checkpatch: cache last camelcase hash as .checkpatch-camelcase.<commit>

Add a file to cache the CamelCase variables found by <commit> to reduce
the time it takes to scan the include/ directory.

Filename is '.checkpatch-camelcase.<commit>' and it is created only only
if a .git directory exists.

<commit> is determined by the last non-merge commit id in the
include/ path.

Reduces checkpatch run time by ~12 cpu seconds on my little netbook.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 0d94853079ec..6afcd1239ca5 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -399,7 +399,23 @@ sub seed_camelcase_includes {
         return if ($camelcase_seeded);
 
         my $files;
+        my $camelcase_git_file = "";
+
         if (-d ".git") {
+                my $git_last_include_commit = `git log --no-merges --pretty=format:"%h%n" -1 -- include`;
+                chomp $git_last_include_commit;
+                $camelcase_git_file = ".checkpatch-camelcase.$git_last_include_commit";
+                if (-f $camelcase_git_file) {
+                        open(my $camelcase_file, '<', "$camelcase_git_file")
+                            or warn "$P: Can't read '$camelcase_git_file' $!\n";
+                        while (<$camelcase_file>) {
+                                chomp;
+                                $camelcase{$_} = 1;
+                        }
+                        close($camelcase_file);
+
+                        return;
+                }
                 $files = `git ls-files include`;
         } else {
                 $files = `find $root/include -name "*.h"`;
@@ -409,6 +425,16 @@ sub seed_camelcase_includes {
                 seed_camelcase_file($file);
         }
         $camelcase_seeded = 1;
+
+        if ($camelcase_git_file ne "") {
+                unlink glob ".checkpatch-camelcase.*";
+                open(my $camelcase_file, '>', "$camelcase_git_file")
+                    or warn "$P: Can't write '$camelcase_git_file' $!\n";
+                foreach (sort { lc($a) cmp lc($b) } keys(%camelcase)) {
+                        print $camelcase_file ("$_\n");
+                }
+                close($camelcase_file);
+        }
 }
 
 $chk_signoff = 0 if ($file);