create some nastiness.
You asked. The first form is going to be blazingly fast, the second should be pretty fast as well.
Be sure to do the one item per line (bare, no decoration, no graphics), full path and recurse options of your selected command.
EDIT:
30 minutes just to get a directory listing, wow.
It just struck me that if you use exec(), you can get it's stdout redirected into a pipe instead of writing it to a file.
If you did that, you should start getting the files immediately and be able to begin processing before the command has completed.
The interaction may actually slow things down, but maybe not--you might give it a try.
Wow, I just went to find the syntax of the .exec command for you and came across this, possibly exactly what you want (it lists a directory using exec and "ls" and pipes the result into your program for processing): good link in wayback (Jörg provided in a comment to replace this one from sun that Oracle broke)
Anyway, the idea is straightforward but getting the code right is annoying. I'll go steal some codes from the internets and hack them up--brb
/**
* Note: Only use this as a last resort! It's specific to windows and even
* at that it's not a good solution, but it should be fast.
*
* to use it, extend FileProcessor and call processFiles("...") with a list
* of options if you want them like /s... I highly recommend /b
*
* override processFile and it will be called once for each line of output.
*/
import java.io.*;
public abstract class FileProcessor
{
public void processFiles(String dirOptions)
{
Process theProcess = null;
BufferedReader inStream = null;
// call the Hello class
try
{
theProcess = Runtime.getRuntime().exec("cmd /c dir " + dirOptions);
}
catch(IOException e)
{
System.err.println("Error on exec() method");
e.printStackTrace();
}
// read from the called program's standard output stream
try
{
inStream = new BufferedReader(
new InputStreamReader( theProcess.getInputStream() ));
processFile(inStream.readLine());
}
catch(IOException e)
{
System.err.println("Error on inStream.readLine()");
e.printStackTrace();
}
} // end method
/** Override this method--it will be called once for each file */
public abstract void processFile(String filename);
} // end class
And thank you code donor at IBM

How about using File.list(FilenameFilter filter) method and implementing FilenameFilter.accept(File dir, String name) to process each file and return false.
I ran this on Linux vm for directory with 10K+ files and it took <10 seconds.
import java.io.File;
import java.io.FilenameFilter;
public class Temp {
private static void processFile(File dir, String name) {
File file = new File(dir, name);
System.out.println("processing file " + file.getName());
}
private static void forEachFile(File dir) {
String [] ignore = dir.list(new FilenameFilter() {
public boolean accept(File dir, String name) {
processFile(dir, name);
return false;
}
});
}
public static void main(String[] args) {
long before, after;
File dot = new File(".");
before = System.currentTimeMillis();
forEachFile(dot);
after = System.currentTimeMillis();
System.out.println("after call, delta is " + (after - before));
}
}

An alternative is to have the files served over a different protocol. As I understand you're using SMB for that and java is just trying to list them as a regular file.
The problem here might not be java alone ( how does it behaves when you open that directory with Microsoft Explorer x:\shared ) In my experience it also take a considerably amount of time.
You can change the protocol to something like HTTP, only to fetch the file names. This way you can retrieve the list of files over http ( 10k lines should't be too much ) and let the server deal with file listing. This would be very fast, since it will run with local resources ( those in the server )
Then when you have the list, you can process them one by exactly the way you're doing right now.
The keypoint is to have an aid mechanism in the other side of the node.
Is this feasible?
Today:
File [] content = new File("X:\\remote\\dir").listFiles();
for ( File f : content ) {
process( f );
}
Proposed:
String [] content = fetchViaHttpTheListNameOf("x:\\remote\\dir");
for ( String fileName : content ) {
process( new File( fileName ) );
}
The http server could be a very small small and simple file.
If this is the way you have it right now, what you're doing is to fetch all the 10k files information to your client machine ( I don't know how much of that info ) when you only need the file name for later processing.
If the processing is very fast right now it may be slowed down a bit. This is because the information prefetched is no longer available.
Give it a try.

