File_Namespace::MultiPage Struct Reference

The MultiPage stores versions of the same logical page in a deque. More...

#include <Page.h>

Public Member Functions
	MultiPage (size_t pageSizeIn)
	Constructor. More...
	~MultiPage ()
	Destructor – purges all pages. More...
EpochedPage	current () const
	Returns a reference to the most recent version of the page. More...
void	push (const Page &page, const int epoch)
	Pushes a new page with epoch value. More...
void	pop ()
	Purges the oldest Page. More...
std::vector< EpochedPage >	freePagesBeforeEpoch (const int32_t target_epoch, const int32_t current_epoch)

Public Attributes
size_t	pageSize
std::deque< EpochedPage >	pageVersions

Detailed Description

The MultiPage stores versions of the same logical page in a deque.

The purpose of MultiPage is to support storing multiple versions of the same page, which may be located in different locations and in different files. Associated with each version of a page is an "epoch" value, which is a temporal reference.

Definition at line 79 of file Page.h.

Constructor & Destructor Documentation

File_Namespace::MultiPage::MultiPage ( size_t  pageSizeIn )

inline

Constructor.

Definition at line 84 of file Page.h.

: pageSize(pageSizeIn) {}

File_Namespace::MultiPage::~MultiPage ( )

inline

Destructor – purges all pages.

Definition at line 87 of file Page.h.

References pageVersions, and pop().

               {
    while (pageVersions.size() > 0) {
      pop();
    }
  }

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Member Function Documentation

EpochedPage File_Namespace::MultiPage::current ( ) const

inline

Returns a reference to the most recent version of the page.

Definition at line 94 of file Page.h.

References logger::FATAL, LOG, and pageVersions.

Referenced by File_Namespace::FileBuffer::initMetadataAndPageDataSize().

                                     {
    if (pageVersions.size() < 1) {
      LOG(FATAL) << "No current version of the page exists in this MultiPage.";
    }
    return pageVersions.back();
  }

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std::vector<EpochedPage> File_Namespace::MultiPage::freePagesBeforeEpoch ( const int32_t  target_epoch, const int32_t  current_epoch  )

inline

Definition at line 117 of file Page.h.

References CHECK_LE, and pageVersions.

Referenced by File_Namespace::FileBuffer::freePagesBeforeEpochForMultiPage().

                                                                             {
    std::vector<EpochedPage> pagesBeforeEpoch;
    int32_t next_page_epoch = current_epoch + 1;
    for (auto pageIt = pageVersions.rbegin(); pageIt != pageVersions.rend(); ++pageIt) {
      const int32_t epoch_ceiling = next_page_epoch - 1;
      CHECK_LE(pageIt->epoch, epoch_ceiling);
      if (epoch_ceiling < target_epoch) {
        pagesBeforeEpoch.emplace_back(*pageIt);
      }
      next_page_epoch = pageIt->epoch;
    }
    if (!pagesBeforeEpoch.empty()) {
      pageVersions.erase(pageVersions.begin(),
                         pageVersions.begin() + pagesBeforeEpoch.size());
    }
    return pagesBeforeEpoch;
  }

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void File_Namespace::MultiPage::pop ( )

inline

Purges the oldest Page.

Definition at line 110 of file Page.h.

References logger::FATAL, LOG, and pageVersions.

Referenced by File_Namespace::FileBuffer::freeMetadataPages(), and ~MultiPage().

                    {
    if (pageVersions.size() < 1) {
      LOG(FATAL) << "No page to pop.";
    }
    pageVersions.pop_front();
  }

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void File_Namespace::MultiPage::push ( const Page &  page, const int  epoch  )

inline

Pushes a new page with epoch value.

Definition at line 102 of file Page.h.

References CHECK_GT, and pageVersions.

Referenced by File_Namespace::FileBuffer::addNewMultiPage(), File_Namespace::FileBuffer::FileBuffer(), File_Namespace::FileMgr::init(), and File_Namespace::FileBuffer::writeMetadata().

                                                      {
    if (!pageVersions.empty()) {
      CHECK_GT(epoch, pageVersions.back().epoch);
    }
    pageVersions.push_back({page, epoch});
  }

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Member Data Documentation

size_t File_Namespace::MultiPage::pageSize

Definition at line 80 of file Page.h.

std::deque<EpochedPage> File_Namespace::MultiPage::pageVersions

Definition at line 81 of file Page.h.

Referenced by current(), File_Namespace::FileBuffer::freeMetadataPages(), File_Namespace::FileBuffer::freePagesBeforeEpoch(), freePagesBeforeEpoch(), pop(), push(), and ~MultiPage().

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The documentation for this struct was generated from the following file:

• /home/jenkins-slave/workspace/core-os-doxygen/DataMgr/FileMgr/Page.h