/usr/share/ada/adainclude/gnatcoll/gnatcoll-promises.adb is in libgnatcoll16.1.0-dev 17.0.2017-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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-- G N A T C O L L --
-- --
-- Copyright (C) 2017, AdaCore --
-- --
-- This library is free software; you can redistribute it and/or modify it --
-- under terms of the GNU General Public License as published by the Free --
-- Software Foundation; either version 3, or (at your option) any later --
-- version. This library is distributed in the hope that it will be useful, --
-- but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHAN- --
-- TABILITY or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- --
-- --
-- --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
------------------------------------------------------------------------------
with Ada.Containers.Vectors;
with Ada.Exceptions; use Ada.Exceptions;
with Ada.Unchecked_Deallocation;
with GNAT.Strings; use GNAT.Strings;
with GNATCOLL.Atomic; use GNATCOLL.Atomic;
package body GNATCOLL.Promises is
use type Impl.Promise_Callback_Access;
package Cb_Vectors is new Ada.Containers.Vectors
(Positive, Impl.Promise_Callback_Access, Impl."=");
----------
-- Free --
----------
procedure Free (Self : in out Freeable_Access) is
procedure Unchecked_Free is new Ada.Unchecked_Deallocation
(IFreeable'Class, Freeable_Access);
begin
if Self /= null then
Free (Self.all);
Unchecked_Free (Self);
end if;
end Free;
---------------
-- Subscribe --
---------------
procedure Subscribe (Self : Promise_Chain) is
begin
null;
end Subscribe;
----------
-- Impl --
----------
package body Impl is
-------------------
-- Dispatch_Free --
-------------------
procedure Dispatch_Free (Self : in out IPromise_Data'Class) is
begin
Free (Self);
end Dispatch_Free;
end Impl;
--------------
-- Promises --
--------------
package body Promises is
type T_Access is access all T;
type Promise_Data is new Impl.IPromise_Data with record
State : aliased Promise_State := Pending;
Callbacks : Cb_Vectors.Vector;
-- Need a vector here, but should try to limit memory allocs.
-- A bounded vector might be more efficient, and sufficient in
-- practice.
Value : T_Access;
-- ??? Using the ada-traits-containers approach, we could avoid
-- some memory allocation here.
Reason : GNAT.Strings.String_Access;
end record;
type Promise_Data_Access is access all Promise_Data'Class;
overriding procedure Free (Self : in out Promise_Data);
procedure Unchecked_Free is new Ada.Unchecked_Deallocation
(T, T_Access);
---------------
-- Get_State --
---------------
function Get_State (Self : Promise'Class) return Actual_Promise_State is
D : constant not null access Promise_Data'Class :=
Promise_Data_Access (Impl.Promise_Pointers.Unchecked_Get (Self));
begin
return Actual_Promise_State (D.State);
end Get_State;
------------
-- Create --
------------
function Create return Promise is
begin
return P : Promise do
P.Set
(Data => Promise_Data'
(Callbacks => Cb_Vectors.Empty_Vector,
State => Pending,
Value => null,
Reason => null));
end return;
end Create;
----------
-- Free --
----------
overriding procedure Free (Self : in out Promise_Data) is
begin
Unchecked_Free (Self.Value);
Free (Self.Reason);
end Free;
---------------
-- Set_Value --
---------------
procedure Set_Value (Self : in out Promise; R : T) is
D : constant not null access Promise_Data'Class :=
Promise_Data_Access (Impl.Promise_Pointers.Unchecked_Get (Self));
Old : Actual_Promise_State;
begin
loop
Old := Actual_Promise_State
(Sync_Val_Compare_And_Swap_Counter
(Ptr => D.State'Access,
Oldval => Pending,
Newval => Resolving));
case Old is
when Resolved | Failed =>
-- Promise has already been completed, this is an error
return;
when Resolving | Failing | Subscribing =>
-- Try again
null;
when Pending =>
-- OK, we can change the state
for Cb of D.Callbacks loop
Callback_Access (Cb).On_Next (R);
Free (Freeable_Access (Cb));
end loop;
D.Callbacks.Clear; -- No longer needed, release them
D.Value := new T'(R);
D.State := Resolved; -- Fully resolved now
exit;
end case;
end loop;
end Set_Value;
---------------
-- Set_Error --
---------------
procedure Set_Error (Self : in out Promise; Reason : String) is
D : constant not null access Promise_Data'Class :=
Promise_Data_Access (Impl.Promise_Pointers.Unchecked_Get (Self));
Old : Actual_Promise_State;
begin
loop
Old := Actual_Promise_State
(Sync_Val_Compare_And_Swap_Counter
(Ptr => D.State'Access,
Oldval => Pending,
Newval => Failing));
case Old is
when Resolved | Failed =>
-- Promise has already been completed, this is an error
return;
when Resolving | Failing | Subscribing =>
-- Try again
null;
when Pending =>
-- OK, we can change the state
for Cb of D.Callbacks loop
Callback_Access (Cb).On_Error (Reason);
Free (Freeable_Access (Cb));
end loop;
D.Callbacks.Clear; -- No longer needed, release them
D.Reason := new String'(Reason);
D.State := Failed; -- Fully failed now
exit;
end case;
end loop;
end Set_Error;
---------------
-- Subscribe --
---------------
procedure Subscribe
(Self : Promise; Cb : not null access Callback'Class)
is
D : constant not null access Promise_Data'Class :=
Promise_Data_Access (Impl.Promise_Pointers.Unchecked_Get (Self));
-- ??? Unrestricted_Access is temporary, so that user can
-- use "new Cb" directly in the call to Subscribe.
