Migration now works in larger disk IO chunks

BasicFile and CasLogFile now has new explicit modes instead of create true/false

1 files changed, 18 insertions, 4 deletions

diff --git a/zenstore/caslog.cpp b/zenstore/caslog.cpp
index 909605af9..906c97348 100644
--- a/zenstore/caslog.cpp
+++ b/zenstore/caslog.cpp
@@ -39,13 +39,23 @@ CasLogFile::~CasLogFile()
 }
 
 void
-CasLogFile::Open(std::filesystem::path FileName, size_t RecordSize, bool IsCreate)
+CasLogFile::Open(std::filesystem::path FileName, size_t RecordSize, EMode Mode)
 {
 	m_RecordSize = RecordSize;
 
-	std::error_code Ec;
-	m_File.Open(FileName, IsCreate, Ec);
+	std::error_code	 Ec;
+	BasicFile::EMode FileMode = BasicFile::EMode::kRead;
+	switch (Mode)
+	{
+		case EMode::kWrite:
+			FileMode = BasicFile::EMode::kWrite;
+			break;
+		case EMode::kTruncate:
+			FileMode = BasicFile::EMode::kTruncate;
+			break;
+	}
 
+	m_File.Open(FileName, FileMode, Ec);
 	if (Ec)
 	{
 		throw std::system_error(Ec, fmt::format("Failed to open log file '{}'", FileName));
@@ -53,8 +63,12 @@ CasLogFile::Open(std::filesystem::path FileName, size_t RecordSize, bool IsCreat
 
 	uint64_t AppendOffset = 0;
 
-	if (IsCreate || (m_File.FileSize() < sizeof(FileHeader)))
+	if ((Mode == EMode::kTruncate) || (m_File.FileSize() < sizeof(FileHeader)))
 	{
+		if (Mode == EMode::kRead)
+		{
+			throw std::runtime_error(fmt::format("Mangled log header (file to small) in '{}'", FileName));
+		}
 		// Initialize log by writing header
 		FileHeader Header = {.RecordSize = gsl::narrow<uint32_t>(RecordSize), .LogId = Oid::NewOid(), .ValidatedTail = 0};
 		memcpy(Header.Magic, FileHeader::MagicSequence, sizeof Header.Magic);