[pve-devel] [PATCH qemu-server 1/2] rework kvm_user_version cache mechanism

[Dominik Csapak]

we now also save the mtime of the binary and cache per binary (for each
arch; this is done so we have it already when we sometime decide
that we want to split the qemu package for each arch)
so that we get the real version if only pve-qemu-kvm was updated

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
 PVE/QemuServer.pm | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 8c519b5..220af73 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -1471,25 +1471,33 @@ sub kvm_version {
     return $kvm_api_version;
 }
 
-my $kvm_user_version;
+my $kvm_user_version = {};
+my $kvm_mtime = {};
 
 sub kvm_user_version {
+    my ($binary) = @_;
 
-    return $kvm_user_version if $kvm_user_version;
+    $binary //= get_command_for_arch(get_host_arch()); # get the native arch by default
+    my $st = stat($binary);
 
-    $kvm_user_version = 'unknown';
+    my $cachedmtime = $kvm_mtime->{$binary} // -1;
+    return $kvm_user_version->{$binary} if $kvm_user_version->{$binary} &&
+	$cachedmtime == $st->mtime;
+
+    $kvm_user_version->{$binary} = 'unknown';
+    $kvm_mtime->{$binary} = $st->mtime;
 
     my $code = sub {
 	my $line = shift;
 	if ($line =~ m/^QEMU( PC)? emulator version (\d+\.\d+(\.\d+)?)(\.\d+)?[,\s]/) {
-	    $kvm_user_version = $2;
+	    $kvm_user_version->{$binary} = $2;
 	}
     };
 
-    eval { run_command("kvm -version", outfunc => $code); };
+    eval { run_command([$binary, '--version'], outfunc => $code); };
     warn $@ if $@;
 
-    return $kvm_user_version;
+    return $kvm_user_version->{$binary};
 
 }
 
@@ -3566,13 +3574,14 @@ sub config_to_command {
     my $devices = [];
     my $pciaddr = '';
     my $bridges = {};
-    my $kvmver = kvm_user_version();
     my $vernum = 0; # unknown
     my $ostype = $conf->{ostype};
     my $winversion = windows_version($ostype);
     my $kvm = $conf->{kvm};
 
     my ($arch, $machine_type) = get_basic_machine_info($conf, $forcemachine);
+    my $kvm_binary = get_command_for_arch($arch);
+    my $kvmver = kvm_user_version($kvm_binary);
     $kvm //= 1 if is_native($arch);
 
     if ($kvm) {
@@ -3598,7 +3607,7 @@ sub config_to_command {
     my $cpuunits = defined($conf->{cpuunits}) ?
             $conf->{cpuunits} : $defaults->{cpuunits};
 
-    push @$cmd, get_command_for_arch($arch);
+    push @$cmd, $kvm_binary;
 
     push @$cmd, '-id', $vmid;
 
-- 
2.20.1