From e732909773760e28a68e5293cefa5ef9d4ec2c6c Mon Sep 17 00:00:00 2001
From: Las Zenow <zenow@riseup.net>
Date: Thu, 22 Jan 2015 21:16:20 -0600
Subject: [PATCH] Use io.readerAt to open the books without loading everything
 in memory

---
 reader.go          | 64 +++++++++++++++++++++++++++-------------------
 storage/storage.go |  8 +++++-
 2 files changed, 45 insertions(+), 27 deletions(-)

diff --git a/reader.go b/reader.go
index 0882a3c..8254180 100644
--- a/reader.go
+++ b/reader.go
@@ -3,16 +3,13 @@ package main
 import (
 	log "github.com/cihub/seelog"
 
-	"bytes"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"strconv"
 	"strings"
 
 	"git.gitorious.org/go-pkg/epubgo.git"
 	"git.gitorious.org/trantor/trantor.git/database"
-	"git.gitorious.org/trantor/trantor.git/storage"
 	"github.com/gorilla/mux"
 )
 
@@ -183,13 +180,24 @@ func openReadEpub(h handler) (*epubgo.Epub, database.Book) {
 	if err != nil {
 		return nil, book
 	}
-
 	if !book.Active {
 		if !h.sess.IsAdmin() {
 			return nil, book
 		}
 	}
-	e, err := openBook(book.Id, h.store)
+
+	f, err := h.store.Get(book.Id, EPUB_FILE)
+	if err != nil {
+		return nil, book
+	}
+	defer f.Close()
+
+	info, err := f.Stat()
+	if err != nil {
+		return nil, book
+	}
+
+	e, err := epubgo.Load(f, info.Size())
 	if err != nil {
 		return nil, book
 	}
@@ -205,42 +213,46 @@ func contentHandler(h handler) {
 		return
 	}
 
-	book, err := h.db.GetBookId(id)
+	err := openEpubFile(h, id, file)
 	if err != nil {
 		notFound(h)
 		return
 	}
+}
+
+func openEpubFile(h handler, id string, file string) error {
+	book, err := h.db.GetBookId(id)
+	if err != nil {
+		return err
+	}
 	if !book.Active {
 		if !h.sess.IsAdmin() {
-			notFound(h)
-			return
+			return err
 		}
 	}
-	e, err := openBook(book.Id, h.store)
+
+	f, err := h.store.Get(id, EPUB_FILE)
 	if err != nil {
-		notFound(h)
-		return
+		return err
+	}
+	defer f.Close()
+
+	info, err := f.Stat()
+	if err != nil {
+		return err
+	}
+
+	e, err := epubgo.Load(f, info.Size())
+	if err != nil {
+		return err
 	}
 	defer e.Close()
 
 	html, err := e.OpenFile(file)
 	if err != nil {
-		notFound(h)
-		return
+		return err
 	}
 	defer html.Close()
 	io.Copy(h.w, html)
-}
-
-func openBook(id string, store *storage.Store) (*epubgo.Epub, error) {
-	f, err := store.Get(id, EPUB_FILE)
-	if err != nil {
-		return nil, err
-	}
-	defer f.Close()
-
-	buff, err := ioutil.ReadAll(f)
-	reader := bytes.NewReader(buff)
-
-	return epubgo.Load(reader, int64(len(buff)))
+	return nil
 }
diff --git a/storage/storage.go b/storage/storage.go
index b5f0ba0..531d39d 100644
--- a/storage/storage.go
+++ b/storage/storage.go
@@ -11,6 +11,12 @@ type Store struct {
 	path string
 }
 
+type File interface {
+	io.ReadCloser
+	io.ReaderAt
+	Stat() (fi os.FileInfo, err error)
+}
+
 func Init(path string) (*Store, error) {
 	st := new(Store)
 	st.path = path
@@ -42,7 +48,7 @@ func (st *Store) Store(id string, file io.Reader, name string) (size int64, err
 	return io.Copy(dest, file)
 }
 
-func (st *Store) Get(id string, name string) (io.ReadCloser, error) {
+func (st *Store) Get(id string, name string) (File, error) {
 	path := idPath(st.path, id)
 	return os.Open(p.Join(path, name))
 }