1 files changed, 166 insertions, 0 deletions
diff --git a/src/lib9p/intmap.c b/src/lib9p/intmap.c
new file mode 100644
index 00000000..48695675
--- /dev/null
+++ b/src/lib9p/intmap.c
@@ -0,0 +1,166 @@
+#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;
+}