gecko-dev/js/ipc/JavaScriptParent.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=4 sw=2 et tw=80:
*
* 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_jsipc_JavaScriptParent__
#define mozilla_jsipc_JavaScriptParent__
#include "JavaScriptBase.h"
#include "mozilla/jsipc/PJavaScriptParent.h"
namespace mozilla {
namespace jsipc {
class JavaScriptParent : public JavaScriptBase<PJavaScriptParent> {
public:
Bug 1481998 - Make mozilla::Hash{Map,Set}'s entry storage allocation lazy. r=luke,sfink Entry storage allocation now occurs on the first lookupForAdd()/put()/putNew(). This removes the need for init() and initialized(), and matches how PLDHashTable/nsTHashtable work. It also removes the need for init() functions in a lot of types that are built on top of mozilla::Hash{Map,Set}. Pros: - No need for init() calls and subsequent checks. - No memory allocated for empty tables, which are not that uncommon. Cons: - An extra branch in lookup() and lookupForAdd(), but not in put()/putNew(), because the existing checkOverloaded() can handle it. Specifics: - Construction now can take a length parameter. - init() is removed. Explicit length-setting, when necessary, now occurs in the constructors. - initialized() is removed. - capacity() now returns zero when the entry storage is absent. - lookupForAdd() is no longer `const`, because it can instantiate the storage, which requires modifications. - lookupForAdd() can now return an invalid AddPtr in two cases: - old: hashing failure (due to OOM in the hasher) - new: OOM while instantiating entry storage The existing failure handling paths for the old case work for the new case. - clear(), finish(), and clearAndShrink() are replaced by clear(), compact(), and reserve(). The old compactIfUnderloaded() is also removed. - Capacity computation code is now in its own functions, bestCapacity() and hashShift(). setTableSizeLog2() is removed. - uint32_t is used throughout for capacities, instead of size_t, for consistency with other similar values. - changeTableSize() now takes a capacity instead of a deltaLog2, and it can now handle !mTable. Measurements: - Total source code size is reduced by over 900 lines. Also, lots of existing lines got shorter (i.e. two checks were reduced to one). - Executable size barely changed, down by 2 KiB on Linux64. The extra branches are compensated for by the lack of init() calls. - Speed changed negligibly. The instruction count for Bench_Cpp_MozHash increased from 2.84 billion to 2.89 billion but any execution time change was well below noise.
2018-08-10 08:00:29 +00:00
JavaScriptParent();
virtual ~JavaScriptParent();
void trace(JSTracer* trc);
void drop(JSObject* obj);
bool allowMessage(JSContext* cx) override;
void afterProcessTask();
protected:
virtual bool isParent() override { return true; }
virtual JSObject* scopeForTargetObjects() override;
private:
uint64_t savedNextCPOWNumber_;
};
} // namespace jsipc
} // namespace mozilla
#endif // mozilla_jsipc_JavaScriptWrapper_h__