From: Tom Clegg <tom@tomclegg.ca>
Date: Sat, 25 Sep 2021 13:44:22 +0000 (-0400)
Subject: Scale keep cache to 2*(openfiles+1).
X-Git-Url: https://git.arvados.org/lightning.git/commitdiff_plain/1b6d32146cfdbf4c5befbfc5ddd1651d6c63c735

Scale keep cache to 2*(openfiles+1).

refs #17966

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@curii.com>
---

diff --git a/arvados.go b/arvados.go
index c952a9870c..d4dcf7819e 100644
--- a/arvados.go
+++ b/arvados.go
@@ -520,6 +520,7 @@ var (
 
 type file interface {
 	io.ReadCloser
+	io.Seeker
 	Readdir(n int) ([]os.FileInfo, error)
 }
 
@@ -552,9 +553,23 @@ func open(fnm string) (file, error) {
 		keepClient.BlockCache = &keepclient.BlockCache{MaxBlocks: 4}
 		siteFS = arvadosClientFromEnv.SiteFileSystem(keepClient)
 	} else {
-		keepClient.BlockCache.MaxBlocks++
+		keepClient.BlockCache.MaxBlocks += 2
 	}
 
 	log.Infof("reading %q from %s using Arvados client", fnm[len(mnt):], uuid)
-	return siteFS.Open("by_id/" + uuid + fnm[len(mnt):])
+	f, err := siteFS.Open("by_id/" + uuid + fnm[len(mnt):])
+	if err != nil {
+		return nil, err
+	}
+	return &reduceCacheOnClose{file: f}, nil
+}
+
+type reduceCacheOnClose struct {
+	file
+	once sync.Once
+}
+
+func (rc *reduceCacheOnClose) Close() error {
+	rc.once.Do(func() { keepClient.BlockCache.MaxBlocks -= 2 })
+	return rc.file.Close()
 }