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