From 3b882d7510c4652df14fb53d2a9c1ca3cebd35a3 Mon Sep 17 00:00:00 2001 From: Profpatsch Date: Fri, 20 Oct 2023 23:09:39 +0200 Subject: [PATCH] feat(users/Profpatsch/openlab-tools): introduce handler abstraction MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit I’ve been wanting to experiment with this stuff for a while, abstracting away a handler type. The existentials for parser and body took a bit of mucking about, but in the end hiding the variable behind a `Body` constructor did the trick. Now every handler has its own cache, which means we can start caching arbitrary results. Change-Id: If57230c47f97ef4c548683f2c2f27660817a31f2 Reviewed-on: https://cl.tvl.fyi/c/depot/+/9812 Autosubmit: Profpatsch Reviewed-by: Profpatsch Tested-by: BuildkiteCI --- .../openlab-tools/src/OpenlabTools.hs | 128 +++++++++++++----- 1 file changed, 96 insertions(+), 32 deletions(-) diff --git a/users/Profpatsch/openlab-tools/src/OpenlabTools.hs b/users/Profpatsch/openlab-tools/src/OpenlabTools.hs index 77ed0b04e..a982e32fe 100644 --- a/users/Profpatsch/openlab-tools/src/OpenlabTools.hs +++ b/users/Profpatsch/openlab-tools/src/OpenlabTools.hs @@ -49,7 +49,7 @@ import Text.Blaze.Html.Renderer.Pretty qualified as Html.Pretty import Text.Blaze.Html.Renderer.Utf8 qualified as Html import Text.Blaze.Html5 qualified as Html import Text.HTML.TagSoup qualified as Soup -import UnliftIO hiding (newTVarIO) +import UnliftIO hiding (Handler, newTVarIO) import Prelude hiding (span, until) mapallSpaceOla :: Text @@ -101,7 +101,6 @@ debug = False runApp :: IO () runApp = withTracer $ \tracer -> do - cache <- newCache "" let renderHtml = if debug then Html.Pretty.renderHtml >>> stringToText >>> textToBytesUtf8 >>> toLazyBytes @@ -115,33 +114,47 @@ runApp = withTracer $ \tracer -> do runInIO (logError err) respond (Wai.responseLBS Http.status500 [] "") - catchAppException $ do - let h extra res = respond $ Wai.responseLBS Http.ok200 (("Content-Type", "text/html") : extra) res - case req & Wai.pathInfo & Text.intercalate "/" of - "" -> h [] (renderHtml mainPage) - "snips/table-opening-hours-last-week" -> do - ifModifiedSince <- runInIO $ inSpan' "parse request lol" $ \span -> - req & parseRequest span parseIfModifiedSince - now <- getCurrentTime <&> mkSecondTime - new <- runInIO $ updateCacheIfNewer now cache heatmap - let cacheToHeaders = - [ ("Last-Modified", new.lastModified & formatHeaderTime), - ("Expires", new.until & formatHeaderTime), - ( "Cache-Control", - let maxAge = new.until `diffSecondTime` now - in [fmt|max-age={maxAge & floor @NominalDiffTime @Int & show}, immutable|] - ) - ] - if - -- If the last cache update is newer or equal to the requested version, we can tell the browser it’s fine - | Just modifiedSince <- ifModifiedSince, - modifiedSince >= new.lastModified -> - respond $ Wai.responseLBS Http.status304 cacheToHeaders "" - | otherwise -> - h cacheToHeaders (new.result & toLazyBytes) - _ -> do respond $ Wai.responseLBS Http.status404 [] "nothing here (yet)" + let h extra res = Wai.responseLBS Http.ok200 (("Content-Type", "text/html") : extra) res + catchAppException $ + runInIO $ + runHandlers + [ Handler + { path = "", + body = + Body + (pure ()) + (\((), _) -> pure $ h [] (renderHtml mainPage)) + }, + Handler + { path = "snips/table-opening-hours-last-week", + body = + Body + ((label @"ifModifiedSince" <$> parseIfModifiedSince)) + ( \(req', cache) -> liftIO $ do + now <- getCurrentTime <&> mkSecondTime + new <- runInIO $ updateCacheIfNewer now cache heatmap + let cacheToHeaders = + [ ("Last-Modified", new.lastModified & formatHeaderTime), + ("Expires", new.until & formatHeaderTime), + ( "Cache-Control", + let maxAge = new.until `diffSecondTime` now + in [fmt|max-age={maxAge & floor @NominalDiffTime @Int & show}, immutable|] + ) + ] + if + -- If the last cache update is newer or equal to the requested version, we can tell the browser it’s fine + | Just modifiedSince <- req'.ifModifiedSince, + modifiedSince >= new.lastModified -> + pure $ Wai.responseLBS Http.status304 cacheToHeaders "" + | otherwise -> + pure $ h cacheToHeaders (new.result & toLazyBytes) + ) + } + ] + req + (\resp -> liftIO $ respond resp) - runReaderT appT.unAppT Context {..} + runReaderT (appT :: AppT IO ()).unAppT Context {..} where -- "https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Last-Modified#syntax" headerFormat = "%a, %d %b %0Y %T GMT" @@ -177,9 +190,60 @@ runApp = withTracer $ \tracer -> do ) (Parse.maybe $ Parse.fieldParser parseHeaderTime) & rmap (fmap mkSecondTime) - parseRequest span parser req = - Parse.runParse "Unable to parse the HTTP request" parser req - & assertM span id + +parseRequest :: (MonadThrow f, MonadIO f) => Otel.Span -> Parse from a -> from -> f a +parseRequest span parser req = + Parse.runParse "Unable to parse the HTTP request" parser req + & assertM span id + +data Handler m = Handler + { path :: Text, + body :: Body m + } + +data Body m + = forall a. + Body + (Parse Wai.Request a) + ((a, TVar (Cache ByteString)) -> m Wai.Response) + +runHandlers :: + (Otel.MonadTracer m, MonadUnliftIO m, MonadThrow m) => + [Handler m] -> + Wai.Request -> + (Wai.Response -> m Wai.ResponseReceived) -> + m Wai.ResponseReceived +runHandlers handlers req respond = do + withCaches :: + [ T2 + "handler" + (Handler m) + "cache" + (TVar (Cache ByteString)) + ] <- + handlers + & traverse + ( \h -> do + cache <- liftIO $ newCache "nothing yet" + pure $ T2 (label @"handler" h) (label @"cache" cache) + ) + let mHandler = + withCaches + & List.find + ( \h -> + (h.handler.path) + == (req & Wai.pathInfo & Text.intercalate "/") + ) + case mHandler of + Nothing -> respond $ Wai.responseLBS Http.status404 [] "nothing here (yet)" + Just handler -> do + inSpan' "TODO" $ \span -> do + let h :: Handler m = handler.handler + case h.body of + Body parse runHandler -> do + req' <- req & parseRequest span parse + resp <- runHandler (req', handler.cache) + respond resp heatmap :: AppT IO ByteString heatmap = do @@ -372,7 +436,7 @@ updateCache now cache result' = do updateCacheIfNewer :: (MonadUnliftIO m, NFData b, Eq b) => SecondTime -> TVar (Cache b) -> m b -> m (Cache b) updateCacheIfNewer now cache act = withRunInIO $ \runInIO -> do old <- readTVarIO cache - if old.until < now + if old.until <= now then do res <- runInIO act atomically $ updateCache now cache res