1 files changed, 170 insertions, 173 deletions

diff --git a/source3/lib/tdb/common/transaction.c b/source3/lib/tdb/common/transaction.c
index 7eaacf7a16..2da09face0 100644
--- a/source3/lib/tdb/common/transaction.c
+++ b/source3/lib/tdb/common/transaction.c
@@ -87,13 +87,6 @@
 
 */
 
-struct tdb_transaction_el {
-	struct tdb_transaction_el *next, *prev;
-	tdb_off_t offset;
-	tdb_len_t length;
-	unsigned char *data;
-};
-
 /*
   hold the context of any current transaction
 */
@@ -105,12 +98,12 @@ struct tdb_transaction {
 	/* the original io methods - used to do IOs to the real db */
 	const struct tdb_methods *io_methods;
 
-	/* the list of transaction elements. We use a doubly linked
-	   list with a last pointer to allow us to keep the list
-	   ordered, with first element at the front of the list. It
-	   needs to be doubly linked as the read/write traversals need
-	   to be backwards, while the commit needs to be forwards */
-	struct tdb_transaction_el *elements, *elements_last;
+	/* the list of transaction blocks. When a block is first
+	   written to, it gets created in this list */
+	uint8_t **blocks;
+	uint32_t num_blocks;
+	uint32_t block_size;      /* bytes in each block */
+	uint32_t last_block_size; /* number of valid bytes in the last block */
 
 	/* non-zero when an internal transaction error has
 	   occurred. All write operations will then fail until the
@@ -134,52 +127,48 @@ struct tdb_transaction {
 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf, 
 			    tdb_len_t len, int cv)
 {
-	struct tdb_transaction_el *el;
-
-	/* we need to walk the list backwards to get the most recent data */
-	for (el=tdb->transaction->elements_last;el;el=el->prev) {
-		tdb_len_t partial;
+	uint32_t blk;
 
-		if (off+len <= el->offset) {
-			continue;
-		}
-		if (off >= el->offset + el->length) {
-			continue;
+	/* break it down into block sized ops */
+	while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
+		tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
+		if (transaction_read(tdb, off, buf, len2, cv) != 0) {
+			return -1;
 		}
+		len -= len2;
+		off += len2;
+		buf = (void *)(len2 + (char *)buf);
+	}
 
-		/* an overlapping read - needs to be split into up to
-		   2 reads and a memcpy */
-		if (off < el->offset) {
-			partial = el->offset - off;
-			if (transaction_read(tdb, off, buf, partial, cv) != 0) {
-				goto fail;
-			}
-			len -= partial;
-			off += partial;
-			buf = (void *)(partial + (char *)buf);
-		}
-		if (off + len <= el->offset + el->length) {
-			partial = len;
-		} else {
-			partial = el->offset + el->length - off;
-		}
-		memcpy(buf, el->data + (off - el->offset), partial);
-		if (cv) {
-			tdb_convert(buf, len);
-		}
-		len -= partial;
-		off += partial;
-		buf = (void *)(partial + (char *)buf);
-		
-		if (len != 0 && transaction_read(tdb, off, buf, len, cv) != 0) {
+	if (len == 0) {
+		return 0;
+	}
+
+	blk = off / tdb->transaction->block_size;
+
+	/* see if we have it in the block list */
+	if (tdb->transaction->num_blocks <= blk ||
+	    tdb->transaction->blocks[blk] == NULL) {
+		/* nope, do a real read */
+		if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
 			goto fail;
 		}
-
 		return 0;
 	}
 
-	/* its not in the transaction elements - do a real read */
-	return tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv);
+	/* it is in the block list. Now check for the last block */
+	if (blk == tdb->transaction->num_blocks-1) {
+		if (len > tdb->transaction->last_block_size) {
+			goto fail;
+		}
+	}
+	
+	/* now copy it out of this block */
+	memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
+	if (cv) {
+		tdb_convert(buf, len);
+	}
+	return 0;
 
 fail:
 	TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
@@ -195,12 +184,8 @@ fail:
 static int transaction_write(struct tdb_context *tdb, tdb_off_t off, 
 			     const void *buf, tdb_len_t len)
 {
-	struct tdb_transaction_el *el, *best_el=NULL;
+	uint32_t blk;
 
-	if (len == 0) {
-		return 0;
-	}
-	
 	/* if the write is to a hash head, then update the transaction
 	   hash heads */
 	if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
@@ -209,106 +194,88 @@ static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
 		memcpy(&tdb->transaction->hash_heads[chain], buf, len);
 	}
 
