NAME¶
UR::Context::Transaction - API for software transactions
SYNOPSIS¶
my $o = Some::Obj->create(foo => 1);
print "o's foo is ",$o->foo,"\n"; # prints 1
my $t = UR::Context::Transaction->begin();
$o->foo(4);
print "In transaction, o's foo is ",$o->foo,"\n"; # prints 4
if (&should_we_commit()) {
$t->commit();
print "Transaction committed, o's foo is ",$o->foo,"\n"; # prints 4
} else {
$t->rollback();
print "Transaction rollback, o's foo is ",$o->foo,"\n"; # prints 1
}
DESCRIPTION¶
UR::Context::Transaction instances represent in-memory transactions as a diff of
the contents of the object cache in the Process context. Transactions are
nestable. Their instances exist in the object cache and are subject to the
same scoping rules as other UR-based objects, meaning that they do not
disappear mearly because the lexical variable they're assigned to goes out of
scope. They must be explicitly disposed of via the commit or rollback methods.
INHERITANCE¶
UR::Context::Transaction is a subclass of UR::Context
CONSTRUCTOR¶
- begin
-
$t = UR::Context::Transaction->begin();
Creates a new software transaction context to track changes to UR-based
objects. As all activity to objects occurs in some kind of transaction
context, the newly created transaction exists within whatever context was
current before the call to begin().
METHODS¶
- commit
-
$t->commit();
Causes all objects with changes to save those changes back to the underlying
context.
- rollback
-
$t->rollback();
Causes all objects with changes to have those changes reverted to their
state when the transaction began. Classes with properties whose
meta-property is_transactional => 0 are not tracked within a
transaction and will not be reverted.
- delete
-
$t->delete();
delete() is a synomym for rollback
- has_changes
-
$bool = $t->has_changes();
Returns true if any UR-based objects have changes within the
transaction.
- get_changes
-
@changes = $t->get_changes();
Return a list or UR::Change objects representing changes within the
transaction.
CLASS METHODS¶
- eval
-
UR::Context::Transaction::eval BLOCK
Executes the BLOCK (with no arguments) wrapped by a software transaction and
a CORE::eval. If the BLOCK dies then the exception is caught and the
software transaction is rolled back.
- do
-
UR::Context::Transaction::do BLOCK
Executes the BLOCK (with no arguments) wrapped by a software transaction and
a CORE::eval. If the BLOCK returns a true value and does not die then the
software transaction is committed. If the BLOCK returns false or dies then
the software transaction is rolled back.
If the BLOCK throws an exception, it will be caught, the software
transaction rolled back, and the exception will be re-thrown with
die().
SEE ALSO¶
UR::Context