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db: added notes about custodians and connection-pool, virtual-connection

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This commit is contained in:
Ryan Culpepper 2012-08-22 11:05:25 -04:00
parent c7a6272f4b
commit c4edc684eb
1 changed files with 9 additions and 4 deletions
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13
collects/db/scribblings/connect.scrbl
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@ -344,9 +344,10 @@ connections.
Creates a @tech{connection pool}. The pool consists of up to
@racket[max-connections], divided between leased connections and up to
@racket[max-idle-connections] idle connections. The pool uses
@racket[connect] to create new connections when needed; the
@racket[connect] function must return a fresh connection each time it
is called.
@racket[connect] to create new connections when needed. The
@racket[connect] function is called with the same
@racket[current-custodian] value as when the connection pool was
created, and it must return a fresh connection each time it is called.
@examples[#:eval the-eval
(eval:alts
@ -417,7 +418,11 @@ automatically releases them when they are no longer needed.
Creates a @tech{virtual connection} that creates actual connections on
demand using the @racket[connect] function, or by calling
@racket[(connection-pool-lease connect)] if @racket[connect] is a
@tech{connection pool}. A virtual connection encapsulates a mapping
@tech{connection pool}. If @racket[connect] is a function, it is
called with the same @racket[current-custodian] value as when the
virtual connection was created.
A virtual connection encapsulates a mapping
of threads to actual connections. When a query function is called with
a virtual connection, the current thread's associated actual
connection is used to execute the query. If there is no actual