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bird/lib/resource.c

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/*
* BIRD Resource Manager
*
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* (c) 1998--2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "nest/bird.h"
#include "lib/resource.h"
#include "lib/string.h"
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/**
* DOC: Resource pools
*
* Resource pools (&pool) are just containers holding a list of
* other resources. Freeing a pool causes all the listed resources
* to be freed as well. Each existing &resource is linked to some pool
* except for a root pool which isn't linked anywhere, so all the
* resources form a tree structure with internal nodes corresponding
* to pools and leaves being the other resources.
*
* Example: Almost all modules of BIRD have their private pool which
* is freed upon shutdown of the module.
*/
struct pool {
resource r;
list inside;
const char *name;
};
static void pool_dump(resource *);
static void pool_free(resource *);
static resource *pool_lookup(resource *, unsigned long);
static size_t pool_memsize(resource *P);
static struct resclass pool_class = {
"Pool",
sizeof(pool),
pool_free,
pool_dump,
pool_lookup,
pool_memsize
};
pool root_pool;
static int indent;
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/**
* rp_new - create a resource pool
* @p: parent pool
* @name: pool name (to be included in debugging dumps)
*
* rp_new() creates a new resource pool inside the specified
* parent pool.
*/
pool *
rp_new(pool *p, const char *name)
{
pool *z = ralloc(p, &pool_class);
z->name = name;
init_list(&z->inside);
return z;
}
static void
pool_free(resource *P)
{
pool *p = (pool *) P;
resource *r, *rr;
r = HEAD(p->inside);
while (rr = (resource *) r->n.next)
{
r->class->free(r);
xfree(r);
r = rr;
}
}
static void
pool_dump(resource *P)
{
pool *p = (pool *) P;
resource *r;
debug("%s\n", p->name);
indent += 3;
WALK_LIST(r, p->inside)
rdump(r);
indent -= 3;
}
static size_t
pool_memsize(resource *P)
{
pool *p = (pool *) P;
resource *r;
size_t sum = sizeof(pool) + ALLOC_OVERHEAD;
WALK_LIST(r, p->inside)
sum += rmemsize(r);
return sum;
}
static resource *
pool_lookup(resource *P, unsigned long a)
{
pool *p = (pool *) P;
resource *r, *q;
WALK_LIST(r, p->inside)
if (r->class->lookup && (q = r->class->lookup(r, a)))
return q;
return NULL;
}
/**
* rmove - move a resource
* @res: resource
* @p: pool to move the resource to
*
* rmove() moves a resource from one pool to another.
*/
void rmove(void *res, pool *p)
{
resource *r = res;
if (r)
{
if (r->n.next)
rem_node(&r->n);
add_tail(&p->inside, &r->n);
}
}
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/**
* rfree - free a resource
* @res: resource
*
* rfree() frees the given resource and all information associated
* with it. In case it's a resource pool, it also frees all the objects
* living inside the pool.
*
* It works by calling a class-specific freeing function.
*/
void
rfree(void *res)
{
resource *r = res;
if (!r)
return;
if (r->n.next)
rem_node(&r->n);
r->class->free(r);
r->class = NULL;
xfree(r);
}
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/**
* rdump - dump a resource
* @res: resource
*
* This function prints out all available information about the given
* resource to the debugging output.
*
* It works by calling a class-specific dump function.
*/
void
rdump(void *res)
{
char x[16];
resource *r = res;
bsprintf(x, "%%%ds%%p ", indent);
debug(x, "", r);
if (r)
{
debug("%s ", r->class->name);
r->class->dump(r);
}
else
debug("NULL\n");
}
size_t
rmemsize(void *res)
{
resource *r = res;
if (!r)
return 0;
if (!r->class->memsize)
return r->class->size + ALLOC_OVERHEAD;
return r->class->memsize(r);
}
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/**
* ralloc - create a resource
* @p: pool to create the resource in
* @c: class of the new resource
*
* This function is called by the resource classes to create a new
* resource of the specified class and link it to the given pool.
* Allocated memory is zeroed. Size of the resource structure is taken
* from the @size field of the &resclass.
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*/
void *
ralloc(pool *p, struct resclass *c)
{
resource *r = xmalloc(c->size);
bzero(r, c->size);
r->class = c;
if (p)
add_tail(&p->inside, &r->n);
return r;
}
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/**
* rlookup - look up a memory location
* @a: memory address
*
* This function examines all existing resources to see whether
* the address @a is inside any resource. It's used for debugging
* purposes only.
