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https://github.com/git/git
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2841e8f81c
Some `clean` / `smudge` filters may require a significant amount of
time to process a single blob (e.g. the Git LFS smudge filter might
perform network requests). During this process the Git checkout
operation is blocked and Git needs to wait until the filter is done to
continue with the checkout.
Teach the filter process protocol, introduced in edcc8581
("convert: add
filter.<driver>.process option", 2016-10-16), to accept the status
"delayed" as response to a filter request. Upon this response Git
continues with the checkout operation. After the checkout operation Git
calls "finish_delayed_checkout" which queries the filter for remaining
blobs. If the filter is still working on the completion, then the filter
is expected to block. If the filter has completed all remaining blobs
then an empty response is expected.
Git has a multiple code paths that checkout a blob. Support delayed
checkouts only in `clone` (in unpack-trees.c) and `checkout` operations
for now. The optimization is most effective in these code paths as all
files of the tree are processed.
Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
272 lines
7.6 KiB
Perl
272 lines
7.6 KiB
Perl
#
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# Example implementation for the Git filter protocol version 2
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# See Documentation/gitattributes.txt, section "Filter Protocol"
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#
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# The first argument defines a debug log file that the script write to.
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# All remaining arguments define a list of supported protocol
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# capabilities ("clean", "smudge", etc).
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#
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# This implementation supports special test cases:
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# (1) If data with the pathname "clean-write-fail.r" is processed with
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# a "clean" operation then the write operation will die.
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# (2) If data with the pathname "smudge-write-fail.r" is processed with
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# a "smudge" operation then the write operation will die.
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# (3) If data with the pathname "error.r" is processed with any
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# operation then the filter signals that it cannot or does not want
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# to process the file.
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# (4) If data with the pathname "abort.r" is processed with any
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# operation then the filter signals that it cannot or does not want
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# to process the file and any file after that is processed with the
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# same command.
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# (5) If data with a pathname that is a key in the DELAY hash is
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# requested (e.g. "test-delay10.a") then the filter responds with
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# a "delay" status and sets the "requested" field in the DELAY hash.
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# The filter will signal the availability of this object after
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# "count" (field in DELAY hash) "list_available_blobs" commands.
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# (6) If data with the pathname "missing-delay.a" is processed that the
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# filter will drop the path from the "list_available_blobs" response.
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# (7) If data with the pathname "invalid-delay.a" is processed that the
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# filter will add the path "unfiltered" which was not delayed before
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# to the "list_available_blobs" response.
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#
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use strict;
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use warnings;
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use IO::File;
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my $MAX_PACKET_CONTENT_SIZE = 65516;
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my $log_file = shift @ARGV;
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my @capabilities = @ARGV;
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open my $debug, ">>", $log_file or die "cannot open log file: $!";
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my %DELAY = (
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'test-delay10.a' => { "requested" => 0, "count" => 1 },
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'test-delay11.a' => { "requested" => 0, "count" => 1 },
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'test-delay20.a' => { "requested" => 0, "count" => 2 },
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'test-delay10.b' => { "requested" => 0, "count" => 1 },
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'missing-delay.a' => { "requested" => 0, "count" => 1 },
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'invalid-delay.a' => { "requested" => 0, "count" => 1 },
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);
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sub rot13 {
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my $str = shift;
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$str =~ y/A-Za-z/N-ZA-Mn-za-m/;
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return $str;
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}
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sub packet_bin_read {
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my $buffer;
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my $bytes_read = read STDIN, $buffer, 4;
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if ( $bytes_read == 0 ) {
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# EOF - Git stopped talking to us!
