foedus::storage::Metadata Struct Reference

Metadata of one storage. More...

Detailed Description

Metadata of one storage.

Metadata of a storage is a concise set of information about its structure, not about its data. For example, ID, name, and other stuffs specific to the storage type.

Metadata file format

So far, we use a human-readable XML format for all metadata. The main reason is ease of debugging.

When metadata is written

Currently, all metadata of all storages are written to a single file for each snapshotting. We start from previous snapshot and apply durable logs up to some epoch just like data files. We have a plan to implement a stratified metadata-store equivalent to data files, but it has lower priority. It happens only once per several seconds, and the cost to dump that file, even in XML format, is negligible unless there are many thousands stores. (yes, which might be the case later, but not for now.)

When metadata is read

Snapshot metadata files are read at next snapshotting and at next restart.

No virtual methods and no heap-allocation

Metadata objects are placed in shared memory. It must not have any heap-allocated data (eg std::string) nor virtual methods.

Definition at line 58 of file metadata.hpp.

#include <metadata.hpp>

Inheritance diagram for foedus::storage::Metadata:

Collaboration diagram for foedus::storage::Metadata:

Classes
struct	SnapshotThresholds
	Tuning parameters related to snapshotting. More...

Public Member Functions
	Metadata ()
	Metadata (StorageId id, StorageType type, const StorageName &name)
	Metadata (StorageId id, StorageType type, const StorageName &name, SnapshotPagePointer root_snapshot_page_id)
bool	keeps_all_volatile_pages () const

Static Public Member Functions
static std::string	describe (const Metadata &metadata)
	to_string operator of all Metadata objects. More...

Public Attributes
StorageId	id_
	the unique ID of this storage. More...
StorageType	type_
	type of the storage. More...
StorageName	name_
	the unique name of this storage. More...
SnapshotPagePointer	root_snapshot_page_id_
	Pointer to a snapshotted page this storage is rooted at. More...
SnapshotThresholds	snapshot_thresholds_

Constructor & Destructor Documentation

foedus::storage::Metadata::Metadata ( )

inline

Definition at line 79 of file metadata.hpp.

    : id_(0), type_(kInvalidStorage), name_(""), root_snapshot_page_id_(0), snapshot_thresholds_() {
  }

foedus::storage::Metadata::Metadata ( StorageId  id, StorageType  type, const StorageName &  name  )

inline

Definition at line 82 of file metadata.hpp.

    : id_(id), type_(type), name_(name), root_snapshot_page_id_(0), snapshot_thresholds_() {}

foedus::storage::Metadata::Metadata ( StorageId  id, StorageType  type, const StorageName &  name, SnapshotPagePointer  root_snapshot_page_id  )

inline

Definition at line 84 of file metadata.hpp.

    : id_(id),
    type_(type),
    name_(name),
    root_snapshot_page_id_(root_snapshot_page_id),
    snapshot_thresholds_() {}

Member Function Documentation

std::string foedus::storage::Metadata::describe ( const Metadata &  metadata )

static

to_string operator of all Metadata objects.

Definition at line 35 of file metadata.cpp.

References foedus::storage::kArrayStorage, foedus::storage::kHashStorage, foedus::storage::kMasstreeStorage, foedus::storage::kSequentialStorage, and type_.

                                                     {
  switch (metadata.type_) {
  case kArrayStorage:
    return static_cast<const array::ArrayMetadata&>(metadata).describe();
  case kHashStorage:
    return static_cast<const hash::HashMetadata&>(metadata).describe();
  case kMasstreeStorage:
    return static_cast<const masstree::MasstreeMetadata&>(metadata).describe();
  case kSequentialStorage:
    return static_cast<const sequential::SequentialMetadata&>(metadata).describe();
  default:
    return "Unknown metadata type";
  }
}

bool foedus::storage::Metadata::keeps_all_volatile_pages ( ) const

inline

Definition at line 98 of file metadata.hpp.

References foedus::storage::Metadata::SnapshotThresholds::snapshot_keep_threshold_, and snapshot_thresholds_.

Referenced by 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(), and foedus::storage::masstree::MasstreeComposer::drop_volatiles().

                                        {
    return snapshot_thresholds_.snapshot_keep_threshold_ == 0xFFFFFFFFU;
  }

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Member Data Documentation

StorageId foedus::storage::Metadata::id_

the unique ID of this storage.

Definition at line 103 of file metadata.hpp.

