gecko-dev/js/public/GCHashTable.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* 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 GCHashTable_h
#define GCHashTable_h
#include "js/GCPolicyAPI.h"
#include "js/HashTable.h"
#include "js/RootingAPI.h"
#include "js/SweepingAPI.h"
#include "js/TracingAPI.h"
namespace JS {
// Define a reasonable default GC policy for GC-aware Maps.
template <typename Key, typename Value>
struct DefaultMapSweepPolicy {
static bool needsSweep(Key* key, Value* value) {
return GCPolicy<Key>::needsSweep(key) || GCPolicy<Value>::needsSweep(value);
}
};
// A GCHashMap is a GC-aware HashMap, meaning that it has additional trace and
// sweep methods that know how to visit all keys and values in the table.
// HashMaps that contain GC pointers will generally want to use this GCHashMap
// specialization instead of HashMap, because this conveniently supports tracing
// keys and values, and cleaning up weak entries.
//
// GCHashMap::trace applies GCPolicy<T>::trace to each entry's key and value.
// Most types of GC pointers already have appropriate specializations of
// GCPolicy, so they should just work as keys and values. Any struct type with a
// default constructor and trace and sweep functions should work as well. If you
// need to define your own GCPolicy specialization, generic helpers can be found
// in js/public/TracingAPI.h.
//
// The MapSweepPolicy template parameter controls how the table drops entries
// when swept. GCHashMap::sweep applies MapSweepPolicy::needsSweep to each table
// entry; if it returns true, the entry is dropped. The default MapSweepPolicy
// drops the entry if either the key or value is about to be finalized,
// according to its GCPolicy<T>::needsSweep method. (This default is almost
// always fine: it's hard to imagine keeping such an entry around anyway.)
//
// Note that this HashMap only knows *how* to trace and sweep, but it does not
// itself cause tracing or sweeping to be invoked. For tracing, it must be used
// with Rooted or PersistentRooted, or barriered and traced manually. For
// sweeping, currently it requires an explicit call to <map>.sweep().
template <typename Key,
typename Value,
typename HashPolicy = js::DefaultHasher<Key>,
typename AllocPolicy = js::TempAllocPolicy,
typename MapSweepPolicy = DefaultMapSweepPolicy<Key, Value>>
class GCHashMap : public js::HashMap<Key, Value, HashPolicy, AllocPolicy>
{
using Base = js::HashMap<Key, Value, HashPolicy, AllocPolicy>;
public:
explicit GCHashMap(AllocPolicy a = AllocPolicy()) : Base(a) {}
static void trace(GCHashMap* map, JSTracer* trc) { map->trace(trc); }
void trace(JSTracer* trc) {
if (!this->initialized())
return;
for (typename Base::Enum e(*this); !e.empty(); e.popFront()) {
GCPolicy<Value>::trace(trc, &e.front().value(), "hashmap value");
GCPolicy<Key>::trace(trc, &e.front().mutableKey(), "hashmap key");
}
}
void sweep() {
if (!this->initialized())
return;
for (typename Base::Enum e(*this); !e.empty(); e.popFront()) {
if (MapSweepPolicy::needsSweep(&e.front().mutableKey(), &e.front().value()))
e.removeFront();
}
}
// GCHashMap is movable
GCHashMap(GCHashMap&& rhs) : Base(mozilla::Move(rhs)) {}
void operator=(GCHashMap&& rhs) {
MOZ_ASSERT(this != &rhs, "self-move assignment is prohibited");
Base::operator=(mozilla::Move(rhs));
}
private:
// GCHashMap is not copyable or assignable
GCHashMap(const GCHashMap& hm) = delete;
GCHashMap& operator=(const GCHashMap& hm) = delete;
};
} // namespace JS
namespace js {
// HashMap that supports rekeying.
//
// If your keys are pointers to something like JSObject that can be tenured or
// compacted, prefer to use GCHashMap with MovableCellHasher, which takes
// advantage of the Zone's stable id table to make rekeying unnecessary.