C : Callback_Access := Cb.all'Unrestricted_Access;
Old : Actual_Promise_State;
begin
loop
Old := Actual_Promise_State
(Sync_Val_Compare_And_Swap_Counter
(Ptr => D.State'Access,
Oldval => Pending,
Newval => Subscribing));
case Old is
when Resolving | Failing | Subscribing =>
-- Try again
null;
when Resolved =>
-- We don't need to change D, so we leave the state to
-- Pending
C.On_Next (D.Value.all);
Free (Freeable_Access (C));
return;
when Failed =>
C.On_Error (D.Reason.all);
Free (Freeable_Access (C));
return;
when Pending =>
D.Callbacks.Append (Impl.Promise_Callback_Access (C));
D.State := Pending;
exit;
end case;
end loop;
end Subscribe;
-----------
-- "and" --
-----------
function "and"
(Self : Promise; Cb : Callback_List)
return Promise_Chain is
begin
for C of Cb loop
Self.Subscribe (C);
end loop;
return Promise_Chain'(null record);
end "and";
-----------
-- "and" --
-----------
function "and"
(Self : Promise;
Cb : not null access Callback'Class)
return Promise_Chain is
begin
Self.Subscribe (Cb);
return Promise_Chain'(null record);
end "and";
---------
-- "&" --
---------
function "&"
(Cb : not null access Callback'Class;
Cb2 : not null access Callback'Class)
return Callback_List is
begin
return (Cb.all'Unrestricted_Access,
Cb2.all'Unrestricted_Access);
end "&";
---------
-- "&" --
---------
function "&"
(List : Callback_List;
Cb2 : not null access Callback'Class)
return Callback_List is
begin
return List & (1 => Cb2.all'Unrestricted_Access);
end "&";
end Promises;
------------
-- Chains --
------------
package body Chains is
-----------
-- "and" --
-----------
function "and"
(Input : Input_Promises.Promise;
Cb : not null access Callback'Class)
return Output_Promises.Promise is
begin
Cb.Promise := Output_Promises.Create;
Input_Promises.Subscribe (Input, Cb.all'Unrestricted_Access);
return Cb.Promise;
end "and";
-----------
-- "and" --
-----------
function "and"
(Input : Input_Promises.Promise;
Cb : Callback_List)
return Output_Promises.Promise
is
P : constant Output_Promises.Promise := Input and Cb.Cb;
begin
for C of Cb.Cb2 loop
Input_Promises.Subscribe (Input, C);
end loop;
return P;
end "and";
-------------------
-- Is_Registered --
-------------------
function Is_Registered
(Self : not null access Callback'Class) return Boolean is
begin
return Self.Promise.Is_Created;
end Is_Registered;
-------------------
-- Is_Registered --
-------------------
function Is_Registered
(Self : Callback_List) return Boolean is
begin
return Self.Cb.Promise.Is_Created;
end Is_Registered;
-------------
-- On_Next --
-------------
overriding procedure On_Next
(Self : in out Callback; P : Input_Promises.Result_Type) is
begin
On_Next (Callback'Class (Self), P, Self.Promise);
exception
when E : others =>
Self.Promise.Set_Error (Exception_Message (E));
end On_Next;
--------------
-- On_Error --
--------------
overriding procedure On_Error
(Self : in out Callback; Reason : String) is
begin
-- Propagate the failure
Self.Promise.Set_Error (Reason);
end On_Error;
-----------
-- "&" --
-----------
function "&"
(Cb : not null access Callback'Class;
Cb2 : not null access Input_Promises.Callback'Class)
return Callback_List is
begin
return Callback_List'
(N => 1,
Cb => Cb.all'Unrestricted_Access,
Cb2 => (1 => Cb2.all'Unrestricted_Access));
end "&";
-----------
-- "&" --
-----------
function "&"
(List : Callback_List;
Cb2 : not null access Input_Promises.Callback'Class)
return Callback_List is
begin
return Callback_List'
(N => List.N + 1,
Cb => List.Cb,
Cb2 => List.Cb2 & (1 => Cb2.all'Unrestricted_Access));
end "&";
end Chains;
end GNATCOLL.Promises;
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