foedus::storage::DualPagePointer Struct Reference

Represents a pointer to another page (usually a child page). More...

Detailed Description

Represents a pointer to another page (usually a child page).

Duality of Page Pointer

All page pointers in our storages have duality; a pointer to volatile page and a pointer to snapshot page. The volatile pointer always points to the latest in-memory image of the page. The snapshot page points to a potentially-stale snapshot image of the page which is guaranteed to be read only in all regards, even in its descendent pages.

None, either, or both of the two pointers might null.

• Both are null; the page doesn't exist yet.
• Only snapshot pointer is null; it's a newly created page. no snapshot taken yet.
• Only volatile pointer is null; the snapshot page is the latest and we don't have a modification on the page since then (or not published by RCU-ing thread yet).

Atomic Compare-And-Exchange

Dual page pointer is, unfortunately, 128 bits. When we have to atomically swap either or both 64-bit parts depending on the current value of the entire 128 bit, we need a double-word CAS. The current implementation uses a processor-specific assembly, assuming recent processors. This might restrict our portability, so let's minimize the use of this operation and revisit the design. Do we really need atomic swap for this object?

POD

This is a POD struct. Default destructor/copy-constructor/assignment operator work fine.

Definition at line 271 of file storage_id.hpp.

#include <storage_id.hpp>

Collaboration diagram for foedus::storage::DualPagePointer:

Public Member Functions
	DualPagePointer ()
bool	operator== (const DualPagePointer &other) const
bool	operator!= (const DualPagePointer &other) const
bool	atomic_compare_exchange_strong (const DualPagePointer &expected, const DualPagePointer &desired)
	128-bit atomic CAS (strong version) for the dual pointer. More...
bool	atomic_compare_exchange_weak (const DualPagePointer &expected, const DualPagePointer &desired)
	128-bit atomic CAS (weak version) for the dual pointer. More...
bool	is_both_null () const

Public Attributes
SnapshotPagePointer	snapshot_pointer_
VolatilePagePointer	volatile_pointer_

Friends
std::ostream &	operator<< (std::ostream &o, const DualPagePointer &v)

Constructor & Destructor Documentation

foedus::storage::DualPagePointer::DualPagePointer ( )

inline

Definition at line 272 of file storage_id.hpp.

References volatile_pointer_, and foedus::storage::VolatilePagePointer::word.

                    : snapshot_pointer_(0) {
    volatile_pointer_.word = 0;
  }

Member Function Documentation

bool foedus::storage::DualPagePointer::atomic_compare_exchange_strong ( const DualPagePointer &  expected, const DualPagePointer &  desired  )

inline

128-bit atomic CAS (strong version) for the dual pointer.

Definition at line 287 of file storage_id.hpp.

References foedus::assorted::raw_atomic_compare_exchange_strong_uint128().

                                                                     {
    return assorted::raw_atomic_compare_exchange_strong_uint128(
      reinterpret_cast<uint64_t*>(this),
      reinterpret_cast<const uint64_t*>(&expected),
      reinterpret_cast<const uint64_t*>(&desired));
  }

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bool foedus::storage::DualPagePointer::atomic_compare_exchange_weak ( const DualPagePointer &  expected, const DualPagePointer &  desired  )

inline

128-bit atomic CAS (weak version) for the dual pointer.

Definition at line 295 of file storage_id.hpp.

References foedus::assorted::raw_atomic_compare_exchange_weak_uint128().

                                                                     {
    return assorted::raw_atomic_compare_exchange_weak_uint128(
      reinterpret_cast<uint64_t*>(this),
      reinterpret_cast<const uint64_t*>(&expected),
      reinterpret_cast<const uint64_t*>(&desired));
  }

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bool foedus::storage::DualPagePointer::is_both_null ( ) const

inline

Definition at line 303 of file storage_id.hpp.

References foedus::storage::VolatilePagePointer::is_null(), snapshot_pointer_, and volatile_pointer_.

Referenced by foedus::storage::masstree::MasstreeStoragePimpl::follow_page(), foedus::storage::masstree::SplitIntermediate::migrate_pointers(), foedus::storage::hash::operator<<(), foedus::storage::masstree::MasstreeIntermediatePage::verify_separators(), foedus::storage::masstree::MasstreeStoragePimpl::verify_single_thread_border(), and foedus::storage::masstree::MasstreeStoragePimpl::verify_single_thread_intermediate().

                            {
    return snapshot_pointer_ == 0 && volatile_pointer_.is_null();
  }

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bool foedus::storage::DualPagePointer::operator!= ( const DualPagePointer &  other ) const

inline

Definition at line 280 of file storage_id.hpp.

References operator==().

                                                      {
    return !operator==(other);
  }

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bool foedus::storage::DualPagePointer::operator== ( const DualPagePointer &  other ) const

inline

Definition at line 276 of file storage_id.hpp.

References snapshot_pointer_, volatile_pointer_, and foedus::storage::VolatilePagePointer::word.

Referenced by operator!=().

