ext/pdo_odbc: timeout support

ODBC has both a connection timeout for the connection level and a query
timeout at the statement level. Annoyingly, these are somewhat poorly
defined. The connection timeout, for instance, can be defined as either
a login/connection setup timeout, or as a generic "any action" timeout,
and if the latter, the query timeout may not necessarily be implemented.

Accordingly, because we have no way to differentiate, we have to set
both, and have special handling for the initial connection, as the
setAttribute call won't handle early enough if it only handles initial
connection timeouts. This means changing it after for a connection isn't
relevant for existing statements that have already been constructed;
this commit doesn't add a way to change it for a statement after
changing it on the connection (be it via setAttribute on the statement,
or somehow changing statements from the connection setAttribute).

Also annoying is the difference in behaviour between drivers when a
timeout happens. For example, SQL Server has a query timeout which just
gracefully ends the current query, but Db2i only has a connection
timeout which puts the whole connection into an invalid state (but at
least it should fail a liveness check for a persistent connection). We
don't have much control over this unfortunately.

In the future, we should consider clarifying the PDO timeout attribute
behaviour's on statements vs. connections, or make them separate
attributes, like how PDO_DBLIB has.

Author: NattyNarwhal

ext/pdo_odbc/odbc_driver.c

@@ -152,6 +152,7 @@ static bool odbc_handle_preparer(pdo_dbh_t *dbh, zend_string *sql, pdo_stmt_t *s
 
 	S->H = H;
 	S->assume_utf8 = H->assume_utf8;
+	S->stmt_timeout = H->stmt_timeout;
 
 	/* before we prepare, we need to peek at the query; if it uses named parameters,
 	 * we want PDO to rewrite them for us */
@@ -194,6 +195,16 @@ static bool odbc_handle_preparer(pdo_dbh_t *dbh, zend_string *sql, pdo_stmt_t *s
 		}
 	}
 
+	rc = SQLSetStmtAttr(S->stmt, SQL_ATTR_QUERY_TIMEOUT, (SQLPOINTER)S->stmt_timeout, SQL_IS_INTEGER);
+	if (rc != SQL_SUCCESS && rc != SQL_SUCCESS_WITH_INFO) {
+		pdo_odbc_stmt_error("SQLSetStmtAttr: SQL_ATTR_QUERY_TIMEOUT");
+		SQLFreeHandle(SQL_HANDLE_STMT, S->stmt);
+		if (nsql) {
+			zend_string_release(nsql);
+		}
+		return false;
+	}
+
 	rc = SQLPrepare(S->stmt, (SQLCHAR *) ZSTR_VAL(sql), SQL_NTS);
 	if (nsql) {
 		zend_string_release(nsql);
@@ -341,6 +352,7 @@ static bool odbc_handle_set_attr(pdo_dbh_t *dbh, zend_long attr, zval *val)
 {
 	pdo_odbc_db_handle *H = (pdo_odbc_db_handle *)dbh->driver_data;
 	bool bval;
+	zend_long lval;
 
 	switch (attr) {
 		case PDO_ODBC_ATTR_ASSUME_UTF8:
@@ -373,6 +385,29 @@ static bool odbc_handle_set_attr(pdo_dbh_t *dbh, zend_long attr, zval *val)
 				}
 			}
 			return true;
+		case PDO_ATTR_TIMEOUT:
+			if (!pdo_get_long_param(&lval, val)) {
+				return false;
+			}
+			/* This will only apply to the current connection and
+			 * any new statements; currently no way to set timeout
+			 * for already existing statements.
+			 */
+			H->stmt_timeout = H->conn_timeout = lval;
+			/* set odbc conn attr in case driver cares */
+			RETCODE rc = SQLSetConnectAttr(
+				H->dbc,
+				SQL_ATTR_CONNECTION_TIMEOUT,
+				(SQLPOINTER) lval,
+				SQL_IS_INTEGER
+			);
+			if (rc != SQL_SUCCESS) {
+				pdo_odbc_drv_error(
+					dbh->auto_commit ? "SQLSetConnectAttr AUTOCOMMIT = ON" : "SQLSetConnectAttr AUTOCOMMIT = OFF"
+				);
+				return false;
+			}
+			return true;
 		default:
 			strcpy(H->einfo.last_err_msg, "Unknown Attribute");
 			H->einfo.what = "setAttribute";
@@ -408,6 +443,9 @@ static int odbc_handle_get_attr(pdo_dbh_t *dbh, zend_long attr, zval *val)
 			return pdo_odbc_get_info_string(dbh, SQL_DBMS_VER, val);
 		case PDO_ATTR_SERVER_INFO:
 			return pdo_odbc_get_info_string(dbh, SQL_DBMS_NAME, val);
+		case PDO_ATTR_TIMEOUT:
+			ZVAL_LONG(val, H->conn_timeout);
+			return 1;
 		case PDO_ODBC_ATTR_ASSUME_UTF8:
 			ZVAL_BOOL(val, H->assume_utf8);
 			return 1;
@@ -473,7 +511,7 @@ static int pdo_odbc_handle_factory(pdo_dbh_t *dbh, zval *driver_options) /* {{{
 	pdo_odbc_db_handle *H;
 	RETCODE rc;
 	int use_direct = 0;
-	zend_ulong cursor_lib;
+	zend_ulong cursor_lib, connection_timeout;
 
 	H = pecalloc(1, sizeof(*H), dbh->is_persistent);
 
@@ -523,6 +561,15 @@ static int pdo_odbc_handle_factory(pdo_dbh_t *dbh, zval *driver_options) /* {{{
 		goto fail;
 	}
 
+	/* setup connection timeout */
+	connection_timeout = pdo_attr_lval(driver_options, PDO_ATTR_TIMEOUT, 0);
+	rc = SQLSetConnectAttr(H->dbc, SQL_ATTR_CONNECTION_TIMEOUT, (void*)connection_timeout, SQL_IS_INTEGER);
+	if (rc != SQL_SUCCESS) {
+		pdo_odbc_drv_error("SQLSetConnectAttr SQL_ATTR_CONNECTION_TIMEOUT");
+		goto fail;
+	}
+	H->stmt_timeout = H->conn_timeout = connection_timeout;
+
 	/* a connection string may have = but not ; - i.e. "DSN=PHP" */
 	if (strchr(dbh->data_source, '=')) {
 		SQLCHAR dsnbuf[1024];

ext/pdo_odbc/php_pdo_odbc_int.h

@@ -121,6 +121,8 @@ typedef struct {
 	PDO_ODBC_HENV	env;
 	PDO_ODBC_HDBC	dbc;
 	pdo_odbc_errinfo einfo;
+	SQLUINTEGER conn_timeout;
+	SQLUINTEGER stmt_timeout;
 	unsigned assume_utf8:1;
 	unsigned _spare:31;
 } pdo_odbc_db_handle;
@@ -144,6 +146,7 @@ typedef struct {
 	char *convbuf;
 	zend_ulong convbufsize;
 	HashTable *out_buffers;
+	SQLUINTEGER stmt_timeout;
 	unsigned going_long:1;
 	unsigned assume_utf8:1;
 	unsigned params_dirty:1;