From: Gary Lockyer <gary@catalyst.net.nz>
Date: Thu, 22 Mar 2018 22:29:25 +0000 (+1300)
Subject: ldb_mdb: Remove implicit read lock and remove transaction counter
X-Git-Url: http://git.samba.org/?p=metze%2Fsamba%2Fwip.git;a=commitdiff_plain;h=560ad7c32a12744361f0a155af77be6dd6f1c644

ldb_mdb: Remove implicit read lock and remove transaction counter

The way to know if we are in a transaction is if there is a non-NULL
transaction handle.

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
---

diff --git a/lib/ldb/ldb_mdb/ldb_mdb.c b/lib/ldb/ldb_mdb/ldb_mdb.c
index 6662aae434a3..94dd2096c81a 100644
--- a/lib/ldb/ldb_mdb/ldb_mdb.c
+++ b/lib/ldb/ldb_mdb/ldb_mdb.c
@@ -130,26 +130,21 @@ static struct lmdb_trans *lmdb_private_trans_head(struct lmdb_private *lmdb)
 	return ltx;
 }
 
+
 static MDB_txn *get_current_txn(struct lmdb_private *lmdb)
 {
 	MDB_txn *txn;
-	if (lmdb->read_txn != NULL) {
-		return lmdb->read_txn;
-	}
 
 	txn = lmdb_trans_get_tx(lmdb_private_trans_head(lmdb));
-	if (txn == NULL) {
-		int ret;
-		ret = mdb_txn_begin(lmdb->env, NULL, MDB_RDONLY, &txn);
-		if (ret != 0) {
-			lmdb->error = ret;
-			ldb_asprintf_errstring(lmdb->ldb,
-					       "%s failed: %s\n", __FUNCTION__,
-					       mdb_strerror(ret));
-		}
-		lmdb->read_txn = txn;
+	if (txn != NULL) {
+		return txn;
+	}
+	if (lmdb->read_txn != NULL) {
+		return lmdb->read_txn;
 	}
-	return txn;
+	lmdb->error = MDB_BAD_TXN;
+	ldb_set_errstring(lmdb->ldb, __location__":No active transaction\n");
+	return NULL;
 }
 
 static int lmdb_store(struct ltdb_private *ltdb,
@@ -195,10 +190,6 @@ static int lmdb_store(struct ltdb_private *ltdb,
 		MDB_val value;
 		lmdb->error = mdb_get(txn, dbi, &mdb_key, &value);
 		if (lmdb->error != MDB_SUCCESS) {
-			if (ltdb->read_lock_count == 0 && lmdb->read_txn != NULL) {
-				mdb_txn_commit(lmdb->read_txn);
-				lmdb->read_txn = NULL;
-			}
 			return ldb_mdb_error(lmdb->ldb, lmdb->error);
 		}
 		mdb_flags = 0;
@@ -303,11 +294,6 @@ done:
 		mdb_cursor_close(cursor);
 	}
 
-	if (ltdb->read_lock_count == 0 && lmdb->read_txn != NULL) {
-		mdb_txn_commit(lmdb->read_txn);
-		lmdb->read_txn = NULL;
-	}
-
 	if (lmdb->error != MDB_SUCCESS) {
 		return ldb_mdb_error(lmdb->ldb, lmdb->error);
 	}
@@ -411,10 +397,6 @@ static int lmdb_parse_record(struct ltdb_private *ltdb, struct ldb_val key,
 	if (lmdb->error != MDB_SUCCESS) {
 		/* TODO closing a handle should not even be necessary */
 		mdb_dbi_close(lmdb->env, dbi);
-		if (ltdb->read_lock_count == 0 && lmdb->read_txn != NULL) {
-			mdb_txn_commit(lmdb->read_txn);
-			lmdb->read_txn = NULL;
-		}
 		if (lmdb->error == MDB_NOTFOUND) {
 			return LDB_ERR_NO_SUCH_OBJECT;
 		}
@@ -426,11 +408,6 @@ static int lmdb_parse_record(struct ltdb_private *ltdb, struct ldb_val key,
 	/* TODO closing a handle should not even be necessary */
 	mdb_dbi_close(lmdb->env, dbi);
 
-	/* We created a read transaction, commit it */
-	if (ltdb->read_lock_count == 0 && lmdb->read_txn != NULL) {
-		mdb_txn_commit(lmdb->read_txn);
-		lmdb->read_txn = NULL;
-	}
 	return parser(key, data, ctx);
 }
 
@@ -454,7 +431,7 @@ static int lmdb_lock_read(struct ldb_module *module)
 	}
 
 	lmdb->error = MDB_SUCCESS;
-	if (ltdb->in_transaction == 0 &&
+	if (lmdb_transaction_active(ltdb) == false &&
 	    ltdb->read_lock_count == 0) {
 		lmdb->error = mdb_txn_begin(lmdb->env,
 					    NULL,
@@ -474,7 +451,7 @@ static int lmdb_unlock_read(struct ldb_module *module)
 	void *data = ldb_module_get_private(module);
 	struct ltdb_private *ltdb = talloc_get_type(data, struct ltdb_private);
 
-	if (ltdb->in_transaction == 0 && ltdb->read_lock_count == 1) {
+	if (lmdb_transaction_active(ltdb) == false && ltdb->read_lock_count == 1) {
 		struct lmdb_private *lmdb = ltdb->lmdb_private;
 		mdb_txn_commit(lmdb->read_txn);
 		lmdb->read_txn = NULL;
@@ -514,7 +491,6 @@ static int lmdb_transaction_start(struct ltdb_private *ltdb)
 		return LDB_ERR_PROTOCOL_ERROR;
 	}
 
-
 	ltx_head = lmdb_private_trans_head(lmdb);
 
 	tx_parent = lmdb_trans_get_tx(ltx_head);