A non-portable solution would be to make native calls to the operating system and stream the results.
For Linux
You can look at something like readdir. You can walk the directory structure like a linked list and return results in batches or individually.
For Windows
In windows the behavior would be fairly similar using FindFirstFile and FindNextFile apis.

I doubt the problem is relate to the bug report you referenced.
The issue there is "only" memory usage, but not necessarily speed.
If you have enough memory the bug is not relevant for your problem.
You should measure whether your problem is memory related or not. Turn on your Garbage Collector log and use for example gcviewer to analyze your memory usage.
I suspect that it has to do with the SMB protocol causing the problem.
You can try to write a test in another language and see if it's faster, or you can try to get the list of filenames through some other method, such as described here in another post.

If you need to eventually process all files, then having Iterable over String[] won't give you any advantage, as you'll still have to go and fetch the whole list of files.

If you're on Java 1.5 or 1.6, shelling out "dir" commands and parsing the standard output stream on Windows is a perfectly acceptable approach. I've used this approach in the past for processing network drives and it has generally been a lot faster than waiting for the native java.io.File listFiles() method to return.
Of course, a JNI call should be faster and potentially safer than shelling out "dir" commands. The following JNI code can be used to retrieve a list of files/directories using the Windows API. This function can be easily refactored into a new class so the caller can retrieve file paths incrementally (i.e. get one path at a time). For example, you can refactor the code so that FindFirstFileW is called in a constructor and have a seperate method to call FindNextFileW.
JNIEXPORT jstring JNICALL Java_javaxt_io_File_GetFiles(JNIEnv *env, jclass, jstring directory)
{
HANDLE hFind;
try {
//Convert jstring to wstring
const jchar *_directory = env->GetStringChars(directory, 0);
jsize x = env->GetStringLength(directory);
wstring path; //L"C:\\temp\\*";
path.assign(_directory, _directory + x);
env->ReleaseStringChars(directory, _directory);
if (x<2){
jclass exceptionClass = env->FindClass("java/lang/Exception");
env->ThrowNew(exceptionClass, "Invalid path, less than 2 characters long.");
}
wstringstream ss;
BOOL bContinue = TRUE;
WIN32_FIND_DATAW data;
hFind = FindFirstFileW(path.c_str(), &data);
if (INVALID_HANDLE_VALUE == hFind){
jclass exceptionClass = env->FindClass("java/lang/Exception");
env->ThrowNew(exceptionClass, "FindFirstFileW returned invalid handle.");
}
//HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);
//DWORD dwBytesWritten;
// If we have no error, loop thru the files in this dir
while (hFind && bContinue){
/*
//Debug Print Statment. DO NOT DELETE! cout and wcout do not print unicode correctly.
