From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Antonin Houska <ah@cybertec.at>
Cc: Thomas Munro <thomas.munro@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: Attempt to consolidate reading of XLOG page
Date: Fri, 27 Sep 2019 15:28:38 -0400
Message-ID: <20329.1569612518@sss.pgh.pa.us> (raw)
In-Reply-To: <20190927191736.GA13447@alvherre.pgsql>
References: <20190927191736.GA13447@alvherre.pgsql>
Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> On 2019-Sep-27, Antonin Houska wrote:
>>> You placed the errinfo in XLogRead's stack rather than its callers' ...
>>> I don't think that works, because as soon as XLogRead returns that
>>> memory is no longer guaranteed to exist.
>> I was aware of this problem, therefore I defined the field as static:
>>
>> +XLogReadError *
>> +XLogRead(char *buf, XLogRecPtr startptr, Size count, TimeLineID *tli_p,
>> + WALOpenSegment *seg, WALSegmentContext *segcxt,
>> + WALSegmentOpen openSegment)
>> +{
>> + char *p;
>> + XLogRecPtr recptr;
>> + Size nbytes;
>> + static XLogReadError errinfo;
> I see.
That seems like an absolutely terrible "fix". We don't really want
XLogRead to be defined in a way that forces it to be non-reentrant do we?
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, alvherre@2ndquadrant.com, ah@cybertec.at, thomas.munro@gmail.com, robertmhaas@gmail.com
Subject: Re: Attempt to consolidate reading of XLOG page
In-Reply-To: <20329.1569612518@sss.pgh.pa.us>
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