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#include <u.h>
#include <libc.h>
#include <auth.h>
#include <fcall.h>
#include <thread.h>
#include <9p.h>
enum {
NHASH = 128
};
typedef struct Intlist Intlist;
struct Intlist
{
ulong id;
void* aux;
Intlist* link;
};
struct Intmap
{
RWLock rwlock;
Intlist* hash[NHASH];
void (*inc)(void*);
};
static ulong
hashid(ulong id)
{
return id%NHASH;
}
static void
nop(void *v)
{
USED(v);
}
Intmap*
allocmap(void (*inc)(void*))
{
Intmap *m;
m = emalloc9p(sizeof(*m));
if(inc == nil)
inc = nop;
m->inc = inc;
return m;
}
void
freemap(Intmap *map, void (*destroy)(void*))
{
int i;
Intlist *p, *nlink;
if(destroy == nil)
destroy = nop;
for(i=0; i<NHASH; i++){
for(p=map->hash[i]; p; p=nlink){
nlink = p->link;
destroy(p->aux);
free(p);
}
}
free(map);
}
static Intlist**
llookup(Intmap *map, ulong id)
{
Intlist **lf;
for(lf=&map->hash[hashid(id)]; *lf; lf=&(*lf)->link)
if((*lf)->id == id)
break;
return lf;
}
/*
* The RWlock is used as expected except that we allow
* inc() to be called while holding it. This is because we're
* locking changes to the tree structure, not to the references.
* Inc() is expected to have its own locking.
*/
void*
lookupkey(Intmap *map, ulong id)
{
Intlist *f;
void *v;
rlock(&map->rwlock);
if(f = *llookup(map, id)){
v = f->aux;
map->inc(v);
}else
v = nil;
runlock(&map->rwlock);
return v;
}
void*
insertkey(Intmap *map, ulong id, void *v)
{
Intlist *f;
void *ov;
ulong h;
wlock(&map->rwlock);
if(f = *llookup(map, id)){
/* no decrement for ov because we're returning it */
ov = f->aux;
f->aux = v;
}else{
f = emalloc9p(sizeof(*f));
f->id = id;
f->aux = v;
h = hashid(id);
f->link = map->hash[h];
map->hash[h] = f;
ov = nil;
}
wunlock(&map->rwlock);
return ov;
}
int
caninsertkey(Intmap *map, ulong id, void *v)
{
Intlist *f;
int rv;
ulong h;
wlock(&map->rwlock);
if(*llookup(map, id))
rv = 0;
else{
f = emalloc9p(sizeof *f);
f->id = id;
f->aux = v;
h = hashid(id);
f->link = map->hash[h];
map->hash[h] = f;
rv = 1;
}
wunlock(&map->rwlock);
return rv;
}
void*
deletekey(Intmap *map, ulong id)
{
Intlist **lf, *f;
void *ov;
wlock(&map->rwlock);
if(f = *(lf = llookup(map, id))){
ov = f->aux;
*lf = f->link;
free(f);
}else
ov = nil;
wunlock(&map->rwlock);
return ov;
}
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