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/*
* ContractController.java May 2004
*
* Copyright (C) 2004, Niall Gallagher <niallg@users.sf.net>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package org.simpleframework.common.lease;
import org.simpleframework.common.lease.LeaseException;
/**
* The <code>ContractController</code> forms the interface to the
* lease management system. There are two actions permitted for
* leased resources, these are lease issue and lease renewal. When
* the lease is first issued it is scheduled for the contract
* duration. Once issued the lease can be renewed with another
* duration, which can be less than the previous duration used.
*
* @author Niall Gallagher
*
* @see org.simpleframework.common.lease.ContractMaintainer
*/
interface ContractController<T> {
/**
* This method will establish a contract for the given duration.
* If the contract duration expires before it is renewed then a
* notification is sent, typically to a <code>Cleaner</code> to
* to signify that the resource should be released. The contract
* can also be cancelled by providing a zero length duration.
*
* @param contract a contract representing a leased resource
*
* @exception Exception if the lease could not be done
*/
void issue(Contract<T> contract) throws LeaseException;
/**
* This ensures that the contract is renewed for the duration on
* the contract, which may have changed since it was issued or
* last renewed. If the duration on the contract has changed this
* will insure the previous contract duration is revoked and the
* new duration is used to maintain the leased resource.
*
* @param contract a contract representing a leased resource
*
* @exception Exception if the lease could not be done
*/
void renew(Contract<T> contract) throws LeaseException;
/**
* This will cancel the lease and release the resource. This
* has the same effect as the <code>renew</code> method with
* a zero length duration. Once this has been called the
* <code>Cleaner</code> used should be notified immediately.
* If the lease has already expired this throws an exception.
*
* @param contract a contract representing a leased resource
*
* @exception Exception if the expiry has been passed
*/
void cancel(Contract<T> contract) throws LeaseException;
/**
* This method is used to cancel all outstanding leases and to
* close the controller. Closing the controller ensures that it
* can no longer be used to issue or renew leases. All resources
* occupied by the controller are released, including threads,
* memory, and all leased resources occupied by the instance.
*/
void close();
}
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