Struct cfxcore::block_data_manager::BlockDataWithMultiVersion

pub struct BlockDataWithMultiVersion<Version, T> { /* private fields */ }

The structure to maintain block data under different views.

Note that in database only the data corresponding to the current pivot chain exist. This multi-version version are only maintained in memory and will be garbage collected. When insert_current_data() is called, we always update the version in DB to the current version. If there is no garbage-collection, this guarantees that the version in DB is the latest, and the in-memory version is EVENTUALLY consistent with the one in DB.

FIXME: There is a rare case to cause inconsistency with GC: Assume a thread T1 is writing the latest data and T2 is answering RPC requests, and the in-memory data have been garbage collected.

T2 reads old data from DB-> T1 writes new data to DB -> T1 writes new data to memory -> in-memory data are garbage collected again -> T2 writes old data to memory successfully with insert_data()

Now the data in DB are new, but the ones in memory are old. If we lock the in-memory structure before reading from DB, or we do not update the in-memory data with the one from DB, this inconsistency can be eliminated, but the performance will be affected.

Implementations

impl<Version, T> BlockDataWithMultiVersion<Version, T>

where Version: Copy + Eq + PartialEq, T: Clone,

pub fn get_data_at_version(&self, version: &Version) -> Option<(T, bool)>

Return None if we do not have a corresponding data in the given version. Return (data, is_current) otherwise.

pub fn get_current_data(&self) -> Option<DataVersionTuple<Version, T>>

pub fn set_current_version(&mut self, version: Version)

pub fn insert_current_data(&mut self, version: &Version, data: T)

Insert the latest data with its version. This should be called after we update the version in the database to ensure consistency.

pub fn insert_data(&mut self, version: &Version, data: T)

Insert the data with its version and update the current version if it’s not set. This is used when version is not guaranteed to be the latest.

pub fn retain_version(&mut self, version: &Version)

Only keep the data in the given version. Called when the data on other versions are not likely to be needed.

Trait Implementations

impl<Version, T> Debug for BlockDataWithMultiVersion<Version, T>

where Version: Debug, T: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<Version, T> Default for BlockDataWithMultiVersion<Version, T>

fn default() -> BlockDataWithMultiVersion<Version, T>

Return BlockDataWithMultiVersion { data_version_tuple_array: Default::default(), current_version: Default::default() }

impl<VersionIndex, T> MallocSizeOf for BlockDataWithMultiVersion<VersionIndex, T>

where VersionIndex: MallocSizeOf, T: MallocSizeOf,

fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize

Measure the heap usage of all descendant heap-allocated structures, but not the space taken up by the value itself.