-	/* first see if we can replace an existing entry */
-	for (el=tdb->transaction->elements_last;el;el=el->prev) {
-		tdb_len_t partial;
-
-		if (best_el == NULL && off == el->offset+el->length) {
-			best_el = el;
+	/* break it up into block sized chunks */
+	while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
+		tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
+		if (transaction_write(tdb, off, buf, len2) != 0) {
+			return -1;
 		}
-
-		if (off+len <= el->offset) {
-			continue;
-		}
-		if (off >= el->offset + el->length) {
-			continue;
+		len -= len2;
+		off += len2;
+		if (buf != NULL) {
+			buf = (const void *)(len2 + (const char *)buf);
 		}
+	}
 
-		/* an overlapping write - needs to be split into up to
-		   2 writes and a memcpy */
-		if (off < el->offset) {
-			partial = el->offset - off;
-			if (transaction_write(tdb, off, buf, partial) != 0) {
-				goto fail;
-			}
-			len -= partial;
-			off += partial;
-			buf = (const void *)(partial + (const char *)buf);
-		}
-		if (off + len <= el->offset + el->length) {
-			partial = len;
+	if (len == 0) {
+		return 0;
+	}
+
+	blk = off / tdb->transaction->block_size;
+	off = off % tdb->transaction->block_size;
+
+	if (tdb->transaction->num_blocks <= blk) {
+		uint8_t **new_blocks;
+		/* expand the blocks array */
+		if (tdb->transaction->blocks == NULL) {
+			new_blocks = malloc((blk+1)*sizeof(uint8_t *));
 		} else {
-			partial = el->offset + el->length - off;
+			new_blocks = realloc(tdb->transaction->blocks, (blk+1)*sizeof(uint8_t *));
 		}
-		memcpy(el->data + (off - el->offset), buf, partial);
-		len -= partial;
-		off += partial;
-		buf = (const void *)(partial + (const char *)buf);
-		
-		if (len != 0 && transaction_write(tdb, off, buf, len) != 0) {
+		if (new_blocks == NULL) {
+			tdb->ecode = TDB_ERR_OOM;
 			goto fail;
 		}
-
-		return 0;
+		memset(&new_blocks[tdb->transaction->num_blocks], 0, 
+		       (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
+		tdb->transaction->blocks = new_blocks;
+		tdb->transaction->num_blocks = blk+1;
+		tdb->transaction->last_block_size = 0;
 	}
 
-	/* see if we can append the new entry to an existing entry */
-	if (best_el && best_el->offset + best_el->length == off && 
-	    (off+len < tdb->transaction->old_map_size ||
-	     off > tdb->transaction->old_map_size)) {
-		unsigned char *data = best_el->data;
-		el = best_el;
-		el->data = (unsigned char *)realloc(el->data,
-						    el->length + len);
-		if (el->data == NULL) {
+	/* allocate and fill a block? */
+	if (tdb->transaction->blocks[blk] == NULL) {
+		tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
+		if (tdb->transaction->blocks[blk] == NULL) {
 			tdb->ecode = TDB_ERR_OOM;
 			tdb->transaction->transaction_error = 1;
-			el->data = data;
-			return -1;
+			return -1;			
 		}
-		if (buf) {
-			memcpy(el->data + el->length, buf, len);
-		} else {
-			memset(el->data + el->length, TDB_PAD_BYTE, len);
+		if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
+			tdb_len_t len2 = tdb->transaction->block_size;
+			if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
+				len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
+			}
+			if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size, 
+								   tdb->transaction->blocks[blk], 
+								   len2, 0) != 0) {
+				SAFE_FREE(tdb->transaction->blocks[blk]);				
+				tdb->ecode = TDB_ERR_IO;
+				goto fail;
+			}
+			if (blk == tdb->transaction->num_blocks-1) {
+				tdb->transaction->last_block_size = len2;
+			}			
 		}
-		el->length += len;
-		return 0;
 	}
-
-	/* add a new entry at the end of the list */
-	el = (struct tdb_transaction_el *)malloc(sizeof(*el));
-	if (el == NULL) {
-		tdb->ecode = TDB_ERR_OOM;
-		tdb->transaction->transaction_error = 1;		
-		return -1;
-	}
-	el->next = NULL;
-	el->prev = tdb->transaction->elements_last;
-	el->offset = off;
-	el->length = len;
-	el->data = (unsigned char *)malloc(len);
-	if (el->data == NULL) {
-		free(el);
-		tdb->ecode = TDB_ERR_OOM;
-		tdb->transaction->transaction_error = 1;		
-		return -1;
-	}
-	if (buf) {
-		memcpy(el->data, buf, len);
+	
+	/* overwrite part of an existing block */
+	if (buf == NULL) {
+		memset(tdb->transaction->blocks[blk] + off, 0, len);
 	} else {
-		memset(el->data, TDB_PAD_BYTE, len);
+		memcpy(tdb->transaction->blocks[blk] + off, buf, len);
 	}
-	if (el->prev) {
-		el->prev->next = el;
-	} else {
-		tdb->transaction->elements = el;
+	if (blk == tdb->transaction->num_blocks-1) {
+		if (len + off > tdb->transaction->last_block_size) {
+			tdb->transaction->last_block_size = len + off;
+		}
 	}
-	tdb->transaction->elements_last = el;
+
 	return 0;
 
