Slow calls to clojure proxy - clojure

I have an application in clojure making heavy use of a Java framework called Vaadin. Vaadin uses several callbacks using the Java "proxy" feature of clojure. However, every time a proxy is called in a clojure function there is a significant delay (100s of milliseconds sometimes). Is there any way I can speed this up?

My understanding is that the new reify macro is faster than proxy. You can use it if you only need to implement a single interface.
For example, if you need to implement a java.awt.event.ActionListener you can use code like the following:
(import 'java.awt.event.ActionListener 'javax.swing.JButton)
(let [a-button (JButton. "Click Me")]
(.addActionListener a-button
(reify ActionListener
(actionPerformed [this ev] (comment do something interesting)))))

Related

What is a simple way to write GUI apps with clojure? [duplicate]

What is the best way to do GUIs in Clojure?
Is there an example of some functional Swing or SWT wrapper?
Or some integration with JavaFX declarative GUI description which could be easily wrapped to s-expressions using some macrology?
Any tutorials?
I will humbly suggest Seesaw.
Here's a REPL-based tutorial that assumes no Java or Swing knowledge.
Seesaw's a lot like what #tomjen suggests. Here's "Hello, World":
(use 'seesaw.core)
(-> (frame :title "Hello"
:content "Hello, Seesaw"
:on-close :exit)
pack!
show!)
and here's #Abhijith and #dsm's example, translated pretty literally:
(ns seesaw-test.core
(:use seesaw.core))
(defn handler
[event]
(alert event
(str "<html>Hello from <b>Clojure</b>. Button "
(.getActionCommand event) " clicked.")))
(-> (frame :title "Hello Swing" :on-close :exit
:content (button :text "Click Me" :listen [:action handler]))
pack!
show!)
Stuart Sierra recently published a series of blog posts on GUI-development with clojure (and swing). Start off here: http://stuartsierra.com/2010/01/02/first-steps-with-clojure-swing
If you want to do GUI programming I'd point to Temperature Converter or the ants colony.
Many things in Swing are done by sub-classing, particularly if you are creating custom components. For that there are two essential functions/macros: proxy and gen-class.
Now I understand where you are going with the more Lispy way. I don't think there's anything like that yet. I would strongly advise against trying to build a grandiose GUI-building framework a-la CLIM, but to do something more Lispy: start writing your Swing application and abstract out your common patterns with macros. When doing that you may end up with a language to write your kind of GUIs, or maybe some very generic stuff that can be shared and grow.
One thing you lose when writing the GUIs in Clojure is the use of tools like Matisse. That can be a strong pointing to write some parts in Java (the GUI) and some parts in Clojure (the logic). Which actually makes sense as in the logic you'll be able to build a language for your kind of logic using macros and I think there's more to gain there than with the GUI. Obviously, it depends on your application.
Nobody yet suggested it, so I will: Browser as UI platform. You could write your app in Clojure, including an HTTP server and then develop the UI using anything from HTML to hiccup, ClojureScript and any of the billions of JS libaries you need. If you wanted consistent browser behaviour and "desktop app look'n'feel" you could bundle chrome with your app.
This seems to be how Light Table is distributed.
From this page:
(import '(javax.swing JFrame JButton JOptionPane)) ;'
(import '(java.awt.event ActionListener)) ;'
(let [frame (JFrame. "Hello Swing")
button (JButton. "Click Me")]
(.addActionListener button
(proxy [ActionListener] []
(actionPerformed [evt]
(JOptionPane/showMessageDialog nil,
(str "<html>Hello from <b>Clojure</b>. Button "
(.getActionCommand evt) " clicked.")))))
(.. frame getContentPane (add button))
(doto frame
(.setDefaultCloseOperation JFrame/EXIT_ON_CLOSE)
.pack
(.setVisible true)))
print("code sample");
And, of course, it would be worth looking at the interoperability section of clojure's website.
There is a wrapper for MigLayout in clojure contrib. You can also take a look at this gist. I am basically putting up whatever code I am writing as I am learning swing/miglayout.
dsm's example re-written in a lispy way using contrib.swing-utils
(ns test
(:import (javax.swing JButton JFrame))
(:use (clojure.contrib
[swing-utils :only (add-action-listener)])))
(defn handler
[event]
(JOptionPane/showMessageDialog nil,
(str "<html>Hello from <b>Clojure</b>. Button "
(.getActionCommand event) " clicked.")))
(let [ frame (JFrame. "Hello Swing")
button (JButton. "Click Me") ]
(add-action-listener button handler)
(doto frame
(.setDefaultCloseOperation JFrame/EXIT_ON_CLOSE)
(.add button)
(.pack)
(.setVisible true)))
I would rather go for clojurefx, it is a bit premature, but it does work and saves you time.
