FileManager_private.h

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#ifndef STORAGE_FILEMANAGER_PRIVATE_H
#define STORAGE_FILEMANAGER_PRIVATE_H
 
#include "FileManager.h"
 
namespace taco {
 
constexpr uint64_t DBFILE_MAGIC = 0xdefabc1221cbafedul;
constexpr PageNumber PENDING_CREATION_PID = RESERVED_PID;
 
constexpr PageNumber FM_META_PID = INVALID_PID;
 
constexpr PageNumber PageGroupSize = 64;
 
// FormatMeta() assumes there are at least 3 pages in the first page group.
static_assert(PageGroupSize >= 3);
 
constexpr size_t MaxFileSize = (size_t) 64 * 1024 * 1024 * 1024;
 
constexpr PageNumber MaxNumPagesPerFile =  MaxFileSize / PAGE_SIZE;
 
constexpr uint64_t MaxNumDataFiles =
    ((((uint64_t) MaxPageNumber) + 1) + MaxNumPagesPerFile - 1) /
    MaxNumPagesPerFile;
 
// There're many reasons why we don't want too many physical files:
// 1. We don't want an excessive amount of files in a single directory.
// 2. We preallocate the main data file vector, and we don't want that to be
// huge.
static_assert(MaxNumDataFiles <= 4096);
 
struct MetaPageHeaderData {
    uint16_t m_flags;
    uint16_t m_reserved;
};
static_assert(sizeof(MetaPageHeaderData) == 4);
 
static_assert(FileIdBits <= 19, "we support at most 2^19 files at this time");
 
constexpr FileId
FileIdGetDir1Offset(FileId fid) {
    return fid / 1023;
}
 
constexpr FileId
FileIdGetDir2Offset(FileId fid) {
    return fid % 1023;
}
 
constexpr uint64_t
PageNumberGetDataFileId(PageNumber pid) {
    return pid / MaxNumPagesPerFile;
}
 
constexpr PageNumber
PageNumberGetDataFilePageId(PageNumber pid) {
    return pid % MaxNumPagesPerFile;
}
 
constexpr PageNumber
DataFileIdAndPageIdGetPageNumber(uint64_t fsfileid, PageNumber fspid) {
    return fsfileid * MaxNumPagesPerFile + fspid;
}
 
#define DataFileNameLength 3
static_assert(MaxNumDataFiles <= 1 << (DataFileNameLength * 4));
 
struct FreePageList {
    atomic<PageNumber>      m_next_fp_in_last_pg;
    atomic<PageNumber>      m_last_pg;
 
    // list head of the free page list
    atomic<PageNumber>      m_fp_list;
};
 
struct FMMetaPageData {
    MetaPageHeaderData  m_ph;
    uint64_t        m_magic;
    PageNumber      m_fdir1_pid;
    FreePageList    m_fpl;
 
    atomic<FileId>  m_last_free_fid;
};
 
struct FileDirectoryData {
    MetaPageHeaderData  m_ph;
    atomic<PageNumber>  m_pid[1023];
};
static_assert(sizeof(FileDirectoryData) <= PAGE_SIZE);
 
struct RegularFileMetaPageData {
    PageHeaderData          m_ph;
 
    PageNumber              m_first_pid;
 
    atomic<PageNumber>      m_last_pid;
 
    FreePageList            m_fpl;
};
 
}
 
#endif      // STORAGE_FILEMANAGER_PRIVATE_H