PMDK C++ bindings  1.5.2
This is the C++ bindings documentation for PMDK's libpmemobj.
Classes | Public Member Functions | Static Public Member Functions | Static Private Member Functions | List of all members
pmem::obj::transaction Class Reference

C++ transaction handler class. More...

#include <libpmemobj++/transaction.hpp>


class  automatic
 C++ automatic scope transaction class. More...
class  manual
 C++ manual scope transaction class. More...

Public Member Functions

 ~transaction () noexcept=delete
 Default destructor. More...

Static Public Member Functions

static void abort (int err)
 Manually abort the current transaction. More...
static void commit ()
 Manually commit a transaction. More...
template<typename... Locks>
static void run (pool_base &pool, std::function< void()> tx, Locks &... locks)
 Execute a closure-like transaction and lock locks. More...

Static Private Member Functions

template<typename L , typename... Locks>
static int add_lock (L &lock, Locks &... locks) noexcept
 Recursively add locks to the active transaction. More...
static int add_lock () noexcept
 Method ending the recursive algorithm.

Detailed Description

C++ transaction handler class.

This class is the pmemobj transaction handler. Scoped transactions are handled through two internal classes: manual and automatic.

This class also exposes a closure-like transaction API, which is the preferred way of handling transactions.

The typical usage example would be:

using namespace pmem::obj;
// pool root structure
struct root {
mutex pmutex;
shared_mutex shared_pmutex;
p<int> count;
persistent_ptr<root> another_root;
// create a pmemobj pool
auto pop = pool<root>::create("poolfile", "layout", PMEMOBJ_MIN_POOL);
auto proot = pop.root();
// typical usage schemes
try {
// take locks and start a transaction
[&]() {
// atomically allocate objects
proot->another_root =
// atomically modify objects
proot->pmutex, proot->shared_pmutex);
// a transaction error occurred, transaction got aborted
// reacquire locks if necessary
} catch (...) {
// some other exception got propagated from within the tx
// reacquire locks if necessary

Constructor & Destructor Documentation

◆ ~transaction()

pmem::obj::transaction::~transaction ( )

Default destructor.

End pmemobj transaction. If the transaction has not been committed before object destruction, an abort will be issued.

Member Function Documentation

◆ abort()

static void pmem::obj::transaction::abort ( int  err)

Manually abort the current transaction.

If called within an inner transaction, the outer transactions will also be aborted.

[in]errthe error to be reported as the reason of the abort.
transaction_errorif the transaction is in an invalid state.
manual_tx_abortthis exception is thrown to signify a transaction abort.

◆ add_lock()

template<typename L , typename... Locks>
static int pmem::obj::transaction::add_lock ( L &  lock,
Locks &...  locks 

Recursively add locks to the active transaction.

The locks are taken in the provided order.

[in,out]lockthe lock to add.
[in,out]locksthe rest of the locks to be added to the active transaction.
error number if adding any of the locks failed, 0 otherwise.

◆ commit()

static void pmem::obj::transaction::commit ( )

Manually commit a transaction.

It is the sole responsibility of the caller, that after the call to transaction::commit() no other operations are done within the transaction.

transaction_erroron any errors with ending the transaction.

◆ run()

template<typename... Locks>
static void pmem::obj::transaction::run ( pool_base pool,
std::function< void()>  tx,
Locks &...  locks 

Execute a closure-like transaction and lock locks.

The locks have to be persistent memory resident locks. An attempt to lock the locks will be made. If any of the specified locks is already locked, the method will block. The locks are held until the end of the transaction. The transaction does not have to be committed manually. Manual aborts will end the transaction with an active exception.

If an exception is thrown within the transaction, it gets aborted and the exception is rethrown. Therefore extra care has to be taken with proper error handling.

The locks are held for the entire duration of the transaction. They are released at the end of the scope, so within the catch block, they are already unlocked. If the cleanup action requires access to data within a critical section, the locks have to be manually acquired once again.

[in,out]poolthe pool in which the transaction will take place.
[in]txan std::function<void ()> which will perform operations within this transaction.
[in,out]lockslocks to be taken for the duration of the transaction.
transaction_erroron any error pertaining the execution of the transaction.
manual_tx_aborton manual transaction abort.

The documentation for this class was generated from the following file:
Persistent memory resident mutex implementation.
Definition: mutex.hpp:60
static pool< T > create(const std::string &path, const std::string &layout, std::size_t size=PMEMOBJ_MIN_POOL, mode_t mode=DEFAULT_MODE)
Creates a new transactional object store pool.
Definition: pool.hpp:532
Custom transaction error class.
Definition: pexceptions.hpp:63
Resides on pmem class.
Definition: p.hpp:64
C++ pmemobj pool.
Persistent_ptr transactional allocation functions for objects.
static void run(pool_base &pool, std::function< void()> tx, Locks &... locks)
Execute a closure-like transaction and lock locks.
Definition: transaction.hpp:401
C++ pmemobj transactions.
Persistent pointer class.
Definition: persistent_ptr.hpp:132
Pmem-resident shared mutex.
Convenience extensions for the resides on pmem property template.
Persistent smart pointer.
Persistent memory resident shared_mutex implementation.
Definition: shared_mutex.hpp:59
Pmem-resident mutex.