package caqti-lwt

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Lwt support for Caqti

Install 

dune-project
 Dependency

github.com Readme Changelog Edit opam file Versions (11)

Authors

  1. P
    Petter A. Urkedal <paurkedal@gmail.com>

Maintainers

  1. P
    Petter A. Urkedal <paurkedal@gmail.com>

Sources

caqti-v1.9.0.tbz
sha256=e1f580848faf3a54f23174067f2c75f77f6a2fe50ca8bc923428d0e1841192c5
sha512=7a11edfcfbbe4855347b066e222cf6bf46d1afedcd4978661b9a2b3931921faa1768a6bc24031fd3afa84537fe2adc8b139399deb77120461bee8fb394d68e82

doc/caqti-lwt/Caqti_lwt/index.html

Module Caqti_lwtSource

Connecting with Lwt.

This module contains the signature and connect function specialized for use with Lwt.

include Caqti_connect_sig.S with type 'a future := 'a Lwt.t
module Pool : Caqti_pool_sig.S with type 'a future := 'a Lwt.t

A pool implementation for the current concurrency library.

module Stream : Caqti_stream.S with type 'a future := 'a Lwt.t
Sourcemodule type CONNECTION = Caqti_connection_sig.S with type 'a future := 'a Lwt.t and type ('a, 'err) stream := ('a, 'err) Stream.t

The connection API specialized for the current concurrency library.

Sourcetype connection = (module CONNECTION)

Shortcut for the connection API passed as a value.

Sourceval connect : ?env:(Caqti_driver_info.t -> string -> Caqti_query.t) -> ?tweaks_version:(int * int) -> Uri.t -> (connection, [> Caqti_error.load_or_connect ]) result Lwt.t

connect uri locates and loads a driver which can handle uri, passes uri to the driver, which establish a connection and returns a first-class module implementing Caqti_connection_sig.S.

If you use preemptive threading, note that the connection must only be used from the thread where it was created.

See Database Tweaks for details about the tweaks_version parameter.

  • parameter tweaks_version

    Declares compatibility with database tweaks introduced up to the given version of Caqti. Defaults to a conservative value. See the above reference for more info (not linked here due to odoc issue).

  • parameter env

    If provided, this function will do a final expansion of environment variables which occurs in the query templates of the requests executed on the connection.

Sourceval with_connection : ?env:(Caqti_driver_info.t -> string -> Caqti_query.t) -> ?tweaks_version:(int * int) -> Uri.t -> (connection -> ('a, [> Caqti_error.load_or_connect ] as 'e) result Lwt.t) -> ('a, 'e) result Lwt.t

with_connection uri f calls connect on uri. If connect evaluates to Ok connection, with_connection passes the connection to f. Once f either evaluates to a result, or raises an exception, with_connection closes the database connection.

  • parameter tweaks_version

    Passed to connect.

Sourceval connect_pool : ?max_size:int -> ?max_idle_size:int -> ?max_use_count:int option -> ?post_connect:(connection -> (unit, 'connect_error) result Lwt.t) -> ?env:(Caqti_driver_info.t -> string -> Caqti_query.t) -> ?tweaks_version:(int * int) -> Uri.t -> ((connection, [> Caqti_error.connect ] as 'connect_error) Pool.t, [> Caqti_error.load ]) result

connect_pool uri is a pool of database connections constructed by connect uri.

Do not use pooling for connections to volatile resources like sqlite3::memory: and beware of temporary tables or other objects which may not be shared across connections to the same URI.

If you use preemptive threading, note that the connection pool must only be used from the thread where it was created. Use thread local storage to create a separate pool per thread if necessary.

  • parameter tweaks_version

    Passed to connect when creating new connections.

  • parameter env

    Passed to connect when creating new connections.

  • parameter max_size

    The maximum number of open connections. Must be at least 1. For drivers which does not support concurrent connections, this will be ignored and the value 1 used instead.

  • parameter max_idle_size

    The maximum number of idle connections to put into the pool for reuse. Defaults to max_size. Must be between 0 and max_size. If you set this, you must also set max_size. For drivers which does not support pooling, this will be ignored and the value 0 used instead. For drivers which does not support concurrent connections, but supports pooling, the value will clipped to a maximum of 1.

  • parameter max_use_count

    The maximum number of times to use a connection before dropping it from the pool, or None for no limit. The default is currently 100, but may be changed in the future based on real-world experience. The reason this setting was introduced is that we have seen state being retained on the server side.

Sourceval or_fail : ('a, [< Caqti_error.t ]) result -> 'a Lwt.t

Converts an error to an Lwt future failed with a Caqti_error.Exn exception holding the error.