I started my GUI with seesaw and then tried another component in clojurefx.
I have finished both, and I am convinced that I am going to refactor the seesaw one to clojurefx.
After all, JavaFX is the way to go forward.
It feels lighter than seesaw. Or at least, writing it..
Bindings work, listeners work, most of the component work, otherwise, just use one of the macros to create a constructor for that particular case and job done. Or, if you find it difficult, write some methods in Java and ask for help to improve clojurefx.
The guy who wrote clojurefx is busy at the moment, but you can fork the project and do some fixes.
There's been talk on the mailing list about a few Cells (a la Kenny Tilton's Cells) implementations. It's a pretty neat way to do GUI programming.
Here is another very basic swing wrapping example:
; time for some swing
(import '(javax.swing JFrame JTable JScrollPane))
(import '(javax.swing.table DefaultTableModel))
(let
[frame (JFrame. "Hello Swing")
dm (DefaultTableModel.)
table (JTable. dm)
scroll (JScrollPane. table)]
(doto dm
(.setNumRows 30)
(.setColumnCount 5))
(.. frame getContentPane (add scroll))
(doto frame
(.setDefaultCloseOperation JFrame/EXIT_ON_CLOSE)
(.pack)
(.setVisible true)))
I asked myself the same question of writing a GUI in Clojure with Swing and came up with the library signe
It lets you use represent your domain model as a single Clojure data structure wrapped inside an atom.
See the examples here.
I've been developing a Java applet in which everything is written in Clojure except the applet code, which is written in Java. The applet invokes the Clojure code's callbacks of init, paint, etc from java's hooks for those methods that are defined by the applet model. So the code ends up being 99.999 percent Clojure and you don't have to think about the tiny Java piece at all for the most part.
There are some drawbacks to this approach, which I hope to discuss in more detail on the Clojure Google Group. I think the Clojure developers should include a native way of building applications. Presently you can do whatever GUI stuff you like from the REPL, but if you want a deliverable GUI application, it is necessary to write some Java to call the Clojure code. Also, it seems like the architecture of a Java Applet kind of forces you outside of Clojure's more idiomatic best practices, requiring you to use mutable state, etc.
But also, I am not very far along with Clojure yet and it might be the case that it is possible and I just haven't discovered how to do it correctly yet.
I don't think there is an official one, but personally I would take advantage of the fact that I am using one of the most powerful language in the world and just imagine what the perfect gui code would look like:
(form {:title :on-close dispose :x-size 500 :y-size 450}
[(button {:text "Close" :id 5 :on-click #(System/exit 0) :align :bottom})
(text-field {:text "" :on-change #(.println System/out (:value %)) :align :center})
(combo-box {:text "Chose background colour" :on-change background-update-function
:items valid-colours})])
Your idea would differ but this should hopefully the above gives you some idea.
My preferred Clojure UI environment uses IO.js (Node for ES6) + Electron (Container) + Quiescent (ReactJS wrapper).
So I didn't see Fn-Fx on this list, from Timothy Baldridge (halgiri). This is a Clojure library providing a functional abstraction over JavaFX.
It can be found on Github at https://github.com/halgari/fn-fx.
To use, make sure you are using a recent version of Java (1.8 90+) and add a dependency to the github repo by adding the following to your project.clj:
:plugins [[lein-git-deps "0.0.1-SNAPSHOT"]]
:git-dependencies [["https://github.com/halgari/fn-fx.git"]]
I have tried it, and it works out of the box.
Clojure and SWT is the best approach for doing GUI(s). Essentially, SWT is a plug and play style approach for developing software.
I know that you are hinting for classical desktop solutions, but web fits quite well with clojure. I've written a complete audio application where everything is hooked up so that if you add music to the audio folder it is reflected in the web UI. Just saying that Desktop application isn't the only way :)
cljfx is described as a
Declarative, functional and extensible wrapper of JavaFX inspired by better parts of react and re-frame
and JavaFx as
... an open source, next generation client application platform for desktop, mobile and embedded systems built on Java. It is a collaborative effort by many individuals and companies with the goal of producing a modern, efficient, and fully featured toolkit for developing rich client applications.
Its creator uses it to build reveal, and a hackernews demo that features various capabilities and some bundling for multiple OSs via jpackage.
You can get Clojure REPL-driven development with this by leveraging JavaFX to build UIs for desktop, mobile, and web.

