From 3c817d5bb997a3aaf906be6a5b249a58f3afedfe Mon Sep 17 00:00:00 2001
From: Stefan Boberg <stefan@boberg.org>
Date: Tue, 19 Oct 2021 16:33:27 +0200
Subject: cas: implemented manifest update/upgrade

---
 zenstore/CAS.cpp | 80 +++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 56 insertions(+), 24 deletions(-)

diff --git a/zenstore/CAS.cpp b/zenstore/CAS.cpp
index a43759283..a71e251e5 100644
--- a/zenstore/CAS.cpp
+++ b/zenstore/CAS.cpp
@@ -5,6 +5,9 @@
 #include "compactcas.h"
 #include "filecas.h"
 
+#include <zencore/compactbinary.h>
+#include <zencore/compactbinarybuilder.h>
+#include <zencore/compactbinaryvalidation.h>
 #include <zencore/except.h>
 #include <zencore/fmtutils.h>
 #include <zencore/logging.h>
@@ -14,9 +17,6 @@
 #include <zencore/testutils.h>
 #include <zencore/thread.h>
 #include <zencore/uid.h>
-#include <zencore/compactbinary.h>
-#include <zencore/compactbinarybuilder.h>
-#include <zencore/compactbinaryvalidation.h>
 
 #include <gsl/gsl-lite.hpp>
 
@@ -108,15 +108,17 @@ private:
 	CasContainerStrategy m_TinyStrategy;
 	CasContainerStrategy m_SmallStrategy;
 	FileCasStrategy		 m_LargeStrategy;
-	CbObject 			 m_ManifestObject;
-	
+	CbObject			 m_ManifestObject;
+
 	enum class StorageScheme
 	{
-		Legacy = 0,
+		Legacy		   = 0,
 		WithCbManifest = 1
 	};
 
-	StorageScheme	m_StorageScheme = StorageScheme::Legacy;
+	StorageScheme m_StorageScheme = StorageScheme::Legacy;
+
+	void UpdateManifest(bool IsNewStore);
 };
 
 CasImpl::CasImpl() : m_TinyStrategy(m_Config), m_SmallStrategy(m_Config), m_LargeStrategy(m_Config)
@@ -150,49 +152,55 @@ CasImpl::Initialize(const CasStoreConfiguration& InConfig)
 		ManifestPath /= ".ucas_root";
 
 		std::error_code Ec;
-		BasicFile		Marker;
-		Marker.Open(ManifestPath.c_str(), /* IsCreate */ false, Ec);
+		BasicFile		ManifestFile;
+		ManifestFile.Open(ManifestPath.c_str(), /* IsCreate */ false, Ec);
+
+		bool ManifestIsOk = false;
 
 		if (Ec)
 		{
 			if (Ec == std::errc::no_such_file_or_directory)
 			{
 				IsNewStore = true;
-
-				CbObjectWriter Cbo;
-
-				Cbo << "id" << zen::Oid::NewOid();
-
-				Marker.Open(ManifestPath.c_str(), /* IsCreate */ true);
-				m_ManifestObject = Cbo.Save();
-
-				Marker.Write(m_ManifestObject.GetBuffer(), 0);
 			}
 		}
 		else
 		{
-			IoBuffer ManifestBuffer = Marker.ReadAll();
+			IoBuffer ManifestBuffer = ManifestFile.ReadAll();
+			ManifestFile.Close();
 
 			if (ManifestBuffer.Size() > 0 && ManifestBuffer.Data<uint8_t>()[0] == '#')
 			{
-				// Old-style manifest, does not contain any useful information (so we may as well update it?)
-				m_StorageScheme = StorageScheme::Legacy;
+				// Old-style manifest, does not contain any useful information, so we may as well update it
 			}
 			else
 			{
-				CbObject Manifest{SharedBuffer(ManifestBuffer)};
+				CbObject		Manifest{SharedBuffer(ManifestBuffer)};
 				CbValidateError ValidationResult = ValidateCompactBinary(ManifestBuffer, CbValidateMode::All);
 
 				if (ValidationResult == CbValidateError::None)
 				{
-					m_ManifestObject = std::move(Manifest);
+					if (Manifest["id"])
+					{
+						ManifestIsOk = true;
+					}
 				}
 				else
 				{
-					ZEN_ERROR("Store manifest validation failed: {:#x}", ValidationResult);
+					ZEN_ERROR("Store manifest validation failed: {:#x}, will generate new manifest to recover", ValidationResult);
+				}
+
+				if (ManifestIsOk)
+				{
+					m_ManifestObject = std::move(Manifest);
 				}
 			}
 		}
+
+		if (!ManifestIsOk)
+		{
+			UpdateManifest(true);
+		}
 	}
 
 	// Initialize payload storage
@@ -201,6 +209,30 @@ CasImpl::Initialize(const CasStoreConfiguration& InConfig)
 	m_SmallStrategy.Initialize("sobs", 4096, IsNewStore);
 }
 
+void
+CasImpl::UpdateManifest(bool IsNewStore)
+{
+	if (!m_ManifestObject)
+	{
+		CbObjectWriter Cbo;
+		Cbo << "id" << zen::Oid::NewOid() << "created" << DateTime::Now();
+		m_ManifestObject = Cbo.Save();
+	}
+
+	// Write manifest to file
+
+	std::filesystem::path ManifestPath = m_Config.RootDirectory;
+	ManifestPath /= ".ucas_root";
+
+	// This will throw on failure
+
+	ZEN_TRACE("Writing new manifest to '{}'", ManifestPath);
+
+	BasicFile Marker;
+	Marker.Open(ManifestPath.c_str(), /* IsCreate */ true);
+	Marker.Write(m_ManifestObject.GetBuffer(), 0);
+}
+
 CasStore::InsertResult
 CasImpl::InsertChunk(IoBuffer Chunk, const IoHash& ChunkHash)
 {
-- 
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