*
* It works by calling a class-specific lookup function for each
* resource.
*/
void
rlookup(unsigned long a)
{
resource *r;
debug("Looking up %08lx\n", a);
if (r = pool_lookup(&root_pool.r, a))
rdump(r);
else
debug("Not found.\n");
}
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/**
* resource_init - initialize the resource manager
*
* This function is called during BIRD startup. It initializes
* all data structures of the resource manager and creates the
* root pool.
*/
void
resource_init(void)
{
root_pool.r.class = &pool_class;
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root_pool.name = "Root";
init_list(&root_pool.inside);
}
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/**
* DOC: Memory blocks
*
* Memory blocks are pieces of contiguous allocated memory.
* They are a bit non-standard since they are represented not by a pointer
* to &resource, but by a void pointer to the start of data of the
* memory block. All memory block functions know how to locate the header
* given the data pointer.
*
* Example: All "unique" data structures such as hash tables are allocated
* as memory blocks.
*/
struct mblock {
resource r;
unsigned size;
uintptr_t data_align[0];
byte data[0];
};
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static void mbl_free(resource *r UNUSED)
{
}
static void mbl_debug(resource *r)
{
struct mblock *m = (struct mblock *) r;
debug("(size=%d)\n", m->size);
}
static resource *
mbl_lookup(resource *r, unsigned long a)
{
struct mblock *m = (struct mblock *) r;
if ((unsigned long) m->data <= a && (unsigned long) m->data + m->size > a)
return r;
return NULL;
}
static size_t
mbl_memsize(resource *r)
{
struct mblock *m = (struct mblock *) r;
return ALLOC_OVERHEAD + sizeof(struct mblock) + m->size;
}
static struct resclass mb_class = {
"Memory",
0,
mbl_free,
mbl_debug,
mbl_lookup,
mbl_memsize
};
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/**
* mb_alloc - allocate a memory block
* @p: pool
* @size: size of the block
*
* mb_alloc() allocates memory of a given size and creates
* a memory block resource representing this memory chunk
* in the pool @p.
*
* Please note that mb_alloc() returns a pointer to the memory
* chunk, not to the resource, hence you have to free it using
* mb_free(), not rfree().
*/
void *
mb_alloc(pool *p, unsigned size)
{
struct mblock *b = xmalloc(sizeof(struct mblock) + size);
b->r.class = &mb_class;
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b->r.n = (node) {};
add_tail(&p->inside, &b->r.n);
b->size = size;
return b->data;
}
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/**
* mb_allocz - allocate and clear a memory block
* @p: pool
* @size: size of the block
*
* mb_allocz() allocates memory of a given size, initializes it to
* zeroes and creates a memory block resource representing this memory
* chunk in the pool @p.
*
* Please note that mb_allocz() returns a pointer to the memory
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* chunk, not to the resource, hence you have to free it using
* mb_free(), not rfree().
*/
void *
mb_allocz(pool *p, unsigned size)
{
void *x = mb_alloc(p, size);
bzero(x, size);
return x;
}
/**
* mb_realloc - reallocate a memory block
* @m: memory block
* @size: new size of the block
*
* mb_realloc() changes the size of the memory block @m to a given size.
* The contents will be unchanged to the minimum of the old and new sizes;
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* newly allocated memory will be uninitialized. Contrary to realloc()
* behavior, @m must be non-NULL, because the resource pool is inherited
* from it.
*
* Like mb_alloc(), mb_realloc() also returns a pointer to the memory
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* chunk, not to the resource, hence you have to free it using
* mb_free(), not rfree().
*/
void *
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mb_realloc(void *m, unsigned size)
{
struct mblock *b = SKIP_BACK(struct mblock, data, m);
b = xrealloc(b, sizeof(struct mblock) + size);
update_node(&b->r.n);
b->size = size;
return b->data;
}
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/**
* mb_free - free a memory block
* @m: memory block
*
* mb_free() frees all memory associated with the block @m.
*/
void
mb_free(void *m)
{
if (!m)
return;
struct mblock *b = SKIP_BACK(struct mblock, data, m);
rfree(b);
}
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#define STEP_UP(x) ((x) + (x)/2 + 4)
void
buffer_realloc(void **buf, unsigned *size, unsigned need, unsigned item_size)
{
unsigned nsize = MIN(*size, need);
while (nsize < need)
nsize = STEP_UP(nsize);
*buf = mb_realloc(*buf, nsize * item_size);
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*size = nsize;
}