Std.Db.withConnection
1 declaration
fn
withConnection: &Std.Db.Pool -> fn(Std.Db.Session.Connection) -> (Result[T, Std.Db.Session.DbError], Std.Db.Session.Connection) -> Result[T, Std.Db.Session.DbError]This is a callable function.
What it does
Take a connection, hand it to an action, and put it back however the action
ended.
There is no return a caller can forget. A connection not put back is one
the pool has lost, and a pool that has lost all of them stops every thread
waiting on it — a failure that appears only under load and looks like the
database being slow.
A connection that cannot be lent again — its socket dropped, the server
restarted, the protocol went wrong — is closed and its place kept empty, so
the next borrower opens a fresh one. Closing the whole pool instead would
turn one lost socket into every later request failing until the program
restarts.
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- The text after the name is the type checked by Pudu.
- Read arrows from left to right: inputs come first, and the final type is returned.
- & borrows a value for this call instead of moving or copying it.
- Names inside [ ] are type arguments, such as the item type held by a collection.
- Result makes success and recoverable failure part of the function's type.