Referenced by foedus::storage::CreateLogType::apply_storage(), foedus::storage::CreateLogType::assert_valid(), foedus::storage::array::ArrayStoragePimpl::create(), foedus::storage::StorageManager::create_array(), foedus::storage::StorageManager::create_hash(), foedus::storage::StorageManager::create_masstree(), foedus::storage::StorageManager::create_sequential(), foedus::storage::StorageManagerPimpl::create_storage(), foedus::storage::StorageManagerPimpl::create_storage_and_log(), foedus::storage::StorageManagerPimpl::create_storage_apply(), foedus::storage::array::ArrayStoragePimpl::get_id(), foedus::storage::Storage< MasstreeStorageControlBlock >::get_id(), foedus::storage::StorageManagerPimpl::initialize_read_latest_snapshot(), foedus::storage::MetadataSerializer::load_base(), foedus::storage::sequential::SequentialStorageControlBlock::optimistic_read_truncate_epoch(), and foedus::storage::MetadataSerializer::save_base().

StorageName foedus::storage::Metadata::name_

the unique name of this storage.

Definition at line 107 of file metadata.hpp.

Referenced by foedus::storage::StorageManagerPimpl::create_storage(), foedus::storage::StorageManagerPimpl::create_storage_and_log(), foedus::storage::StorageManagerPimpl::create_storage_apply(), foedus::storage::StorageManagerPimpl::drop_storage(), foedus::snapshot::SnapshotManagerPimpl::drop_volatile_pages_parallel(), foedus::storage::StorageManager::get_name(), foedus::storage::Storage< MasstreeStorageControlBlock >::get_name(), foedus::storage::StorageManagerPimpl::initialize_read_latest_snapshot(), foedus::storage::MetadataSerializer::load_base(), foedus::storage::array::ArrayStoragePimpl::prefetch_pages(), and foedus::storage::MetadataSerializer::save_base().

SnapshotPagePointer foedus::storage::Metadata::root_snapshot_page_id_

Pointer to a snapshotted page this storage is rooted at.

This is 0 until this storage has the first snapshot.

Definition at line 112 of file metadata.hpp.

Referenced by foedus::storage::array::ArrayComposer::construct_root(), foedus::storage::hash::HashComposer::construct_root(), foedus::storage::sequential::SequentialComposer::construct_root(), foedus::snapshot::SnapshotManagerPimpl::drop_volatile_pages_parallel(), foedus::storage::StorageManagerPimpl::initialize_read_latest_snapshot(), foedus::storage::array::ArrayStoragePimpl::load(), foedus::storage::masstree::MasstreeStoragePimpl::load(), foedus::storage::hash::HashStoragePimpl::load(), foedus::storage::MetadataSerializer::load_base(), foedus::storage::array::ArrayStoragePimpl::load_empty(), and foedus::storage::MetadataSerializer::save_base().

SnapshotThresholds foedus::storage::Metadata::snapshot_thresholds_

Definition at line 114 of file metadata.hpp.

Referenced by keeps_all_volatile_pages(), foedus::storage::MetadataSerializer::load_base(), and foedus::storage::MetadataSerializer::save_base().

StorageType foedus::storage::Metadata::type_

type of the storage.

Definition at line 105 of file metadata.hpp.

Referenced by foedus::storage::StorageManagerPimpl::create_storage(), foedus::storage::StorageManagerPimpl::create_storage_and_log(), foedus::storage::StorageManagerPimpl::create_storage_apply(), describe(), foedus::storage::StorageManagerPimpl::drop_storage(), foedus::storage::StorageManagerPimpl::drop_storage_apply(), foedus::storage::Storage< MasstreeStorageControlBlock >::get_type(), foedus::storage::StorageManagerPimpl::hcc_reset_all_temperature_stat(), foedus::storage::StorageManagerPimpl::initialize_read_latest_snapshot(), foedus::storage::MetadataSerializer::load_base(), foedus::storage::operator<<(), foedus::storage::Partitioner::Partitioner(), foedus::storage::MetadataSerializer::save_all_storages_to_xml(), foedus::storage::MetadataSerializer::save_base(), and foedus::storage::StorageManagerPimpl::track_moved_record().

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

• /home/shino/foedus_code/foedus-core/include/foedus/storage/metadata.hpp
• /home/shino/foedus_code/foedus-core/src/foedus/storage/metadata.cpp