core/java/android/database/sqlite/SQLiteClosable.java

/*
 * 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.
 */

package android.database.sqlite;

/**
 * An object create from a SQLiteDatabase that can be closed.
 */
public abstract class SQLiteClosable {    
    private int mReferenceCount = 1;
    private Object mLock = new Object();
    protected abstract void onAllReferencesReleased();
    protected void onAllReferencesReleasedFromContainer(){}
    
    public void acquireReference() {
        synchronized(mLock) {
            if (mReferenceCount <= 0) {
                throw new IllegalStateException(
                        "attempt to acquire a reference on a close SQLiteClosable");
            }
            mReferenceCount++;     
        }
    }
    
    public void releaseReference() {
        synchronized(mLock) {
            mReferenceCount--;
            if (mReferenceCount == 0) {
                onAllReferencesReleased();
            }
        }
    }
    
    public void releaseReferenceFromContainer() {
        synchronized(mLock) {
            mReferenceCount--;
            if (mReferenceCount == 0) {
                onAllReferencesReleasedFromContainer();
            }
        }        
    }
}