22144afa8d
For instance, it's pointless to keep copy-from-other-stores running if there are no other stores, or download-using-manifests if there are no manifests. This also speeds things up because we don't send queries to those substituters.
377 lines
11 KiB
Perl
Executable file
377 lines
11 KiB
Perl
Executable file
#! @perl@ -w @perlFlags@
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use strict;
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use Nix::Config;
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use Nix::Manifest;
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use Nix::Store;
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use Nix::Utils;
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use POSIX qw(strftime);
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use File::Temp qw(tempdir);
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STDOUT->autoflush(1);
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my $logFile = "$Nix::Config::logDir/downloads";
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# For queries, skip expensive calls to nix-hash etc. We're just
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# estimating the expected download size.
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my $fast = 1;
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# ‘--insecure’ is fine because Nix verifies the hash of the result.
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my $curl = "$Nix::Config::curl --fail --location --insecure";
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# Open the manifest cache and update it if necessary.
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my $dbh = updateManifestDB();
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exit 0 unless defined $dbh; # exit if there are no manifests
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print "\n";
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# $hashCache->{$algo}->{$path} yields the $algo-hash of $path.
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my $hashCache;
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sub parseHash {
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my $hash = shift;
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if ($hash =~ /^(.+):(.+)$/) {
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return ($1, $2);
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} else {
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return ("md5", $hash);
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}
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}
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# Compute the most efficient sequence of downloads to produce the
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# given path.
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sub computeSmallestDownload {
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my $targetPath = shift;
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# Build a graph of all store paths that might contribute to the
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# construction of $targetPath, and the special node "start". The
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# edges are either patch operations, or downloads of full NAR
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# files. The latter edges only occur between "start" and a store
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# path.
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my %graph;
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$graph{"start"} = {d => 0, pred => undef, edges => []};
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my @queue = ();
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my $queueFront = 0;
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my %done;
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sub addNode {
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my $graph = shift;
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my $u = shift;
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$$graph{$u} = {d => 999999999999, pred => undef, edges => []}
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unless defined $$graph{$u};
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}
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sub addEdge {
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my $graph = shift;
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my $u = shift;
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my $v = shift;
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my $w = shift;
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my $type = shift;
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my $info = shift;
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addNode $graph, $u;
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push @{$$graph{$u}->{edges}},
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{weight => $w, start => $u, end => $v, type => $type, info => $info};
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my $n = scalar @{$$graph{$u}->{edges}};
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}
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push @queue, $targetPath;
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while ($queueFront < scalar @queue) {
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my $u = $queue[$queueFront++];
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next if defined $done{$u};
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$done{$u} = 1;
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addNode \%graph, $u;
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# If the path already exists, it has distance 0 from the
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# "start" node.
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if (isValidPath($u)) {
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addEdge \%graph, "start", $u, 0, "present", undef;
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}
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else {
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# Add patch edges.
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my $patchList = $dbh->selectall_arrayref(
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"select * from Patches where storePath = ?",
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{ Slice => {} }, $u);
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foreach my $patch (@{$patchList}) {
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if (isValidPath($patch->{basePath})) {
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my ($baseHashAlgo, $baseHash) = parseHash $patch->{baseHash};
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my $hash = $hashCache->{$baseHashAlgo}->{$patch->{basePath}};
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if (!defined $hash) {
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$hash = $fast && $baseHashAlgo eq "sha256"
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? queryPathHash($patch->{basePath})
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: hashPath($baseHashAlgo, $baseHashAlgo ne "md5", $patch->{basePath});
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$hash =~ s/.*://;
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$hashCache->{$baseHashAlgo}->{$patch->{basePath}} = $hash;
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}
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next if $hash ne $baseHash;
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}
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push @queue, $patch->{basePath};
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addEdge \%graph, $patch->{basePath}, $u, $patch->{size}, "patch", $patch;
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}
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# Add NAR file edges to the start node.
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my $narFileList = $dbh->selectall_arrayref(
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"select * from NARs where storePath = ?",
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{ Slice => {} }, $u);
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foreach my $narFile (@{$narFileList}) {
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# !!! how to handle files whose size is not known in advance?