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print $debug "STOP\n";
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exit();
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}
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elsif ( $bytes_read != 4 ) {
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die "invalid packet: '$buffer'";
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}
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my $pkt_size = hex($buffer);
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if ( $pkt_size == 0 ) {
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return ( 1, "" );
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}
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elsif ( $pkt_size > 4 ) {
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my $content_size = $pkt_size - 4;
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$bytes_read = read STDIN, $buffer, $content_size;
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if ( $bytes_read != $content_size ) {
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die "invalid packet ($content_size bytes expected; $bytes_read bytes read)";
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}
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return ( 0, $buffer );
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}
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else {
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die "invalid packet size: $pkt_size";
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}
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}
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sub packet_txt_read {
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my ( $res, $buf ) = packet_bin_read();
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unless ( $buf eq '' or $buf =~ s/\n$// ) {
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die "A non-binary line MUST be terminated by an LF.";
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}
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return ( $res, $buf );
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}
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sub packet_bin_write {
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my $buf = shift;
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print STDOUT sprintf( "%04x", length($buf) + 4 );
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print STDOUT $buf;
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STDOUT->flush();
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}
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sub packet_txt_write {
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packet_bin_write( $_[0] . "\n" );
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}
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sub packet_flush {
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print STDOUT sprintf( "%04x", 0 );
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STDOUT->flush();
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}
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print $debug "START\n";
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$debug->flush();
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( packet_txt_read() eq ( 0, "git-filter-client" ) ) || die "bad initialize";
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( packet_txt_read() eq ( 0, "version=2" ) ) || die "bad version";
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( packet_bin_read() eq ( 1, "" ) ) || die "bad version end";
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packet_txt_write("git-filter-server");
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packet_txt_write("version=2");
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packet_flush();
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( packet_txt_read() eq ( 0, "capability=clean" ) ) || die "bad capability";
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( packet_txt_read() eq ( 0, "capability=smudge" ) ) || die "bad capability";
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( packet_txt_read() eq ( 0, "capability=delay" ) ) || die "bad capability";
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( packet_bin_read() eq ( 1, "" ) ) || die "bad capability end";
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foreach (@capabilities) {
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packet_txt_write( "capability=" . $_ );
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}
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packet_flush();
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print $debug "init handshake complete\n";
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$debug->flush();
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while (1) {
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my ( $command ) = packet_txt_read() =~ /^command=(.+)$/;
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print $debug "IN: $command";
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$debug->flush();
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if ( $command eq "list_available_blobs" ) {
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# Flush
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packet_bin_read();
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foreach my $pathname ( sort keys %DELAY ) {
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if ( $DELAY{$pathname}{"requested"} >= 1 ) {
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$DELAY{$pathname}{"count"} = $DELAY{$pathname}{"count"} - 1;
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if ( $pathname eq "invalid-delay.a" ) {
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# Send Git a pathname that was not delayed earlier
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packet_txt_write("pathname=unfiltered");
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}
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if ( $pathname eq "missing-delay.a" ) {
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# Do not signal Git that this file is available
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} elsif ( $DELAY{$pathname}{"count"} == 0 ) {
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print $debug " $pathname";
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packet_txt_write("pathname=$pathname");
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}
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}
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}
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packet_flush();
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print $debug " [OK]\n";
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$debug->flush();
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packet_txt_write("status=success");
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packet_flush();
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}
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else {
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my ( $pathname ) = packet_txt_read() =~ /^pathname=(.+)$/;
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print $debug " $pathname";
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$debug->flush();
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if ( $pathname eq "" ) {
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die "bad pathname '$pathname'";
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}
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# Read until flush
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my ( $done, $buffer ) = packet_txt_read();
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while ( $buffer ne '' ) {
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if ( $buffer eq "can-delay=1" ) {
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if ( exists $DELAY{$pathname} and $DELAY{$pathname}{"requested"} == 0 ) {
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$DELAY{$pathname}{"requested"} = 1;
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}
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} else {
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die "Unknown message '$buffer'";
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}
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( $done, $buffer ) = packet_txt_read();
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}
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my $input = "";
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{
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binmode(STDIN);
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my $buffer;
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my $done = 0;
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while ( !$done ) {
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( $done, $buffer ) = packet_bin_read();
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$input .= $buffer;
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}
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print $debug " " . length($input) . " [OK] -- ";
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$debug->flush();
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}
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my $output;
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if ( exists $DELAY{$pathname} and exists $DELAY{$pathname}{"output"} ) {
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$output = $DELAY{$pathname}{"output"}
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}
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elsif ( $pathname eq "error.r" or $pathname eq "abort.r" ) {
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$output = "";
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}
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elsif ( $command eq "clean" and grep( /^clean$/, @capabilities ) ) {
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$output = rot13($input);
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}
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elsif ( $command eq "smudge" and grep( /^smudge$/, @capabilities ) ) {
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$output = rot13($input);
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}
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else {
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die "bad command '$command'";
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}
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if ( $pathname eq "error.r" ) {
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print $debug "[ERROR]\n";
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$debug->flush();
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packet_txt_write("status=error");
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packet_flush();
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}
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elsif ( $pathname eq "abort.r" ) {
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print $debug "[ABORT]\n";
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$debug->flush();
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packet_txt_write("status=abort");
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packet_flush();
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}
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elsif ( $command eq "smudge" and
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exists $DELAY{$pathname} and
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$DELAY{$pathname}{"requested"} == 1
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) {
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print $debug "[DELAYED]\n";
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$debug->flush();
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packet_txt_write("status=delayed");
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packet_flush();
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$DELAY{$pathname}{"requested"} = 2;
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$DELAY{$pathname}{"output"} = $output;
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}
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else {
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packet_txt_write("status=success");
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packet_flush();
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if ( $pathname eq "${command}-write-fail.r" ) {
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print $debug "[WRITE FAIL]\n";
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$debug->flush();
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die "${command} write error";
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}
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print $debug "OUT: " . length($output) . " ";
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$debug->flush();
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while ( length($output) > 0 ) {
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my $packet = substr( $output, 0, $MAX_PACKET_CONTENT_SIZE );
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packet_bin_write($packet);
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# dots represent the number of packets
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print $debug ".";
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if ( length($output) > $MAX_PACKET_CONTENT_SIZE ) {
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$output = substr( $output, $MAX_PACKET_CONTENT_SIZE );
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}
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else {
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$output = "";
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}
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}
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packet_flush();
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print $debug " [OK]\n";
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$debug->flush();
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packet_flush();
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}
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}
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}
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