[pve-devel] [PATCH common] run_command: improve performance for outfunc and long lines

[pve-devel] [PATCH common] run_command: improve performance for outfunc and long lines

[Dominik Csapak]

to call outfunc with each line, we search for a newline and call
outfunc/logfunc with everything before that

since we do a select/read (with 4096 size) in a loop, this means
that if we have very long lines, we search for a newline in an
ever growing buffer (for which we know does not contain a newline)

so instead, only search the new data for newlines

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
this reduces a 'pvesm list' for a pbs storage with ~5000 snapshots from 66s to 4.7s

todo: the backspace/\r handling is weird, maybe we should improve that?
for now its compatible

 src/PVE/Tools.pm | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/PVE/Tools.pm b/src/PVE/Tools.pm
index 4399b2f..350cb27 100644
--- a/src/PVE/Tools.pm
+++ b/src/PVE/Tools.pm
@@ -496,12 +496,14 @@ sub run_command {
 		if ($h eq $reader) {
 		    if ($outfunc || $logfunc) {
 			eval {
-			    $outlog .= $buf;
-			    while ($outlog =~ s/^([^\010\r\n]*)(\r|\n|(\010)+|\r\n)//s) {
-				my $line = $1;
+			    while ($buf =~ m/^([^\010\r\n]*)(?:\r|\n|(?:\010)+|\r\n)(.*)$/) {
+				my $line = $outlog . $1;
+				$outlog = "";
+				$buf = $2;
 				&$outfunc($line) if $outfunc;
 				&$logfunc($line) if $logfunc;
 			    }
+			    $outlog .= $buf;
 			};
 			my $err = $@;
 			if ($err) {
-- 
2.20.1