A transaction provides a consistent view on the database. More...
#include <itransaction.h>
Public Member Functions | |
Static properties | |
virtual const char * | get_id () const =0 |
Returns the ID of this transaction. More... | |
virtual IScope * | get_scope () const =0 |
Returns the scope of this transaction. More... | |
Committing and aborting | |
virtual bool | is_open () const =0 |
Indicates whether the transaction is open. More... | |
virtual Sint32 | commit ()=0 |
Commits the transaction. More... | |
virtual void | abort ()=0 |
Aborts the transaction. More... | |
Creation of DB elements | |
virtual base::IInterface * | create (const char *type_name, Uint32 argc=0, const base::IInterface *argv[]=nullptr)=0 |
Creates an object of the type type_name . More... | |
template<class T> | |
T * | create (const char *type_name, Uint32 argc=0, const base::IInterface *argv[]=nullptr) |
Creates an object of the type type_name . More... | |
template<class T> | |
T * | create () |
Creates an object of the type T . More... | |
Storing of DB elements | |
virtual Sint32 | store (base::IInterface *db_element, const char *name, Uint8 privacy=LOCAL_SCOPE)=0 |
Stores the element db_element in the database under the name name and with the privacy level privacy . More... | |
Accessing and editing DB elements | |
virtual const base::IInterface * | access (const char *name)=0 |
Retrieves an element from the database. More... | |
template<class T> | |
const T * | access (const char *name) |
Retrieves an element from the database. More... | |
virtual base::IInterface * | edit (const char *name)=0 |
Retrieves an element from the database and returns it ready for editing. More... | |
template<class T> | |
T * | edit (const char *name) |
Retrieves an element from the database and returns it ready for editing. More... | |
Copies, removal, and properties of DB elements | |
virtual Sint32 | copy (const char *source, const char *target, Uint8 privacy=LOCAL_SCOPE)=0 |
Creates a copy of a database element. More... | |
virtual Sint32 | remove (const char *name, bool only_localized=false)=0 |
Marks the element with the name name for removal from the database. More... | |
virtual const char * | name_of (const base::IInterface *db_element) const =0 |
Returns the name of a database element. More... | |
virtual Sint32 | get_privacy_level (const char *name) const =0 |
Returns the privacy level of the element with the name name . More... | |
Time stamps | |
virtual const char * | get_time_stamp () const =0 |
Returns the time stamp describing the current "time". More... | |
virtual const char * | get_time_stamp (const char *element) const =0 |
Returns the time stamp of the last change of a database element. More... | |
virtual bool | has_changed_since_time_stamp (const char *element, const char *time_stamp) const =0 |
Checks whether an element has been stored or changed in the database since a given time stamp. More... | |
Traversal | |
virtual IArray * | list_elements (const char *root_element, const char *name_pattern=nullptr, const IArray *type_names=nullptr) const =0 |
Returns scene elements of a subgraph originating at a given scene element. More... | |
Public Member Functions inherited from mi::base::IInterface | |
virtual Uint32 | retain () const =0 |
Increments the reference count. More... | |
virtual Uint32 | release () const =0 |
Decrements the reference count. More... | |
virtual const IInterface * | get_interface (const Uuid &interface_id) const =0 |
Acquires a const interface from another. More... | |
template<class T> | |
const T * | get_interface () const |
Acquires a const interface from another. More... | |
virtual IInterface * | get_interface (const Uuid &interface_id)=0 |
Acquires a mutable interface from another. More... | |
template<class T> | |
T * | get_interface () |
Acquires a mutable interface from another. More... | |
virtual Uuid | get_iid () const =0 |
Returns the interface ID of the most derived interface. More... | |
Static Public Attributes | |
static const mi::Uint8 | LOCAL_SCOPE = 255 |
Symbolic privacy level for the privacy level of the scope of this transaction. More... | |
Additional Inherited Members | |
Public Types inherited from mi::base::Interface_declare< 0x6ca1f0c2, ... > | |
using | Self = Interface_declare< id1, ... > |
Own type. More... | |
using | IID = Uuid_t< id1, ... > |
Declares the interface ID (IID) of this interface. More... | |
Public Types inherited from mi::base::IInterface | |
using | IID = Uuid_t<0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0> |
Declares the interface ID (IID) of this interface. More... | |
Static Public Member Functions inherited from mi::base::Interface_declare< 0x6ca1f0c2, ... > | |
static bool | compare_iid (const Uuid &iid) |
Compares the interface ID iid against the interface ID of this interface and of its ancestors. More... | |
Static Public Member Functions inherited from mi::base::IInterface | |
static bool | compare_iid (const Uuid &iid) |
Compares the interface ID iid against the interface ID of this interface. More... | |
A transaction provides a consistent view on the database.
