unikernel/duniverse/ocaml-caqti/caqti/lib/caqti_pool_sig.ml

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+(* Copyright (C) 2017--2023  Petter A. Urkedal <paurkedal@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version, with the LGPL-3.0 Linking Exception.
+ *
+ * This library is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * and the LGPL-3.0 Linking Exception along with this library.  If not, see
+ * <http://www.gnu.org/licenses/> and <https://spdx.org>, respectively.
+ *)
+
+(** Resource pool signature. *)
+
+module type S = sig
+
+  type +'a fiber
+
+  type ('a, +'e) t
+
+  val size : ('a, 'e) t -> int
+  (** [size pool] is the current number of open resources in [pool]. *)
+
+  val use :
+    ?priority: float ->
+    ('a -> ('b, 'e) result fiber) -> ('a, 'e) t -> ('b, 'e) result fiber
+  (** [use f pool] calls [f] on a resource drawn from [pool], handing back the
+      resource to the pool when [f] exits.
+
+      @param priority
+        Requests for the resource are handled in decreasing order of priority.
+        The default priority is [0.0]. *)
+
+  val drain : ('a, 'e) t -> unit fiber
+  (** [drain pool] closes all resources in [pool]. The pool is still usable, as
+      new resources will be created on demand. *)
+
+end