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308 | -- Copyright (C) 2024 Simon Wright <simon@pushface.org>
-- Licence: Apache 2.0
with Ada.Containers.Ordered_Maps;
with Ada.Containers.Vectors;
with Ada.Strings.Fixed;
with Ada.Strings.Unbounded;
with Ada.Text_IO;
with Ada.Unchecked_Conversion;
with GNAT.Command_Line;
with GNAT.OS_Lib;
with GNAT.Strings;
with System.Multiprocessors;
with Commands;
procedure Parallelize is
-- This program reads a set of commands (jobs) from standard
-- input, one per line, terminated by end-of-file or a blank
-- line. It then executes them in parallel subprocesses, where the
-- number defaults to the number of CPUs available.
--
-- Any standard error output from a job is merged with its
-- standard output. The overall output consists of the output from
-- each job, in the order in which the jobs were presented.
-- Unbounded String utilities.
function "+" (L : String) return Ada.Strings.Unbounded.Unbounded_String
renames Ada.Strings.Unbounded.To_Unbounded_String;
function "+" (L : Ada.Strings.Unbounded.Unbounded_String) return String
renames Ada.Strings.Unbounded.To_String;
--- If Verbose is True, this procedure outputs Message via standard error.
procedure Log (Message : String);
-- Information on a job.
type Job is record
Command : Ada.Strings.Unbounded.Unbounded_String;
Executable : Boolean := False;
Started : Boolean := False;
Finished : Boolean := False;
Status : Boolean := False;
Complete : Boolean := False;
Output_File_Name : GNAT.OS_Lib.String_Access;
end record;
-- The index of a Job in the Job Vector, renamed for clarity.
subtype Job_Index is Positive;
package Job_Vectors is new Ada.Containers.Vectors
(Index_Type => Job_Index,
Element_Type => Job);
use Job_Vectors;
-- Each Job will be run in a Process. We need a map from
-- Process_Id to Job, so that when the Process completes we can
-- find the Job it was running. This comparison function is needed
-- to support an Ordered Map (a Hashed Map would require a hash
-- function, so _something_ is needed).
function "<" (L, R : GNAT.OS_Lib.Process_Id) return Boolean;
package Process_Maps is new Ada.Containers.Ordered_Maps
(Key_Type => GNAT.OS_Lib.Process_Id,
Element_Type => Job_Index);
use Process_Maps;
-- This procedure starts as many Jobs as currently possible.
procedure Start_Processes;
Command_Line_Config : GNAT.Command_Line.Command_Line_Configuration;
Verbose : aliased Boolean := False;
Max_Processes : aliased Integer
:= Positive (System.Multiprocessors.Number_Of_CPUs);
-- This has to be an Integer, because of its use in option processing.
Jobs : Job_Vectors.Vector;
Processes : Process_Maps.Map;
procedure Log (Message : String) is
begin
if Verbose then
Ada.Text_IO.Put_Line (Ada.Text_IO.Standard_Error, Message);
end if;
end Log;
function "<" (L, R : GNAT.OS_Lib.Process_Id) return Boolean
is
-- Process_Id (on Darwin, anyway) is new Integer.
function Convert
is new Ada.Unchecked_Conversion (GNAT.OS_Lib.Process_Id, Integer);
begin
return Convert (L) < Convert (R);
end "<";
procedure Start_Processes is
begin
Next_Job :
for J in Jobs.Iterate loop
exit Next_Job when Natural (Processes.Length) = Max_Processes;
if not Jobs (J).Started then
Set_Up_Job :
declare
The_Job : Job renames Jobs (J);
Whole_Command : constant String := +The_Job.Command;
Command : constant String
:= Commands.Command_Part (Whole_Command);
Executable : GNAT.OS_Lib.String_Access
:= GNAT.OS_Lib.Locate_Exec_On_Path (Command);
Pid : GNAT.OS_Lib.Process_Id;
use type GNAT.OS_Lib.Process_Id;
Unused_FD : GNAT.OS_Lib.File_Descriptor;
use type GNAT.Strings.String_Access; -- for Executable
begin
The_Job.Started := True;
if Executable = null then
Log ("'" & Command & "' not executable");
else
The_Job.Executable := True;
-- This is the temporary file in which we keep the
-- Job's output.
GNAT.OS_Lib.Create_Temp_Output_File
(Unused_FD, The_Job.Output_File_Name);
Pid := GNAT.OS_Lib.Non_Blocking_Spawn
(Program_Name => Executable.all,
Args => GNAT.OS_Lib.Argument_String_To_List
(Commands.Argument_Part (Whole_Command)).all,
Output_File => The_Job.Output_File_Name.all,
Err_To_Out => True);
if Pid = GNAT.OS_Lib.Invalid_Pid then
-- Not sure why this happened; did we run out of
-- processes?
