Note: This class is not available with the PO_NO_THREAD_CLASSES
parse option.
AutoReadLock objects, when used along with a RWLock object, allow Qore programmers to safely acquire and release a read lock, even if exceptions are thrown or return statements are executed in the block where the AutoReadLock object is created. AutoReadLock objects are helper objects that acquire a read lock for the lifetime of the AutoReadLock object. For this reason, it is only appropriate to assign an AutoReadLock object to a local variable, so when the local variable goes out of scope, the AutoReadLock object will be deleted and the read lock will be automatically released.
For example:
our $rwl = new RWLock(); sub check_error($error) { # note that the read lock is acquired in the AutoReadLock constructor, and # the read lock will be released as soon as the block is exited below. # (with either the throw statement or the return statement) my $arl = new AutoReadLock($rwl); if ($error) throw "ERROR", "sorry, an error happened"; return "OK"; }
Table 4.856. AutoReadLock Method Overview
Method | Except? | Description |
---|---|---|
Y | Creates the AutoReadLock object based on the RWLock argument passed and immediately calls RWLock::readLock(). | |
Y | Calls RWLock::readUnlock() on the saved RWLock and destroys the AutoReadLock object. | |
Y | Throws an exception; objects of this class cannot be copied. |
Creates the AutoReadLock object based on the RWLock argument passed. The AutoReadLock object immediately calls RWLock::readLock() on the RWLock object passed, and saves it so it can be released when the AutoReadLock object is destroyed.
new AutoReadLock(rwlock_object
)
my $arl = new AutoReadLock($rwlock);
Table 4.857. Arguments for AutoReadLock::constructor()
Argument | Type | Description |
---|---|---|
| The RWLock object to manage for the lifetime of this object. |
Table 4.858. Return Values for AutoReadLock::constructor()
Return Type | Description |
---|---|
AutoReadLock Object | The new AutoReadLock object. |
Calls RWLock::readUnlock() on the saved RWLock and destroys the AutoReadLock object.
delete lvalue
delete $arl;
Throws an exception; objects of this class cannot be copied.
Table 4.859. Arguments for AutoReadLock::copy()
Argument | Type | Description |
---|---|---|
n/a | n/a | This method takes no arguments. |
Table 4.860. Return Values for AutoReadLock::copy()
Return Type | Description |
---|---|
n/a | This method returns no value because it throws an exception. |
Table 4.861. Exceptions Thrown by AutoReadLock::copy()
err | desc |
---|---|
| Objects of this class cannot be copied. |