WriteConsole(hStdOut, data.cFileName, (DWORD)_tcslen(data.cFileName), &dwBytesWritten, NULL);
WriteConsole(hStdOut, L"\n", 1, &dwBytesWritten, NULL);
*/
//Check if this entry is a directory
if (data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY){
// Make sure this dir is not . or ..
if (wstring(data.cFileName) != L"." &&
wstring(data.cFileName) != L"..")
{
ss << wstring(data.cFileName) << L"\\" << L"\n";
}
}
else{
ss << wstring(data.cFileName) << L"\n";
}
bContinue = FindNextFileW(hFind, &data);
}
FindClose(hFind); // Free the dir structure
wstring cstr = ss.str();
int len = cstr.size();
//WriteConsole(hStdOut, cstr.c_str(), len, &dwBytesWritten, NULL);
//WriteConsole(hStdOut, L"\n", 1, &dwBytesWritten, NULL);
jchar* raw = new jchar[len];
memcpy(raw, cstr.c_str(), len*sizeof(wchar_t));
jstring result = env->NewString(raw, len);
delete[] raw;
return result;
}
catch(...){
FindClose(hFind);
jclass exceptionClass = env->FindClass("java/lang/Exception");
env->ThrowNew(exceptionClass, "Exception occured.");
}
return NULL;
}
Credit:
https://sites.google.com/site/jozsefbekes/Home/windows-programming/miscellaneous-functions
Even with this approach, there are still efficiencies to be gained. If you serialize the path to a java.io.File, there is a huge performance hit - especially if the path represents a file on a network drive. I have no idea what Sun/Oracle is doing under the hood but if you need additional file attributes other than the file path (e.g. size, mod date, etc), I have found that the following JNI function is much faster than instantiating a java.io.File object on a network the path.
JNIEXPORT jlongArray JNICALL Java_javaxt_io_File_GetFileAttributesEx(JNIEnv *env, jclass, jstring filename)
{
//Convert jstring to wstring
const jchar *_filename = env->GetStringChars(filename, 0);
jsize len = env->GetStringLength(filename);
wstring path;
path.assign(_filename, _filename + len);
env->ReleaseStringChars(filename, _filename);
//Get attributes
WIN32_FILE_ATTRIBUTE_DATA fileAttrs;
BOOL result = GetFileAttributesExW(path.c_str(), GetFileExInfoStandard, &fileAttrs);
if (!result) {
jclass exceptionClass = env->FindClass("java/lang/Exception");
env->ThrowNew(exceptionClass, "Exception Occurred");
}
//Create an array to store the WIN32_FILE_ATTRIBUTE_DATA
jlong buffer[6];
buffer[0] = fileAttrs.dwFileAttributes;
buffer[1] = date2int(fileAttrs.ftCreationTime);
buffer[2] = date2int(fileAttrs.ftLastAccessTime);
buffer[3] = date2int(fileAttrs.ftLastWriteTime);
buffer[4] = fileAttrs.nFileSizeHigh;
buffer[5] = fileAttrs.nFileSizeLow;
jlongArray jLongArray = env->NewLongArray(6);
env->SetLongArrayRegion(jLongArray, 0, 6, buffer);
return jLongArray;
}
You can find a full working example of this JNI-based approach in the javaxt-core library. In my tests using Java 1.6.0_38 with a Windows host hitting a Windows share, I have found this JNI approach approximately 10x faster then calling java.io.File listFiles() or shelling out "dir" commands.

