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Task safe random generation
U503-007 * src/core/aws-utils.adb (Shared_Random): Object to protect random number generator from multi task concurrency. (Random_Reset): New routine to initate predictable random sequence. * regtests/0336_random_task_safe/test.adb, regtests/0336_random_task_safe/test.gpr, regtests/0336_random_task_safe/test.py: Test for random generation concurrency.
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‎regtests/0336_random_task_safe/test.adb

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with Ada.Containers.Hashed_Sets;
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with Ada.Exceptions; use Ada.Exceptions;
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with Ada.Text_IO; use Ada.Text_IO;
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with AWS.Utils; use AWS.Utils;
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procedure Test is
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type Test_Random_Mode is (None, Save, Lookup);
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package Random_Sets is new Ada.Containers.Hashed_Sets
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(Random_Integer, Ada.Containers.Hash_Type'Mod, "=");
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Set : Random_Sets.Set;
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Locker : RW_Semaphore (1);
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Wrong_Data_Set : exception;
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procedure Test_Random_Sequence
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(Count : Positive; Mode : Test_Random_Mode);
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function Test_Random_Sequence
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(Initialor : Integer; Count : Positive) return String;
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task Secondary is
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entry Start (Count : Positive; Mode : Test_Random_Mode);
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entry Done (Quit : Boolean);
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end Secondary;
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--------------------------
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-- Test_Random_Sequence --
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--------------------------
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function Test_Random_Sequence
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(Initialor : Integer; Count : Positive) return String is
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begin
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Random_Reset (Initialor);
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Test_Random_Sequence (Count, None);
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return Random_String (77);
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end Test_Random_Sequence;
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procedure Test_Random_Sequence
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(Count : Positive; Mode : Test_Random_Mode)
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is
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R : Random_Integer;
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begin
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for J in 1 .. Count loop
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R := Random;
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case Mode is
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when None =>
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null;
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when Save =>
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Locker.Write;
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Set.Include (R);
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Locker.Release_Write;
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when Lookup =>
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if not Set.Contains (R) then
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raise Wrong_Data_Set with
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"Expected random element" & R'Img & " absent at" & J'Img;
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end if;
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end case;
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end loop;
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end Test_Random_Sequence;
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---------------
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-- Secondary --
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---------------
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task body Secondary is
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Count : Positive;
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Mode : Test_Random_Mode;
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Quit : Boolean;
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begin
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loop
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accept Start (Count : Positive; Mode : Test_Random_Mode) do
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Secondary.Count := Count;
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Secondary.Mode := Mode;
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end Start;
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Test_Random_Sequence (Count, Mode);
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accept Done (Quit : Boolean) do
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Secondary.Quit := Quit;
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end Done;
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exit when Quit;
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end loop;
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exception
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when E : others =>
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Put_Line ("Secondary task: " & Exception_Message (E));
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end Secondary;
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begin
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if Test_Random_Sequence (321, 256) /= Test_Random_Sequence (321, 256) then
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Put_Line ("Random_Reset with same initialor error");
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end if;
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for Mode in Save .. Lookup loop
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Random_Reset (112344);
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Test_Random_Sequence (4096, Mode);
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end loop;
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Set.Clear;
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for Mode in Save .. Lookup loop
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Random_Reset (44552211);
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Secondary.Start (8196, Mode);
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Test_Random_Sequence (8196, Mode);
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Secondary.Done (Mode = Lookup);
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end loop;
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exception
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when E : others =>
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Put_Line ("Main task: " & Exception_Message (E));
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end Test;

‎regtests/0336_random_task_safe/test.gpr

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with "aws.gpr";
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project Test is
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for Main use ("test.adb");
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end Test;

‎regtests/0336_random_task_safe/test.py

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from test_support import *
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build_and_run('test');

‎src/core/aws-net-websocket-protocol-rfc6455.adb

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Original file line numberDiff line numberDiff line change
@@ -130,7 +130,7 @@ package body AWS.Net.WebSocket.Protocol.RFC6455 is
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is
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pragma Unreferenced (Protocol);
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Ints : array (1 .. 4) of AWS.Utils.Random_Integer :=
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(others => AWS.Utils.Random);
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(others => Utils.Random);
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H : Stream_Element_Array (1 .. 16) with Import, Address => Ints'Address;
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begin
@@ -183,7 +183,7 @@ package body AWS.Net.WebSocket.Protocol.RFC6455 is
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------------------------
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function Create_Random_Mask return Masking_Key is
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Int : constant AWS.Utils.Random_Integer := AWS.Utils.Random;
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Int : constant Utils.Random_Integer := Utils.Random;
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Arr : Masking_Key with Import, Address => Int'Address;
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begin
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return Arr;

‎src/core/aws-utils.adb

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Original file line numberDiff line numberDiff line change
@@ -68,7 +68,13 @@ package body AWS.Utils is
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-- Returns True if the string pointed to by Str and terminating to Last
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-- is well-formed UTF-8.
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Random_Generator : Integer_Random.Generator;
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protected Shared_Random is
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function Generate return Random_Integer;
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procedure Reset;
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procedure Reset (Seed : Integer);
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private
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Random_Generator : Integer_Random.Generator;
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end Shared_Random;
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---------------------
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-- Append_With_Sep --
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function Random return Random_Integer is
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begin
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return Integer_Random.Random (Random_Generator);
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return Shared_Random.Generate;
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end Random;
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------------------
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-- Random_Reset --
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------------------
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procedure Random_Reset (Seed : Integer) is
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begin
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Shared_Random.Reset (Seed);
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end Random_Reset;
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-------------------
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-- Random_String --
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-------------------
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end Semaphore;
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-------------------
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-- Shared_Random --
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-------------------
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protected body Shared_Random is
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--------------
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-- Generate --
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--------------
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function Generate return Random_Integer is
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begin
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return Integer_Random.Random (Random_Generator);
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end Generate;
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-----------
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-- Reset --
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-----------
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procedure Reset is
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begin
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Integer_Random.Reset (Random_Generator);
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end Reset;
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procedure Reset (Seed : Integer) is
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begin
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Integer_Random.Reset (Random_Generator, Seed);
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end Reset;
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end Shared_Random;
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-----------------------
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-- Significant_Image --
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-----------------------
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end Time_Zone;
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11611207
begin
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Integer_Random.Reset (Random_Generator);
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Shared_Random.Reset;
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end AWS.Utils;

‎src/core/aws-utils.ads

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@@ -94,6 +94,12 @@ package AWS.Utils is
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=> C in '0' .. '9' | 'a' .. 'z' | 'A' .. 'Z');
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-- Returns random string
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procedure Random_Reset (Seed : Integer);
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-- This function is needed only if the user wants to get predictable random
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-- numbers. It means that after calling Random_Reset with the same Seed the
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-- same sequence of Random and Random_String calls will give the same
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-- results.
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function Image (N : Natural) return String with
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Post => Image'Result'Length > 0
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and then Image'Result (Image'Result'First) /= ' ';

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