Syntax and Semantic

Recently, I have been working on integrating Click Modular Router to work with both WiFi cards and USRPs to facilitate the development of cognitive radio testbeds. I am using GNURadio to control N210 USRPs . I found that developing routing hops to be interesting and worth sharing as it requires the USRP to simultaneously send and receive. This requires the transmission and reception to be on separated frequencies.  For transmission, first a client socket must be created in the click configuration code. Socket(TCP, localhost, 4002, Client true) Then, I used a thread to constantly listens on that socket and transmits the data once a new packet is received. This allows for the separation of tasks and good visibility of the transmission code. I noticed that there is a trend to include the transmission code within the main function which degrades the code readability. The thread takes as a parameter the top_block describing the data path on the USRP. clas...

Most programmers think “Threads” when they are told to make a piece of code that should run concurrently. Also it hits them right in the face the last time they tried to make a threaded programs when they were faced by the usual problems (Races, deadlocks, etc) which are hard to detect, debug and at some time to reproduce. The behavior of threads is too unexpected as it's fully controlled by the threads scheduler not by the programmer. Another issue, the overhead of creating threads which sometimes is painful which produces an important question “What is the alternative ?” Lets think of concurrency in the following way: we will receive all the requests at the same time and queue them. Then we will assign each of them to a specific function. When this function blocks (i.e. for IO requests) or finishes we will make another one start till it blocks or finishes and so on. The question you'll have in mind “Wait a minute, that's not concurrency!!” Well, think of it this way. You ...