| /* |
| * Copyright (C) 2009 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; |
| |
| import android.util.Log; |
| |
| /** |
| * This class encapsulates compilation of sql statement and release of the compiled statement obj. |
| * Once a sql statement is compiled, it is cached in {@link SQLiteDatabase} |
| * and it is released in one of the 2 following ways |
| * 1. when {@link SQLiteDatabase} object is closed. |
| * 2. dalvikVM wants to reclaim some memory and releases it from the cache in |
| * {@link SQLiteDatabase}. |
| */ |
| /* package */ class SQLiteCompiledSql { |
| |
| private static final String TAG = "SQLiteCompiledSql"; |
| |
| /** The database this program is compiled against. */ |
| /* package */ SQLiteDatabase mDatabase; |
| |
| /** |
| * Native linkage, do not modify. This comes from the database. |
| */ |
| /* package */ int nHandle = 0; |
| |
| /** |
| * Native linkage, do not modify. When non-0 this holds a reference to a valid |
| * sqlite3_statement object. It is only updated by the native code, but may be |
| * checked in this class when the database lock is held to determine if there |
| * is a valid native-side program or not. |
| */ |
| /* package */ int nStatement = 0; |
| |
| /** the following are for debugging purposes */ |
| private String mSqlStmt = null; |
| private Throwable mStackTrace = null; |
| |
| /** when in cache and is in use, this member is set */ |
| private boolean mInUse = false; |
| |
| /* package */ SQLiteCompiledSql(SQLiteDatabase db, String sql) { |
| mDatabase = db; |
| mSqlStmt = sql; |
| mStackTrace = new Exception().fillInStackTrace(); |
| this.nHandle = db.mNativeHandle; |
| compile(sql, true); |
| } |
| |
| /** |
| * Compiles the given SQL into a SQLite byte code program using sqlite3_prepare_v2(). If |
| * this method has been called previously without a call to close and forCompilation is set |
| * to false the previous compilation will be used. Setting forceCompilation to true will |
| * always re-compile the program and should be done if you pass differing SQL strings to this |
| * method. |
| * |
| * <P>Note: this method acquires the database lock.</P> |
| * |
| * @param sql the SQL string to compile |
| * @param forceCompilation forces the SQL to be recompiled in the event that there is an |
| * existing compiled SQL program already around |
| */ |
| private void compile(String sql, boolean forceCompilation) { |
| // Only compile if we don't have a valid statement already or the caller has |
| // explicitly requested a recompile. |
| if (forceCompilation) { |
| mDatabase.lock(); |
| try { |
| // Note that the native_compile() takes care of destroying any previously |
| // existing programs before it compiles. |
| native_compile(sql); |
| } finally { |
| mDatabase.unlock(); |
| } |
| } |
| } |
| |
| /* package */ void releaseSqlStatement() { |
| // Note that native_finalize() checks to make sure that nStatement is |
| // non-null before destroying it. |
| if (nStatement != 0) { |
| try { |
| mDatabase.lock(); |
| native_finalize(); |
| nStatement = 0; |
| } finally { |
| mDatabase.unlock(); |
| } |
| } |
| } |
| |
| /** |
| * returns true if acquire() succeeds. false otherwise. |
| */ |
| /* package */ synchronized boolean acquire() { |
| if (mInUse) { |
| // someone already has acquired it. |
| return false; |
| } |
| mInUse = true; |
| return true; |
| } |
| |
| /* package */ synchronized void release() { |
| mInUse = false; |
| } |
| |
| /** |
| * Make sure that the native resource is cleaned up. |
| */ |
| @Override |
| protected void finalize() throws Throwable { |
| try { |
| if (nStatement == 0) return; |
| // finalizer should NEVER get called |
| Log.w(TAG, "finalizer should never be called. sql: " + mSqlStmt, mStackTrace); |
| releaseSqlStatement(); |
| } finally { |
| super.finalize(); |
| } |
| } |
| |
| /** |
| * Compiles SQL into a SQLite program. |
| * |
| * <P>The database lock must be held when calling this method. |
| * @param sql The SQL to compile. |
| */ |
| private final native void native_compile(String sql); |
| private final native void native_finalize(); |
| } |