template <typename Key,
typename Value,
typename HashPolicy = DefaultHasher<Key>,
typename AllocPolicy = TempAllocPolicy,
typename MapSweepPolicy = JS::DefaultMapSweepPolicy<Key, Value>>
class GCRekeyableHashMap : public JS::GCHashMap<Key, Value, HashPolicy, AllocPolicy, MapSweepPolicy>
{
using Base = JS::GCHashMap<Key, Value, HashPolicy, AllocPolicy>;
public:
explicit GCRekeyableHashMap(AllocPolicy a = AllocPolicy()) : Base(a) {}
void sweep() {
if (!this->initialized())
return;
for (typename Base::Enum e(*this); !e.empty(); e.popFront()) {
Key key(e.front().key());
if (MapSweepPolicy::needsSweep(&key, &e.front().value()))
e.removeFront();
else if (!HashPolicy::match(key, e.front().key()))
e.rekeyFront(key);
}
}
// GCRekeyableHashMap is movable
GCRekeyableHashMap(GCRekeyableHashMap&& rhs) : Base(mozilla::Move(rhs)) {}
void operator=(GCRekeyableHashMap&& rhs) {
MOZ_ASSERT(this != &rhs, "self-move assignment is prohibited");
Base::operator=(mozilla::Move(rhs));
}
};
template <typename Outer, typename... Args>
class GCHashMapOperations
{
using Map = JS::GCHashMap<Args...>;
using Lookup = typename Map::Lookup;
const Map& map() const { return static_cast<const Outer*>(this)->get(); }
public:
using AddPtr = typename Map::AddPtr;
using Ptr = typename Map::Ptr;
using Range = typename Map::Range;
bool initialized() const { return map().initialized(); }
Ptr lookup(const Lookup& l) const { return map().lookup(l); }
AddPtr lookupForAdd(const Lookup& l) const { return map().lookupForAdd(l); }
Range all() const { return map().all(); }
bool empty() const { return map().empty(); }
uint32_t count() const { return map().count(); }
size_t capacity() const { return map().capacity(); }
bool has(const Lookup& l) const { return map().lookup(l).found(); }
size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return map().sizeOfExcludingThis(mallocSizeOf);
}
size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return mallocSizeOf(this) + map().sizeOfExcludingThis(mallocSizeOf);
}
};
template <typename Outer, typename... Args>
class MutableGCHashMapOperations
: public GCHashMapOperations<Outer, Args...>
{
using Map = JS::GCHashMap<Args...>;
using Lookup = typename Map::Lookup;
Map& map() { return static_cast<Outer*>(this)->get(); }
public:
using AddPtr = typename Map::AddPtr;
struct Enum : public Map::Enum { explicit Enum(Outer& o) : Map::Enum(o.map()) {} };
using Ptr = typename Map::Ptr;
using Range = typename Map::Range;
bool init(uint32_t len = 16) { return map().init(len); }
void clear() { map().clear(); }
void finish() { map().finish(); }
void remove(Ptr p) { map().remove(p); }
template<typename KeyInput, typename ValueInput>
bool add(AddPtr& p, KeyInput&& k, ValueInput&& v) {
return map().add(p, mozilla::Forward<KeyInput>(k), mozilla::Forward<ValueInput>(v));
}
template<typename KeyInput>
bool add(AddPtr& p, KeyInput&& k) {
return map().add(p, mozilla::Forward<KeyInput>(k), Map::Value());
}
template<typename KeyInput, typename ValueInput>
bool relookupOrAdd(AddPtr& p, KeyInput&& k, ValueInput&& v) {
return map().relookupOrAdd(p, k,
mozilla::Forward<KeyInput>(k),
mozilla::Forward<ValueInput>(v));
}
template<typename KeyInput, typename ValueInput>
bool put(KeyInput&& k, ValueInput&& v) {
return map().put(mozilla::Forward<KeyInput>(k), mozilla::Forward<ValueInput>(v));
}
template<typename KeyInput, typename ValueInput>
bool putNew(KeyInput&& k, ValueInput&& v) {
return map().putNew(mozilla::Forward<KeyInput>(k), mozilla::Forward<ValueInput>(v));
}
};
template <typename A, typename B, typename C, typename D, typename E>
class RootedBase<JS::GCHashMap<A,B,C,D,E>>
: public MutableGCHashMapOperations<JS::Rooted<JS::GCHashMap<A,B,C,D,E>>, A,B,C,D,E>
{};
template <typename A, typename B, typename C, typename D, typename E>
class MutableHandleBase<JS::GCHashMap<A,B,C,D,E>>
: public MutableGCHashMapOperations<JS::MutableHandle<JS::GCHashMap<A,B,C,D,E>>, A,B,C,D,E>
{};
template <typename A, typename B, typename C, typename D, typename E>
class HandleBase<JS::GCHashMap<A,B,C,D,E>>
: public GCHashMapOperations<JS::Handle<JS::GCHashMap<A,B,C,D,E>>, A,B,C,D,E>
{};
template <typename A, typename B, typename C, typename D, typename E>
class WeakCacheBase<JS::GCHashMap<A,B,C,D,E>>
: public MutableGCHashMapOperations<JS::WeakCache<JS::GCHashMap<A,B,C,D,E>>, A,B,C,D,E>
{};
} // namespace js
namespace JS {
// A GCHashSet is a HashSet with an additional trace method that knows
// be traced to be kept alive will generally want to use this GCHashSet
// specialization in lieu of HashSet.
//
// Most types of GC pointers can be traced with no extra infrastructure. For
// structs and non-gc-pointer members, ensure that there is a specialization of
// GCPolicy<T> with an appropriate trace method available to handle the custom
// type. Generic helpers can be found in js/public/TracingAPI.h.