This view on the database is isolated from changes by other (parallel) transactions. Eventually, each transaction must be either committed or aborted, i.e., all changes become either atomically visible to transactions started afterwards, or not at all.
Transactions are associated with a scope of the database and can be created with mi::neuraylib::IScope::create_transaction().
Transactions are not thread-safe. If you use a particular transaction from multiple threads, then you have to serialize all transaction uses. This does not only apply to methods of mi::neuraylib::ITransaction, but all methods that implicitly use the transaction. For example, such a use can happen by methods of DB elements returned from access() or edit() calls, or by objects returned from factories taking the transaction as an argument, like mi::neuraylib::IMdl_factory::create_module_builder().
Access to database elements is provided by access() (read-only) and edit() (for modification). The interface pointers returned by these methods must be released when you are done, in particular before the transaction is committed or aborted.
If the same database element is edited in multiple overlapping transactions, the changes from the transaction created last survive, independent of the order in which the transactions are committed.
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pure virtual |
Aborts the transaction.
Note that an abort() implicitly closes the transaction. A closed transaction does not allow any future operations and needs to be released.
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inline |
Retrieves an element from the database.
The database searches for the most recent version of the named DB element visible for the current transaction. That version will be returned.
This templated member function is a wrapper of the non-template variant for the user's convenience. It eliminates the need to call mi::base::IInterface::get_interface(const Uuid&) on the returned pointer, since the return type already is a const pointer to the type T
specified as template parameter.
name | The name of the element to retrieve. |
T | The interface type of the element to retrieve. |
nullptr
if name
is invalid, no DB element with that name exists, the transaction is already closed, or the element is not of type T
.
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pure virtual |
Retrieves an element from the database.
The database searches for the most recent version of the named DB element visible for the current transaction. That version will be returned.
name | The name of the element to retrieve. |
nullptr
if name
is invalid, no DB element with that name exists, or the transaction is already closed.
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pure virtual |
Commits the transaction.
Note that a commit() implicitly closes the transaction. A closed transaction does not allow any future operations and needs to be released.
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pure virtual |
Creates a copy of a database element.
Note that DB elements of type mi::neuraylib::IModule and mi::neuraylib::IFunction_definition can not be copied.
source | The name of the element to be copied. |
target | The desired name of the copy. |
privacy | The desired privacy level of the copy (in the range from 0 to the privacy level of the scope of this transaction). In addition, the constant LOCAL_SCOPE can be used as a shortcut to indicate the privacy level of the scope of this transaction without supplying the actual value itself. |
nullptr
).source
visible in this transaction.name
and overwriting elements of that type is not supported. This applies to elements of type mi::neuraylib::IModule and mi::neuraylib::IFunction_definition. It also applies to elements of type mi::neuraylib::IFunction_call that are used as defaults in an mi::neuraylib::IFunction_definition.
|
inline |
Creates an object of the type T
.
Objects created with this method are typically Types and Scene elements. Note that most types can also be created via the API component mi::neuraylib::IFactory which does not require the context of a transaction.
This method can not be used to create MDL modules, definitions, or function calls. To create instances of mi::neuraylib::IFunction_call, use the method mi::neuraylib::IFunction_definition::create_function_call().
The created object will be initialized in a manner dependent upon the passed type name. Each class has its own policy on initialization. So, one should not make any assumptions on the values of the various class members.
Note that there are two versions of this templated member function, one that takes no arguments, and another one that takes one or three arguments (the type name, and two optional arguments passed to the constructor or factory). The version with no arguments can only be used to create a subset of supported types derived from mi::IData: it supports only those types where the type name can be deduced from the template parameter, i.e., it does not support arrays, structures, maps, and pointers. The version with one or three arguments can be used to create any type (but requires the type name as parameter, which is redundant for many types). Attempts to use the version with no arguments with a template parameter where the type name can not be deduced results in compiler errors.
This templated member function is a wrapper of the non-template variant for the user's convenience. It eliminates the need to call mi::base::IInterface::get_interface(const Uuid&) on the returned pointer, since the return type already is a pointer to the type T
specified as template parameter.
T | The interface type of the class to create. |
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inline |
Creates an object of the type type_name
.
Objects created with this method are typically Types and Scene elements. Note that most types can also be created via the API component mi::neuraylib::IFactory which does not require the context of a transaction.
