store cache rawhash and rawsize for unstructured cache values (#234)

* refactored MemoryCacheBucket to allow for storing RawHash/RawSize.
* remove redundant conversions in AccessTime
* reduce max count for memory cache bucket to 32-bit value
* refactored DiskCacheBucket to allow for storing RawHash/RawSize.
* Use CompressedBuffer::ValidateCompressedHeader when applicable
* Make sure we rewrite the snapshot if we read an legacy existing index/log
* changelog

1 files changed, 43 insertions, 1 deletions

diff --git a/zenstore/caslog.cpp b/zenstore/caslog.cpp
index 9c5258bce..2a978ae12 100644
--- a/zenstore/caslog.cpp
+++ b/zenstore/caslog.cpp
@@ -38,6 +38,42 @@ CasLogFile::~CasLogFile()
 {
 }
 
+bool
+CasLogFile::IsValid(std::filesystem::path FileName, size_t RecordSize)
+{
+	if (!std::filesystem::is_regular_file(FileName))
+	{
+		return false;
+	}
+	BasicFile File;
+
+	std::error_code Ec;
+	File.Open(FileName, BasicFile::Mode::kRead, Ec);
+	if (Ec)
+	{
+		return false;
+	}
+
+	FileHeader Header;
+	if (File.FileSize() < sizeof(Header))
+	{
+		return false;
+	}
+
+	// Validate header and log contents and prepare for appending/replay
+	File.Read(&Header, sizeof Header, 0);
+
+	if ((0 != memcmp(Header.Magic, FileHeader::MagicSequence, sizeof Header.Magic)) || (Header.Checksum != Header.ComputeChecksum()))
+	{
+		return false;
+	}
+	if (Header.RecordSize != RecordSize)
+	{
+		return false;
+	}
+	return true;
+}
+
 void
 CasLogFile::Open(std::filesystem::path FileName, size_t RecordSize, Mode Mode)
 {
@@ -82,7 +118,6 @@ CasLogFile::Open(std::filesystem::path FileName, size_t RecordSize, Mode Mode)
 	}
 	else
 	{
-		// Validate header and log contents and prepare for appending/replay
 		FileHeader Header;
 		m_File.Read(&Header, sizeof Header, 0);
 
@@ -90,6 +125,13 @@ CasLogFile::Open(std::filesystem::path FileName, size_t RecordSize, Mode Mode)
 		{
 			throw std::runtime_error(fmt::format("Mangled log header (invalid header magic) in '{}'", FileName));
 		}
+		if (Header.RecordSize != RecordSize)
+		{
+			throw std::runtime_error(fmt::format("Mangled log header (mismatch in record size, expected {}, found {}) in '{}'",
+												 RecordSize,
+												 Header.RecordSize,
+												 FileName));
+		}
 
 		AppendOffset = m_File.FileSize();