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authorVolker Lendecke <vl@sernet.de>2007-11-09 23:43:24 +0100
committerVolker Lendecke <vl@samba.org>2007-12-10 16:06:32 +0100
commitd5ab80054d3c1dde396c18ae506bb3713e84e7e6 (patch)
treec6953bf605e9aca1ebfbc10ab1160019ae1665f4 /source3/lib
parent8a8b146ead07149de57069ed803051ce460fa94b (diff)
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dbwrap_rbt
This is meant as a replacement for the internal tdb. To me it seems a bit silly that for in-memory structures we do our own memory management. With this rbt based approach we can make use of the system-supplied malloc. (This used to be commit 54e5d4404619443caed32e2acff8921cdbff9ed1)
Diffstat (limited to 'source3/lib')
-rw-r--r--source3/lib/dbwrap_rbt.c303
1 files changed, 303 insertions, 0 deletions
diff --git a/source3/lib/dbwrap_rbt.c b/source3/lib/dbwrap_rbt.c
new file mode 100644
index 0000000000..df568a0410
--- /dev/null
+++ b/source3/lib/dbwrap_rbt.c
@@ -0,0 +1,303 @@
+/*
+ Unix SMB/CIFS implementation.
+ Database interface wrapper around red-black trees
+ Copyright (C) Volker Lendecke 2007
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "rbtree.h"
+
+struct db_rbt_ctx {
+ struct rb_root tree;
+};
+
+struct db_rbt_rec {
+ struct db_rbt_ctx *db_ctx;
+ struct db_rbt_node *node;
+};
+
+/* The structure that ends up in the tree */
+
+struct db_rbt_node {
+ struct rb_node rb_node;
+ size_t keysize, valuesize;
+
+ /*
+ * key and value are appended implicitly, "data" is only here as a
+ * target for offsetof()
+ */
+
+ char data[];
+};
+
+/*
+ * dissect a db_rbt_node into its implicit key and value parts
+ */
+
+static void db_rbt_parse_node(struct db_rbt_node *node,
+ TDB_DATA *key, TDB_DATA *value)
+{
+ key->dptr = ((uint8 *)node) + offsetof(struct db_rbt_node, data);
+ key->dsize = node->keysize;
+ value->dptr = key->dptr + node->keysize;
+ value->dsize = node->valuesize;
+}
+
+static NTSTATUS db_rbt_store(struct db_record *rec, TDB_DATA data, int flag)
+{
+ struct db_rbt_rec *rec_priv = talloc_get_type_abort(
+ rec->private_data, struct db_rbt_rec);
+
+ struct db_rbt_node *node;
+
+ struct rb_node ** p;
+ struct rb_node * parent;
+
+ TDB_DATA this_key, this_val;
+
+ if (rec_priv->node != NULL) {
+
+ /*
+ * The record was around previously
+ */
+
+ db_rbt_parse_node(rec_priv->node, &this_key, &this_val);
+
+ SMB_ASSERT(this_key.dsize == rec->key.dsize);
+ SMB_ASSERT(memcmp(this_key.dptr, rec->key.dptr,
+ this_key.dsize) == 0);
+
+ if (this_val.dsize >= data.dsize) {
+ /*
+ * The new value fits into the old space
+ */
+ memcpy(this_val.dptr, data.dptr, data.dsize);
+ rec_priv->node->valuesize = data.dsize;
+ return NT_STATUS_OK;
+ }
+
+ /*
+ * We need to delete the key from the tree and start fresh,
+ * there's not enough space in the existing record
+ */
+
+ rb_erase(&rec_priv->node->rb_node, &rec_priv->db_ctx->tree);
+ SAFE_FREE(rec_priv->node);
+ }
+
+ node = (struct db_rbt_node *)SMB_MALLOC(
+ offsetof(struct db_rbt_node, data) + rec->key.dsize
+ + data.dsize);
+
+ if (node == NULL) {
+ return NT_STATUS_NO_MEMORY;
+ }
+
+ ZERO_STRUCT(node->rb_node);
+
+ node->keysize = rec->key.dsize;
+ node->valuesize = data.dsize;
+
+ db_rbt_parse_node(node, &this_key, &this_val);
+
+ memcpy(this_key.dptr, rec->key.dptr, node->keysize);
+ memcpy(this_val.dptr, data.dptr, node->valuesize);
+
+ parent = NULL;
+ p = &rec_priv->db_ctx->tree.rb_node;
+
+ while (*p) {
+ struct db_rbt_node *r;
+ TDB_DATA search_key, search_val;
+ int res;
+
+ parent = (*p);
+
+ r = (struct db_rbt_node *)
+ ((char *)(*p) - offsetof(struct db_rbt_node, rb_node));
+
