On Fri, Sep 28, 2018 at 5:31 PM Haribabu Kommi <kommi.harib...@gmail.com> wrote:
> > On Thu, Jul 19, 2018 at 10:59 PM Haribabu Kommi <kommi.harib...@gmail.com> > wrote: > >> >> On Wed, Jul 18, 2018 at 10:53 PM Robert Haas <robertmh...@gmail.com> >> wrote: >> >>> On Wed, Jul 4, 2018 at 9:14 AM, Laurenz Albe <laurenz.a...@cybertec.at> >>> wrote: >>> > What about keeping the first successful connection open and storing >>> it in a >>> > variable if we are in "prefer-read" mode. >>> > If we get the read-only connection we desire, close that cached >>> connection, >>> > otherwise use it. >>> >>> I like this idea. If I recall correctly, the logic in this area is >>> getting pretty complex, so we might need to refactor it for better >>> readability and maintainability. >>> >> >> OK. I will work on the code refactoring first and then provide the >> prefer-read option on top it. >> > > commits d1c6a14bacf and 5ca00774194 have refactored the logic > of handling the different connection states. > > Attached is a rebased patch after further refactoring the new option > code for easier maintenance. > [some how i didn't receive this mail, copy pasted from mailing list ] >The code is much more readable now, thanks. Thanks for the review. >--- a/src/interfaces/libpq/libpq-int.h >+++ b/src/interfaces/libpq/libpq-int.h >@@ -397,6 +397,7 @@ struct pg_conn > int nconnhost; /* # of hosts named in conn string */ > int whichhost; /* host we're currently trying/connected to */ > pg_conn_host *connhost; /* details about each named host */ >+ int read_write_host_index; /* index for first read-write host in connhost */ > > /* Connection data */ > pgsocket sock; /* FD for socket, PGINVALID_SOCKET if > > >I think the comment could use more love. > >This would be the place to document the logic: >Initial value is -1, then then index of the first working server >we found, and -2 for the second attempt to connect to that server. Added comments along the lines that you mentioned. And also try to update some more comments. >I notice that you don't keep the first connection open, but close >and reopen it. I guess that is a matter of taste, but it would be >easier on resources (and reduce connection time) if the connection >were kept open. >Admittedly, it would be more difficult and might further complicate >code that is not very clear as it is. Yes, I didn't add that logic of keeping the first connection open, Currently I feel that adds more complexity in supporting the same. If everyone feels that is required, I will add that logic. Updated patch attached. Regards, Haribabu Kommi Fujitsu Australia
0001-Allow-taget-session-attrs-to-accept-prefer-read-opti_v4.patch
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