Add CHECK_FOR_INTERRUPTS in ExecInsert's speculative insertion loop.

Ordinarily the functions called in this loop ought to have plenty
of CFIs themselves; but we've now seen a case where no such CFI is
reached, making the loop uninterruptible.  Even though that's from
a recently-introduced bug, it seems prudent to install a CFI at
the loop level in all branches.

Per discussion of bug #17558 from Andrew Kesper (an actual fix for
that bug will follow).

Discussion: https://postgr.es/m/17558-3f6599ffcf52fd4a@postgresql.org

diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index a49c3da5b6c9a3d5d26b31d561e242ea2bc68898..deda32150288c961e42e2dce1517d83dade7dcfa 100644 (file)
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -956,9 +956,11 @@ ExecInsert(ModifyTableContext *context,
                         *
                         * We loop back here if we find a conflict below, either during
                         * the pre-check, or when we re-check after inserting the tuple
-                        * speculatively.
+                        * speculatively.  Better allow interrupts in case some bug makes
+                        * this an infinite loop.
                         */
        vlock:
+                       CHECK_FOR_INTERRUPTS();
                        specConflict = false;
                        if (!ExecCheckIndexConstraints(resultRelInfo, slot, estate,
                                                                                   &conflictTid, arbiterIndexes))