add basic caching of Issue's

1 files changed, 16 insertions, 2 deletions

diff --git a/app/History.hs b/app/History.hs
index fad911a..0621fd8 100644
--- a/app/History.hs
+++ b/app/History.hs
@@ -5,6 +5,7 @@ module History (getIssues, InvalidTreeGrepperResult (..), UnknownFileExtension (
 
 import Control.Exception (Exception, catch, handle, throw)
 import Data.Aeson (eitherDecode)
+import Data.Binary (Binary, decodeFile, encodeFile)
 import Data.ByteString.Lazy.Char8 qualified as L8
 import Data.List (intercalate)
 import Data.Maybe (catMaybes, mapMaybe)
@@ -14,7 +15,7 @@ import Data.Text.Encoding (decodeUtf8)
 import Issue (Issue (..), fromMatch, id)
 import Issue.Filter (Filter, applyFilter)
 import Process (quote, sh, sh_)
-import System.Directory (getCurrentDirectory, setCurrentDirectory)
+import System.Directory (createDirectoryIfMissing, doesFileExist, getCurrentDirectory, setCurrentDirectory)
 import System.Exit (ExitCode (ExitFailure), exitWith)
 import System.FilePath (takeExtension, (</>))
 import System.IO.Temp (withSystemTempDirectory)
@@ -41,7 +42,7 @@ instance Exception InvalidTreeGrepperResult
 listIssues :: [Filter] -> [FilePath] -> IO [Issue]
 listIssues filters files = do
   commits <- fmap (lines . decodeUtf8 . L8.toStrict) $ sh ("git log --format=%H")
-  issueses <- mapM (\commit -> listIssuesOf commit filters files) commits
+  issueses <- mapM (\commit -> cached commit (\_ -> listIssuesOf commit filters files)) commits
   (currentIssues, historicalIssues) <-
     case issueses of
       currentIssues : historicalIssueses ->
@@ -65,6 +66,19 @@ merge (issue, issues) =
     provenance : _ ->
       issue {provenance = Just provenance}
 
+cached :: Binary a => Text -> (Text -> IO a) -> IO a
+cached commit func = do
+  cwd <- getCurrentDirectory
+  createDirectoryIfMissing True (cwd ++ "/.anissue")
+  let file = (cwd ++ "/.anissue/" ++ unpack commit)
+  fileExists <- doesFileExist file
+  if fileExists
+    then decodeFile file
+    else do
+      blob <- func commit
+      encodeFile file blob
+      pure blob
+
 listIssuesOf :: Text -> [Filter] -> [FilePath] -> IO [Issue]
 listIssuesOf commit filters files = do
   cwd <- getCurrentDirectory