Expanded error details if/when a transaction fails to renew, #164

dependencies/lmdb/libraries/liblmdb/mdb.c

@@ -3438,14 +3438,26 @@ mdb_txn_renew(MDB_txn *txn)
 {
 	int rc;
 
-	if (!txn || !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY|MDB_TXN_FINISHED))
+	if (!txn || !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY|MDB_TXN_FINISHED)) {
+		if (!txn)
+			last_error = "No transaction to renew";
+		else if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
+			// Txn is already renewed, we can just keep using it
+			return MDB_SUCCESS;
+		} else {
+			last_error = malloc(100);
+			sprintf(last_error, "Transaction flag was invalid for renew: %u", txn->mt_flags);
+		}
 		return EINVAL;
+	}
 
 	rc = mdb_txn_renew0(txn);
 	if (rc == MDB_SUCCESS) {
 		DPRINTF(("renew txn %"Yu"%c %p on mdbenv %p, root page %"Yu,
 			txn->mt_txnid, (txn->mt_flags & MDB_TXN_RDONLY) ? 'r' : 'w',
 			(void *)txn, (void *)txn->mt_env, txn->mt_dbs[MAIN_DBI].md_root));
+	} else {
+		last_error = mdb_strerror(rc);
 	}
 	return rc;
 }
@@ -7755,9 +7767,10 @@ mdb_get(MDB_txn *txn, MDB_dbi dbi,
 			last_error = "No key was provided";
 		else if (!data)
 			last_error = "No data was provided";
-		else if (!txn)
-			last_error = "No transaction available";
-		else if ((dbi)>=(txn)->mt_numdbs) {
+		else if (!txn) {
+			if (!last_error)
+				last_error = "No transaction available";
+		} else if ((dbi)>=(txn)->mt_numdbs) {
 			last_error = malloc(100);
 			sprintf(last_error, "The dbi %u was out of range for the number of dbis (%u)", dbi, (txn)->mt_numdbs);
 		} else {

read.js

@@ -566,6 +566,8 @@ export function addReadMethods(LMDBStore, {
 				}
 			} while (retries++ < 100);
 		}
+		// we actually don't renew here, we let the renew take place in the next 
+		// lmdb native read/call so as to avoid an extra native call
 		readTxnRenewed = setTimeout(resetReadTxn, 0);
 		store.emit('begin-transaction');
 		return readTxn;

src/cursor.cpp

@@ -105,8 +105,14 @@ int32_t CursorWrap::doPosition(uint32_t offset, uint32_t keySize, uint64_t endKe
 	//char* keyBuffer = dw->ew->keyBuffer;
 	MDB_val key, data;
 	int rc;
-	if (flags & 0x2000) // TODO: check the txn_id to determine if we need to renew
-		mdb_cursor_renew(txn = dw->ew->getReadTxn(), cursor);
+	if (flags & 0x2000) { // TODO: check the txn_id to determine if we need to renew
+		rc = mdb_cursor_renew(txn = dw->ew->getReadTxn(), cursor);
+		if (rc) {
+			if (rc > 0)
+				rc = -rc;
+			return rc;
+		}
+	}
 	if (endKeyAddress) {
 		uint32_t* keyBuffer = (uint32_t*) endKeyAddress;
 		endKey.mv_size = *keyBuffer;

src/dbi.cpp

@@ -71,7 +71,7 @@ int DbiWrap::open(int flags, char* name, bool hasVersions, LmdbKeyType keyType,
 	this->keyType = keyType;
 	this->flags = flags;
 	flags &= ~HAS_VERSIONS;
-	int rc = mdb_dbi_open(txn, name, flags, &this->dbi);
+	int rc = txn ? mdb_dbi_open(txn, name, flags, &this->dbi) : EINVAL;
 	if (rc)
 		return rc;
 	this->isOpen = true;

src/env.cpp

@@ -117,9 +117,10 @@ MDB_txn* EnvWrap::getReadTxn() {
 	txn = currentReadTxn;
 	if (readTxnRenewed)
 		return txn;
-	if (txn)
-		mdb_txn_renew(txn);
-	else {
+	if (txn) {
+		if (mdb_txn_renew(txn))
+			return nullptr; // if there was an error, signal with nullptr and let error propagate with last_error 
+	} else {
 		fprintf(stderr, "No current read transaction available");
 		return nullptr;
 	}