This method can not be used to create MDL modules, definitions, or function calls. To create instances of mi::neuraylib::IFunction_call, use the method mi::neuraylib::IFunction_definition::create_function_call().
The created object will be initialized in a manner dependent upon the passed type name. Each class has its own policy on initialization. So, one should not make any assumptions on the values of the various class members.
Note that there are two versions of this templated member function, one that takes no arguments, and another one that takes one or three arguments (the type name, and two optional arguments passed to the constructor or factory). The version with no arguments can only be used to create a subset of supported types derived from mi::IData: it supports only those types where the type name can be deduced from the template parameter, i.e., it does not support arrays, structures, maps, and pointers. The version with one or three arguments can be used to create any type (but requires the type name as parameter, which is redundant for many types). Attempts to use the version with no arguments with a template parameter where the type name can not be deduced results in compiler errors.
This templated member function is a wrapper of the non-template variant for the user's convenience. It eliminates the need to call mi::base::IInterface::get_interface(const Uuid&) on the returned pointer, since the return type already is a pointer to the type T
specified as template parameter.
type_name | The type name of the object to create. See Types for possible type names. In addition, Scene elements can be created by passing the name of the requested interfaces without namespace qualifiers and the leading "I" , e.g., "Image" for mi::neuraylib::IImage. Note that you can not create instances of mi::neuraylib::IAttribute_set or mi::neuraylib::IScene_element, only instances of the derived interfaces. |
argc | The number of elements in argv . Passed to the constructor of factory of the object to create. |
argv | The array of arguments passed to the constructor. Passed to the constructor of factory of the object to create. |
T | The interface type of the class to create. |
nullptr
if type_name
is invalid (nullptr
), not a valid type name, or does not create an object of type T
.
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pure virtual |
Creates an object of the type type_name
.
Objects created with this method are typically Types and Scene elements. Note that most types can also be created via the API component mi::neuraylib::IFactory which does not require the context of a transaction.
This method can not be used to create MDL modules, definitions, or function calls. To create instances of mi::neuraylib::IFunction_call, use the method mi::neuraylib::IFunction_definition::create_function_call().
The created object will be initialized in a manner dependent upon the passed type name. Each class has its own policy on initialization. So, one should not make any assumptions on the values of the various class members.
type_name | The type name of the object to create. See Types for possible type names. In addition, Scene elements can be created by passing the name of the requested interfaces without namespace qualifiers and the leading "I" , e.g., "Image" for mi::neuraylib::IImage. Note that you can not create instances of mi::neuraylib::IAttribute_set or mi::neuraylib::IScene_element, only instances of the derived interfaces. |
argc | The number of elements in argv . Passed to the constructor of factory of the object to create. |
argv | The array of arguments passed to the constructor. Passed to the constructor of factory of the object to create. |
nullptr
if type_name
is invalid (nullptr
) or not a valid type name.
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inline |
Retrieves an element from the database and returns it ready for editing.
The database searches for the most recent version of the named database element visible for the current transaction. It will then make a copy of that version and return the copy. The edited DB element will be committed to the database automatically, when the obtained interface is released. It is neither necessary nor possible to store the edited element manually in the database using the store() method.
This templated member function is a wrapper of the non-template variant for the user's convenience. It eliminates the need to call mi::base::IInterface::get_interface(const Uuid&) on the returned pointer, since the return type already is a pointer to the type T
specified as template parameter.
name | The name of the element to retrieve. |
T | The interface type of the element to retrieve. no DB element with that name exists, the transaction is already closed, or the element is not of type T . |
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pure virtual |
Retrieves an element from the database and returns it ready for editing.
The database searches for the most recent version of the named DB element visible for the current transaction. It will then make a copy of that version and return the copy. The edited DB element will be committed to the database automatically, when the obtained interface is released. It is neither necessary nor possible to store the edited element manually in the database using the store() method.
name | The name of the element to retrieve. |
nullptr
if name
is invalid, no DB element with that name exists, or the transaction is already closed.
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pure virtual |
Returns the ID of this transaction.
The transaction ID is of most use when debugging an application as the value returned allows one to correlate log messages and admin HTTP server output with the API actions.
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pure virtual |
Returns the privacy level of the element with the name name
.
name | The name of the element. |
nullptr
).name
visible in this transaction.
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pure virtual |
Returns the scope of this transaction.
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pure virtual |
Returns the time stamp describing the current "time".
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pure virtual |
Returns the time stamp of the last change of a database element.