Log ("couldn't spawn '" & Whole_Command & "'");
GNAT.Strings.Free (The_Job.Output_File_Name);
else
Log ("starting '" & Whole_Command & "'");
Processes.Insert (Key => Pid,
New_Item => Job_Vectors.To_Index (J));
end if;
GNAT.Strings.Free (Executable);
end if; -- Job was executable
end Set_Up_Job;
end if;
end loop Next_Job;
end Start_Processes;
begin
GNAT.Command_Line.Set_Usage
(Command_Line_Config,
Usage => "[switches]",
Help => "Run the jobs defined in standard input (one per line)");
GNAT.Command_Line.Define_Switch
(Command_Line_Config,
Verbose'Access,
"-v",
Long_Switch => "--verbose",
Help => "Report progress");
GNAT.Command_Line.Define_Switch
(Command_Line_Config,
Max_Processes'Access,
"-j!",
Long_Switch => "--jobs=",
Initial => Positive (System.Multiprocessors.Number_Of_CPUs),
Help => "Number of jobs to run in parallel (D=number of CPUs)");
GNAT.Command_Line.Getopt (Command_Line_Config);
pragma Assert (Max_Processes in Positive,
"the number of processes must be >0");
Read_Commands :
loop
begin
Read_Command :
declare
Input : constant String
:= Ada.Strings.Fixed.Trim
(Ada.Text_IO.Get_Line, Ada.Strings.Both);
begin
exit Read_Commands when Input'Length = 0;
Log ("read '" & Input & "'");
Jobs.Append (New_Item => Job'(Command => +Input,
others => <>));
end Read_Command;
exception
when Ada.Text_IO.End_Error =>
exit Read_Commands;
end;
end loop Read_Commands;
Run :
declare
-- Keep track of the Jobs that have been output so far.
Last_Job_Output : Natural := Job_Index'First - 1;
begin
Monitor_Process_Completion :
loop
Find_Finished_Process :
declare
Finished_Pid : GNAT.OS_Lib.Process_Id;
use type GNAT.OS_Lib.Process_Id;
Job_Status : Boolean;
begin
-- We get here either because we've just started
-- (i.e. first time round the Monitor_Process_Completion
-- loop), in which case we'll start up to Max_Processes
-- Processes (or the number of Jobs, if less), or because
-- a Process has just finished, in which case we'll start
-- one Process (unless we've started all the Jobs).
Start_Processes;
GNAT.OS_Lib.Wait_Process (Pid => Finished_Pid,
Success => Job_Status);
-- If there are no subprocesses, we're done.
exit Monitor_Process_Completion
when Finished_Pid = GNAT.OS_Lib.Invalid_Pid;
Handle_Completed_Job :
declare
Job_ID : constant Job_Index := Processes (Finished_Pid);
The_Job : Job renames Jobs (Job_ID);
begin
Log ("finished '" & (+The_Job.Command) & "'");
The_Job.Status := Job_Status;
The_Job.Finished := True;
Processes.Delete (Finished_Pid);
-- freeing a slot for another Job, if there are any left
end Handle_Completed_Job;
Output_Completed_Jobs_In_Order :
for J in Last_Job_Output + 1 .. Jobs.Last_Index loop
-- A Job isn't executable if the Command part (the
-- first word) isn't executable. In that case, there
-- was never a Process, not any output.
if Jobs (J).Executable then
-- We're presenting the output, in Job order, of
-- each of the Jobs that have Finished. If a job
-- hasn't Finished, there will still be output to
-- come, so we stop here to wait for it.
exit Output_Completed_Jobs_In_Order
when not Jobs (J).Finished;
Last_Job_Output := J;
Output_Job :
declare
The_Job : Job renames Jobs (J);
File : Ada.Text_IO.File_Type;
begin
-- Copy the Job's output to Parallelize's
-- standard output.
Ada.Text_IO.Open (File,
Name => The_Job.Output_File_Name.all,
Mode => Ada.Text_IO.In_File);
while not Ada.Text_IO.End_Of_File (File) loop
Ada.Text_IO.Put_Line (Ada.Text_IO.Get_Line (File));
end loop;
-- When done, delete the temporary file and its
-- name.
Ada.Text_IO.Delete (File);
GNAT.Strings.Free (The_Job.Output_File_Name);
-- This isn't strictly necessary, because next
-- time round we continue from the next Job (the
-- one after Last_Job_Ouput).
The_Job.Complete := True;
Log ("completed '" & (+The_Job.Command) & "'");
end Output_Job;
end if;
end loop Output_Completed_Jobs_In_Order;
end Find_Finished_Process;
end loop Monitor_Process_Completion;
end Run;
exception
-- This happens when parallelize is called with -h/--help.
when GNAT.Command_Line.Exit_From_Command_Line => null;
end Parallelize;
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