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Created by Dr. Xi on April 27, 2011 15:58:31    Last update: April 27, 2011 20:05:22
From JavaDoc : java.util.concurrent.locks.ReentrantLock is a reentrant mutual exclusion Lock with the same basic behavior and semantics as the implicit monitor lock accessed using synchronized methods and statements, but with extended capabilities. The extended capabilities are: tryLock() : acquire the lock if possible, otherwise immediately return false. tryLock(long timeout, TimeUnit unit) : acquire the lock within the timeout, return false after timeout. lockInterruptibly() : try to acquire the lock and enter wait state, but can be interrupted by other threads and exit waiting. The following shows how java.util.concurrent.locks.ReentrantLock can be used. Start two threads to manipulate the same counter, one incrementing, the other decrementing. Since the counter is incremented and decremented the same number of times, in the end, it should be 0. Without locking,...
Created by Dr. Xi on February 09, 2011 15:35:41    Last update: February 09, 2011 15:36:08
Perl BEGIN and END blocks are executed at the beginning and at the end of a running Perl program. By the Perl doc : A BEGIN code block is executed a s soon as possible , that is, the moment it is completely defined, even before the rest of the containing file (or string) is parsed . You may have multiple BEGIN blocks within a file (or eval'ed string); they will execute in order of definition. Because a BEGIN code block executes immediately, it can pull in definitions of subroutines and such from other files in time to be visible to the rest of the compile and run time. Once a BEGIN has run, it is immediately undefined and any code it used is returned...
Created by Dr. Xi on September 29, 2008 23:21:38    Last update: January 16, 2010 23:36:05
Create a startup script for inetd Copy /etc/init.d/skeleton to /etc/init.d/inetd . Change the top section of the script to read: PATH=/usr/sbin:/usr/bin:/sbin:/bin DESC="In... Now inetd can be stopped/started/restarted like this: sudo /etc/init.d/inetd stop sudo /etc/init.... Add links to rc*.d $ sudo update-rc.d inetd defaults Adding sy... If you no longer need to start inetd at boot up: $ sudo update-rc.d -f inetd remove update-r... This would remove the links from the start up sequence but leave /etc/init.d/inetd in place. Contents of /etc/init.d/skeleton : #! /bin/sh ### BEGIN INIT INFO # Provide...
Created by Dr. Xi on October 09, 2009 19:27:22    Last update: October 09, 2009 19:30:01
PL/SQL code from Pandazen : CREATE OR REPLACE FUNCTION GET_INSERT_SCRIPT(V_TAB... Usage: To create the script for generating the INSERT statements: set head off set pages 0 set trims on set... Run the resulting script to generate the INSERT script: set pages 0 set trims on set lines 2000 ... PL/SQL code from Oracle Ask Tom set serveroutput on size 100000 set feedbac...