The Tor Browser: storage/public/mozStorageHelper.h@b8a032363ba2 (annotated)

storage/public/mozStorageHelper.h@b8a032363ba2 (annotated)

storage/public/mozStorageHelper.h

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

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

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storage/public/mozStorageHelper.h@b8a032363ba2 (annotated)

storage/public/mozStorageHelper.h