Clojure: how to tell if out is going to console or is being piped?

I'm writing a clojure cli and would like to know if there is a way to test if the out (i.e. println) is being written to a console or is being piped to another program?
This is similar to this question but for clojure.
Clojure is hosted language, so system interaction related stuff is more or less equivalent to Java. For Java there exists only partial solution described in this answer. You can of course implement isatty() using JNI and then interop from Clojure.
However, from ClojureScript hosted on Node.js it's easily achievable using process.stdin.isTTY (in ClojureScript would be (-> process .-stdin .-isTTY)). More details are in this answer.
You could use jnr-posix Java library
[com.github.jnr/jnr-posix "3.0.10"]
to call native posix methods directly from Clojure (using Java Interop):
(import 'jnr.posix.POSIXFactory)
(def posix (POSIXFactory/getPOSIX))
(.isatty posix java.io.FileDescriptor/out)
N.B. If you'll run you Clojure application using lein run command, Clojure will not be able to identify TTY terminal since lein will internally pipe stdio between two java processes. You could avoid internal piping by using lein trampoline run command or compiled jar file.

Sharing an atom between Clojure and Clojurescript?

Assume I have a Clojurescript namespace called main with a atom within it called state.
(ns main)
(atom state nil)
I compile my Clojurescript app, run it on a server, fire up the Clojurescript repl and then connect to my server using a browser. Everything works dandy.
In the Clojurescript repl, I can comfirm the usual
> (+ 1 1)
2
> (js/alert "Hey there") //shows an alert dialog with "Hey there" in the browser
nil
> main.state
(atom nil)
The Clojurescript repl is great for development. So, clearly I can get and (using swap! or reset!) set the value of a Clojurescript atom from a Clojure application. I was wondering if there was a way to have a connection between the value of an atom in my Clojurescript project and a running Clojure application. Perhaps the Clojurescript client connects to a specified port and sends the result to some Clojure server waiting on that port. Simply stated, I was wondering if it might be possible to have a running server application share the value of the state client atom.
Why, you might ask? Well, I was thinking it would be nice to write the value of the state atom to a actual file (state.clj) whenever state is modified in the running Clojurescript application. This way, I could always have a view of the current value of state. I could use something like emacs (global-auto-revert-mode t) to make sure that state.clj buffer was always fairly recent. This is a little like having a debugger.
Beyond that, my real desire is to then make it so that the running Clojure application would also periodically poll state.clj itself. When the server detects that I modified state.clj, it would accept the modification as the new value of the Clojurescript state atom. It would then do something like what the Clojurescript repl does, illustrated in the following pseudo code:
(send-to-client-for-evaluation
(compile-into-js
(reset!
main.state
the-read-string-value-of-the-content-of-state.clj)))
Basically, I want the ability for the server to have something akin to a shared atom between the client and the server. I want the value of state to be bidirectionally shared between the client and the server. Is any of this possible, or am I just dreaming?
Sure, just make requests to a rest API sending data in EDN format, and voila! If you want to avoid polling, consider running your Jetty or Tomcat behind an Nginx instance to make use of the Nginx HTTP Push Module. I have a somewhat cobwebby example here (this was pre-ClojureScript, so I wrote the client in plain JS). And there is also gifsockets.