//
// Note that although this HashSet's trace will deal correctly with moved
// elements, it does not itself know when to barrier or trace elements. To
// function properly it must either be used with Rooted or barriered and traced
// manually.
template <typename T,
typename HashPolicy = js::DefaultHasher<T>,
typename AllocPolicy = js::TempAllocPolicy>
class GCHashSet : public js::HashSet<T, HashPolicy, AllocPolicy>
{
using Base = js::HashSet<T, HashPolicy, AllocPolicy>;
public:
explicit GCHashSet(AllocPolicy a = AllocPolicy()) : Base(a) {}
static void trace(GCHashSet* set, JSTracer* trc) { set->trace(trc); }
void trace(JSTracer* trc) {
if (!this->initialized())
return;
for (typename Base::Enum e(*this); !e.empty(); e.popFront())
GCPolicy<T>::trace(trc, &e.mutableFront(), "hashset element");
}
void sweep() {
if (!this->initialized())
return;
for (typename Base::Enum e(*this); !e.empty(); e.popFront()) {
if (GCPolicy<T>::needsSweep(&e.mutableFront()))
e.removeFront();
}
}
// GCHashSet is movable
GCHashSet(GCHashSet&& rhs) : Base(mozilla::Move(rhs)) {}
void operator=(GCHashSet&& rhs) {
MOZ_ASSERT(this != &rhs, "self-move assignment is prohibited");
Base::operator=(mozilla::Move(rhs));
}
private:
// GCHashSet is not copyable or assignable
GCHashSet(const GCHashSet& hs) = delete;
GCHashSet& operator=(const GCHashSet& hs) = delete;
};
} // namespace JS
namespace js {
template <typename Outer, typename... Args>
class GCHashSetOperations
{
using Set = JS::GCHashSet<Args...>;
using Lookup = typename Set::Lookup;
const Set& set() const { return static_cast<const Outer*>(this)->get(); }
public:
using AddPtr = typename Set::AddPtr;
using Entry = typename Set::Entry;
using Ptr = typename Set::Ptr;
using Range = typename Set::Range;
bool initialized() const { return set().initialized(); }
Ptr lookup(const Lookup& l) const { return set().lookup(l); }
AddPtr lookupForAdd(const Lookup& l) const { return set().lookupForAdd(l); }
Range all() const { return set().all(); }
bool empty() const { return set().empty(); }
uint32_t count() const { return set().count(); }
size_t capacity() const { return set().capacity(); }
bool has(const Lookup& l) const { return set().lookup(l).found(); }
size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return set().sizeOfExcludingThis(mallocSizeOf);
}
size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return mallocSizeOf(this) + set().sizeOfExcludingThis(mallocSizeOf);
}
};
template <typename Outer, typename... Args>
class MutableGCHashSetOperations
: public GCHashSetOperations<Outer, Args...>
{
using Set = JS::GCHashSet<Args...>;
using Lookup = typename Set::Lookup;
Set& set() { return static_cast<Outer*>(this)->get(); }
public:
using AddPtr = typename Set::AddPtr;
using Entry = typename Set::Entry;
struct Enum : public Set::Enum { explicit Enum(Outer& o) : Set::Enum(o.set()) {} };
using Ptr = typename Set::Ptr;
using Range = typename Set::Range;
bool init(uint32_t len = 16) { return set().init(len); }
void clear() { set().clear(); }
void finish() { set().finish(); }
void remove(Ptr p) { set().remove(p); }
void remove(const Lookup& l) { set().remove(l); }
template<typename TInput>
bool add(AddPtr& p, TInput&& t) {
return set().add(p, mozilla::Forward<TInput>(t));
}
template<typename TInput>
bool relookupOrAdd(AddPtr& p, const Lookup& l, TInput&& t) {
return set().relookupOrAdd(p, l, mozilla::Forward<TInput>(t));
}
template<typename TInput>
bool put(TInput&& t) {
return set().put(mozilla::Forward<TInput>(t));
}
template<typename TInput>
bool putNew(TInput&& t) {
return set().putNew(mozilla::Forward<TInput>(t));
}
template<typename TInput>
bool putNew(const Lookup& l, TInput&& t) {
return set().putNew(l, mozilla::Forward<TInput>(t));
}
};
template <typename T, typename HP, typename AP>
class RootedBase<JS::GCHashSet<T, HP, AP>>
: public MutableGCHashSetOperations<JS::Rooted<JS::GCHashSet<T, HP, AP>>, T, HP, AP>
{
};
template <typename T, typename HP, typename AP>
class MutableHandleBase<JS::GCHashSet<T, HP, AP>>
: public MutableGCHashSetOperations<JS::MutableHandle<JS::GCHashSet<T, HP, AP>>, T, HP, AP>
{
};
template <typename T, typename HP, typename AP>
class HandleBase<JS::GCHashSet<T, HP, AP>>
: public GCHashSetOperations<JS::Handle<JS::GCHashSet<T, HP, AP>>, T, HP, AP>
{
};
template <typename T, typename HP, typename AP>
class WeakCacheBase<JS::GCHashSet<T, HP, AP>>
: public MutableGCHashSetOperations<JS::WeakCache<JS::GCHashSet<T, HP, AP>>, T, HP, AP>
{
};
} /* namespace js */
#endif /* GCHashTable_h */