387 lines
12 KiB
Perl
Executable file
387 lines
12 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 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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# Open the manifest cache and update it if necessary.
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my $dbh = updateManifestDB();
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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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my $cmd = $_; chomp $cmd;
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if ($cmd eq "have") {
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my $storePath = <STDIN>; chomp $storePath;
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print STDOUT (
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scalar @{$dbh->selectcol_arrayref("select 1 from NARs where storePath = ?", {}, $storePath)} > 0
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? "1\n" : "0\n");
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}
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elsif ($cmd eq "info") {
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my $storePath = <STDIN>; chomp $storePath;
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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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my $info;
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if (scalar @{$infos} > 0) {
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$info = @{$infos}[0];
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}
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else {
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print "0\n";
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next; # not an error
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}
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print "1\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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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 == 2;
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my $targetPath = $ARGV[1];
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$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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sub downloadFile {
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my $url = shift;
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$ENV{"PRINT_PATH"} = 1;
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$ENV{"QUIET"} = 1;
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my ($hash, $path) = `$Nix::Config::binDir/nix-prefetch-url '$url'`;
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die "download of `$url' failed" . ($! ? ": $!" : "") . "\n" unless $? == 0;
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chomp $path;
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return $path;
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}
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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 = downloadFile "$patch->{url}";
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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";
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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 $v < $tmpNar2") == 0
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or die "cannot unpack $tmpNar2 into `$v'";
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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}' into `$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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# Download the archive.
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print STDERR " downloading archive...\n";
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my $narFilePath = downloadFile "$narFile->{url}";
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if ($curStep < $maxStep) {
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# The archive will be used a base to a patch.
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system("$Nix::Config::bzip2 -d < '$narFilePath' > $tmpNar") == 0
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or die "cannot unpack `$narFilePath' into `$v'";
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} else {
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# Unpack the archive into the target path.
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print STDERR " unpacking archive...\n";
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system("$Nix::Config::bzip2 -d < '$narFilePath' | $Nix::Config::binDir/nix-store --restore '$v'") == 0
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or die "cannot unpack `$narFilePath' into `$v'";
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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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# Make sure that the hash declared in the manifest matches what we
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# downloaded and unpacked.
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if (defined $finalNarHash) {
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my ($hashAlgo, $hash) = parseHash $finalNarHash;
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# The hash in the manifest can be either in base-16 or base-32.
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# Handle both.
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my $hash2 = hashPath($hashAlgo, $hashAlgo eq "sha256" && length($hash) != 64, $targetPath);
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die "hash mismatch in downloaded path $targetPath; expected $hash, got $hash2\n"
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if $hash ne $hash2;
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} else {
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die "cannot check integrity of the downloaded path since its hash is not known\n";
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}
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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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