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126 | -----------------------------------------------------------------------
-- util-concurrent-sequence_queues -- Concurrent Sequence Queues
-- Copyright (C) 2019 Stephane Carrez
-- Written by Stephane Carrez (Stephane.Carrez@gmail.com)
-- SPDX-License-Identifier: Apache-2.0
-----------------------------------------------------------------------
with Ada.Finalization;
-- == Sequence Queues ==
-- The sequence queue associates a sequence number to each element inserted in
-- the queue. Elements can be inserted in any sequence order but they are
-- always dequeued in the increasing sequence order.
generic
type Element_Type is private;
type Sequence_Type is (<>);
-- The default queue size.
Default_Size : in Positive;
-- After a dequeue, clear the element stored in the queue.
Clear_On_Dequeue : in Boolean := False;
package Util.Concurrent.Sequence_Queues is
FOREVER : constant Duration := -1.0;
-- Exception raised if the enqueue or dequeue timeout exceeded.
Timeout : exception;
-- Exception raised if the sequence number is out of bounds.
Invalid_Sequence : exception;
-- Fifo of objects
type Queue is new Ada.Finalization.Limited_Controlled with private;
-- Put the element with the sequence in the queue.
procedure Enqueue (Into : in out Queue;
Item : in Element_Type;
Sequence : in Sequence_Type;
Wait : in Duration := FOREVER);
-- Get the next element in sequence from the queue.
-- Wait until the element with the last sequence gets available.
-- The current sequence is then incremented.
procedure Dequeue (From : in out Queue;
Item : out Element_Type;
Sequence : out Sequence_Type;
Wait : in Duration := FOREVER);
-- Get the number of elements in the queue.
function Get_Count (From : in Queue) return Natural;
-- Get the sequence number that will be returned by the next Dequeue.
function Get_Sequence (From : in Queue) return Sequence_Type;
-- Reset the sequence number.
procedure Reset_Sequence (Into : in out Queue;
Start : in Sequence_Type := Sequence_Type'First);
-- Set the queue size.
procedure Set_Size (Into : in out Queue;
Capacity : in Positive);
-- Initializes the queue.
overriding
procedure Initialize (Object : in out Queue);
-- Release the queue elements.
overriding
procedure Finalize (Object : in out Queue);
private
-- To store the queue elements, we use an array which is allocated dynamically
-- by the <b>Set_Size</b> protected operation. The generated code is smaller
-- compared to the use of Ada vectors container.
type Element_Array is array (Natural range <>) of Element_Type;
type Element_Array_Access is access all Element_Array;
type Boolean_Array is array (Natural range <>) of Boolean;
type Boolean_Array_Access is access all Boolean_Array;
Null_Element_Array : constant Element_Array_Access := null;
Null_Boolean_Array : constant Boolean_Array_Access := null;
-- Queue of objects.
protected type Protected_Queue is
-- Put the element in the queue.
-- If the queue is full, wait until some room is available.
entry Enqueue (Item : in Element_Type;
Sequence : in Sequence_Type);
-- Get an element from the queue.
-- Wait until one element gets available.
entry Dequeue (Item : out Element_Type;
Sequence : out Sequence_Type);
-- Get the number of elements in the queue.
function Get_Count return Natural;
-- Get the sequence number that will be returned by the next Dequeue.
function Get_Sequence return Sequence_Type;
-- Reset the sequence number.
procedure Set_Sequence (Start : in Sequence_Type);
-- Set the queue size.
procedure Set_Size (Capacity : in Natural);
private
First : Positive := 1;
Last : Positive := 1;
Seq : Sequence_Type := Sequence_Type'First;
Last_Seq : Sequence_Type := Sequence_Type'Last;
Count : Natural := 0;
Elements : Element_Array_Access := Null_Element_Array;
States : Boolean_Array_Access := Null_Boolean_Array;
end Protected_Queue;
type Queue is new Ada.Finalization.Limited_Controlled with record
Buffer : Protected_Queue;
end record;
end Util.Concurrent.Sequence_Queues;
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