Set default_transaction_* GUC if session state is changed in autocomit

4 files changed, 102 insertions, 30 deletions

diff --git a/psycopg/connection_int.c b/psycopg/connection_int.c
index 0cb4cf3..e6906eb 100644
--- a/psycopg/connection_int.c
+++ b/psycopg/connection_int.c
@@ -41,7 +41,7 @@ const char *srv_isolevels[] = {
     "REPEATABLE READ",
     "SERIALIZABLE",
     "READ UNCOMMITTED",
-    ""      /* default */
+    "default"       /* only to set GUC, not for BEGIN */
 };
 
 /* Read only false, true */
@@ -58,6 +58,15 @@ const char *srv_deferrable[] = {
     ""      /* default */
 };
 
+/* On/Off/Default GUC states
+ */
+const char *srv_state_guc[] = {
+    "off",
+    "on",
+    "default"
+};
+
+
 /* Return a new "string" from a char* from the database.
  *
  * On Py2 just get a string, on Py3 decode it in the connection codec.
@@ -1186,6 +1195,10 @@ RAISES_NEG int
 conn_set_session(connectionObject *self, int autocommit,
         int isolevel, int readonly, int deferrable)
 {
+    int rv = -1;
+    PGresult *pgres = NULL;
+    char *error = NULL;
+
     /* Promote an isolation level to one of the levels supported by the server */
     if (self->server_version < 80000) {
         if (isolevel == ISOLATION_LEVEL_READ_UNCOMMITTED) {
@@ -1199,19 +1212,75 @@ conn_set_session(connectionObject *self, int autocommit,
     Py_BEGIN_ALLOW_THREADS;
     pthread_mutex_lock(&self->lock);
 
+    if (autocommit) {
+        /* we are in autocommit state, so no BEGIN will be issued:
+         * configure the session with the characteristics requested */
+        if (isolevel != self->isolevel) {
+            if (0 > pq_set_guc_locked(self,
+                    "default_transaction_isolation", srv_isolevels[isolevel],
+                    &pgres, &error, &_save)) {
+                goto endlock;
+            }
+        }
+        if (readonly != self->readonly) {
+            if (0 > pq_set_guc_locked(self,
+                    "default_transaction_read_only", srv_state_guc[readonly],
+                    &pgres, &error, &_save)) {
+                goto endlock;
+            }
+        }
+        if (deferrable != self->deferrable && self->server_version >= 90100) {
+            if (0 > pq_set_guc_locked(self,
+                    "default_transaction_deferrable", srv_state_guc[deferrable],
+                    &pgres, &error, &_save)) {
+                goto endlock;
+            }
+        }
+    }
+    else if (self->autocommit) {
+        /* we are moving from autocommit to not autocommit, so revert the
+         * characteristics to defaults to let BEGIN do its work */
+        if (0 > pq_set_guc_locked(self,
+                "default_transaction_isolation", "default",
+                &pgres, &error, &_save)) {
+            goto endlock;
+        }
+        if (0 > pq_set_guc_locked(self,
+                "default_transaction_read_only", "default",
+                &pgres, &error, &_save)) {
+            goto endlock;
+        }
+        if (self->server_version >= 90100) {
+            if (0 > pq_set_guc_locked(self,
+                    "default_transaction_deferrable", "default",
+                    &pgres, &error, &_save)) {
+                goto endlock;
+            }
+        }
+    }
+
+    self->autocommit = autocommit;
     self->isolevel = isolevel;
     self->readonly = readonly;
     self->deferrable = deferrable;
-    self->autocommit = autocommit;
+    rv = 0;
 
+endlock:
     pthread_mutex_unlock(&self->lock);
     Py_END_ALLOW_THREADS;
 
+    if (rv < 0) {
+        pq_complete_error(self, &pgres, &error);
+        goto exit;
+    }
+
     Dprintf(
         "conn_set_session: autocommit %d, isolevel %d, readonly %d, deferrable %d",
         autocommit, isolevel, readonly, deferrable);
 
-    return 0;
+
+exit:
+    return rv;
 }
 
 
diff --git a/psycopg/connection_type.c b/psycopg/connection_type.c
index 7b58e3f..7647056 100644
--- a/psycopg/connection_type.c
+++ b/psycopg/connection_type.c
@@ -671,7 +671,7 @@ psyco_conn_set_isolation_level(connectionObject *self, PyObject *args)
 
     if (!PyArg_ParseTuple(args, "i", &level)) return NULL;
 