+ db_rbt_parse_node(r, &search_key, &search_val);
+
+ res = memcmp(this_key.dptr, search_key.dptr,
+ MIN(this_key.dsize, search_key.dsize));
+
+ if ((res < 0)
+ || ((res == 0)
+ && (this_key.dsize < search_key.dsize))) {
+ p = &(*p)->rb_left;
+ }
+ else if ((res > 0)
+ || ((res == 0)
+ && (this_key.dsize > search_key.dsize))) {
+ p = &(*p)->rb_right;
+ }
+ else {
+ smb_panic("someone messed with the tree");
+ }
+ }
+
+ rb_link_node(&node->rb_node, parent, p);
+ rb_insert_color(&node->rb_node, &rec_priv->db_ctx->tree);
+
+ return NT_STATUS_OK;
+}
+
+static NTSTATUS db_rbt_delete(struct db_record *rec)
+{
+ struct db_rbt_rec *rec_priv = talloc_get_type_abort(
+ rec->private_data, struct db_rbt_rec);
+
+ if (rec_priv->node == NULL) {
+ return NT_STATUS_OK;
+ }
+
+ rb_erase(&rec_priv->node->rb_node, &rec_priv->db_ctx->tree);
+ SAFE_FREE(rec_priv->node);
+
+ return NT_STATUS_OK;
+}
+
+static struct db_record *db_rbt_fetch_locked(struct db_context *db_ctx,
+ TALLOC_CTX *mem_ctx,
+ TDB_DATA key)
+{
+ struct db_rbt_ctx *ctx = talloc_get_type_abort(
+ db_ctx->private_data, struct db_rbt_ctx);
+
+ struct db_rbt_rec *rec_priv;
+ struct db_record *result;
+ struct rb_node *n;
+
+ result = talloc(mem_ctx, struct db_record);
+
+ if (result == NULL) {
+ return NULL;
+ }
+
+ rec_priv = talloc(result, struct db_rbt_rec);
+
+ if (rec_priv == NULL) {
+ TALLOC_FREE(result);
+ return NULL;
+ }
+
+ rec_priv->db_ctx = ctx;
+
+ result->store = db_rbt_store;
+ result->delete_rec = db_rbt_delete;
+ result->private_data = rec_priv;
+
+ n = ctx->tree.rb_node;
+
+ while (n != NULL) {
+ struct db_rbt_node *r;
+ TDB_DATA search_key, search_val;
+ int res;
+
+ r = (struct db_rbt_node *)
+ ((char *)n - offsetof(struct db_rbt_node, rb_node));
+
+ db_rbt_parse_node(r, &search_key, &search_val);
+
+ res = memcmp(key.dptr, search_key.dptr,
+ MIN(key.dsize, search_key.dsize));
+
+ if ((res < 0)
+ || ((res == 0) && (key.dsize < search_key.dsize))) {
+ n = n->rb_left;
+ }
+ else if ((res > 0)
+ || ((res == 0) && (key.dsize > search_key.dsize))) {
+ n = n->rb_right;
+ }
+ else {
+ rec_priv->node = r;
+ result->key = search_key;
+ result->value = search_val;
+ return result;
+ }
+ }
+
+ result->key.dsize = key.dsize;
+ result->key.dptr = (uint8_t *)talloc_memdup(
+ result, key.dptr, key.dsize);
+
+ if (result->key.dptr == NULL) {
+ TALLOC_FREE(result);
+ return NULL;
+ }
+
+ rec_priv->node = NULL;
+ result->value.dsize = 0;
+ result->value.dptr = NULL;
+ return result;
+}
+
+static int db_rbt_fetch(struct db_context *db, TALLOC_CTX *mem_ctx,
+ TDB_DATA key, TDB_DATA *data)
+{
+ struct db_record *rec;
+
+ if (!(rec = db->fetch_locked(db, mem_ctx, key))) {
+ return -1;
+ }
+
+ data->dsize = rec->value.dsize;
+ data->dptr = (uint8 *)talloc_memdup(mem_ctx, rec->value.dptr,
+ rec->value.dsize);
+ TALLOC_FREE(rec);
+ return 0;
+}
+
+
+static int db_rbt_traverse(struct db_context *db,
+ int (*f)(struct db_record *db,
+ void *private_data),
+ void *private_data)
+{
+ return -1;
+}
+
+static int db_rbt_get_seqnum(struct db_context *db)
+{
+ return 0;
+}
+
+struct db_context *db_open_rbt(TALLOC_CTX *mem_ctx)
+{
+ struct db_context *result;
+
+ result = talloc(mem_ctx, struct db_context);
+
+ if (result == NULL) {
+ return NULL;
+ }
+
+ result->private_data = TALLOC_ZERO_P(result, struct db_rbt_ctx);
+
+ if (result->private_data == NULL) {
+ TALLOC_FREE(result);
+ return NULL;
+ }
+
+ result->fetch_locked = db_rbt_fetch_locked;
+ result->fetch = db_rbt_fetch;
+ result->traverse = db_rbt_traverse;
+ result->traverse_read = db_rbt_traverse;
+ result->get_seqnum = db_rbt_get_seqnum;
+
+ return result;
+}