michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef MOZSTORAGEHELPER_H
michael@0: #define MOZSTORAGEHELPER_H
michael@0: 
michael@0: #include "nsAutoPtr.h"
michael@0: 
michael@0: #include "mozIStorageAsyncConnection.h"
michael@0: #include "mozIStorageConnection.h"
michael@0: #include "mozIStorageStatement.h"
michael@0: #include "nsError.h"
michael@0: 
michael@0: /**
michael@0:  * This class wraps a transaction inside a given C++ scope, guaranteeing that
michael@0:  * the transaction will be completed even if you have an exception or
michael@0:  * return early.
michael@0:  *
michael@0:  * aCommitOnComplete controls whether the transaction is committed or rolled
michael@0:  * back when it goes out of scope. A common use is to create an instance with
michael@0:  * commitOnComplete = FALSE (rollback), then call Commit on this object manually
michael@0:  * when your function completes successfully.
michael@0:  *
michael@0:  * Note that nested transactions are not supported by sqlite, so if a transaction
michael@0:  * is already in progress, this object does nothing. Note that in this case,
michael@0:  * you may not get the transaction type you ask for, and you won't be able
michael@0:  * to rollback.
michael@0:  *
michael@0:  * Note: This class is templatized to be also usable with internal data
michael@0:  * structures. External users of this class should generally use
michael@0:  * |mozStorageTransaction| instead.
michael@0:  */
michael@0: template<typename T, typename U>
michael@0: class mozStorageTransactionBase
michael@0: {
michael@0: public:
michael@0:   mozStorageTransactionBase(T* aConnection,
michael@0:                             bool aCommitOnComplete,
michael@0:                             int32_t aType = mozIStorageConnection::TRANSACTION_DEFERRED)
michael@0:     : mConnection(aConnection),
michael@0:       mHasTransaction(false),
michael@0:       mCommitOnComplete(aCommitOnComplete),
michael@0:       mCompleted(false)
michael@0:   {
michael@0:     // We won't try to get a transaction if one is already in progress.
michael@0:     if (mConnection)
michael@0:       mHasTransaction = NS_SUCCEEDED(mConnection->BeginTransactionAs(aType));
michael@0:   }
michael@0:   ~mozStorageTransactionBase()
michael@0:   {
michael@0:     if (mConnection && mHasTransaction && ! mCompleted) {
michael@0:       if (mCommitOnComplete)
michael@0:         mConnection->CommitTransaction();
michael@0:       else
michael@0:         mConnection->RollbackTransaction();
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Commits the transaction if one is in progress. If one is not in progress,
michael@0:    * this is a NOP since the actual owner of the transaction outside of our
michael@0:    * scope is in charge of finally comitting or rolling back the transaction.
michael@0:    */
michael@0:   nsresult Commit()
michael@0:   {
michael@0:     if (!mConnection || mCompleted)
michael@0:       return NS_OK; // no connection, or already done
michael@0:     mCompleted = true;
michael@0:     if (! mHasTransaction)
michael@0:       return NS_OK; // transaction not ours, ignore
michael@0:     nsresult rv = mConnection->CommitTransaction();
michael@0:     if (NS_SUCCEEDED(rv))
michael@0:       mHasTransaction = false;
michael@0: 
michael@0:     return rv;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Rolls back the transaction in progress. You should only call this function
michael@0:    * if this object has a real transaction (HasTransaction() = true) because
michael@0:    * otherwise, there is no transaction to roll back.
michael@0:    */
michael@0:   nsresult Rollback()
michael@0:   {
michael@0:     if (!mConnection || mCompleted)
michael@0:       return NS_OK; // no connection, or already done
michael@0:     mCompleted = true;
michael@0:     if (! mHasTransaction)
michael@0:       return NS_ERROR_FAILURE;
michael@0: 
michael@0:     // It is possible that a rollback will return busy, so we busy wait...
michael@0:     nsresult rv = NS_OK;
michael@0:     do {
michael@0:       rv = mConnection->RollbackTransaction();
michael@0:       if (rv == NS_ERROR_STORAGE_BUSY)
michael@0:         (void)PR_Sleep(PR_INTERVAL_NO_WAIT);
michael@0:     } while (rv == NS_ERROR_STORAGE_BUSY);
michael@0: 
michael@0:     if (NS_SUCCEEDED(rv))
michael@0:       mHasTransaction = false;
michael@0: 
michael@0:     return rv;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Returns whether this object wraps a real transaction. False means that
michael@0:    * this object doesn't do anything because there was already a transaction in
michael@0:    * progress when it was created.
michael@0:    */
michael@0:   bool HasTransaction()
michael@0:   {
michael@0:     return mHasTransaction;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * This sets the default action (commit or rollback) when this object goes
michael@0:    * out of scope.
michael@0:    */
michael@0:   void SetDefaultAction(bool aCommitOnComplete)
michael@0:   {
michael@0:     mCommitOnComplete = aCommitOnComplete;
michael@0:   }
michael@0: 
michael@0: protected:
michael@0:   U mConnection;
michael@0:   bool mHasTransaction;
michael@0:   bool mCommitOnComplete;
michael@0:   bool mCompleted;
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * An instance of the mozStorageTransaction<> family dedicated
michael@0:  * to |mozIStorageConnection|.
michael@0:  */
michael@0: typedef mozStorageTransactionBase<mozIStorageConnection,
michael@0:                                   nsCOMPtr<mozIStorageConnection> >
michael@0: mozStorageTransaction;
michael@0: 
michael@0: 
michael@0: 
michael@0: /**
michael@0:  * This class wraps a statement so that it is guaraneed to be reset when
michael@0:  * this object goes out of scope.
michael@0:  *
michael@0:  * Note that this always just resets the statement. If the statement doesn't
michael@0:  * need resetting, the reset operation is inexpensive.
michael@0:  */
michael@0: class MOZ_STACK_CLASS mozStorageStatementScoper
michael@0: {
michael@0: public:
michael@0:   mozStorageStatementScoper(mozIStorageStatement* aStatement)
michael@0:       : mStatement(aStatement)
michael@0:   {
michael@0:   }
michael@0:   ~mozStorageStatementScoper()
michael@0:   {
michael@0:     if (mStatement)
michael@0:       mStatement->Reset();
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Call this to make the statement not reset. You might do this if you know
michael@0:    * that the statement has been reset.
michael@0:    */
michael@0:   void Abandon()
michael@0:   {
michael@0:     mStatement = nullptr;
michael@0:   }
michael@0: 
michael@0: protected:
michael@0:   nsCOMPtr<mozIStorageStatement> mStatement;
michael@0: };
michael@0: 
michael@0: // Use this to make queries uniquely identifiable in telemetry
michael@0: // statistics, especially PRAGMAs.  We don't include __LINE__ so that
michael@0: // queries are stable in the face of source code changes.
michael@0: #define MOZ_STORAGE_UNIQUIFY_QUERY_STR "/* " __FILE__ " */ "
michael@0: 
michael@0: #endif /* MOZSTORAGEHELPER_H */