pgbench: Fail cleanly when finding a COPY result state

Currently, pgbench aborts when a COPY response is received in
readCommandResponse().  However, as PQgetResult() returns an empty
result when there is no asynchronous result, through getCopyResult(),
the logic done at the end of readCommandResponse() for the error path
leads to an infinite loop.

This commit forcefully exits the COPY state with PQendcopy() before
moving to the error handler when fiding a COPY state, avoiding the
infinite loop.  The COPY protocol is not supported by pgbench anyway, as
an error is assumed in this case, so giving up is better than having the
tool be stuck forever.  pgbench was interruptible in this state.

A TAP test is added to check that an error happens if trying to use
COPY.

Author: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Discussion: https://postgr.es/m/CAO6_XqpHyF2m73ifV5a=5jhXxH2chk=XrgefY+eWWPe2Eft3=A@mail.gmail.com
Backpatch-through: 13

diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index fa15c84ba8d2abbe003a9b4b29b7bab49d4827ea..afe3ce65fb73a23ea59f875ee9666cbd0010d07c 100644 (file)
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -3359,6 +3359,20 @@ readCommandResponse(CState *st, MetaCommand meta, char *varprefix)
                                                                 PQresultErrorMessage(res));
                                break;
 
+                       case PGRES_COPY_IN:
+                       case PGRES_COPY_OUT:
+                       case PGRES_COPY_BOTH:
+                               pg_log_error("COPY is not supported in pgbench, aborting");
+
+                               /*
+                                * We need to exit the copy state.  Otherwise, PQgetResult()
+                                * will always return an empty PGresult as an effect of
+                                * getCopyResult(), leading to an infinite loop in the error
+                                * cleanup done below.
+                                */
+                               PQendcopy(st->con);
+                               goto error;
+
                        case PGRES_NONFATAL_ERROR:
                        case PGRES_FATAL_ERROR:
                                st->estatus = getSQLErrorStatus(PQresultErrorField(res,

diff --git a/src/bin/pgbench/t/001_pgbench_with_server.pl b/src/bin/pgbench/t/001_pgbench_with_server.pl
index 7dd78940300328b7fc5e869bfe67cd7be17befee..f61dcf682341b3d9b7698b1df132f9f398966986 100644 (file)
--- a/src/bin/pgbench/t/001_pgbench_with_server.pl
+++ b/src/bin/pgbench/t/001_pgbench_with_server.pl
@@ -1810,6 +1810,17 @@ update counter set i = i+1 returning i \gset
 }
        });
 
+# Test copy in pgbench
+$node->pgbench(
+       '-t 10',
+       2,
+       [],
+       [ qr{COPY is not supported in pgbench, aborting} ],
+       'Test copy in script',
+       {
+               '001_copy' => q{ COPY pgbench_accounts FROM stdin }
+       });
+
 # Clean up
 $node->safe_psql('postgres', 'DROP TABLE counter;');