Added 'pq_get_last_result()' function.

The function reads the last result after an asynchronous query.

psycopg/green.c

@@ -29,6 +29,7 @@
 #include "psycopg/psycopg.h"
 #include "psycopg/green.h"
 #include "psycopg/connection.h"
+#include "psycopg/pqpath.h"
 
 HIDDEN PyObject *wait_callback = NULL;
 
@@ -143,8 +144,7 @@ psyco_wait(connectionObject *conn)
 PGresult *
 psyco_exec_green(connectionObject *conn, const char *command)
 {
-    PGconn *pgconn = conn->pgconn;
-    PGresult *result = NULL, *res;
+    PGresult *result = NULL;
     PyObject *cb, *pyrv;
 
     if (!(cb = have_wait_callback())) {
@@ -153,7 +153,7 @@ psyco_exec_green(connectionObject *conn, const char *command)
 
     /* Send the query asynchronously */
     Dprintf("psyco_exec_green: sending query async");
-    if (0 == PQsendQuery(pgconn, command)) {
+    if (0 == PQsendQuery(conn->pgconn, command)) {
         Dprintf("psyco_exec_green: PQsendQuery returned 0");
         goto clear;
     }
@@ -172,19 +172,8 @@ psyco_exec_green(connectionObject *conn, const char *command)
     }
     Py_DECREF(pyrv);
 
-    /* Now we can read the data without fear of blocking.
-     * Read until PQgetResult gives a NULL */
-    while (NULL != (res = PQgetResult(pgconn))) {
-        if (result) {
-            /* TODO too bad: we are discarding results from all the queries
-             * except the last. We could have populated `nextset()` with it
-             * but it would be an incompatible change (apps currently issue
-             * groups of queries expecting to receive the last result: they
-             * would start receiving the first instead). */
-            PQclear(result);
-        }
-        result = res;
-    }
+    /* Now we can read the data without fear of blocking. */
+    result = pq_get_last_result(conn);
 
 clear:
     conn->async_status = ASYNC_DONE;

psycopg/pqpath.c

@@ -782,6 +782,33 @@ pq_execute(cursorObject *curs, const char *query, int async)
     return 1-async;
 }
 
+/* Return the last result available on the connection.
+ *
+ * The function will block will block only if a command is active and the
+ * necessary response data has not yet been read by PQconsumeInput.
+ *
+ * The result should be disposed using PQclear()
+ */
+PGresult *
+pq_get_last_result(connectionObject *conn)
+{
+    PGresult *result = NULL, *res;
+
+    /* Read until PQgetResult gives a NULL */
+    while (NULL != (res = PQgetResult(conn->pgconn))) {
+        if (result) {
+            /* TODO too bad: we are discarding results from all the queries
+             * except the last. We could have populated `nextset()` with it
+             * but it would be an incompatible change (apps currently issue
+             * groups of queries expecting to receive the last result: they
+             * would start receiving the first instead). */
+            PQclear(result);
+        }
+        result = res;
+    }
+
+    return result;
+}
 
 /* pq_fetch - fetch data after a query
 

psycopg/pqpath.h

@@ -35,6 +35,7 @@
 #define CLEARPGRES(pgres)    PQclear(pgres); pgres = NULL
 
 /* exported functions */
+HIDDEN PGresult *pq_get_last_result(connectionObject *conn);
 HIDDEN int pq_fetch(cursorObject *curs);
 HIDDEN int pq_execute(cursorObject *curs, const char *query, int async);
 HIDDEN int pq_begin_locked(connectionObject *conn, PGresult **pgres,