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diff --git a/lib/resource.sgml b/lib/resource.sgml new file mode 100644 index 0000000..4123dd6 --- /dev/null +++ b/lib/resource.sgml @@ -0,0 +1,50 @@ +<!-- + BIRD Programmer's Guide: Resources + + (c) 2000 Martin Mares <mj@ucw.cz> +--> + +<chapt>Resources + +<sect>Introduction + +<p>Most large software projects implemented in classical procedural +programming languages usually end up with lots of code taking care +of resource allocation and deallocation. Bugs in such code are often +very difficult to find, because they cause only `resource leakage', +that is keeping a lot of memory and other resources which nobody +references to. + +<p>We've tried to solve this problem by employing a resource tracking +system which keeps track of all the resources allocated by all the +modules of BIRD, deallocates everything automatically when a module +shuts down and it's is able to print out the list of resources and +the corresponding modules they are allocated by. + +<p>Each allocated resource (and from now we'll speak about allocated +resources only) is represented by a structure starting with a standard +header (struct <struct/resource/) consisting of a list node (resources are +often linked to various lists) and a pointer to <struct/resclass/ -- a resource +class structure pointing to functions implementing generic resource +operations (such as freeing of the resource) for the particular resource +type. + +<p>There exist the following types of resources: + +<itemize> +<item><it/Resource pools/ (<struct/pool/) +<item><it/Memory blocks/ +<item><it/Linear memory pools/ (<struct/linpool/) +<item><it/Slabs/ (<struct/slab/) +<item><it/Sockets/ (<struct/socket/) +<item><it/Events/ (<struct/event/) +<!-- + are there to keep track of deferred execution. + Since BIRD is single-threaded, it requires long lasting tasks to be split to smaller + parts, so that no module can monopolize the CPU. To split such a task, just create + an <struct/event/ resource, point it to the function you want to have called and call <func/ev_schedule()/ + to ask the core to run the event when nothing more important will require attention. + The actual implementation is system dependent. +--> +<item><it/Timers/ (<struct/timer/) +</itemize> |