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// Copyright Epic Games, Inc. All Rights Reserved.
#include <zenstore/caslog.h>
#include <zencore/except.h>
#include <zencore/filesystem.h>
#include <zencore/fmtutils.h>
#include <zencore/logging.h>
#include <zencore/memory.h>
#include <zencore/string.h>
#include <xxhash.h>
#include <gsl/gsl-lite.hpp>
#include <filesystem>
#include <functional>
//////////////////////////////////////////////////////////////////////////
namespace zen {
uint32_t
CasLogFile::FileHeader::ComputeChecksum()
{
return XXH32(&this->Magic, sizeof(FileHeader) - 4, 0xC0C0'BABA);
}
CasLogFile::CasLogFile()
{
}
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)
{
m_RecordSize = RecordSize;
std::error_code Ec;
BasicFile::Mode FileMode = BasicFile::Mode::kRead;
switch (Mode)
{
case Mode::kWrite:
FileMode = BasicFile::Mode::kWrite;
break;
case Mode::kTruncate:
FileMode = BasicFile::Mode::kTruncate;
break;
}
m_File.Open(FileName, FileMode, Ec);
if (Ec)
{
throw std::system_error(Ec, fmt::format("Failed to open log file '{}'", FileName));
}
uint64_t AppendOffset = 0;
if ((Mode == Mode::kTruncate) || (m_File.FileSize() < sizeof(FileHeader)))
{
if (Mode == Mode::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);
Header.Finalize();
m_File.Write(&Header, sizeof Header, 0);
AppendOffset = sizeof(FileHeader);
m_Header = Header;
}
else
{
FileHeader Header;
m_File.Read(&Header, sizeof Header, 0);
if ((0 != memcmp(Header.Magic, FileHeader::MagicSequence, sizeof Header.Magic)) || (Header.Checksum != Header.ComputeChecksum()))
{
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();
// Adjust the offset to ensure we end up on a good boundary, in case there is some garbage appended
AppendOffset -= sizeof Header;
AppendOffset -= AppendOffset % RecordSize;
AppendOffset += sizeof Header;
m_Header = Header;
}
m_AppendOffset = AppendOffset;
}
void
CasLogFile::Close()
{
// TODO: update header and maybe add trailer
Flush();
m_File.Close();
}
uint64_t
CasLogFile::GetLogSize()
{
return m_File.FileSize();
}
uint64_t
CasLogFile::GetLogCount()
{
uint64_t LogFileSize = m_AppendOffset.load(std::memory_order_acquire);
if (LogFileSize < sizeof(FileHeader))
{
return 0;
}
const uint64_t LogBaseOffset = sizeof(FileHeader);
const size_t LogEntryCount = (LogFileSize - LogBaseOffset) / m_RecordSize;
return LogEntryCount;
}
void
CasLogFile::Replay(std::function<void(const void*)>&& Handler, uint64_t SkipEntryCount)
{
uint64_t LogFileSize = m_File.FileSize();
// Ensure we end up on a clean boundary
uint64_t LogBaseOffset = sizeof(FileHeader);
size_t LogEntryCount = (LogFileSize - LogBaseOffset) / m_RecordSize;
if (LogEntryCount <= SkipEntryCount)
{
return;
}
LogBaseOffset += SkipEntryCount * m_RecordSize;
LogEntryCount -= SkipEntryCount;
const uint64_t LogDataSize = LogEntryCount * m_RecordSize;
uint64_t LogDataRemain = LogDataSize;
const uint64_t MaxBufferSize = 1024 * 1024;
std::vector<uint8_t> ReadBuffer;
ReadBuffer.resize((Min(LogDataSize, MaxBufferSize) / m_RecordSize) * m_RecordSize);
uint64_t ReadOffset = 0;
while (LogDataRemain)
{
const uint64_t BytesToRead = Min(ReadBuffer.size(), LogDataRemain);
const uint64_t EntriesToRead = BytesToRead / m_RecordSize;
m_File.Read(ReadBuffer.data(), BytesToRead, LogBaseOffset + ReadOffset);
for (int i = 0; i < int(EntriesToRead); ++i)
{
Handler(ReadBuffer.data() + (i * m_RecordSize));
}
LogDataRemain -= BytesToRead;
ReadOffset += BytesToRead;
}
m_AppendOffset = LogBaseOffset + (m_RecordSize * LogEntryCount);
}
void
CasLogFile::Append(const void* DataPointer, uint64_t DataSize)
{
ZEN_ASSERT((DataSize % m_RecordSize) == 0);
uint64_t AppendOffset = m_AppendOffset.fetch_add(DataSize);
std::error_code Ec;
m_File.Write(DataPointer, gsl::narrow<uint32_t>(DataSize), AppendOffset, Ec);
if (Ec)
{
std::error_code Dummy;
throw std::system_error(Ec, fmt::format("Failed to write to log file '{}'", PathFromHandle(m_File.Handle(), Dummy)));
}
}
void
CasLogFile::Flush()
{
m_File.Flush();
}
} // namespace zen
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