From 1df9be9873b9ea080906a30c5eaa5bfe97d173e3 Mon Sep 17 00:00:00 2001
From: "Diogo Franco (Kovensky)" <diogomfranco@gmail.com>
Date: Sun, 14 Jul 2013 02:04:35 -0300
Subject: [PATCH] anidb: (*cacheDir).Get(): reduce the time a file lock is
 retained

When reading from cache, read the entire file into a buffer before
attempting to decode; release the lock as soon as the read is done.

Also move the parameter sanity check to be earlier in the method.
---
 cache.go | 44 ++++++++++++++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 14 deletions(-)

diff --git a/cache.go b/cache.go
index 64cae67..faf2ce4 100644
--- a/cache.go
+++ b/cache.go
@@ -145,30 +145,46 @@ func (c *cacheDir) Get(v Cacheable, keys ...cacheKey) (err error) {
 	defer func() {
 		log.Println("Got entry", keys, "(error", err, ")")
 	}()
-	if flock := lockFile(cachePath(keys...)); flock != nil {
+
+	val := reflect.ValueOf(v)
+	if k := val.Kind(); k == reflect.Ptr || k == reflect.Interface {
+		val = val.Elem()
+	}
+	if !val.CanSet() {
+		// panic because this is an internal coding mistake
+		panic("(*cacheDir).Get(): given Cacheable is not setable")
+	}
+
+	flock := lockFile(cachePath(keys...))
+	if flock != nil {
 		flock.Lock()
-		defer flock.Unlock()
 	}
+	defer func() {
+		if flock != nil {
+			flock.Unlock()
+		}
+	}()
 
 	fh, err := c.Open(keys...)
 	if err != nil {
 		return err
 	}
-	defer func() {
-		if e := fh.Close(); err == nil {
-			err = e
-		}
-	}()
 
-	val := reflect.ValueOf(v)
-	if k := val.Kind(); k == reflect.Ptr || k == reflect.Interface {
-		val = val.Elem()
+	buf := bytes.Buffer{}
+	if _, err = io.Copy(&buf, fh); err != nil {
+		fh.Close()
+		return err
 	}
-	if !val.CanSet() {
-		// panic because this is an internal coding mistake
-		panic("(*cacheDir).Get(): given Cacheable is not setable")
+	if err = fh.Close(); err != nil {
+		return err
+	}
+
+	if flock != nil {
+		flock.Unlock()
+		flock = nil
 	}
-	gz, err := gzip.NewReader(fh)
+
+	gz, err := gzip.NewReader(&buf)
 	if err != nil {
 		return err
 	}
-- 
2.44.0