 fail:
-	TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n", off, len));
-	tdb->ecode = TDB_ERR_IO;
+	TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n", 
+		 (blk*tdb->transaction->block_size) + off, len));
 	tdb->transaction->transaction_error = 1;
 	return -1;
 }
@@ -419,10 +386,14 @@ int tdb_transaction_start(struct tdb_context *tdb)
 		return -1;
 	}
 
+	/* a page at a time seems like a reasonable compromise between compactness and efficiency */
+	tdb->transaction->block_size = tdb->page_size;
+
 	/* get the transaction write lock. This is a blocking lock. As
 	   discussed with Volker, there are a number of ways we could
 	   make this async, which we will probably do in the future */
 	if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
+		SAFE_FREE(tdb->transaction->blocks);
 		SAFE_FREE(tdb->transaction);
 		return -1;
 	}
@@ -460,21 +431,12 @@ int tdb_transaction_start(struct tdb_context *tdb)
 	tdb->transaction->io_methods = tdb->methods;
 	tdb->methods = &transaction_methods;
 
-	/* by calling this transaction write here, we ensure that we don't grow the
-	   transaction linked list due to hash table updates */
-	if (transaction_write(tdb, FREELIST_TOP, tdb->transaction->hash_heads, 
-			      TDB_HASHTABLE_SIZE(tdb)) != 0) {
-		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to prime hash table\n"));
-		tdb->ecode = TDB_ERR_IO;
-		tdb->methods = tdb->transaction->io_methods;
-		goto fail;
-	}
-
 	return 0;
 	
 fail:
 	tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
 	tdb_transaction_unlock(tdb);
+	SAFE_FREE(tdb->transaction->blocks);
 	SAFE_FREE(tdb->transaction->hash_heads);
 	SAFE_FREE(tdb->transaction);
 	return -1;
@@ -486,6 +448,8 @@ fail:
 */
 int tdb_transaction_cancel(struct tdb_context *tdb)
 {	
+	int i;
+
 	if (tdb->transaction == NULL) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
 		return -1;
@@ -499,13 +463,13 @@ int tdb_transaction_cancel(struct tdb_context *tdb)
 
 	tdb->map_size = tdb->transaction->old_map_size;
 
-	/* free all the transaction elements */
-	while (tdb->transaction->elements) {
-		struct tdb_transaction_el *el = tdb->transaction->elements;
-		tdb->transaction->elements = el->next;
-		free(el->data);
-		free(el);
+	/* free all the transaction blocks */
+	for (i=0;i<tdb->transaction->num_blocks;i++) {
+		if (tdb->transaction->blocks[i] != NULL) {
+			free(tdb->transaction->blocks[i]);
+		}
 	}
+	SAFE_FREE(tdb->transaction->blocks);
 
 	/* remove any global lock created during the transaction */
 	if (tdb->global_lock.count != 0) {
@@ -515,7 +479,6 @@ int tdb_transaction_cancel(struct tdb_context *tdb)
 
 	/* remove any locks created during the transaction */
 	if (tdb->num_locks != 0) {
-		int i;
 		for (i=0;i<tdb->num_lockrecs;i++) {
 			tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
 				   F_UNLCK,F_SETLKW, 0, 1);
@@ -567,16 +530,24 @@ static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t
 */
 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
 {
-	struct tdb_transaction_el *el;
 	tdb_len_t recovery_size = 0;
+	int i;
 
 	recovery_size = sizeof(uint32_t);
-	for (el=tdb->transaction->elements;el;el=el->next) {
-		if (el->offset >= tdb->transaction->old_map_size) {
+	for (i=0;i<tdb->transaction->num_blocks;i++) {
+		if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
+			break;
+		}
+		if (tdb->transaction->blocks[i] == NULL) {
 			continue;
 		}
-		recovery_size += 2*sizeof(tdb_off_t) + el->length;
-	}
+		recovery_size += 2*sizeof(tdb_off_t);
+		if (i == tdb->transaction->num_blocks-1) {
+			recovery_size += tdb->transaction->last_block_size;
+		} else {
+			recovery_size += tdb->transaction->block_size;
+		}
+	}	
 
