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  One reason why mcrypt responds slowly

This morning one colleague came over and talked about one script which used mcrypt responded very slowly, the server configurations are fine. But the reason for the slowness is unknown. Here is one script which reproduces the issue: <?php $dmcryptText = "dummy"; $key = "foobar"; $size = mcrypt_get_iv_size(MCRYPT_BLOWFISH,MCRYPT_MODE_ECB); $iv = mcrypt_create_iv($size); //Take care $m = mcrypt_ecb(MCRYPT_BLOWFISH, $key, $dmcryptText, MCRYPT_DECRYPT, $iv); var_dump($m); When 20 requests of&...

   SOLUTION,SLOW,MCRYPT,RESPONSE,PHP     2012-09-27 12:03:16

  Understanding abstract interface in Java

Have you read about an interface declaration as public abstract interface InterfaceName in Java? At the first glance, is it a weird declaration? Why should we declare an interface as abstract? For example, we may see below code in some projects: public abstract interface MyInterface { public void check(); public abstract boolean check(boolean really); } Actually here abstract is redundant, an interface is implicitly abstract, we no need to put an abstract in front of interface. But it do...

   Java,abstract interface     2014-08-18 23:07:27

  When will resizing be triggered in Java HashMap?

HashMap is one of the most frequently used collection types in Java, it stores key-value pairs. Ideally it expects to use hash table which expects the data access time complexity to be O(1), however, due to hash conflicts, in reality, it uses linked list or red-black tree to store data which makes the worst case time complexity to be O(logn).  Although collections are using data structures like arrays and linked lists, unlike arrays, they will dynamically resize when there is not enough spa...

   JAVA,RESIZE,HASHMAP,THRESHOLD     2020-05-02 20:41:19

  An alternative way to parse URL in JavaScript

Normally when we need to process URL in JavaScript, we may use the location object. Then we can use location.hostname,location.href,location.port etc to get the information we need. In this post, we will parse an URL with an alternative way. We can use an URL to create a DOM object by calling document.createElement("a"). The complete code is: function parseURL(url) { var a = document.createElement('a'); a.href = url; return { source: url, protocol: a.protocol.replace(':',''), host: a.ho...

   URL,location,parse     2014-03-03 07:05:11

  Use progressive JPEG to improve user experience

JPEG image files can have two different save types : Baseline JPEG and Progressive JPEG. Both of them have the same extension name but with different display effect. Baseline JPEG This type of JPEG files are scanned from top to bottom consecutively, each line of the image data will be saved sequentially. When opening this kind of images, data will be displayed with the save order line by line until all the data are read. If the image size is very large or network speed is very slow, the image wi...

   USER EXPERIENCE,PROGRESSIVE JPEG,BASELINE JPEG     2013-07-25 08:11:50

  What does super.clone() do?

Object class has a protected clone() method declared to make it possible for all classes make a clone of itself when needed. The clone() is often used when a new instance of the class is needed while at the same time to maintain the same state as the original object. Any class which wants to have clone enabled has to implement the marker interface Cloneable. If a class which implements Cloneable doesn't override the Object.clone() method, the Object.clone() method will be called to just make a b...

   Cloneable,super.clone(),clone,Java     2015-01-07 05:25:52

  PHP buffer: output_buffering and ob_start

buffer is one piece of memory section, it is usually 4Kb in Linux. It is mainly used between different devices with different speed or different priorities. With buffer, the waiting time between different processes will be reduced. Here is one simple example, when you type something in a text editor, every time when you type a character, the operating system will not write it to the disk directly, instead it will write it to buffer first When the buffer is full, the data in the buffer will be wr...

   PHP buffer,output_buffering,ob_start     2013-06-20 22:54:15

  Maybe we need //Comment comment

Do we need comment in our programs? Depends, if we can write a program which can clearly tell s the reader what the program does, then we had better to avoid unnecessary comments. However, if the program we develop is complex enough and it involves some uncommon logic which needs more explanation, then we have to add comment and make sure the comment we add can correctly tell the readers what we do. The worst scenarios is not you forget or you don't want to add comment, it's that you add comment...

   comment,programming     2014-07-23 04:38:04

  Find max subarray of an array

In computer science, the maximum subarray problem is the task of finding the contiguous subarray within a one-dimensional array of numbers (containing at least one positive number) which has the largest sum. For example, for the sequence of values −2, 1, −3, 4, −1, 2, 1, −5, 4; the contiguous subarray with the largest sum is 4, −1, 2, 1, with sum 6. The problem was first posed by Ulf Grenander of Brown University in 1977,...

   Max Subarray, Divide and conquer,Kadane     2013-04-22 11:50:35

  Remove browse button from input type=file

In Web 2.0 era, many websites will ask the user to upload their avatar when creating their profile. In HTML, the input control we should use is input="file". This is a file control provided by the browser vendor and it should be ran in a sandbox for security consideration. Browsers don't provide ways to choose file from local and upload to the remote server without the input="file" control.  There is one annoying part about the input="file", which is a default button named "Choose File" or...

   file,html,browse,remove browse button     2015-07-12 05:17:51

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