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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 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 vm_SharedScriptDataTableHolder_h
#define vm_SharedScriptDataTableHolder_h
#include "mozilla/Assertions.h" // MOZ_ASSERT
#include "mozilla/Maybe.h" // mozilla::Maybe
#include "threading/Mutex.h" // js::Mutex
#include "vm/SharedStencil.h" // js::SharedImmutableScriptDataTable
namespace js {
class AutoLockGlobalScriptData {
static js::Mutex mutex_;
public:
AutoLockGlobalScriptData();
~AutoLockGlobalScriptData();
};
// A class to provide an access to SharedImmutableScriptDataTable,
// with or without a mutex lock.
//
// js::globalSharedScriptDataTableHolder singleton can be used by any thread,
// and it needs a mutex lock.
//
// AutoLockGlobalScriptData lock;
// auto& table = js::globalSharedScriptDataTableHolder::get(lock);
//
// Private SharedScriptDataTableHolder instance can be created for thread-local
// storage, and it can be configured not to require a mutex lock.
//
// SharedScriptDataTableHolder holder(
// SharedScriptDataTableHolder::NeedsLock::No);
// ...
// auto& table = holder.getWithoutLock();
//
// getMaybeLocked method can be used for both type of instances.
//
// Maybe<AutoLockGlobalScriptData> lock;
// auto& table = holder.getMaybeLocked(lock);
//
// Private instance is supposed to be held by the each JSRuntime, including
// both main thread runtime and worker thread runtime, and used in for
// non-helper-thread compilation.
//
// js::globalSharedScriptDataTableHolder singleton is supposed to be used by
// all helper-thread compilation.
class SharedScriptDataTableHolder {
bool needsLock_ = true;
js::SharedImmutableScriptDataTable scriptDataTable_;
public:
enum class NeedsLock { No, Yes };
explicit SharedScriptDataTableHolder(NeedsLock needsLock = NeedsLock::Yes)
: needsLock_(needsLock == NeedsLock::Yes) {}
js::SharedImmutableScriptDataTable& get(
const js::AutoLockGlobalScriptData& lock) {
MOZ_ASSERT(needsLock_);
return scriptDataTable_;
}
js::SharedImmutableScriptDataTable& getWithoutLock() {
MOZ_ASSERT(!needsLock_);
return scriptDataTable_;
}
js::SharedImmutableScriptDataTable& getMaybeLocked(
mozilla::Maybe<js::AutoLockGlobalScriptData>& lock) {
if (needsLock_) {
lock.emplace();
}
return scriptDataTable_;
}
};
extern SharedScriptDataTableHolder globalSharedScriptDataTableHolder;
} /* namespace js */
#endif /* vm_SharedScriptDataTableHolder_h */
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