How do I programmatically set gzip in Jetty?

I'm writing a web app using Noir and clojure, which uses Jetty. Jetty has two ways of using gzip, one for static, and one for dynamic, they are described in https://stackoverflow.com/a/9113129/104021. I want to turn on both static and dynamic gzipping, but our project doesn't use web.xml files, and doesn't want to start.
How do I programmatically set jetty to use gzip (ie without having a web.xml)?
In a Compojure app I'm working on, I have a Ring/Jetty adapter based on ring-jetty-adapter which programmatically configures Jetty to use a GzipHandler to gzip content dynamically.
(defn- configurator [server ring-handler]
(.setHandler server
(doto (new HandlerCollection)
(.addHandler (doto (new GzipHandler)
(.setHandler (proxy-handler ring-handler))
(.setMimeTypes "text/html,text/plain,text/xml,application/xhtml+xml,text/css,application/javascript,text/javascript,image/svg+xml")))
(.addHandler (doto (new RequestLogHandler) (.setRequestLog (NCSARequestLog.)))))))
This function takes a Server instance and my Ring handler and sets it up with some handlers. Note that the GzipHandler is a HandlerWrapper, so it takes my (proxied) Ring handler and delegates to it. I also add a logging handler which will be executed after the (gzip-wrapped) Ring handler.
Check out the complete working version.
See the startServer method in here:
http://git.eclipse.org/c/jetty/org.eclipse.jetty.project.git/tree/jetty-servlets/src/test/java/org/eclipse/jetty/servlets/GzipWithPipeliningTest.java
jetty uses itself extensively for testing so most embedded scenarios people need already exist in the unit tests somewhere, course finding them can be a bit of an issue :)

Executing code at regularly timed intervals in Clojure

What's the best way to make code run at regular intervals in Clojure ? I'm currently using java.util.concurrent.ScheduledExecutorService, but that's Java - is there a Clojure way of scheduling code to run at regular intervals, after a delay, cancellably ? All the Clojure code examples I've seen use Thread/sleep, which also seems too Java.
Well worth looking at the source code for Overtone, in particular the code for scheduling events at a particular time.
It's a music synthesis system so you have to hope they have the timing code right!!
Also they have helpfully separated the timing code out into a separate project (overtone/at-at) so that you can easily import it if you want. This provides a nice Clojure wrapper to the underlying Java libraries (i.e. ScheduledThreadPoolExecutor and friends). The syntax is like this:
;; run some-function every 500ms
(every 500 some-function)
You can also shedule events at specific times:
;; run some-other-function 10 seconds from now
(at (+ 10000 (now)) some-other-function)
From the clojure website http://clojure.org/concurrent_programming:
In all cases, Clojure does not replace the Java thread system, rather it works with it. Clojure functions are java.util.concurrent.Callable, therefore they work with the Executor framework etc.
It sounds like you are already doing it the right way.
(import 'java.util.concurrent.Executors)
(import 'java.util.concurrent.TimeUnit)
(.scheduleAtFixedRate (Executors/newScheduledThreadPool 1)
#(println "Hello") 0 5 TimeUnit/SECONDS)
I answered my own question # Implementing a cron type scheduler in clojure
maybe cronj might help?
The "tools.timer" library is a Java Timer wrapper: https://github.com/Ruiyun/tools.timer
It is very easy to use:
(use 'ruiyun.tools.timer)
(run-task! #(println "Say hello every 5 seconds.") :period 5000)