android.database.sqlite.SQLiteClosable Maven / Gradle / Ivy
/*
* Copyright (C) 2007 The Android Open Source Project
*
* 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.
*/
/*
** Modified to support SQLite extensions by the SQLite developers:
** [email protected].
*/
package android.database.sqlite;
import java.io.Closeable;
/**
* An object created from a SQLiteDatabase that can be closed.
*
* This class implements a primitive reference counting scheme for database objects.
*/
public abstract class SQLiteClosable implements Closeable {
private int mReferenceCount = 1;
/**
* Called when the last reference to the object was released by
* a call to {@link #releaseReference()} or {@link #close()}.
*/
protected abstract void onAllReferencesReleased();
/**
* Called when the last reference to the object was released by
* a call to {@link #releaseReferenceFromContainer()}.
*
* @deprecated Do not use.
*/
@Deprecated
protected void onAllReferencesReleasedFromContainer() {
onAllReferencesReleased();
}
/**
* Acquires a reference to the object.
*
* @throws IllegalStateException if the last reference to the object has already
* been released.
*/
public void acquireReference() {
synchronized(this) {
if (mReferenceCount <= 0) {
throw new IllegalStateException(
"attempt to re-open an already-closed object: " + this);
}
mReferenceCount++;
}
}
/**
* Releases a reference to the object, closing the object if the last reference
* was released.
*
* @see #onAllReferencesReleased()
*/
public void releaseReference() {
boolean refCountIsZero = false;
synchronized(this) {
refCountIsZero = --mReferenceCount == 0;
}
if (refCountIsZero) {
onAllReferencesReleased();
}
}
/**
* Releases a reference to the object that was owned by the container of the object,
* closing the object if the last reference was released.
*
* @see #onAllReferencesReleasedFromContainer()
* @deprecated Do not use.
*/
@Deprecated
public void releaseReferenceFromContainer() {
boolean refCountIsZero = false;
synchronized(this) {
refCountIsZero = --mReferenceCount == 0;
}
if (refCountIsZero) {
onAllReferencesReleasedFromContainer();
}
}
/**
* Releases a reference to the object, closing the object if the last reference
* was released.
*
* Calling this method is equivalent to calling {@link #releaseReference}.
*
* @see #releaseReference()
* @see #onAllReferencesReleased()
*/
public void close() {
releaseReference();
}
}