Building 64 bit lzma file

Meilix contains the kernel and casper file in image-i386.tar.lzma. This lzma is a compression method for files. It provides a high compression ratio and fast decompression.

Lzma files contains the Meilix file system, we get the same content inside it which we get when when we mount an ISO file. Lzma file is basically an image of the Meilix Operating System.

Solution:

We need to build a lzma file of 64 bit for Meilix. If we extract the lzma file we will find a README file which contains all the information of the ISO used to build this lzma file.

When we search through the files we find a file named README.diskdefines which contains the information of the file system.

#define DISKNAME  Lubuntu 12.10 "Quantal Quetzal" - Release i386
#define TYPE  binary
#define TYPEbinary  1
#define ARCH  i386
#define ARCHi386  1
#define DISKNUM  1
#define DISKNUM1  1
#define TOTALNUM  0
#define TOTALNUM0  1

The first line depicts that name and version of the ISO with the architecture from where this file system has been taken.

So we thought to build the same system with release amd64.

We download the ISO and tried to compress it into lzma.tar.

Decompression of lzma.tar file is easy but to compress a file into lzma.tar is done as follows:

When using tar, the first word after -f is the output filename

tar -c --lzma -f foo.tar.lzma sourcefile(s)

We mounted the lubuntu 12.10 64 bit ISO and copied it into another folder. Then tried to compress it with lzma algorithm. It resulted in a big size file which can’t be pushed to Github.

So we find out that a file name filesystem.casper is largest in size and can also be removed. Therefore we removed that file and build the ISO again and pushed.
We tested the ISO and file that the build is working file.

Changes made:

  • One we need to push the 64 bit lzma
  • We need to edit this line in build.sh of Meilix

# Arch to build ISO for, i386 or amd64
arch=${1:-i386}

Finally we got the file as image-amd64.tar.lzma

So, if we look into the Readme file we can found the version which it used for building the zip.

#define DISKNAME  Ubuntu 12.10 "Quantal Quetzal" - Release amd64
#define TYPE  binary
#define TYPEbinary  1
#define ARCH  amd64
#define ARCHamd64  1
#define DISKNUM  1
#define DISKNUM1  1
#define TOTALNUM  0
#define TOTALNUM0  1

We can see that it is based on the same version but the architecture is different.

Resources

  1. GNU lzma tar: https://www.gnu.org/software/tar/manual/html_node/gzip.html
  2. Python lzma compression: https://docs.python.org/3/library/lzma.html

 

 

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Compressing Albums in the Phimpme Android Application

The Phimpme Android application comes in with all the functionalities ranging from viewing images to taking photos, editing pictures  and sharing them with the world from within a single application without having to switch to or install other social media apps on your mobile phone. Apart from these basic functionalities, the Phimpme Android app also comes with additional features to enhance user experience like the ability to compress the whole album with a large number of photos so that it becomes easier to share them. In this post, I will be explaining how we achieved this functionality to compress the Albums.

Step 1

The first thing we need to do before compressing an album is to get all the paths of the images in that album and store it in an ArrayList<String> so that it can be used later for the compression process. This can be done using the code snippet provided below, it stores all the paths of the file in a particular folder whose name ends with .jpg

path = new ArrayList<>();
File folder = new File(getAlbums().getSelectedAlbum(0).getPath() + "/");
File[] fpath = folder.listFiles();
for(int i = 0; i < fpath.length; i++){
   if(fpath[i].getPath().endsWith(".jpg") ){
       path.add(fpath[i].getPath());
   }
}

Step 2

Since the compression is a heavy task, we can make use of an AsyncTask to run the task on the background thread so that the user experience is not at all hampered. In the onPreExecute method of the AsyncTask, we need to display the Notification that the compression of the particular album has started, for this we have made use of the Notification handler class that we have created in the Phimpme Android application to ease the process of displaying the notification and to avoid repetition of codes. The onPreExecute method of the AsyncTask is given below.

@Override
protected void onPreExecute() {
   super.onPreExecute();
   NotificationHandler.make(R.string.folder, R.string.zip_fol, R.drawable.ic_archive_black_24dp );
}

Step 3

On the doInBackground method of the AsyncTask, we run the process to compress the files one by one. For this we will make use of the ZipEntry class which is used to represent a zip file entry in Android/Java. First we will create a File with the .zip extension.  After this, we will make use of an object of the class ZipOutputStream as depicted in the code snippet provided below.

