Clarify some comments around SharedRecoveryState in xlog.c

SharedRecoveryState has been switched from a boolean to an enum as of
commit 4e87c48, but some comments still referred to it as a boolean.

Author: Amul Sul
Reviewed-by: Dilip Kumar, Kyotaro Horiguchi
Discussion: https://postgr.es/m/CAAJ_b97Hf+1SXnm8jySpO+Fhm+-VKFAAce1T_cupUYtnE3Nxig

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index f03bd473e2b30d2464089f17692e5aaeca89f16f..8e3b5df7dcb86bef4c7768d3796719d217281e68 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7998,17 +7998,16 @@ StartupXLOG(void)
         * All done with end-of-recovery actions.
         *
         * Now allow backends to write WAL and update the control file status in
-        * consequence.  The boolean flag allowing backends to write WAL is
-        * updated while holding ControlFileLock to prevent other backends to look
-        * at an inconsistent state of the control file in shared memory.  There
-        * is still a small window during which backends can write WAL and the
-        * control file is still referring to a system not in DB_IN_PRODUCTION
+        * consequence.  SharedRecoveryState, that controls if backends can write
+        * WAL, is updated while holding ControlFileLock to prevent other backends
+        * to look at an inconsistent state of the control file in shared memory.
+        * There is still a small window during which backends can write WAL and
+        * the control file is still referring to a system not in DB_IN_PRODUCTION
         * state while looking at the on-disk control file.
         *
-        * Also, although the boolean flag to allow WAL is probably atomic in
-        * itself, we use the info_lck here to ensure that there are no race
-        * conditions concerning visibility of other recent updates to shared
-        * memory.
+        * Also, we use info_lck to update SharedRecoveryState to ensure that
+        * there are no race conditions concerning visibility of other recent
+        * updates to shared memory.
         */
        LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
        ControlFile->state = DB_IN_PRODUCTION;