From 33028c11a7cb48e3cde76790236e2ebb5adfc635 Mon Sep 17 00:00:00 2001 From: Sylvain Baubeau Date: Tue, 30 Jun 2015 14:17:12 +0200 Subject: [PATCH] Add code documentation Signed-off-by: Sylvain Baubeau --- registry/storage/driver/swift/swift.go | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/registry/storage/driver/swift/swift.go b/registry/storage/driver/swift/swift.go index e0284b9c..7de6f8de 100644 --- a/registry/storage/driver/swift/swift.go +++ b/registry/storage/driver/swift/swift.go @@ -4,8 +4,18 @@ // This package leverages the ncw/swift client library for interfacing with // Swift. // -// Because Swift is a key, value store the Stat call does not support last modification -// time for directories (directories are an abstraction for key, value stores) +// It supports both TempAuth authentication and Keystone authentication +// (up to version 3). +// +// Since Swift has no concept of directories (directories are an abstration), +// empty objects are created with the MIME type application/vnd.swift.directory. +// +// As Swift has a limit on the size of a single uploaded object (by default +// this is 5GB), the driver makes use of the Swift Large Object Support +// (http://docs.openstack.org/developer/swift/overview_large_objects.html). +// Only one container is used for both manifests and data objects. Manifests +// are stored in the 'files' pseudo directory, data objects are stored under +// 'segments'. package swift import ( @@ -33,8 +43,10 @@ import ( const driverName = "swift" +// defaultChunkSize defines the default size of a segment const defaultChunkSize = 20 * 1024 * 1024 +// minChunkSize defines the minimum size of a segment const minChunkSize = 1 << 20 const directoryMimeType = "application/directory" @@ -80,8 +92,8 @@ type baseEmbed struct { base.Base } -// Driver is a storagedriver.StorageDriver implementation backed by Amazon Swift -// Objects are stored at absolute keys in the provided bucket. +// Driver is a storagedriver.StorageDriver implementation backed by Openstack Swift +// Objects are stored at absolute keys in the provided container. type Driver struct { baseEmbed }