Allow retrying start_replication after syntax or data error.

psycopg/pqpath.c

@@ -1870,8 +1870,11 @@ pq_fetch(cursorObject *curs, int no_result)
         Dprintf("pq_fetch: data from a streaming replication slot (no tuples)");
         curs->rowcount = -1;
         ex = 0;
-        /* nothing to do here: pq_copy_both will be called separately */
+        /* Nothing to do here: pq_copy_both will be called separately.
-        CLEARPGRES(curs->pgres);
+
+           Also don't clear the result status: it's checked in
+           consume_stream. */
+        /*CLEARPGRES(curs->pgres);*/
         break;
 
     case PGRES_TUPLES_OK:

psycopg/replication_cursor.h

@@ -38,7 +38,6 @@ extern HIDDEN PyTypeObject replicationCursorType;
 typedef struct replicationCursorObject {
     cursorObject cur;
 
-    int         started:1;        /* if replication is started */
     int         consuming:1;      /* if running the consume loop */
     int         decode:1;         /* if we should use character decoding on the messages */
 
@@ -53,23 +52,6 @@ typedef struct replicationCursorObject {
 
 RAISES_NEG int psyco_repl_curs_datetime_init(void);
 
-/* exception-raising macros */
-#define EXC_IF_REPLICATING(self, cmd) \
-do \
-    if ((self)->started) { \
-        PyErr_SetString(ProgrammingError, \
-            #cmd " cannot be used when replication is already in progress"); \
-    return NULL; } \
-while (0)
-
-#define EXC_IF_NOT_REPLICATING(self, cmd) \
-do \
-    if (!(self)->started) { \
-        PyErr_SetString(ProgrammingError, \
-            #cmd " cannot be used when replication is not in progress"); \
-    return NULL; } \
-while (0)
-
 #ifdef __cplusplus
 }
 #endif

psycopg/replication_cursor_type.c

@@ -59,7 +59,6 @@ psyco_repl_curs_start_replication_expert(replicationCursorObject *self,
     EXC_IF_CURS_CLOSED(curs);
     EXC_IF_GREEN(start_replication_expert);
     EXC_IF_TPC_PREPARED(conn, start_replication_expert);
-    EXC_IF_REPLICATING(self, start_replication_expert);
 
     Dprintf("psyco_repl_curs_start_replication_expert: '%s'; decode: %d", command, decode);
 
@@ -67,7 +66,6 @@ psyco_repl_curs_start_replication_expert(replicationCursorObject *self,
         res = Py_None;
         Py_INCREF(res);
 
-        self->started = 1;
         self->decode = decode;
         gettimeofday(&self->last_io, NULL);
     }
@@ -96,13 +94,6 @@ psyco_repl_curs_consume_stream(replicationCursorObject *self,
     EXC_IF_CURS_ASYNC(curs, consume_stream);
     EXC_IF_GREEN(consume_stream);
     EXC_IF_TPC_PREPARED(self->cur.conn, consume_stream);
-    EXC_IF_NOT_REPLICATING(self, consume_stream);
-
-    if (self->consuming) {
-        PyErr_SetString(ProgrammingError,
-                        "consume_stream cannot be used when already in the consume loop");
-        return NULL;
-    }
 
     Dprintf("psyco_repl_curs_consume_stream");
 
@@ -111,6 +102,19 @@ psyco_repl_curs_consume_stream(replicationCursorObject *self,
         return NULL;
     }
 
+    if (self->consuming) {
+        PyErr_SetString(ProgrammingError,
+                        "consume_stream cannot be used when already in the consume loop");
+        return NULL;
+    }
+
+    if (curs->pgres == NULL || PQresultStatus(curs->pgres) != PGRES_COPY_BOTH) {
+        PyErr_SetString(ProgrammingError,
+                        "consume_stream: not replicating, call start_replication first");
+        return NULL;
+    }
+    CLEARPGRES(curs->pgres);
+
     self->consuming = 1;
 
     if (pq_copy_both(self, consume, keepalive_interval) >= 0) {
@@ -135,7 +139,6 @@ psyco_repl_curs_read_message(replicationCursorObject *self)
     EXC_IF_CURS_CLOSED(curs);
     EXC_IF_GREEN(read_message);
     EXC_IF_TPC_PREPARED(self->cur.conn, read_message);
-    EXC_IF_NOT_REPLICATING(self, read_message);
 
     if (pq_read_replication_message(self, &msg) < 0) {
         return NULL;
@@ -160,7 +163,6 @@ psyco_repl_curs_send_feedback(replicationCursorObject *self,
     static char* kwlist[] = {"write_lsn", "flush_lsn", "apply_lsn", "reply", NULL};
 
     EXC_IF_CURS_CLOSED(curs);
-    EXC_IF_NOT_REPLICATING(self, send_feedback);
 
     if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|KKKi", kwlist,
                                      &write_lsn, &flush_lsn, &apply_lsn, &reply)) {
@@ -246,7 +248,6 @@ static struct PyGetSetDef replicationCursorObject_getsets[] = {
 static int
 replicationCursor_setup(replicationCursorObject* self)
 {
-    self->started = 0;
     self->consuming = 0;
     self->decode = 0;
 

tests/test_replication.py

@@ -118,6 +118,18 @@ class ReplicationTest(ReplicationTestCase):
         self.create_replication_slot(cur)
         cur.start_replication(self.slot)
 
+    @skip_before_postgres(9, 4) # slots require 9.4
+    def test_start_and_recover_from_error(self):
+        conn = self.repl_connect(connection_factory=LogicalReplicationConnection)
+        if conn is None: return
+        cur = conn.cursor()
+
+        self.create_replication_slot(cur, output_plugin='test_decoding')
+
+        self.assertRaises(psycopg2.DataError, cur.start_replication,
+                          slot_name=self.slot, options=dict(invalid_param='value'))
+        cur.start_replication(slot_name=self.slot)
+
     @skip_before_postgres(9, 4) # slots require 9.4
     def test_stop_replication(self):
         conn = self.repl_connect(connection_factory=LogicalReplicationConnection)
@@ -162,6 +174,7 @@ class AsyncReplicationTest(ReplicationTestCase):
 
             cur.send_feedback(flush_lsn=msg.data_start)
 
+        # cannot be used in asynchronous mode
         self.assertRaises(psycopg2.ProgrammingError, cur.consume_stream, consume)
 
         def process_stream():