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# For now, assume some arbitrary size (1 GB).
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# This has the side-effect of preferring non-Hydra downloads.
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addEdge \%graph, "start", $u, ($narFile->{size} || 1000000000), "narfile", $narFile;
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}
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}
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}
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# Run Dijkstra's shortest path algorithm to determine the shortest
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# sequence of download and/or patch actions that will produce
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# $targetPath.
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my @todo = keys %graph;
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while (scalar @todo > 0) {
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# Remove the closest element from the todo list.
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# !!! inefficient, use a priority queue
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@todo = sort { -($graph{$a}->{d} <=> $graph{$b}->{d}) } @todo;
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my $u = pop @todo;
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my $u_ = $graph{$u};
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foreach my $edge (@{$u_->{edges}}) {
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my $v_ = $graph{$edge->{end}};
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if ($v_->{d} > $u_->{d} + $edge->{weight}) {
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$v_->{d} = $u_->{d} + $edge->{weight};
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# Store the edge; to edge->start is actually the
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# predecessor.
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$v_->{pred} = $edge;
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}
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}
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}
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# Retrieve the shortest path from "start" to $targetPath.
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my @path = ();
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my $cur = $targetPath;
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return () unless defined $graph{$targetPath}->{pred};
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while ($cur ne "start") {
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push @path, $graph{$cur}->{pred};
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$cur = $graph{$cur}->{pred}->{start};
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}
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return @path;
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}
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# Parse the arguments.
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if ($ARGV[0] eq "--query") {
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while (<STDIN>) {
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chomp;
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my ($cmd, @args) = split " ", $_;
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if ($cmd eq "have") {
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foreach my $storePath (@args) {
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print "$storePath\n" if scalar @{$dbh->selectcol_arrayref("select 1 from NARs where storePath = ?", {}, $storePath)} > 0;
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}
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print "\n";
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}
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elsif ($cmd eq "info") {
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foreach my $storePath (@args) {
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my $infos = $dbh->selectall_arrayref(
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"select * from NARs where storePath = ?",
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{ Slice => {} }, $storePath);
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next unless scalar @{$infos} > 0;
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my $info = @{$infos}[0];
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print "$storePath\n";
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print "$info->{deriver}\n";
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my @references = split " ", $info->{refs};
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print scalar @references, "\n";
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print "$_\n" foreach @references;
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my @path = computeSmallestDownload $storePath;
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my $downloadSize = 0;
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while (scalar @path > 0) {
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my $edge = pop @path;
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my $u = $edge->{start};
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my $v = $edge->{end};
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if ($edge->{type} eq "patch") {
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$downloadSize += $edge->{info}->{size} || 0;
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}
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elsif ($edge->{type} eq "narfile") {
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$downloadSize += $edge->{info}->{size} || 0;
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}
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}
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print "$downloadSize\n";
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my $narSize = $info->{narSize} || 0;
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print "$narSize\n";
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}
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print "\n";
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}
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else { die "unknown command `$cmd'"; }
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}
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exit 0;
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}
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elsif ($ARGV[0] ne "--substitute") {
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die;
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}
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die unless scalar @ARGV == 3;
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my $targetPath = $ARGV[1];
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my $destPath = $ARGV[2];
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$fast = 0;
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# Create a temporary directory.
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my $tmpDir = tempdir("nix-download.XXXXXX", CLEANUP => 1, TMPDIR => 1)
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or die "cannot create a temporary directory";
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my $tmpNar = "$tmpDir/nar";
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my $tmpNar2 = "$tmpDir/nar2";
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open LOGFILE, ">>$logFile" or die "cannot open log file $logFile";
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my $date = strftime ("%F %H:%M:%S UTC", gmtime (time));
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print LOGFILE "$$ get $targetPath $date\n";
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print STDERR "\n*** Trying to download/patch `$targetPath'\n";
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# Compute the shortest path.
