C Coding Tip - Self-Manage Memory Alllocation

An anonymous reader inputs: "The C programming language defines two standard memory management functions: malloc() and free(). C programmers frequently use those functions to allocate buffers at run time to pass data between functions. In many situations, however, you cannot predetermine the actual sizes required for the buffers, which may cause several fundamental problems for constructing complex C programs. This article advocates a self-managing, abstract data buffer. It outlines a pseudo-C implementation of the abstract buffer and details the advantages of adopting this mechanism."

Comments

Re:Um

[Tom7]

Of course, there are also hard real-time garbage collectors (ie Cheng's), though I don't think you'll find them in general-purpose production compilers. However, you will find good garbage collectors in a number of real production compilers (say, in mlton). It's definitely worth benchmarking.

Vstr

[Nevyn]

The article basically proposes a very bad implementation of Vstr, most of the advise was extremly simplified at best but more likely just uninformed: an "efficient" abstract buffer that mixes shorts and pointers -- words almost fail me, how to solve the problem of "what do you do with the data when it's all in the buffer" -- "let's just copy it back out again (hey whats a couple of extra copies between friends). Representing in memory object sizes with "long int" *sigh*.

If you are interested in the article, go read this explanation of why you want it for security and this explanation of why you want it for speed .

Vstr is LGPL, has actual benchmark data behind the block sizes it picks, has an extensive test suite ... and has documentation for the many functions that come with the library (including a fully compliant printf like function). Of course, I don't have a PhD ... but after reading this, you might well count that as a plus too

Not News

[SkewlD00d]

Embedded systems do this, they have a pool of Buffers and a BufferManager that allows you to do effectively your own memory mangement (and in some cases, static memory management). malloc() and free() are usually really slow, so if you can save 99% of those calls by reusing memory blocks, you can really speed up your programs.