cuttlefish::DataViewer Class Reference

#include <data_viewer.h>

Collaboration diagram for cuttlefish::DataViewer:

Classes
class	DeadlockProtector

Public Member Functions
	DataViewer (const std::string &backing_file)
template<typename R >
Result< R >	WithSharedLock (std::function< Result< R >(const cvd::PersistentData &)> task) const
template<typename R >
Result< R >	WithExclusiveLock (std::function< Result< R >(cvd::PersistentData &)> task)

Private Member Functions
Result< SharedFD >	LockBackingFile (int op) const
Result< cvd::PersistentData >	LoadData (SharedFD fd) const
Result< void >	StoreData (SharedFD fd, cvd::PersistentData data)

Private Attributes
std::mutex	lock_map_mtx_
std::unordered_map< std::thread::id, bool >	lock_held_by_
std::string	backing_file_

Detailed Description

Synchronizes loading and storing the instance database from and to a file.

Guarantees atomic access to the information stored in the backing file at the cost of high lock contention.

Constructor & Destructor Documentation

DataViewer()

cuttlefish::DataViewer::DataViewer ( const std::string &  backing_file )

inline

Member Function Documentation

LoadData()

Result< cvd::PersistentData > cuttlefish::DataViewer::LoadData ( SharedFD  fd ) const

private

LockBackingFile()

Result< SharedFD > cuttlefish::DataViewer::LockBackingFile ( int  op ) const

private

StoreData()

Result< void > cuttlefish::DataViewer::StoreData ( SharedFD  fd, cvd::PersistentData  data  )

private

WithExclusiveLock()

template<typename R >

Result< R > cuttlefish::DataViewer::WithExclusiveLock ( std::function< Result< R >(cvd::PersistentData &)>  task )

inline

Provides read-write access to the data while holding an exclusive lock.

This function may block until the lock can be acquired. Others can't access the data concurrently with this one. Any changes to the data will be persisted to the file when the task functor returns successfully, no changes to the backed data occur if an error is returned.

WithSharedLock()

template<typename R >

Result< R > cuttlefish::DataViewer::WithSharedLock ( std::function< Result< R >(const cvd::PersistentData &)>  task ) const

inline

Provides read-only access to the data while holding a shared lock.

This function may block until the lock can be acquired. Others can access the data in read-only mode concurrently, but write access is blocked at least until this function returns.

Member Data Documentation

backing_file_

std::string cuttlefish::DataViewer::backing_file_

private

lock_held_by_

std::unordered_map<std::thread::id, bool> cuttlefish::DataViewer::lock_held_by_

mutableprivate

lock_map_mtx_

std::mutex cuttlefish::DataViewer::lock_map_mtx_

mutableprivate

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

• cuttlefish/host/commands/cvd/instances/data_viewer.h
• cuttlefish/host/commands/cvd/instances/data_viewer.cpp