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my @path = computeSmallestDownload $targetPath;
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die "don't know how to produce $targetPath\n" if scalar @path == 0;
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# We don't need the manifest anymore, so close it as an optimisation:
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# if we still have SQLite locks blocking other processes (we
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# shouldn't), this gets rid of them.
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$dbh->disconnect;
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# Traverse the shortest path, perform the actions described by the
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# edges.
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my $curStep = 1;
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my $maxStep = scalar @path;
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my $finalNarHash;
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while (scalar @path > 0) {
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my $edge = pop @path;
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my $u = $edge->{start};
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my $v = $edge->{end};
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print STDERR "\n*** Step $curStep/$maxStep: ";
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if ($edge->{type} eq "present") {
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print STDERR "using already present path `$v'\n";
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print LOGFILE "$$ present $v\n";
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if ($curStep < $maxStep) {
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# Since this is not the last step, the path will be used
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# as a base to one or more patches. So turn the base path
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# into a NAR archive, to which we can apply the patch.
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print STDERR " packing base path...\n";
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system("$Nix::Config::binDir/nix-store --dump $v > $tmpNar") == 0
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or die "cannot dump `$v'";
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}
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}
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elsif ($edge->{type} eq "patch") {
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my $patch = $edge->{info};
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print STDERR "applying patch `$patch->{url}' to `$u' to create `$v'\n";
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print LOGFILE "$$ patch $patch->{url} $patch->{size} $patch->{baseHash} $u $v\n";
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# Download the patch.
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print STDERR " downloading patch...\n";
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my $patchPath = "$tmpDir/patch";
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checkURL $patch->{url};
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system("$curl '$patch->{url}' -o $patchPath") == 0
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or die "cannot download patch `$patch->{url}'\n";
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# Apply the patch to the NAR archive produced in step 1 (for
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# the already present path) or a later step (for patch sequences).
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print STDERR " applying patch...\n";
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system("$Nix::Config::libexecDir/bspatch $tmpNar $tmpNar2 $patchPath") == 0
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or die "cannot apply patch `$patchPath' to $tmpNar\n";
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if ($curStep < $maxStep) {
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# The archive will be used as the base of the next patch.
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rename "$tmpNar2", "$tmpNar" or die "cannot rename NAR archive: $!";
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} else {
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# This was the last patch. Unpack the final NAR archive
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# into the target path.
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print STDERR " unpacking patched archive...\n";
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system("$Nix::Config::binDir/nix-store --restore $destPath < $tmpNar2") == 0
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or die "cannot unpack $tmpNar2 to `$v'\n";
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}
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$finalNarHash = $patch->{narHash};
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}
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elsif ($edge->{type} eq "narfile") {
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my $narFile = $edge->{info};
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print STDERR "downloading `$narFile->{url}' to `$v'\n";
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my $size = $narFile->{size} || -1;
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print LOGFILE "$$ narfile $narFile->{url} $size $v\n";
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checkURL $narFile->{url};
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my $decompressor =
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$narFile->{compressionType} eq "bzip2" ? "$Nix::Config::bzip2 -d" :
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$narFile->{compressionType} eq "xz" ? "$Nix::Config::xz -d" :
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die "unknown compression type `$narFile->{compressionType}'";
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if ($curStep < $maxStep) {
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# The archive will be used a base to a patch.
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system("$curl '$narFile->{url}' | $decompressor > $tmpNar") == 0
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or die "cannot download and unpack `$narFile->{url}' to `$v'\n";
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} else {
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# Unpack the archive to the target path.
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system("$curl '$narFile->{url}' | $decompressor | $Nix::Config::binDir/nix-store --restore '$destPath'") == 0
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or die "cannot download and unpack `$narFile->{url}' to `$v'\n";
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}
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$finalNarHash = $narFile->{narHash};
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}
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$curStep++;
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}
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# Tell Nix about the expected hash so it can verify it.
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die "cannot check integrity of the downloaded path since its hash is not known\n"
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unless defined $finalNarHash;
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print "$finalNarHash\n";
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print STDERR "\n";
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print LOGFILE "$$ success\n";
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close LOGFILE;
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