Add a in-memory cache

This is a more general API that caches data with a LRU scheme. See
include/cache.h. No comments yet, I'm still working on it. But Jeremy has given
me a hint in one of his checkins that he would like to make use of this now.

The idea is that we get rid of all our silly little caches and merge them all
into one cache that we can then very easily trim, for example even with a
smbcontrol message if someone decides memory is tight. The main user is the
stat cache, this patch also converts the getwd cache. More caches to come.
(This used to be commit 7a911b35713538d82001a3c9f34152e293fe1943)

2 files changed, 89 insertions, 0 deletions

diff --git a/source3/torture/torture.c b/source3/torture/torture.c
index ad57470c61..082949e0af 100644
--- a/source3/torture/torture.c
+++ b/source3/torture/torture.c
@@ -5042,6 +5042,81 @@ static bool run_local_rbtree(int dummy)
 	return ret;
 }
 
+static bool data_blob_equal(DATA_BLOB a, DATA_BLOB b)
+{
+	if (a.length != b.length) {
+		printf("a.length=%d != b.length=%d\n",
+		       (int)a.length, (int)b.length);
+		return false;
+	}
+	if (memcmp(a.data, b.data, a.length) != 0) {
+		printf("a.data and b.data differ\n");
+		return false;
+	}
+	return true;
+}
+
+static bool run_local_memcache(int dummy)
+{
+	struct memcache *cache;
+	DATA_BLOB k1, k2;
+	DATA_BLOB d1, d2, d3;
+	DATA_BLOB v1, v2, v3;
+
+	cache = memcache_init(NULL, 100);
+
+	if (cache == NULL) {
+		printf("memcache_init failed\n");
+		return false;
+	}
+
+	d1 = data_blob_const("d1", 2);
+	d2 = data_blob_const("d2", 2);
+	d3 = data_blob_const("d3", 2);
+
+	k1 = data_blob_const("d1", 2);
+	k2 = data_blob_const("d2", 2);
+
+	memcache_add(cache, STAT_CACHE, k1, d1);
+	memcache_add(cache, GETWD_CACHE, k2, d2);
+
+	if (!memcache_lookup(cache, STAT_CACHE, k1, &v1)) {
+		printf("could not find k1\n");
+		return false;
+	}
+	if (!data_blob_equal(d1, v1)) {
+		return false;
+	}
+
+	if (!memcache_lookup(cache, GETWD_CACHE, k2, &v2)) {
+		printf("could not find k2\n");
+		return false;
+	}
+	if (!data_blob_equal(d2, v2)) {
+		return false;
+	}
+
+	memcache_add(cache, STAT_CACHE, k1, d3);
+
+	if (!memcache_lookup(cache, STAT_CACHE, k1, &v3)) {
+		printf("could not find replaced k1\n");
+		return false;
+	}
+	if (!data_blob_equal(d3, v3)) {
+		return false;
+	}
+
+	memcache_add(cache, GETWD_CACHE, k1, d1);
+
+	if (memcache_lookup(cache, GETWD_CACHE, k2, &v2)) {
+		printf("Did find k2, should have been purged\n");
+		return false;
+	}
+
+	TALLOC_FREE(cache);
+	return true;
+}
+
 static double create_procs(bool (*fn)(int), bool *result)
 {
 	int i, status;
@@ -5196,6 +5271,7 @@ static struct {
 	{ "LOCAL-SUBSTITUTE", run_local_substitute, 0},
 	{ "LOCAL-GENCACHE", run_local_gencache, 0},
 	{ "LOCAL-RBTREE", run_local_rbtree, 0},
+	{ "LOCAL-MEMCACHE", run_local_memcache, 0},
 	{NULL, NULL, 0}};
 
 
diff --git a/source3/torture/vfstest.c b/source3/torture/vfstest.c
index 1436ecc022..7e4ee624a1 100644
--- a/source3/torture/vfstest.c
+++ b/source3/torture/vfstest.c
@@ -495,6 +495,19 @@ struct messaging_context *smbd_messaging_context(void)
 	return ctx;
 }
 
+struct memcache *smbd_memcache(void)
+{
+	static struct memcache *cache;
+
+	if (!cache
+	    && !(cache = memcache_init(NULL,
+				       lp_max_stat_cache_size()*1024))) {
+
+		smb_panic("Could not init smbd memcache");
+	}
+	return cache;
+}
+
 /* Main function */
 
 int main(int argc, char *argv[])