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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.database.sqlite;
     18 
     19 import android.database.CursorWindow;
     20 
     21 /**
     22  * An object created from a SQLiteDatabase that can be closed.
     23  */
     24 public abstract class SQLiteClosable {
     25     private int mReferenceCount = 1;
     26     private Object mLock = new Object();
     27 
     28     protected abstract void onAllReferencesReleased();
     29     protected void onAllReferencesReleasedFromContainer() {}
     30 
     31     public void acquireReference() {
     32         synchronized(mLock) {
     33             if (mReferenceCount <= 0) {
     34                 throw new IllegalStateException(
     35                         "attempt to re-open an already-closed object: " + getObjInfo());
     36             }
     37             mReferenceCount++;
     38         }
     39     }
     40 
     41     public void releaseReference() {
     42         synchronized(mLock) {
     43             mReferenceCount--;
     44             if (mReferenceCount == 0) {
     45                 onAllReferencesReleased();
     46             }
     47         }
     48     }
     49 
     50     public void releaseReferenceFromContainer() {
     51         synchronized(mLock) {
     52             mReferenceCount--;
     53             if (mReferenceCount == 0) {
     54                 onAllReferencesReleasedFromContainer();
     55             }
     56         }
     57     }
     58 
     59     private String getObjInfo() {
     60         StringBuilder buff = new StringBuilder();
     61         buff.append(this.getClass().getName());
     62         buff.append(" (");
     63         if (this instanceof SQLiteDatabase) {
     64             buff.append("database = ");
     65             buff.append(((SQLiteDatabase)this).getPath());
     66         } else if (this instanceof SQLiteProgram || this instanceof SQLiteStatement ||
     67                 this instanceof SQLiteQuery) {
     68             buff.append("mSql = ");
     69             buff.append(((SQLiteProgram)this).mSql);
     70         } else if (this instanceof CursorWindow) {
     71             buff.append("mStartPos = ");
     72             buff.append(((CursorWindow)this).getStartPosition());
     73         }
     74         buff.append(") ");
     75         return buff.toString();
     76     }
     77 }
     78