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