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3cfadec356
Rather than attempting to determine when the Once policy StaticPrefs should be set we initialize them when one of the getter gets called. They become immutable after that. In a future change we will prevent those values to ever be changed once they have been initialized. Differential Revision: https://phabricator.services.mozilla.com/D33440 --HG-- extra : moz-landing-system : lando
127 lines
4.2 KiB
C++
127 lines
4.2 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_StaticPrefs_h
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#define mozilla_StaticPrefs_h
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#include "gfxPlatform.h"
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#include "mozilla/Assertions.h"
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#include "mozilla/Atomics.h"
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#include "mozilla/TypeTraits.h"
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#include "mozilla/gfx/LoggingConstants.h"
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#include "MainThreadUtils.h"
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#include <atomic>
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#include <cmath> // for M_PI
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namespace mozilla {
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class SharedPrefMapBuilder;
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// These typedefs are for use within StaticPrefList.h.
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typedef const char* String;
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typedef Atomic<bool, Relaxed> RelaxedAtomicBool;
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typedef Atomic<bool, ReleaseAcquire> ReleaseAcquireAtomicBool;
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typedef Atomic<bool, SequentiallyConsistent> SequentiallyConsistentAtomicBool;
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typedef Atomic<int32_t, Relaxed> RelaxedAtomicInt32;
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typedef Atomic<int32_t, ReleaseAcquire> ReleaseAcquireAtomicInt32;
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typedef Atomic<int32_t, SequentiallyConsistent>
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SequentiallyConsistentAtomicInt32;
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typedef Atomic<uint32_t, Relaxed> RelaxedAtomicUint32;
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typedef Atomic<uint32_t, ReleaseAcquire> ReleaseAcquireAtomicUint32;
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typedef Atomic<uint32_t, SequentiallyConsistent>
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SequentiallyConsistentAtomicUint32;
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// Atomic<float> currently doesn't work (see bug 1552086), once this tast has
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// been completed we will be able to use Atomic<float> instead.
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typedef std::atomic<float> AtomicFloat;
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template <typename T>
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struct StripAtomicImpl {
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typedef T Type;
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};
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template <typename T, MemoryOrdering Order>
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struct StripAtomicImpl<Atomic<T, Order>> {
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typedef T Type;
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};
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template <typename T>
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struct StripAtomicImpl<std::atomic<T>> {
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typedef T Type;
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};
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template <typename T>
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using StripAtomic = typename StripAtomicImpl<T>::Type;
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template <typename T>
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struct IsAtomic : FalseType {};
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template <typename T, MemoryOrdering Order>
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struct IsAtomic<Atomic<T, Order>> : TrueType {};
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template <typename T>
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struct IsAtomic<std::atomic<T>> : TrueType {};
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class StaticPrefs {
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// For a VarCache pref like this:
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//
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// VARCACHE_PREF("my.varcache", my_varcache, int32_t, 99)
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//
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// we generate a static variable declaration, a getter and a setter
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// definition. A StaticPref can be set by using the corresponding Set method.
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// For example, if the accessor is Foo() then calling SetFoo(...) will update
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// the preference and also change the return value of subsequent Foo() calls.
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// Changing StaticPrefs is only allowed on the parent process' main thread.
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//
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// private:
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// static int32_t sVarCache_my_varcache;
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// public:
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// static int32_t my_varcache();
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// static void Setmy_varcache(int32_t aValue);
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// static const char* Getmy_varcachePrefName() { return "my.varcache"; }
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// static int32_t Getmy_varcachePrefDefault() { return 99; }
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//
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public:
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// Enums for the update policy.
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enum class UpdatePolicy {
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Skip, // Set the value to default, skip any Preferences calls.
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Once, // Evaluate the preference once, unchanged during the session.
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Live // Evaluate the preference and set callback so it stays current/live.
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};
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#define PREF(str, cpp_type, default_value)
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#define VARCACHE_PREF(policy, str, id, cpp_type, default_value) \
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private: \
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static cpp_type sVarCache_##id; \
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\
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public: \
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static StripAtomic<cpp_type> id(); \
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static void Set##id(StripAtomic<cpp_type> aValue); \
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static const char* Get##id##PrefName() { return str; } \
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static StripAtomic<cpp_type> Get##id##PrefDefault() { return default_value; }
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#include "mozilla/StaticPrefList.h"
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#undef PREF
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#undef VARCACHE_PREF
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private:
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friend class Preferences;
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static void InitAll(bool aIsStartup);
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static void InitOncePrefs();
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static void InitOncePrefsFromShared();
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static void MaybeInitOncePrefs();
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static void RegisterOncePrefs(SharedPrefMapBuilder& aBuilder);
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};
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} // namespace mozilla
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#endif // mozilla_StaticPrefs_h
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