I wonder why there are 10k files in a directory. Some file systems do not work well with so many files. There are specifics limitations for file systems like max amount of files per directory and max amount of levels of subdirectory.
I solve a similar problem with an iterator solution.
I needed to walk across huge directorys and several levels of directory tree recursively.
I try FileUtils.iterateFiles() of Apache commons io. But it implement the iterator by adding all the files in a List and then returning List.iterator(). It's very bad for memory.
So I prefer to write something like this:
private static class SequentialIterator implements Iterator<File> {
private DirectoryStack dir = null;
private File current = null;
private long limit;
private FileFilter filter = null;
public SequentialIterator(String path, long limit, FileFilter ff) {
current = new File(path);
this.limit = limit;
filter = ff;
dir = DirectoryStack.getNewStack(current);
}
public boolean hasNext() {
while(walkOver());
return isMore && (limit > count || limit < 0) && dir.getCurrent() != null;
}
private long count = 0;
public File next() {
File aux = dir.getCurrent();
dir.advancePostition();
count++;
return aux;
}
private boolean walkOver() {
if (dir.isOutOfDirListRange()) {
if (dir.isCantGoParent()) {
isMore = false;
return false;
} else {
dir.goToParent();
dir.advancePostition();
return true;
}
} else {
if (dir.isCurrentDirectory()) {
if (dir.isDirectoryEmpty()) {
dir.advancePostition();
} else {
dir.goIntoDir();
}
return true;
} else {
if (filter.accept(dir.getCurrent())) {
return false;
} else {
dir.advancePostition();
return true;
}
}
}
}
private boolean isMore = true;
public void remove() {
throw new UnsupportedOperationException();
}
}
Note that the iterator stop by an amount of files iterateds and it has a FileFilter also.
And DirectoryStack is:
public class DirectoryStack {
private class Element{
private File files[] = null;
private int currentPointer;
public Element(File current) {
currentPointer = 0;
if (current.exists()) {
if(current.isDirectory()){
files = current.listFiles();
Set<File> set = new TreeSet<File>();
for (int i = 0; i < files.length; i++) {
File file = files[i];
set.add(file);
}
set.toArray(files);
}else{
throw new IllegalArgumentException("File current must be directory");
}
} else {
throw new IllegalArgumentException("File current not exist");
}
}
public String toString(){
return "current="+getCurrent().toString();
}
public int getCurrentPointer() {
return currentPointer;
}
public void setCurrentPointer(int currentPointer) {
this.currentPointer = currentPointer;
}
public File[] getFiles() {
return files;
}
public File getCurrent(){
File ret = null;
try{
ret = getFiles()[getCurrentPointer()];
}catch (Exception e){
}
return ret;
}
public boolean isDirectoryEmpty(){
return !(getFiles().length>0);
}
public Element advancePointer(){
setCurrentPointer(getCurrentPointer()+1);
return this;
}
}
private DirectoryStack(File first){
getStack().push(new Element(first));
}
public static DirectoryStack getNewStack(File first){
return new DirectoryStack(first);
}
public String toString(){
String ret = "stack:\n";
int i = 0;
for (Element elem : stack) {
ret += "nivel " + i++ + elem.toString()+"\n";
}
return ret;
}
private Stack<Element> stack=null;
private Stack<Element> getStack(){
if(stack==null){
stack = new Stack<Element>();
}
return stack;
}
public File getCurrent(){
return getStack().peek().getCurrent();
}
public boolean isDirectoryEmpty(){
return getStack().peek().isDirectoryEmpty();
}
public DirectoryStack downLevel(){
getStack().pop();
return this;
}
public DirectoryStack goToParent(){
return downLevel();
}
public DirectoryStack goIntoDir(){
return upLevel();
}
public DirectoryStack upLevel(){
if(isCurrentNotNull())
getStack().push(new Element(getCurrent()));
return this;
}
public DirectoryStack advancePostition(){
getStack().peek().advancePointer();
return this;
}
public File[] peekDirectory(){
return getStack().peek().getFiles();
}
public boolean isLastFileOfDirectory(){
return getStack().peek().getFiles().length <= getStack().peek().getCurrentPointer();
}
public boolean gotMoreLevels() {
return getStack().size()>0;
}
public boolean gotMoreInCurrentLevel() {
return getStack().peek().getFiles().length > getStack().peek().getCurrentPointer()+1;
}
public boolean isRoot() {
return !(getStack().size()>1);
}
public boolean isCurrentNotNull() {
if(!getStack().isEmpty()){
int currentPointer = getStack().peek().getCurrentPointer();
int maxFiles = getStack().peek().getFiles().length;
return currentPointer < maxFiles;
}else{
return false;
}
}
public boolean isCurrentDirectory() {
return getStack().peek().getCurrent().isDirectory();
}
public boolean isLastFromDirList() {
return getStack().peek().getCurrentPointer() == (getStack().peek().getFiles().length-1);
}
public boolean isCantGoParent() {
return !(getStack().size()>1);
}
public boolean isOutOfDirListRange() {
return getStack().peek().getFiles().length <= getStack().peek().getCurrentPointer();
}
}

Using an Iterable doesn't imply that the Files will be streamed to you. In fact its usually the opposite. So an array is typically faster than an Iterable.

Are you sure it's due to Java, not just a general problem with having 10k entries in one directory, particularly over the network?
Have you tried writing a proof-of-concept program to do the same thing in C using the win32 findfirst/findnext functions to see whether it's any faster?
I don't know the ins and outs of SMB, but I strongly suspect that it needs a round trip for every file in the list - which is not going to be fast, particularly over a network with moderate latency.
Having 10k strings in an array sounds like something which should not tax the modern Java VM too much either.