Re: Thread safe connection-name mapping in ECPG. Is it - Mailing list pgsql-hackers
From | Lee Kindness |
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Subject | Re: Thread safe connection-name mapping in ECPG. Is it |
Date | |
Msg-id | 006a01c40176$9892e930$2c8fe150@coulter Whole thread Raw |
In response to | Re: Thread safe connection-name mapping in ECPG. Is it (Bruce Momjian <pgman@candle.pha.pa.us>) |
Responses |
Re: Thread safe connection-name mapping in ECPG. Is it
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List | pgsql-hackers |
Shridhar, want to discuss this off list a bit to work through the various options and then revent back to the list with a suitable to-do (for discussion)? L. ----- Original Message ----- From: "Shridhar Daithankar" <shridhar@frodo.hserus.net> To: "Bruce Momjian" <pgman@candle.pha.pa.us> Cc: "PostgreSQL-development" <pgsql-hackers@postgresql.org> Sent: Wednesday, March 03, 2004 2:10 PM Subject: Re: Thread safe connection-name mapping in ECPG. Is it > Oh.. By all means..Please do.. > > The reason I posted it because I didn't wanted to work on it if core is not > going to accept it on account of non-compliance with spec. > > Is this fine? > * Allow a 'connection *' pointer to be specified instead of a string to denote > a connection. > > I plan to work on it whenever possible. What I would like to do is eliminate the > locks around name->connection mapping as we would be directly using the > connection instead of a name. > > I think we can also add the SQL-CA to connection structure so that each > connection gets it's own SQL-CA. That way ECPG is as thread-safe as the calling > application gets. > > And on the plus side we don't have to worry about platform specific threading > models either. > > Thoughts? > > Shridhar > > Bruce Momjian wrote: > > > Should I add this to the TODO list? > > > > -------------------------------------------------------------------------- - > > > > Lee Kindness wrote: > > > >>Sort of related, I was thinking about adding some more thread-related > >>code such that if a connection wasn't explicitely specified then the > >>last connection SET or CONNECTed to for the current thread is used, > >>rather than just the "last connection". > >> > >>But yeah, specifying the connection by variable (be it string or > >>connection ptr) would be a definite step forward. Currently you cannot > >>write a generic function like: > >> > >> int getit(char *using_connection) > >> { > >> EXEC SQL BEGIN DECLARE SECTION; > >> char *s_connection = using_connection; > >> int s_it; > >> EXEC SQL END DECLARE SECTION; > >> > >> EXEC SQL AT :s_connection SELECT it INTO :s_it FROM some_table; > >> return( s_it ); > >> } > >> > >>which could be run concurrently by multiple threads. > >> > >>L. > >> > >>Shridhar Daithankar writes: > >> > On Friday 27 February 2004 20:54, Michael Meskes wrote: > >> > > On Fri, Feb 27, 2004 at 04:22:33PM +0530, Shridhar Daithankar wrote: > >> > > > How about, allowing 'connection *'? If somebody puts a 'connection *' > >> > > > there it is used. If it is a string a name search is performed. Best of > >> > > > both worlds. > >> > > > >> > > How shall anyone put a pointer to a connection struct inside the SQL > >> > > statement? > >> > > > >> > > It would help me a lot if you'd be able to give some examples. > >> > > >> > EXEC SQL BEGIN DECLARE SECTION; > >> > connect *connectionPtr; > >> > EXEC SQL END DECLARE SECTION; > >> > > >> > EXEC SQL CONNECT TO db AS connectionPtr; > >> > EXEC SQL AT connectionPtr SELECT 1; > >> > > >> > After all, it is matter of parsing some code and emitting equivalent C code, > >> > isn't it? > >> > > >> > Shridhar > >> > >>---------------------------(end of broadcast)--------------------------- > >>TIP 4: Don't 'kill -9' the postmaster > >> > > > > > >
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