Bug 362392: mddepend.pl stat() optimizations. r=neil, moa=bsmedberg, a=schrep

build/unix/mddepend.pl

@@ -46,63 +46,94 @@
 #
 # Send comments, improvements, bugs to Steve Lamm (slamm@netscape.com).
 
-#$debug = 1;
+use strict;
 
-$outfile = shift @ARGV;
+use constant DEBUG => 0;
+
+my $outfile = shift @ARGV;
 my $silent = $ENV{MAKEFLAGS} =~ /^\w*s|\s-s/;
 
-%alldeps={};
+my $line = '';
+my %alldeps;
 # Parse dependency files
-while ($line = <>) {
-  $line =~ s/\r?\n$//; # Handle both unix and DOS line endings
-  ($obj,$rest) = split /\s*:\s+/, $line, 2;
-  next if $obj eq '' || $rest eq '';
-
+while (<>) {
+  s/\r?\n$//; # Handle both unix and DOS line endings
+  $line .= $_;
   if ($line =~ /\\$/) {
-    chop $rest;
-    $hasSlash = 1;
-  } else {
-    $hasSlash = 0;
+    chop $line;
+    next;
   }
-  push @{$alldeps{$obj}}, split /\s+/, $rest;
-  print "add $obj $rest\n" if $debug;
 
-  while ($hasSlash and $line = <>) {
-    $line =~ s/\r?\n$//; # Handle both unix and DOS line endings
-    if ($line =~ /\\$/) {
-      chop $line;
-    } else {
-      $hasSlash = 0;
-    }
-    $line =~ s/^\s+//;
-    push @{$alldeps{$obj}}, split /\s+/, $line;
-    print "add $obj $line\n" if $debug;
+  my ($obj,$rest) = split /\s*:\s+/, $line, 2;
+  $line = '';
+  next if !$obj || !$rest;
+
+  my @deps = split /\s+/, $rest;
+  push @{$alldeps{$obj}}, @deps;
+  if (DEBUG >= 2) {
+    foreach my $dep (@deps) { print "add $obj $dep\n"; }
   }
 }
 
 # Test dependencies
-foreach $obj (keys %alldeps) {
-  $deps = $alldeps{$obj};
+my %modtimes; # cache
+my @objs;     # force rebuild on these
+OBJ_LOOP: foreach my $obj (keys %alldeps) {
+  my $mtime = (stat $obj)[9] or next;
 
-  $mtime = (stat $obj)[9] or next;
+  my %not_in_cache;
+  my $deps = $alldeps{$obj};
+  foreach my $dep_file (@{$deps}) {
+    my $dep_mtime = $modtimes{$dep_file};
+    if (not defined $dep_mtime) {
+      print "Skipping $dep_file for $obj, will stat() later\n" if DEBUG >= 2;
+      $not_in_cache{$dep_file} = 1;
+      next;
+    }
 
-  foreach $dep_file (@{$deps}) {
-    if (not defined($dep_mtime = $modtimes{$dep_file})) {
-      $dep_mtime = (stat $dep_file)[9];
-      $modtimes{$dep_file} = $dep_mtime;
+    print "Found $dep_file in cache\n" if DEBUG >= 2;
+
+    if ($dep_mtime > $mtime) {
+      print "$dep_file($dep_mtime) newer than $obj($mtime)\n" if DEBUG;
     }
-    if ($dep_mtime ne '' and $dep_mtime > $mtime) {
-      print "$obj($mtime) older than $dep_file($dep_mtime)\n" if $debug;
-      push @objs, $obj;
-      # Object will be marked for rebuild. No need to check other dependencies.
-      last;
+    elsif ($dep_mtime == -1) {
+      print "Couldn't stat $dep_file for $obj\n" if DEBUG;
     }
+    else {
+      print "$dep_file($dep_mtime) older than $obj($mtime)\n" if DEBUG >= 2;
+      next;
+    }
+
+    push @objs, $obj; # dependency is missing or newer
+    next OBJ_LOOP; # skip checking the rest of the dependencies
   }
+
+  foreach my $dep_file (keys %not_in_cache) {
+    print "STAT $dep_file for $obj\n" if DEBUG >= 2;
+    my $dep_mtime = $modtimes{$dep_file} = (stat $dep_file)[9] || -1;
+
+    if ($dep_mtime > $mtime) {
+      print "$dep_file($dep_mtime) newer than $obj($mtime)\n" if DEBUG;
+    }
+    elsif ($dep_mtime == -1) {
+      print "Couldn't stat $dep_file for $obj\n" if DEBUG;
+    }
+    else {
+      print "$dep_file($dep_mtime) older than $obj($mtime)\n" if DEBUG >= 2;
+      next;
+    }
+
+    push @objs, $obj; # dependency is missing or newer
+    next OBJ_LOOP; # skip checking the rest of the dependencies
+  }
+
+  # If we get here it means nothing needs to be done for $obj
 }
 
 # Output objects to rebuild (if needed).
 if (@objs) {
-  $new_output = "@objs: FORCE\n";
+  my $old_output;
+  my $new_output = "@objs: FORCE\n";
 
   # Read in the current dependencies file.
   open(OLD, "<$outfile")
@@ -113,7 +144,7 @@ if (@objs) {
   if ($new_output ne $old_output) {
     open(OUT, ">$outfile") and print OUT "$new_output";
     print "Updating dependencies file, $outfile\n" unless $silent;
-    if ($debug) {
+    if (DEBUG) {
       print "new: $new_output\n";
       print "was: $old_output\n" if $old_output ne '';
     }
@@ -122,7 +153,8 @@ if (@objs) {
   # Remove the old dependencies because all objects are up to date.
   print "Removing old dependencies file, $outfile\n" unless $silent;
 
-  if ($debug) {
+  if (DEBUG) {
+    my $old_output;
     open(OLD, "<$outfile")
       and $old_output = <OLD>;
     close(OLD);