manualgc

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A manual garbage collector for C

Copyright (c) 2008 ,
 	Cloud Wu . All rights reserved.

http://code.google.com/p/manualgc/
http://www.codingnow.com

ANY USE IS AT YOUR OWN RISK

At first, you should call "gc_init" to initialize the environment. You may not call "gc_exit" at the end, becuase the OS will release all the resouce used by your process.

void
gc_init();

void
gc_exit();

Then, you can use 'gc_malloc' to allocate a memory block . It's return value is the pointer to the memory (like malloc).

void* 
gc_malloc(size_t sz,void *parent,void (*finalizer)(void *));

void* 
gc_realloc(void *p,size_t sz,void *parent);

*sz* is the the size requested

*parent* should be the memory's life time depend on.
	*parent* can be 0 , that is to say the memory is temporary.

*finalizer* will be called when the memory collect.
	*finalizer* can be 0 , collector will do nothing.

"gc_enter" and "gc_leave" is important , they tell the collector the life time of temporary memory blocks. All the memory allocated by "gc_new" after a "gc_enter" can be collect after "gc_leave", only if you link them to the others be related to the root , or tell "gc_leave" what you want to extend the life time.

void 
gc_enter();

void 
gc_leave(void *p,...);

You don't need put enter/leave in every function. If your program have a main loop, put one "gc_enter" before entering the main loop, and put one "gc_leave" is enough. For example:

while (!quit) {
	gc_enter();
	quit=mainloop();
	gc_leave(0);
}

You can use "gc_link" to establish or remove the relationship of two memory block. (ps. Pass parent into gc_malloc or gc_realloc will establish the relationship automatic)

void 
gc_link(void *parent,void *prev,void *now);

Unlink "prev" from "parent" first, and then link "now" to the 
"parent". For example, If you do 

	a->b = c;	// a and c are both gc memory block

Then you should call

	gc_link(a,a->b,c);

You can also link a memory block to the root by pass "parent" 0.
This is useful when you want to hold a global variable.

Collector will not be executed automatically.

void 
gc_collect();

This will collect all the memory block that can no longer be 
otherwise accessed. Before free it , collector will call the 
finalizer if you provided.

void 
gc_dryrun();

Only for debug, it will print some useful information instead of 
collecting the garbage.