lib/resource.sgml

   1 <!--
   2         BIRD Programmer's Guide: Resources
   3
   4         (c) 2000 Martin Mares <mj@ucw.cz>
   5 -->
   6
   7 <chapt>Resources
   8
   9 <sect>Introduction
  10
  11 <p>Most large software projects implemented in classical procedural
  12 programming languages usually end up with lots of code taking care
  13 of resource allocation and deallocation. Bugs in such code are often
  14 very difficult to find, because they cause only `resource leakage',
  15 that is keeping a lot of memory and other resources which nobody
  16 references to.
  17
  18 <p>We've tried to solve this problem by employing a resource tracking
  19 system which keeps track of all the resources allocated by all the
  20 modules of BIRD, deallocates everything automatically when a module
  21 shuts down and it is able to print out the list of resources and
  22 the corresponding modules they are allocated by.
  23
  24 <p>Each allocated resource (from now we'll speak about allocated
  25 resources only) is represented by a structure starting with a standard
  26 header (struct <struct/resource/) consisting of a list node (resources are
  27 often linked to various lists) and a pointer to <struct/resclass/ -- a resource
  28 class structure pointing to functions implementing generic resource
  29 operations (such as freeing of the resource) for the particular resource
  30 type.
  31
  32 <p>There exist the following types of resources:
  33
  34 <itemize>
  35 <item><it/Resource pools/ (<struct/pool/)
  36 <item><it/Memory blocks/
  37 <item><it/Linear memory pools/ (<struct/linpool/)
  38 <item><it/Slabs/ (<struct/slab/)
  39 <item><it/Events/ (<struct/event/)
  40 <item><it/Timers/ (<struct/timer/)
  41 <item><it/Sockets/ (<struct/socket/)
  42 </itemize>