-    if (level < 0 || level > 4) {
+    if (level < 0 || level > 5) {
         PyErr_SetString(PyExc_ValueError,
             "isolation level must be between 0 and 4");
         return NULL;
diff --git a/psycopg/pqpath.c b/psycopg/pqpath.c
index 8a4d78f..c686402 100644
--- a/psycopg/pqpath.c
+++ b/psycopg/pqpath.c
@@ -495,8 +495,10 @@ pq_begin_locked(connectionObject *conn, PGresult **pgres, char **error,
 
     snprintf(buf, bufsize, "BEGIN%s%s%s%s%s",
         conn->server_version < 80000 ? ";SET TRANSACTION" : "",
-        (conn->isolevel >= 1 && conn->isolevel <= 4) ? " ISOLATION LEVEL " : "",
-        srv_isolevels[conn->isolevel],
+        (conn->isolevel >= 1 && conn->isolevel <= 4)
+            ? " ISOLATION LEVEL " : "",
+        (conn->isolevel >= 1 && conn->isolevel <= 4)
+            ? srv_isolevels[conn->isolevel] : "",
         srv_readonly[conn->readonly],
         srv_deferrable[conn->deferrable]);
 
diff --git a/tests/test_connection.py b/tests/test_connection.py
index 5b304ee..314aa07 100755
--- a/tests/test_connection.py
+++ b/tests/test_connection.py
@@ -529,7 +529,26 @@ class IsolationLevelsTestCase(ConnectingTestCase):
             conn.commit()
 
         self.assertRaises(ValueError, conn.set_isolation_level, -1)
-        self.assertRaises(ValueError, conn.set_isolation_level, 5)
+        self.assertRaises(ValueError, conn.set_isolation_level, 6)
+
+    def test_set_isolation_level_default(self):
+        conn = self.connect()
+        curs = conn.cursor()
+
+        conn.autocommit = True
+        curs.execute("set default_transaction_isolation to 'read committed'")
+
+        conn.autocommit = False
+        conn.set_isolation_level(psycopg2.extensions.ISOLATION_LEVEL_SERIALIZABLE)
+        self.assertEqual(conn.isolation_level,
+            psycopg2.extensions.ISOLATION_LEVEL_SERIALIZABLE)
+        curs.execute("show transaction_isolation")
+        self.assertEqual(curs.fetchone()[0], "serializable")
+
+        conn.rollback()
+        conn.set_isolation_level(psycopg2.extensions.ISOLATION_LEVEL_DEFAULT)
+        curs.execute("show transaction_isolation")
+        self.assertEqual(curs.fetchone()[0], "read committed")
 
     def test_set_isolation_level_abort(self):
         conn = self.connect()
@@ -541,32 +560,14 @@ class IsolationLevelsTestCase(ConnectingTestCase):
         self.assertEqual(psycopg2.extensions.TRANSACTION_STATUS_INTRANS,
             conn.get_transaction_status())
 
-        conn.set_isolation_level(
+        # changed in psycopg 2.7
+        self.assertRaises(psycopg2.ProgrammingError,
+            conn.set_isolation_level,
             psycopg2.extensions.ISOLATION_LEVEL_SERIALIZABLE)
-        self.assertEqual(psycopg2.extensions.TRANSACTION_STATUS_IDLE,
-            conn.get_transaction_status())
-        cur.execute("select count(*) from isolevel;")
-        self.assertEqual(0, cur.fetchone()[0])
-
-        cur.execute("insert into isolevel values (10);")
         self.assertEqual(psycopg2.extensions.TRANSACTION_STATUS_INTRANS,
             conn.get_transaction_status())
-        conn.set_isolation_level(
-            psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT)
-        self.assertEqual(psycopg2.extensions.TRANSACTION_STATUS_IDLE,
-            conn.get_transaction_status())
-        cur.execute("select count(*) from isolevel;")
-        self.assertEqual(0, cur.fetchone()[0])
-
-        cur.execute("insert into isolevel values (10);")
-        self.assertEqual(psycopg2.extensions.TRANSACTION_STATUS_IDLE,
-            conn.get_transaction_status())
-        conn.set_isolation_level(
-            psycopg2.extensions.ISOLATION_LEVEL_READ_COMMITTED)
-        self.assertEqual(psycopg2.extensions.TRANSACTION_STATUS_IDLE,
-            conn.get_transaction_status())
-        cur.execute("select count(*) from isolevel;")
-        self.assertEqual(1, cur.fetchone()[0])
+        self.assertEqual(conn.isolation_level,
+            psycopg2.extensions.ISOLATION_LEVEL_DEFAULT)
 
     def test_isolation_level_autocommit(self):
         cnn1 = self.connect()