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perf(CCUnix): avoid reading stderr when it's not used afterwards

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This commit is contained in:
Simon Cruanes 2020-06-06 16:17:28 -04:00
parent a25656edd7
commit 56ca1b3753
1 changed files with 21 additions and 3 deletions
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24
src/unix/CCUnix.ml
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@ -74,6 +74,18 @@ let read_all ?(size=1024) ic =
with Exit ->
Bytes.sub_string !buf 0 !len
(* read content but do not store it. This prevents writers from
starving while not allocating anything more than the initial buffer. *)
let read_all_and_discard ?(size=1024) ic : unit =
let buf = Bytes.create size in
try
while true do
let n = input ic buf 0 size in
if n = 0 then raise Exit; (* exhausted *)
done;
assert false (* never reached*)
with Exit -> ()
type call_result =
< stdout:string;
stderr:string;
@ -83,7 +95,8 @@ type call_result =
let kbprintf' buf fmt k = Printf.kbprintf k buf fmt
let call_full_inner ?(bufsize=2048) ?(stdin=`Str "") ?(env=Unix.environment()) ~f cmd =
let call_full_inner ?(discard_stderr=false)
?(bufsize=2048) ?(stdin=`Str "") ?(env=Unix.environment()) ~f cmd =
(* render the command *)
let buf = Buffer.create 256 in
kbprintf' buf cmd
@ -103,7 +116,11 @@ let call_full_inner ?(bufsize=2048) ?(stdin=`Str "") ?(env=Unix.environment()) ~
(fun oc ->
out := read_all ~size:bufsize oc)
oc in
let err = read_all ~size:bufsize errc in
let err =
if discard_stderr then (
read_all_and_discard ~size:bufsize errc; ""
) else read_all ~size:bufsize errc
in
Thread.join t_out;
let status = Unix.close_process_full (oc, ic, errc) in
f (!out,err,status)
@ -143,7 +160,8 @@ let call ?bufsize ?stdin ?env cmd =
~f:(fun (out,err,status) -> out, err, int_of_process_status status)
let call_stdout ?bufsize ?stdin ?env cmd =
call_full_inner ?bufsize ?stdin ?env cmd
(* no need to store stderr *)
call_full_inner ~discard_stderr:true ?bufsize ?stdin ?env cmd
~f:(fun (out,_err,_status) -> out)
(*$T