* Speed up manifest generation.

src/Hydra/lib/Hydra/Helper/Nix.pm

@@ -7,7 +7,8 @@ use File::Basename;
 
 our @ISA = qw(Exporter);
 our @EXPORT = qw(
-    isValidPath getHydraPath getHydraDBPath openHydraDB
+    isValidPath queryPathInfo
+    getHydraPath getHydraDBPath openHydraDB
     registerRoot getGCRootsDir
     getPrimaryBuildsForReleaseSet getRelease getLatestSuccessfulRelease );
 
@@ -22,6 +23,39 @@ sub isValidPath {
 }
 
 
+sub queryPathInfo {
+    my $path = shift;
+
+    # !!! like above, this breaks abstraction.  What we really need is
+    # Perl bindings for libstore :-)
+
+    open FH, "</nix/var/nix/db/info/" . basename $path
+        or die "cannot open info file for $path";
+
+    my $hash;
+    my $deriver;
+    my @refs = ();
+
+    while (<FH>) {
+        if (/^Hash: (\S+)$/) {
+            $hash = $1;
+        }
+        elsif (/^Deriver: (\S+)$/) {
+            $deriver = $1;
+        }
+        elsif (/^References: (.*)$/) {
+            @refs = split / /, $1;
+        }
+    }
+
+    close FH;
+
+    die unless defined $hash;
+
+    return ($hash, $deriver, \@refs);
+}
+
+
 sub getHydraPath {
     my $dir = $ENV{"HYDRA_DATA"};
     die "The HYDRA_DATA environment variable is not set!\n" unless defined $dir;

src/Hydra/lib/Hydra/View/NixManifest.pm

@@ -2,8 +2,7 @@ package Hydra::View::NixManifest;
 
 use strict;
 use base qw/Catalyst::View/;
-use IO::Pipe;
+use Hydra::Helper::Nix;
-use POSIX qw(dup2);
 
 
 sub process {
@@ -22,24 +21,15 @@ sub process {
         "}\n";
     
     foreach my $path (@paths) {
-        my @refs = split '\n', `nix-store --query --references $path`;
+        my ($hash, $deriver, $refs) = queryPathInfo $path;
-        die "cannot query references of `$path': $?" if $? != 0;
         
-        my $hash = `nix-store --query --hash $path`
-            or die "cannot query hash of `$path': $?";
-        chomp $hash;
-
         my $url = $c->stash->{narBase} . $path;
 
-        my $deriver = `nix-store --query --deriver $path`
-            or die "cannot query deriver of `$path': $?";
-        chomp $deriver;
-        
         $manifest .=
             "{\n" .
             "  StorePath: $path\n" .
-            (scalar @refs > 0 ? "  References: @refs\n" : "") .
+            (scalar @{$refs} > 0 ? "  References: @{$refs}\n" : "") .
-            ($deriver ne "unknown-deriver" ? "  Deriver: $deriver\n" : "") .
+            (defined $deriver ? "  Deriver: $deriver\n" : "") .
             "  NarURL: $url\n" .
             "  NarHash: $hash\n" .
             "}\n";