Dataquay::TransactionalStore Class Reference
TransactionalStore is an RDF data store implementing the Store interface, providing transaction support as a wrapper around a non-transactional store such as a BasicStore. More...
#include <dataquay/TransactionalStore.h>
Classes | |
| class | TSTransaction |
Public Types | |
| enum | DirectWriteBehaviour { NoAutoTransaction, AutoTransaction } |
DirectWriteBehaviour controls how TransactionalStore responds when called directly (not through a Transaction) for a write operation (add, remove, change, or revert). More... | |
Signals | |
| void | transactionCommitted (const ChangeSet &cs) |
| Emitted after a transaction has been committed. | |
| void | transactionCommitted () |
| Emitted after a transaction has been committed. | |
Public Member Functions | |
| TransactionalStore (Store *store, DirectWriteBehaviour dwb=NoAutoTransaction) | |
| Create a TransactionalStore operating on the given (presumably non-transactional) data store. | |
| ~TransactionalStore () | |
| Delete the TransactionalStore. | |
| Transaction * | startTransaction () |
| Start a transaction and obtain a Transaction through which to carry out its operations. | |
| bool | add (Triple t) |
| Add a triple to the store. | |
| bool | remove (Triple t) |
| Remove a triple from the store. | |
| void | change (ChangeSet changes) |
| Atomically apply the sequence of add/remove changes described in the given ChangeSet. | |
| void | revert (ChangeSet changes) |
| Atomically apply the sequence of add/remove changes described in the given ChangeSet, in reverse (ie removing adds and adding removes, in reverse order). | |
| bool | contains (Triple t) const |
| Return true if the store contains the given triple, false otherwise. | |
| Triples | match (Triple t) const |
| Return all triples matching the given wildcard triple. | |
| ResultSet | query (QString sparql) const |
| Run a SPARQL query against the store and return its results. | |
| Triple | matchFirst (Triple t) const |
| Return the first triple to match the given wildcard triple. | |
| Node | queryFirst (QString sparql, QString bindingName) const |
| Run a SPARQL query against the store and return the node of the first result for the given query binding. | |
| Uri | getUniqueUri (QString prefix) const |
| Get a new URI, starting with the given prefix (e.g. | |
| Node | addBlankNode () |
| Create and return a new blank node. | |
| Uri | expand (QString uri) const |
| Expand the given URI (which may use local namespaces) and prefix-expand it, returning the result as a Uri. | |
| void | save (QString filename) const |
| Export the store to an RDF/TTL file with the given filename. | |
Detailed Description
TransactionalStore is an RDF data store implementing the Store interface, providing transaction support as a wrapper around a non-transactional store such as a BasicStore.
Write access to the store is permitted only in the context of a transaction. If you call a modifying function directly on TransactionalStore, the store will either throw RDFException (if set to NoAutoTransaction) or create a single-use Transaction object for the duration of that modification (if set to AutoTransaction). Note that the latter behaviour will deadlock if a transaction is in progress already.
Read access may be carried out through a Transaction, in which case the read state will reflect the changes made so far in that transaction, or directly on the TransactionalStore, in which case the read will be isolated from any pending transaction.
Call startTransaction to obtain a new Transaction object and start its transaction; use the Transaction's Store interface for all accesses associated with that transaction; delete the Transaction object once done, to finish and commit the transaction; or call Transaction::rollback() if you decide you do not wish to commit it.
TransactionalStore is thread-safe.
!!! ... but the individual Transactions that you get from it are _not_ thread-safe -- document this (it's probably acceptable) or fix it
Definition at line 72 of file TransactionalStore.h.
Member Enumeration Documentation
DirectWriteBehaviour controls how TransactionalStore responds when called directly (not through a Transaction) for a write operation (add, remove, change, or revert).
NoAutoTransaction (the default) means that an RDF exception will be thrown whenever a write is attempted without a transaction.
AutoTransaction means that a Transaction object will be created, used for the single access, and then closed. This may cause a deadlock if another transaction is already ongoing elsewhere.
Definition at line 91 of file TransactionalStore.h.
Constructor & Destructor Documentation
| Dataquay::TransactionalStore::TransactionalStore | ( | Store * | store, | |
| DirectWriteBehaviour | dwb = NoAutoTransaction | |||
| ) |
Create a TransactionalStore operating on the given (presumably non-transactional) data store.
Nothing in the code prevents the given _underlying_ store being used non-transactionally elsewhere at the same time. Don't do that: once you have set up a transactional store, you should use it for all routine accesses to the underlying store.
Definition at line 554 of file TransactionalStore.cpp.
| Dataquay::TransactionalStore::~TransactionalStore | ( | ) |
Delete the TransactionalStore.
This does _not_ delete the underlying Store that is being wrapped (the one that was passed to the constructor).
Definition at line 559 of file TransactionalStore.cpp.
Member Function Documentation
| Transaction * Dataquay::TransactionalStore::startTransaction | ( | ) |
Start a transaction and obtain a Transaction through which to carry out its operations.
Once the transaction is complete, you must call commit on the Transaction object to finish the transaction, and then you must delete the object.
Definition at line 565 of file TransactionalStore.cpp.
Referenced by add(), addBlankNode(), change(), remove(), and revert().
| bool Dataquay::TransactionalStore::add | ( | Triple | t | ) | [virtual] |
Add a triple to the store.
Prefix expansion is performed on URI nodes in the triple. Return false if the triple was already in the store. (Dataquay does not permit duplicate triples in a store.) Throw RDFException if the triple can not be added for some other reason.
Implements Dataquay::Store.
