зеркало из https://github.com/mozilla/pjs.git
196 строки
6.1 KiB
C++
196 строки
6.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Storage code
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*
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* The Initial Developer of the Original Code is
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* Google Inc.
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* Portions created by the Initial Developer are Copyright (C) 2005
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Brett Wilson <brettw@gmail.com>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef MOZSTORAGEHELPER_H
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#define MOZSTORAGEHELPER_H
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#include "nsAutoPtr.h"
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#include "mozIStorageConnection.h"
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#include "mozIStorageStatement.h"
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#include "mozStorage.h"
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/**
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* This class wraps a transaction inside a given C++ scope, guaranteeing that
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* the transaction will be completed even if you have an exception or
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* return early.
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*
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* aCommitOnComplete controls whether the transaction is committed or rolled
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* back when it goes out of scope. A common use is to create an instance with
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* commitOnComplete = FALSE (rollback), then call Commit on this object manually
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* when your function completes successfully.
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*
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* Note that nested transactions are not supported by sqlite, so if a transaction
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* is already in progress, this object does nothing. Note that in this case,
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* you may not get the transaction type you ask for, and you won't be able
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* to rollback.
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*/
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class mozStorageTransaction
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{
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public:
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mozStorageTransaction(mozIStorageConnection* aConnection,
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PRBool aCommitOnComplete,
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PRInt32 aType = mozIStorageConnection::TRANSACTION_DEFERRED)
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: mConnection(aConnection),
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mHasTransaction(PR_FALSE),
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mCommitOnComplete(aCommitOnComplete),
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mCompleted(PR_FALSE)
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{
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// We won't try to get a transaction if one is already in progress.
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if (mConnection)
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mHasTransaction = NS_SUCCEEDED(mConnection->BeginTransactionAs(aType));
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}
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~mozStorageTransaction()
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{
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if (mConnection && mHasTransaction && ! mCompleted) {
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if (mCommitOnComplete)
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mConnection->CommitTransaction();
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else
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mConnection->RollbackTransaction();
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}
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}
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/**
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* Commits the transaction if one is in progress. If one is not in progress,
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* this is a NOP since the actual owner of the transaction outside of our
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* scope is in charge of finally comitting or rolling back the transaction.
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*/
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nsresult Commit()
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{
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if (!mConnection || mCompleted)
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return NS_OK; // no connection, or already done
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mCompleted = PR_TRUE;
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if (! mHasTransaction)
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return NS_OK; // transaction not ours, ignore
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nsresult rv = mConnection->CommitTransaction();
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if (NS_SUCCEEDED(rv))
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mHasTransaction = PR_FALSE;
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return rv;
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}
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/**
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* Rolls back the transaction in progress. You should only call this function
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* if this object has a real transaction (HasTransaction() = true) because
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* otherwise, there is no transaction to roll back.
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*/
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nsresult Rollback()
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{
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if (!mConnection || mCompleted)
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return NS_OK; // no connection, or already done
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mCompleted = PR_TRUE;
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if (! mHasTransaction)
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return NS_ERROR_FAILURE;
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// It is possible that a rollback will return busy, so we busy wait...
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nsresult rv = NS_OK;
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do {
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rv = mConnection->RollbackTransaction();
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if (rv == NS_ERROR_STORAGE_BUSY)
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(void)PR_Sleep(PR_INTERVAL_NO_WAIT);
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} while (rv == NS_ERROR_STORAGE_BUSY);
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if (NS_SUCCEEDED(rv))
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mHasTransaction = PR_FALSE;
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return rv;
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}
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/**
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* Returns whether this object wraps a real transaction. False means that
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* this object doesn't do anything because there was already a transaction in
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* progress when it was created.
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*/
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PRBool HasTransaction()
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{
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return mHasTransaction;
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}
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/**
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* This sets the default action (commit or rollback) when this object goes
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* out of scope.
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*/
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void SetDefaultAction(PRBool aCommitOnComplete)
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{
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mCommitOnComplete = aCommitOnComplete;
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}
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protected:
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nsCOMPtr<mozIStorageConnection> mConnection;
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PRBool mHasTransaction;
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PRBool mCommitOnComplete;
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PRBool mCompleted;
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};
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/**
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* This class wraps a statement so that it is guaraneed to be reset when
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* this object goes out of scope.
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*
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* Note that this always just resets the statement. If the statement doesn't
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* need resetting, the reset operation is inexpensive.
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*/
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class NS_STACK_CLASS mozStorageStatementScoper
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{
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public:
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mozStorageStatementScoper(mozIStorageStatement* aStatement)
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: mStatement(aStatement)
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{
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}
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~mozStorageStatementScoper()
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{
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if (mStatement)
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mStatement->Reset();
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}
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/**
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* Call this to make the statement not reset. You might do this if you know
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* that the statement has been reset.
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*/
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void Abandon()
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{
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mStatement = nsnull;
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}
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protected:
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nsCOMPtr<mozIStorageStatement> mStatement;
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};
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#endif /* MOZSTORAGEHELPER_H */
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