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WebSVN – planix.SVN – Blame – /os/branches/feature_fixcpp/sys/src/libndb/ndbcache.c – Rev 2

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#include <u.h>
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#include <libc.h>
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#include <bio.h>
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#include <ndb.h>
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struct Ndbcache
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{
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	Ndbcache	*next;
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	char		*attr;
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	char		*val;
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	Ndbs		s;
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	Ndbtuple	*t;
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};
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enum
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{
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	Maxcached=	128,
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};
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static void
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ndbcachefree(Ndbcache *c)
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{
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	free(c->val);
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	free(c->attr);
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	if(c->t)
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		ndbfree(c->t);
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	free(c);
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}
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static Ndbtuple*
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ndbcopy(Ndb *db, Ndbtuple *from_t, Ndbs *from_s, Ndbs *to_s)
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{
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	Ndbtuple *first, *to_t, *last, *line;
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	int newline;
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	*to_s = *from_s;
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	to_s->t = nil;
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	to_s->db = db;
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	newline = 1;
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	last = nil;
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	first = nil;
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	line = nil;
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	for(; from_t != nil; from_t = from_t->entry){
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		to_t = ndbnew(from_t->attr, from_t->val);
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		/* have s point to matching tuple */
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		if(from_s->t == from_t)
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			to_s->t = to_t;
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		if(newline)
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			line = to_t;
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		else
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			last->line = to_t;
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		if(last != nil)
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			last->entry = to_t;
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		else {
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			first = to_t;
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			line = to_t;
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		}
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		to_t->entry = nil;
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		to_t->line = line;
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		last = to_t;
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		newline = from_t->line != from_t->entry;
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	}
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	ndbsetmalloctag(first, getcallerpc(&db));
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	return first;
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}
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/*
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 *  if found, move to front
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 */
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int
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_ndbcachesearch(Ndb *db, Ndbs *s, char *attr, char *val, Ndbtuple **t)
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{
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	Ndbcache *c, **l;
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	*t = nil;
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	c = nil;
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	for(l = &db->cache; *l != nil; l = &(*l)->next){
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		c = *l;
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		if(strcmp(c->attr, attr) == 0 && strcmp(c->val, val) == 0)
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			break;
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	}
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	if(*l == nil)
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		return -1;
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	/* move to front */
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	*l = c->next;
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	c->next = db->cache;
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	db->cache = c;
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	*t = ndbcopy(db, c->t, &c->s, s);
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	return 0;
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}
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Ndbtuple*
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_ndbcacheadd(Ndb *db, Ndbs *s, char *attr, char *val, Ndbtuple *t)
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{
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	Ndbcache *c, **l;
102 
 
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	c = mallocz(sizeof *c, 1);
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	if(c == nil)
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		return nil;
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	c->attr = strdup(attr);
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	if(c->attr == nil)
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		goto err;
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	c->val = strdup(val);
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	if(c->val == nil)
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		goto err;
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	c->t = ndbcopy(db, t, s, &c->s);
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	if(c->t == nil && t != nil)
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		goto err;
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	/* add to front */
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	c->next = db->cache;
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	db->cache = c;
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120 
	/* trim list */
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	if(db->ncache < Maxcached){
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		db->ncache++;
123 
		return t;
124 
	}
125 
	for(l = &db->cache; (*l)->next; l = &(*l)->next)
126 
		;
127 
	c = *l;
128 
	*l = nil;
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err:
130 
	ndbcachefree(c);
131 
	ndbsetmalloctag(t, getcallerpc(&db));
132 
	return t;
133 
}
134 
 
135 
void
136 
_ndbcacheflush(Ndb *db)
137 
{
138 
	Ndbcache *c;
139 
 
140 
	while(db->cache != nil){
141 
		c = db->cache;
142 
		db->cache = c->next;
143 
		ndbcachefree(c);
144 
	}
145 
	db->ncache = 0;
146 
}