From 4298cc2332d0d0bf0ad7bc8cf186324da1d0f9c9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Sat, 8 May 2021 14:57:08 +0200
Subject: Add caching of runs as a fallback in case of failure

---
 gen.pl | 58 +++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 37 insertions(+), 21 deletions(-)

diff --git a/gen.pl b/gen.pl
index 6a0ec7c..2a6b6e8 100755
--- a/gen.pl
+++ b/gen.pl
@@ -16,11 +16,12 @@ use Getopt::Std;
 
 my %opt;
 $Getopt::Std::STANDARD_HELP_VERSION = 1;
-getopts('d', \%opt);
+getopts('cd', \%opt);
 
 sub main::HELP_MESSAGE {
 	print <<HELP;
 usage: $0 [-d]
+  -c	use cached run results
   -d	enable debug messages
 HELP
 }
@@ -35,48 +36,63 @@ chdir $Bin;
 mkdir 'out' if ! -d 'out';
 open my $src, '<', 'src/index.html' or die "Could not open < src/index.html: $!";
 open my $out, '>', 'out/index.html.tmp' or die "Could not open > out/index.html.tmp: $!";
+select $out;
 for (<$src>) {
 	when (/^\.inc (.*)/) {
-		open my $h, '<', "inc/$1" or do {
+		open my $inc, '<', "inc/$1" or do {
 			warn "Could not open inc/$1: $!";
 			next;
 		};
 		print STDERR "INCLUDE: $_\n" if $opt{d};
-		print $out $_ while <$h>;
-		close $h;
+		print $_ while <$inc>;
+		close $inc;
 	}
 	when (/^\.eval (.*)/) {
 		print STDERR "EVAL: $1\n" if $opt{d};
 		{
 			no strict; no warnings; no experimental;
-			select $out;
 			eval $1;
-			select STDOUT;
 			warn $@ if $@;
 		}
 	}
 	when (/^\.run (.*)/) {
-		open my $h, '<', "run/$1" or do {
-			warn "Could not open run/$1: $!";
+		if (not $opt{c}) {
+			open my $run, '-|', "run/$1" or do {
+				warn "Could not start run/$1: $!";
+				next;
+			};
+			open my $cache, '>', "cache/$1.tmp" or do {
+				warn "Could not open cache/$1.tmp: $!";
+				next;
+			};
+			print STDERR "RUN: $1\n" if $opt{d};
+			my $i;
+			for (<$run>) {
+				$i++;
+				print;
+				print $cache $_;
+			}
+			close $cache;
+			close $run;
+			if ($i) {
+				move "cache/$1.tmp" => "cache/$1";
+				next;
+			}
+		}
+		# Fall back to cached run
+		open my $cache, '<', "cache/$1" or do {
+			warn "Could not open cache/$1: $!";
 			next;
 		};
-		print STDERR "RUN: $1\n" if $opt{d};
-		my $c = do { local $/; <$h> };
-		close $h;
-		{
-			no strict; no warnings; no experimental;
-			local $0 = "run/$1";
-			select $out;
-			eval $c;
-			select STDOUT;
-			warn $@ if $@;
-		}
-		# I guess you *could* just run the script in a separate process...
+		print STDERR "GET CACHED RUN: $1\n" if $opt{d};
+		print for <$cache>;
+		close $cache;
 	}
 	default {
-		print $out $_;
+		print $_;
 	}
 }
+select STDOUT;
 close $out;
 close $src;
 
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