storage/mozStorageAsyncStatementJSHelper.h
author Masayuki Nakano <masayuki@d-toybox.com>
Thu, 10 Jan 2019 08:50:41 +0000
changeset 453219 99a977d519a0b78e267d3dce4afb009b8d3be769
parent 448947 6f3709b3878117466168c40affa7bca0b60cf75b
child 472056 e1993a1f09ac53cd1a04fdf6a87f8cad8e44f73e
permissions -rw-r--r--
Bug 181137 - part 8: Make ContentIteratorBase and its subclasses non-refcountable r=smaug This patch makes ContentIteratorBase, PostContentIterator, PreContentIterator and ContentSubtreeIterator classes non-refcountable because most users can create their instances in stack and such users may be in a hot path. So, we can save a lot of cost of instantiation. Unfortunately, only ScriptableContentIterator creates one of the concrete classes and needs to destroy it properly. Therefore, its EnsureContentIterator(), destructor, traverse and unlink code becomes messy. However, ScriptableContentIterator was designed for automated tests and we need to maintain it not so many times. Therefore, improvement of other users must be worthwhiler than this demerit. Differential Revision: https://phabricator.services.mozilla.com/D15928

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
 * 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 mozilla_storage_mozStorageAsyncStatementJSHelper_h_
#define mozilla_storage_mozStorageAsyncStatementJSHelper_h_

#include "nsIXPCScriptable.h"
#include "nsIXPConnect.h"

namespace mozilla {
namespace storage {

class AsyncStatement;
class AsyncStatementParams;

/**
 * A modified version of StatementJSHelper that only exposes the async-specific
 * 'params' helper.  We do not expose 'row' or 'step' as they do not apply to
 * us.
 */
class AsyncStatementJSHelper : public nsIXPCScriptable {
 public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIXPCSCRIPTABLE

 private:
  nsresult getParams(AsyncStatement *, JSContext *, JSObject *, JS::Value *);
};

/**
 * Wrapper used to clean up the references JS helpers hold to the statement.
 * For cycle-avoidance reasons they do not hold reference-counted references,
 * so it is important we do this.
 */
class AsyncStatementParamsHolder final : public nsISupports {
 public:
  NS_DECL_ISUPPORTS

  explicit AsyncStatementParamsHolder(AsyncStatementParams *aParams)
      : mParams(aParams) {}

  AsyncStatementParams *Get() const {
    MOZ_ASSERT(mParams);
    return mParams;
  }

 private:
  virtual ~AsyncStatementParamsHolder();

  RefPtr<AsyncStatementParams> mParams;
};

}  // namespace storage
}  // namespace mozilla

#endif  // mozilla_storage_mozStorageAsyncStatementJSHelper_h_