Definition at line 578 of file TransactionalStore.cpp.
References startTransaction().
| bool Dataquay::TransactionalStore::remove | ( | Triple | t | ) | [virtual] |
Remove a triple from the store.
Prefix expansion is performed on URI nodes in the triple. If some nodes in the triple are Nothing nodes, remove all matching triples. Return false if no matching triple was found in the store. Throw RDFException if removal failed for some other reason.
Implements Dataquay::Store.
Definition at line 589 of file TransactionalStore.cpp.
References startTransaction().
| void Dataquay::TransactionalStore::change | ( | ChangeSet | changes | ) | [virtual] |
Atomically apply the sequence of add/remove changes described in the given ChangeSet.
Throw RDFException if any operation fails for any reason (including duplication etc).
Implements Dataquay::Store.
Definition at line 599 of file TransactionalStore.cpp.
References startTransaction().
| void Dataquay::TransactionalStore::revert | ( | ChangeSet | changes | ) | [virtual] |
Atomically apply the sequence of add/remove changes described in the given ChangeSet, in reverse (ie removing adds and adding removes, in reverse order).
Throw RDFException if any operation fails for any reason (including duplication etc).
Implements Dataquay::Store.
Definition at line 609 of file TransactionalStore.cpp.
References startTransaction().
| bool Dataquay::TransactionalStore::contains | ( | Triple | t | ) | const [virtual] |
Return true if the store contains the given triple, false otherwise.
Prefix expansion is performed on URI nodes in the triple. Throw RDFException if the triple is not complete or if the test failed for any other reason.
Implements Dataquay::Store.
Definition at line 619 of file TransactionalStore.cpp.
Return all triples matching the given wildcard triple.
A node of type Nothing in any part of the triple matches any node in the data store. Prefix expansion is performed on URI nodes in the triple. Return an empty list if there are no matches; may throw RDFException if matching fails in some other way.
Implements Dataquay::Store.
Definition at line 626 of file TransactionalStore.cpp.
| ResultSet Dataquay::TransactionalStore::query | ( | QString | sparql | ) | const [virtual] |
Run a SPARQL query against the store and return its results.
Any prefixes added previously using addQueryPrefix will be available in this query without needing to be declared in the SPARQL given here (equivalent to writing "PREFIX prefix: <uri>" for each prefix,uri pair set with addPrefix).
May throw RDFException.
Note that the RDF store must have an absolute base URI (rather than the default "#") in order to perform queries, as relative URIs in the query will be interpreted relative to the query base rather than the store and without a proper base URI there is no way to override that internally.
Implements Dataquay::Store.
Definition at line 633 of file TransactionalStore.cpp.
Return the first triple to match the given wildcard triple.
A node of type Nothing in any part of the triple matches any node in the data store. Prefix expansion is performed on URI nodes in the triple. Return an empty triple (three Nothing nodes) if there are no matches. May throw RDFException.
Implements Dataquay::Store.
Definition at line 640 of file TransactionalStore.cpp.
| Node Dataquay::TransactionalStore::queryFirst | ( | QString | sparql, | |
| QString | bindingName | |||
| ) | const [virtual] |
Run a SPARQL query against the store and return the node of the first result for the given query binding.
This is a shorthand for use with queries that are only expected to have one result. May throw RDFException.
Implements Dataquay::Store.
Definition at line 647 of file TransactionalStore.cpp.
| Uri Dataquay::TransactionalStore::getUniqueUri | ( | QString | prefix | ) | const [virtual] |
Get a new URI, starting with the given prefix (e.g.
":event_"), that does not currently exist within this store. The URI will be prefix expanded.
Implements Dataquay::Store.
Definition at line 654 of file TransactionalStore.cpp.
| Node Dataquay::TransactionalStore::addBlankNode | ( | ) | [virtual] |
Create and return a new blank node.
This node can only be referred to using the given Node object, and only during its lifetime within this instance of the store.
Implements Dataquay::Store.
Definition at line 661 of file TransactionalStore.cpp.
References startTransaction().
| Uri Dataquay::TransactionalStore::expand | ( | QString | uri | ) | const [virtual] |
Expand the given URI (which may use local namespaces) and prefix-expand it, returning the result as a Uri.
(The Uri class cannot be used to store URIs that have unexpanded namespace prefixes.)
The set of available prefixes for expansion depends on the subclass implementation. See, for example, BasicStore::addPrefix.
Implements Dataquay::Store.
Definition at line 671 of file TransactionalStore.cpp.
| void Dataquay::TransactionalStore::save | ( | QString | filename | ) | const [virtual] |
Export the store to an RDF/TTL file with the given filename.
The saved state of the store will be isolated from any pending transactions. If the file already exists, it will if possible be overwritten. May throw RDFException, FileOperationFailed, FailedToOpenFile, etc.
Implements Dataquay::Store.
Definition at line 571 of file TransactionalStore.cpp.
| void Dataquay::TransactionalStore::transactionCommitted | ( | const ChangeSet & | cs | ) | [signal] |
Emitted after a transaction has been committed.
Note that the transaction lock on the store is unlocked before the signal is emitted, so that in a multi-threaded context it is possible that other users of the store may have carried out further transactions before this signal can be acted on.
| void Dataquay::TransactionalStore::transactionCommitted | ( | ) | [signal] |
Emitted after a transaction has been committed.
Note that the transaction lock on the store is unlocked before the signal is emitted, so that in a multi-threaded context it is possible that other users of the store may have carried out further transactions before this signal can be acted on.
The documentation for this class was generated from the following files:
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