                                                      {
    return snapshot_pointer_ == other.snapshot_pointer_
      && volatile_pointer_.word == other.volatile_pointer_.word;
  }

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Friends And Related Function Documentation

std::ostream& operator<< ( std::ostream &  o, const DualPagePointer &  v  )

friend

Definition at line 56 of file storage_id.cpp.

                                                                {
  o << "<DualPagePointer>";
  describe_snapshot_pointer(&o, v.snapshot_pointer_);
  describe_volatile_pointer(&o, v.volatile_pointer_);
  o << "</DualPagePointer>";
  return o;
}

Member Data Documentation

SnapshotPagePointer foedus::storage::DualPagePointer::snapshot_pointer_

Definition at line 307 of file storage_id.hpp.

Referenced by foedus::storage::masstree::Adopt::adopt_case_b(), foedus::storage::masstree::MasstreeIntermediatePage::append_minipage_snapshot(), foedus::storage::masstree::MasstreeBorderPage::append_next_layer_snapshot(), foedus::storage::masstree::MasstreeIntermediatePage::append_pointer_snapshot(), foedus::storage::sequential::SequentialComposer::compose(), foedus::storage::array::ArrayComposer::construct_root(), foedus::storage::masstree::MasstreeComposer::construct_root(), foedus::storage::hash::HashStoragePimpl::debugout_single_thread(), foedus::storage::masstree::MasstreeStoragePimpl::debugout_single_thread(), foedus::storage::hash::HashStoragePimpl::debugout_single_thread_data(), foedus::storage::masstree::MasstreeStoragePimpl::debugout_single_thread_follow(), foedus::storage::hash::HashStoragePimpl::debugout_single_thread_intermediate(), foedus::storage::masstree::SplitIntermediate::decide_strategy(), foedus::storage::array::ArrayPartitioner::design_partition(), foedus::storage::masstree::MasstreePartitioner::design_partition(), foedus::storage::array::ArrayComposer::drop_volatiles(), foedus::storage::hash::HashComposer::drop_volatiles(), foedus::storage::hash::HashStoragePimpl::follow_page(), foedus::storage::hash::HashStoragePimpl::follow_page_bin_head(), foedus::thread::ThreadPimpl::follow_page_pointer(), foedus::thread::ThreadPimpl::follow_page_pointers_for_read_batch(), foedus::thread::ThreadPimpl::follow_page_pointers_for_write_batch(), foedus::storage::hash::ComposedBinsMergedStream::init(), foedus::storage::StorageControlBlock::initialize(), foedus::storage::masstree::MasstreeBorderPage::initialize_as_layer_root_physical(), foedus::storage::StorageManagerPimpl::initialize_read_latest_snapshot(), foedus::storage::sequential::SequentialPage::initialize_snapshot_page(), foedus::storage::sequential::SequentialPage::initialize_volatile_page(), foedus::thread::ThreadPimpl::install_a_volatile_page(), is_both_null(), foedus::storage::array::ArrayStoragePimpl::load(), foedus::storage::array::ArrayStoragePimpl::load_empty(), foedus::storage::masstree::MasstreeStoragePimpl::load_empty(), foedus::storage::hash::HashStoragePimpl::locate_record_in_snapshot(), foedus::storage::hash::ComposedBinsMergedStream::open_path(), foedus::storage::operator<<(), operator==(), foedus::storage::masstree::MasstreeStoragePimpl::prefetch_pages_follow(), foedus::storage::array::ArrayStoragePimpl::prefetch_pages_recurse(), foedus::storage::hash::ComposedBinsMergedStream::process_a_bin(), foedus::storage::StorageManagerPimpl::reinitialize_for_recovered_snapshot(), foedus::storage::masstree::MasstreeBorderPage::replace_next_layer_snapshot(), foedus::storage::masstree::ReserveRecords::run(), and foedus::storage::hash::HashStoragePimpl::track_moved_record_search().

VolatilePagePointer foedus::storage::DualPagePointer::volatile_pointer_

Definition at line 308 of file storage_id.hpp.