BufferedInputStream origin = null; 
FileOutputStream dest = new FileOutputStream(_zipFile); 
ZipOutputStream out = new ZipOutputStream(new BufferedOutputStream(dest)); 
byte data[] = new byte[BUFFER];

After initializing the ZipOutPutStream object, we will put the zip entries in it by using the putNextEntry function of the class. To create a Zip entry of a file, we need to make use of for loop to generate the object of type ZipEntry and after that by using the putNextEntry function of the class, we will put the entries one by one as depicted in the code snippet given below.

for (int i = 0; i < path.size(); i++) {
FileInputStream fi = new FileInputStream(path.get(i));
origin = new BufferedInputStream(fi, BUFFER);
ZipEntry entry = new ZipEntry(path.get(i).substring(path.get(i).lastIndexOf("/") + 1));
out.putNextEntry(entry);

While preparing the Zip file, we will update the progress of the compression operation by making use of the Notification handler class.

This is how we have implemented the feature to compress the Albums in the Phimpme Android Application. To get the full source code for the same, please check the Phimpme Android GitHub repository listed on the resources below.

Resources

  1. StackOverflow – Compressing Files in Android – https://stackoverflow.com/questions/25562262/how-to-compress-files-into-zip-folder-in-android
  2. Blog – Compressing Files in Android programmatically – http://stacktips.com/tutorials/android/how-to-programmatically-zip-and-unzip-file-in-android
  3. GitHub – Phimpme Android Repository – https://github.com/fossasia/phimpme-android/
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Optimizing page load time

The average size of a web page has been growing at an accelerating rate over the last few years. Last week, when the open-event webapp was tested, it was very slow to load because of loading 67.2 MB data ( which contained audio and image files ) on the web page.I have taken following steps which are good to read to make any web application load faster.

1. Stop preloading of audio files

The HTML5 audio player loads all audio files by default on the page. To stop this we have to change the code as

<audio controls preload="none">
 <source src="{{audio}}" type="audio/mpeg">
 </audio>

Setting preload option to none help us to load audio only when it is clicked. Hence it decreases the HTTP calls and decreases the page loading time.

Previously

Network tab with Audio files takes 68.0MB  load and 13.6 minute loading time.

fail

Now

29

Network tab with option <audio controls preloaded=”none”> takes 1.1 MB load and  1 minute loading time. This was a huge improvement but more optimizations can be done.

2. Using Compression Middleware

Express compression middleware works like a charm by compressing the response coming to the web page. It is too simple to add.

$ npm install compression
var compression = require('compression')
var express = require('express')

var app = express()

// compress all requests
app.use(compression())

// add all routes

This has compressed the responses and decreased the page load time.

3.  Reduce the number of HTTP requests

Another great way of speeding up your web pages is to simply reduce the number of files that need to be loaded.

Combine files

Combining multiple stylesheets into one file is a really useful way of eliminating extra HTTP requests. This strategy can also be adopted for your JavaScript files. A single larger CSS or JavaScript file will often load quicker because more time can be spent downloading the data rather than establishing multiple connections to a server.

After such optimizations, the webapp loads now in 8-15 seconds with DOM loaded in 2 seconds.

fulloptimize

The result of these optimizations are awesome. We can test the page speed by using various tools like pagespeed, speedtracer etc.

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Using compression middleware in Node/Express

If you’re using ExpressJS to host your server, there’s a small performance tweak that you can do (works on universally on any kind of server – HTML templates to JSON REST APIs to image servers) – which is to enable GZIP compression.

The changed required to do it should be very simple. First install the compression npm package

 npm install --save compression

In you app.js (or wherever you start your express server), modify the code to include the compression middleware like this

var express = require('express);
var app = express();

var compression = require('compression');

app.use(compression());

// Rest of your app code
// app.get (endpoint, callback) 
// app.listen(port, callback)

This should easily reduce page loads time to the order of 15-20%.

For example, page load before compression middleware added 72f7abf2-4899-11e6-9cd5-68a7addaf3a6

 

And Page load time after compression is added69e6fba8-4899-11e6-9626-a25c26ea7d2b

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