CODEWITHSUNDEEP
javanetwork-programmingtheorybandwidth-throttling
Naftuli Kay
Naftuli Kay

Reputation: 91630

Limiting upload speed on Java?

I'd like to programmatically limit an upload or download operation in Java. I would assume that all I'd need to do was do check how fast the upload is going and insert Thread.sleep() accordingly like so:

while (file.hasMoreLines()) {
    String line = file.readLine();
    for (int i = 0; i < line.length(); i+=128) {
        outputStream.writeBytes(line.substr(i, i+128).getBytes());
        if (isHittingLimit())
            Thread.sleep(500);
    }
}

Will the above code work? If not, is there a better way to do this? Is there a tutorial which describes the theory?

Upvotes: 5

Views: 7295

Answers (3)

Franck
Franck

Reputation: 986

Token Bucket Algorithm is a way to limit an upload or a download's bandwidth. You should read this article : it explains the use of this algorithm.

Using Guava RateLimiter :

// rate = 512 permits per second or 512 bytes per second in this case
final RateLimiter rateLimiter = RateLimiter.create(512.0); 

while (file.hasMoreLines()) {
    String line = file.readLine();
    for (int i = 0; i < line.length(); i+=128) {
        byte[] bytes = line.substr(i, i+128).getBytes();
        rateLimiter.acquire(bytes.length);
        outputStream.writeBytes(bytes);
    }
}

As explained in Guava docs: It is important to note that the number of permits requested never affects the throttling of the request itself (an invocation to acquire(1) and an invocation to acquire(1000) will result in exactly the same throttling, if any), but it affects the throttling of the next request. I.e., if an expensive task arrives at an idle RateLimiter, it will be granted immediately, but it is the next request that will experience extra throttling, thus paying for the cost of the expensive task.

Upvotes: 8

gub
gub

Reputation: 5229

This is an old post, but how about this:

import com.google.common.util.concurrent.RateLimiter;
import java.io.IOException;
import java.io.OutputStream;

public final class ThrottledOutputStream extends OutputStream {
    private final OutputStream out;
    private final RateLimiter rateLimiter;

    public ThrottledOutputStream(OutputStream out, double bytesPerSecond) {
        this.out = out;
        this.rateLimiter = RateLimiter.create(bytesPerSecond);
    }

    public void setRate(double bytesPerSecond) {
        rateLimiter.setRate(bytesPerSecond);
    }

    @Override
    public void write(int b) throws IOException {
        rateLimiter.acquire();
        out.write(b);
    }

    @Override
    public void write(byte[] b) throws IOException {
        rateLimiter.acquire(b.length);
        out.write(b);
    }

    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        rateLimiter.acquire(len);
        out.write(b, off, len);
    }

    @Override
    public void flush() throws IOException {
        out.flush();
    }

    @Override
    public void close() throws IOException {
        out.close();
    }
}

Depends on Guava, specifically the RateLimiter.

Upvotes: 1

Ted Hopp
Ted Hopp

Reputation: 234795

You'll need some way for isHittingLimit to know how many bytes have been transmitted over how long. There's an interesting approach in this thread that you may be able to adapt.

Upvotes: 0

Related Questions