 	return recovery_size;
 }
@@ -669,7 +640,6 @@ static int tdb_recovery_allocate(struct tdb_context *tdb,
 static int transaction_setup_recovery(struct tdb_context *tdb, 
 				      tdb_off_t *magic_offset)
 {
-	struct tdb_transaction_el *el;
 	tdb_len_t recovery_size;
 	unsigned char *data, *p;
 	const struct tdb_methods *methods = tdb->transaction->io_methods;
@@ -677,6 +647,7 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
 	tdb_off_t recovery_offset, recovery_max_size;
 	tdb_off_t old_map_size = tdb->transaction->old_map_size;
 	uint32_t magic, tailer;
+	int i;
 
 	/*
 	  check that the recovery area has enough space
@@ -704,30 +675,43 @@ static int transaction_setup_recovery(struct tdb_context *tdb,
 	/* build the recovery data into a single blob to allow us to do a single
 	   large write, which should be more efficient */
 	p = data + sizeof(*rec);
-	for (el=tdb->transaction->elements;el;el=el->next) {
-		if (el->offset >= old_map_size) {
+	for (i=0;i<tdb->transaction->num_blocks;i++) {
+		tdb_off_t offset;
+		tdb_len_t length;
+
+		if (tdb->transaction->blocks[i] == NULL) {
 			continue;
 		}
-		if (el->offset + el->length > tdb->transaction->old_map_size) {
+
+		offset = i * tdb->transaction->block_size;
+		length = tdb->transaction->block_size;
+		if (i == tdb->transaction->num_blocks-1) {
+			length = tdb->transaction->last_block_size;
+		}
+		
+		if (offset >= old_map_size) {
+			continue;
+		}
+		if (offset + length > tdb->transaction->old_map_size) {
 			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
 			free(data);
 			tdb->ecode = TDB_ERR_CORRUPT;
 			return -1;
 		}
-		memcpy(p, &el->offset, 4);
-		memcpy(p+4, &el->length, 4);
+		memcpy(p, &offset, 4);
+		memcpy(p+4, &length, 4);
 		if (DOCONV()) {
 			tdb_convert(p, 8);
 		}
 		/* the recovery area contains the old data, not the
 		   new data, so we have to call the original tdb_read
 		   method to get it */
-		if (methods->tdb_read(tdb, el->offset, p + 8, el->length, 0) != 0) {
+		if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
 			free(data);
 			tdb->ecode = TDB_ERR_IO;
 			return -1;
 		}
-		p += 8 + el->length;
+		p += 8 + length;
 	}
 
 	/* and the tailer */
@@ -780,6 +764,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 	const struct tdb_methods *methods;
 	tdb_off_t magic_offset = 0;
 	uint32_t zero = 0;
+	int i;
 
 	if (tdb->transaction == NULL) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
@@ -799,7 +784,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 	}		
 
 	/* check for a null transaction */
-	if (tdb->transaction->elements == NULL) {
+	if (tdb->transaction->blocks == NULL) {
 		tdb_transaction_cancel(tdb);
 		return 0;
 	}
@@ -858,10 +843,21 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 	}
 
 	/* perform all the writes */
-	while (tdb->transaction->elements) {
-		struct tdb_transaction_el *el = tdb->transaction->elements;
+	for (i=0;i<tdb->transaction->num_blocks;i++) {
+		tdb_off_t offset;
+		tdb_len_t length;
 
-		if (methods->tdb_write(tdb, el->offset, el->data, el->length) == -1) {
+		if (tdb->transaction->blocks[i] == NULL) {
+			continue;
+		}
+
+		offset = i * tdb->transaction->block_size;
+		length = tdb->transaction->block_size;
+		if (i == tdb->transaction->num_blocks-1) {
+			length = tdb->transaction->last_block_size;
+		}
+
+		if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
 			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
 			
 			/* we've overwritten part of the data and
@@ -876,11 +872,12 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 			TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
 			return -1;
 		}
-		tdb->transaction->elements = el->next;
-		free(el->data); 
-		free(el);
+		SAFE_FREE(tdb->transaction->blocks[i]);
 	} 
 
+	SAFE_FREE(tdb->transaction->blocks);
+	tdb->transaction->num_blocks = 0;
+
 	if (!(tdb->flags & TDB_NOSYNC)) {
 		/* ensure the new data is on disk */
 		if (transaction_sync(tdb, 0, tdb->map_size) == -1) {