From 22c3f63a91361fddfe8315d7e7d5daef42700957 Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Sun, 8 Jul 2012 23:31:37 -0400
Subject: [PATCH] Use parallel-io instead of mapM to download images and full
 stories.

---
 lwn-epub.cabal  | 1 +
 src/LWN/HTTP.hs | 3 ++-
 src/LWN/Page.hs | 4 ++--
 src/Main.hs     | 4 ++++
 4 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/lwn-epub.cabal b/lwn-epub.cabal
index c9a505c..08ee1bf 100644
--- a/lwn-epub.cabal
+++ b/lwn-epub.cabal
@@ -24,6 +24,7 @@ executable lwn-epub
     MissingH                == 1.1.*,
     network                 == 2.3.*,
     pandoc                  == 1.9.*,
+    parallel-io             == 0.3.*,
     regex-posix             == 0.95.*,
     temporary               == 1.*,
     test-framework          == 0.6.*,
diff --git a/src/LWN/HTTP.hs b/src/LWN/HTTP.hs
index 63079fd..ef4fc5a 100644
--- a/src/LWN/HTTP.hs
+++ b/src/LWN/HTTP.hs
@@ -3,6 +3,7 @@
 module LWN.HTTP
 where
 
+import Control.Concurrent.ParallelIO (parallel)
 import qualified Data.ByteString as B (hPut)
 import qualified Data.Map as Map (Map, empty, insert)
 import Data.Maybe (fromJust, isNothing)
@@ -177,7 +178,7 @@ type ImageMap = Map.Map URL FilePath
 
 download_image_urls :: [URL] -> IO ImageMap
 download_image_urls image_urls = do
-  files <- mapM save_image image_urls
+  files <- parallel $ map save_image image_urls
   let pairs = zip image_urls files
   return $ foldl my_insert empty_map pairs
   where
diff --git a/src/LWN/Page.hs b/src/LWN/Page.hs
index f0ada7c..c61bf6a 100644
--- a/src/LWN/Page.hs
+++ b/src/LWN/Page.hs
@@ -3,6 +3,7 @@
 module LWN.Page
 where
 
+import Control.Concurrent.ParallelIO (parallel)
 import qualified Data.Map as Map (lookup)
 import Data.Time (getCurrentTime)
 import qualified Data.ByteString.Lazy as B (ByteString, hPut)
@@ -172,7 +173,7 @@ type StoryMap = Map.Map URL Article
 -- These come *before* preprocessing.
 download_full_story_urls :: Cfg -> [URL] -> IO StoryMap
 download_full_story_urls cfg story_urls = do
-  pages <- mapM (page_from_url cfg) story_urls
+  pages <- parallel $ map (page_from_url cfg) story_urls
   let pairs = zip story_urls pages
   return $ foldl my_insert empty_map pairs
   where
@@ -352,7 +353,6 @@ fp_parse_articles xml = do
                           []    -> []
   -- Put the separator back, it was lost during the split.
   let split_articles = map (article_separator ++) split_articles'
-  --_ <- mapM print_article split_articles
   real_articles <- mapM parse_html_article split_articles
   let just_articles = catMaybes real_articles
   return just_articles
diff --git a/src/Main.hs b/src/Main.hs
index a1230d6..3ce1eef 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -2,6 +2,7 @@
 module Main
 where
 
+import Control.Concurrent.ParallelIO (stopGlobalPool)
 import System.Directory (doesFileExist)
 import System.IO (
   Handle,
@@ -47,3 +48,6 @@ main = do
     Nothing -> do
       _ <- show_help
       return ()
+
+  -- Necessary, for some reason.
+  stopGlobalPool
-- 
2.44.2