Home » Author Archives: Tomasz Nurkiewicz (page 2)

Author Archives: Tomasz Nurkiewicz

Java EE developer, Scala enthusiast. Enjoying data analysis and visualization. Strongly believes in the power of testing and automation.

Consuming java.util.concurrent.BlockingQueue as rx.Observable

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Classical producer-consumer pattern is relatively simple in Java since we have java.util.concurrent.BlockingQueue. To avoid busy waiting and error-prone manual locking we simply take advantage of put() and take(). They both block if queue is full or empty respectively. All we need is a bunch of threads sharing reference to the same queue: some producing and others consuming. And of course ...

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Writing a download server. Part V: Throttle download speed

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In the age of botnets that you can rent for few hundred bucks and run your very own distributed-denial-of-service attack, having emergency switches that selectively turn off expensive functionality or degrade performance gratefully is a huge win. Your application is still operational while you mitigate the problem. Of course such safety measure are also valuable under peaks or business hours. ...

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Writing a download server. Part III: headers: Content-length and Range

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We will explore more HTTP request and response headers this time to improve download server implementation: Content-length and Range. The former signals how big the download is, the latter allows downloading files partially or continue after failure from where we started.       Content-length response header Content-length response header is tremendously helpful for clients that track download progress. If ...

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Writing a download server. Part I: Always stream, never keep fully in memory

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Downloading various files (either text or binary) is a bread and butter of every enterprise application. PDF documents, attachments, media, executables, CSV, very large files, etc. Almost every application, sooner or later, will have to provide some form of download. Downloading is implemented in terms of HTTP, so it’s important to fully embrace this protocol and take full advantage of ...

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How LongAccumulator and DoubleAccumulator classes work?

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Two classes new in Java 8 deserve some attention: LongAccumulator and DoubleAccumulator. They are designed to accumulate (more on what does that mean later) values across threads safely while being extremely fast. A test is worth a thousand words, so here is how it works: class AccumulatorSpec extends Specification { public static final long A = 1 public static final ...

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Biological computer simulation of selfish genes

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TL;DR: I did a computer simulation of behavior evolution of monkeys, continue reading to see how problem was stated originally in The Selfish Gene. First part shows my Java implementation, second part shows charted results and conclusions. The problem I read The Selfish Gene by Richard Dawkins recently, very wide-opening book despite being 40 years old. While the original text ...

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