87 lines
3.6 KiB
OCaml
87 lines
3.6 KiB
OCaml
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(* Copyright (C) 2023 Petter A. Urkedal <paurkedal@gmail.com>
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*
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* This library is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or (at your
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* option) any later version, with the LGPL-3.0 Linking Exception.
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*
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* This library is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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* License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* and the LGPL-3.0 Linking Exception along with this library. If not, see
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* <http://www.gnu.org/licenses/> and <https://spdx.org>, respectively.
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*)
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(** Pool configuration. *)
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type _ key
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type t
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(** {2 Construction and Generic Operations} *)
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val create :
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?max_size: int ->
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?max_idle_size: int ->
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?max_idle_age: Mtime.Span.t option ->
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?max_use_count: int option ->
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unit -> t
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(** Creates a configuration for the implementation of {!Caqti_pool_sig.S}. The
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main arguments populate the configuration with the corresponding settings,
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which are explaind in {!cpck}. *)
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val default : t
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(** The configuration object with no setting, which gives the built-in defaults.
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Alternatively, use {!default_from_env} for a configuration based on
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environment variables. *)
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val default_from_env : unit -> t
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(** [default_from_env ()] is a configuration constructed from environment
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variables of the form [CAQTI_POOL_<suffix>], with the upper-cased names of
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the configuration keys substituted for [<suffix>]. *)
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val merge_left : t -> t -> t
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(** [merge_left cL cR] is the configuration [cL] with missing settings populated
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by the corresponding present settings from [cR]. *)
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val get : 'a key -> t -> 'a option
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(** [get key config] is the value of [key] in [config] or [None] if unset. *)
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val set : 'a key -> 'a -> t -> t
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(** [set key value config] is [config] with [key] set to [value] regardless of
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any previous mapping. *)
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val unset : 'a key -> t -> t
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(** [unset key config] is [config] without its mapping for [key] if any. *)
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(** {2:cpck Configuration Keys} *)
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val max_size : int key
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(** The maximum number of open connections associated with the pool. When this
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limit is hit, an attempt to use the pool will block until a connection
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becomes available. The value must be at least one. If the selected driver
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does not support concurrent connections, the value [1] is assumed. *)
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val max_idle_size : int key
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(** The maximum number of idle connections to put into the pool for reuse. Must
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be between [0] and {!max_size}. If you set this, you must also ensure
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{!max_size} is set so that the combination is valid. Defaults to
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{!max_size}. For drivers which does not support concurrent connections, the
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value will clipped to a maximum of [1]. *)
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val max_idle_age : Mtime.Span.t option key
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(** The maximum age of idle connections before they are scheduled to be
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disconnected and removed from the pool, or [None] for no limit. Where
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possible, a timer will be used to trigger the cleanup. For the
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[caqti.blocking] library, the cleanup will only be done opportunistically
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when the pool is used. *)
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val max_use_count : int option key
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(** The maximum number of times a pooled connection is reused, or [None] for no
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limit. The default is currently 100, but may be changed in the future based
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on real-world experience. The reason this setting was introduced is that we
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have seen state being retained on the server side. *)
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