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pure virtual |
Checks whether an element has been stored or changed in the database since a given time stamp.
time_stamp
should not stem from another concurrent transaction. Such changes will never be visible in this transaction, but the method might still return true
depending on the start order of the two transactions.element | The name of the element. |
time_stamp | The time stamp obtained from get_time_stamp() or get_time_stamp(const char*)const. |
true
if the element has been stored or changed since the time stamp (or if element
or time_stamp
is invalid, or there is no element with that name), false
otherwise.
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pure virtual |
Indicates whether the transaction is open.
true
if the transaction is still open, or false
if the transaction is closed, i.e., it has been committed or aborted.
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pure virtual |
Returns scene elements of a subgraph originating at a given scene element.
The method iterates over all elements of a subgraph originating at the given scene element and returns their names. Optionally, the results can be filtered by a regular expression for the element names and a list for type names.
Note that the runtime of the method depends on the number of elements in the subgraph. It might be expensive to call this method for large subgraphs.
The returned scene elements are in such an order that all elements referenced by a given element are listed before that element ("before" in the sense of "using smaller array indices").
root_element | The root of the subgraph to traverse. |
name_pattern | An extended regular expression that acts as filter on the names of returned scene elements (see [OGBS7]). The regular expression is matched to any part of the scene element name, not just to the entire scene element name. The value nullptr is handled as ".*" . |
type_names | A list of type names that acts as filter on the names of returned scene elements. Only scene elements with a matching type name pass the filter. The value nullptr lets all scene elements pass the filter irrespective of their type name. |
nullptr
in case of an invalid root element name or an invalid regular expression.
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pure virtual |
Returns the name of a database element.
db_element | The DB element. |
nullptr
if db_element
is invalid (nullptr
), the object is not in the database, or the transaction is already closed.
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pure virtual |
Marks the element with the name name
for removal from the database.
The purpose of global removals is to mark all versions of a database element for garbage collection. Such a marker has no effect while the element is still referenced (in any scope) by other elements or while the transaction where the removal request was made is still open. When these conditions do no longer apply, the element becomes eligible for garbage collection and must no longer be used in any way. There is no guarantee when the garbage collection will actually remove the element.
This implies that a remove() call might actually remove an element that was stored later under the same name. This can potentially lead to invalid tag accesses. Those cases can be avoided by using mi::neuraylib::IDatabase::garbage_collection() after a transaction was committed and before starting the next one to force garbage collection of all possible elements.
The purpose of local removals is to undo the effects of an earlier localization via mi::neuraylib::ITransaction::copy(). A local removal request requires that the element exists in the scope of the transaction, and at least one more version of that element exists in one of the parent scopes. The effect of a local removal request is to immediately hide the version the scope of the transaction (the local copy), and to make the next version in one of the parent scopes accessible from the very same transaction. The hidden local copy will be lazily removed by the garbage collection of the DB. There is no guarantee when this will happen.
name | The name of the element in the database to mark for removal. |
only_localized | false for global removals (the default) or true for local removals. The flag is ignored in favor of global removals if the transaction belongs to the global scope. |
name
visible in this transaction. For local removals: there is no DB element named name
in the scope of this transaction or there is no version of that DB element in one of the parent scopes.nullptr
).
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pure virtual |
Stores the element db_element
in the database under the name name
and with the privacy level privacy
.
After a successful store operation the passed interface pointer must no longer be used, except for releasing it. This is due to the fact that after a store() the database retains ownership of the stored data. You can obtain the stored version from the database using the access() or edit() methods.
db_element | The mi::base::IInterface to store. |
name | The name under which to store db_element . If there exists already a DB element with that name then it will be overwritten |
privacy | The privacy level under which to store db_element (in the range from 0 to the privacy level of the scope of this transaction). In addition, the constant LOCAL_SCOPE can be used as a shortcut to indicate the privacy level of the scope of this transaction without supplying the actual value itself. |
nullptr
).db_element
is not a DB element.db_element
has already been stored previously.name
and overwriting elements of that type is not supported. This applies to elements of type mi::neuraylib::IModule and mi::neuraylib::IFunction_definition. It also applies to elements of type mi::neuraylib::IFunction_call that are used as defaults in an mi::neuraylib::IFunction_definition.
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static |
Symbolic privacy level for the privacy level of the scope of this transaction.
This symbolic constant can be passed to store() and copy() to indicate the privacy level of the scope of this transaction. It has the same affect as passing the result of mi::neuraylib::IScope::get_privacy_level(), but is more convenient.