Referenced by foedus::storage::masstree::Adopt::adopt_case_b(), foedus::storage::masstree::MasstreeIntermediatePage::append_minipage_snapshot(), foedus::storage::masstree::MasstreeBorderPage::append_next_layer_snapshot(), foedus::storage::masstree::MasstreeIntermediatePage::append_pointer_snapshot(), foedus::storage::sequential::SequentialStoragePimpl::append_record(), foedus::storage::hash::ReserveRecords::create_new_record_in_tail_page(), foedus::storage::hash::HashStoragePimpl::debugout_single_thread(), foedus::storage::masstree::MasstreeStoragePimpl::debugout_single_thread(), foedus::storage::hash::HashStoragePimpl::debugout_single_thread_data(), foedus::storage::masstree::MasstreeStoragePimpl::debugout_single_thread_follow(), foedus::storage::hash::HashStoragePimpl::debugout_single_thread_intermediate(), foedus::storage::masstree::SplitIntermediate::decide_strategy(), foedus::storage::array::ArrayPartitioner::design_partition(), foedus::storage::masstree::MasstreePartitioner::design_partition(), foedus::storage::masstree::design_partition_first_parallel_recurse(), foedus::storage::hash::HashPartitioner::design_partition_task(), foedus::storage::array::ArrayComposer::drop_root_volatile(), foedus::storage::hash::HashComposer::drop_root_volatile(), foedus::storage::masstree::MasstreeComposer::drop_root_volatile(), foedus::storage::array::ArrayComposer::drop_volatiles(), foedus::storage::hash::HashComposer::drop_volatiles(), foedus::storage::masstree::MasstreeComposer::drop_volatiles(), foedus::storage::sequential::SequentialComposer::drop_volatiles(), DualPagePointer(), foedus::storage::hash::ReserveRecords::find_and_lock_spacious_tail(), foedus::storage::hash::ReserveRecords::find_or_create_or_expand(), foedus::storage::hash::HashStoragePimpl::follow_page_bin_head(), foedus::thread::ThreadPimpl::follow_page_pointer(), foedus::thread::ThreadPimpl::follow_page_pointers_for_read_batch(), foedus::thread::ThreadPimpl::follow_page_pointers_for_write_batch(), foedus::storage::masstree::grow_case_a_common(), foedus::storage::masstree::grow_case_b_common(), foedus::storage::array::ArrayStoragePimpl::hcc_reset_all_temperature_stat(), foedus::storage::hash::HashStoragePimpl::hcc_reset_all_temperature_stat(), foedus::storage::masstree::MasstreeStoragePimpl::hcc_reset_all_temperature_stat(), foedus::storage::array::ArrayStoragePimpl::hcc_reset_all_temperature_stat_intermediate(), foedus::storage::hash::HashStoragePimpl::hcc_reset_all_temperature_stat_intermediate(), foedus::storage::masstree::MasstreeStoragePimpl::hcc_reset_all_temperature_stat_recurse(), foedus::storage::hash::ComposedBinsMergedStream::init(), foedus::storage::StorageControlBlock::initialize(), foedus::storage::masstree::MasstreeBorderPage::initialize_as_layer_root_physical(), foedus::storage::StorageManagerPimpl::initialize_read_latest_snapshot(), foedus::storage::sequential::SequentialPage::initialize_snapshot_page(), foedus::storage::sequential::SequentialPage::initialize_volatile_page(), is_both_null(), foedus::storage::array::ArrayStoragePimpl::load(), foedus::storage::array::ArrayStoragePimpl::load_empty(), foedus::storage::masstree::MasstreeStoragePimpl::load_empty(), foedus::storage::hash::HashStoragePimpl::locate_bin(), foedus::storage::hash::HashStoragePimpl::locate_record(), foedus::storage::hash::HashStoragePimpl::locate_record_in_snapshot(), foedus::storage::operator<<(), operator==(), foedus::storage::masstree::MasstreeStoragePimpl::peek_volatile_page_boundaries(), foedus::storage::masstree::MasstreeStoragePimpl::peek_volatile_page_boundaries_next_layer(), foedus::storage::masstree::MasstreeStoragePimpl::peek_volatile_page_boundaries_this_layer_recurse(), foedus::thread::ThreadPimpl::place_a_new_volatile_page(), foedus::storage::masstree::MasstreeStoragePimpl::prefetch_pages_follow(), foedus::storage::array::ArrayStoragePimpl::prefetch_pages_recurse(), foedus::storage::hash::ComposedBinsMergedStream::process_a_bin(), foedus::storage::StorageManagerPimpl::reinitialize_for_recovered_snapshot(), foedus::storage::hash::HashIntermediatePage::release_pages_recursive(), foedus::storage::hash::HashDataPage::release_pages_recursive(), foedus::storage::array::ArrayStoragePimpl::release_pages_recursive(), foedus::storage::masstree::MasstreeIntermediatePage::release_pages_recursive(), foedus::storage::masstree::MasstreeBorderPage::release_pages_recursive(), foedus::storage::hash::HashIntermediatePage::release_pages_recursive_parallel(), foedus::storage::masstree::MasstreeIntermediatePage::release_pages_recursive_parallel(), foedus::storage::masstree::MasstreeBorderPage::replace_next_layer_snapshot(), foedus::storage::masstree::GrowFirstLayerRoot::run(), foedus::storage::masstree::GrowNonFirstLayerRoot::run(), foedus::storage::masstree::ReserveRecords::run(), foedus::storage::hash::ReserveRecords::search_within_page(), foedus::storage::masstree::MasstreeBorderPage::track_moved_record_next_layer(), foedus::storage::hash::HashStoragePimpl::track_moved_record_search(), foedus::storage::array::ArrayStoragePimpl::verify_single_thread(), and foedus::storage::hash::HashStoragePimpl::verify_single_thread_intermediate().

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

• /home/shino/foedus_code/foedus-core/include/foedus/storage/storage_id.hpp