roll forward: Make data members of CommonFields be private so that it's easier to change how we store this information internally. PiperOrigin-RevId: 544732832 Change-Id: I0c9a30f18edc71b3c7fffe94e2002ff6c52050f8
diff --git a/absl/container/internal/raw_hash_set.cc b/absl/container/internal/raw_hash_set.cc index 1ccee1e..a40e38d 100644 --- a/absl/container/internal/raw_hash_set.cc +++ b/absl/container/internal/raw_hash_set.cc
@@ -15,6 +15,7 @@ #include "absl/container/internal/raw_hash_set.h" #include <atomic> +#include <cassert> #include <cstddef> #include <cstring> @@ -130,8 +131,8 @@ void DropDeletesWithoutResize(CommonFields& common, const PolicyFunctions& policy, void* tmp_space) { void* set = &common; - void* slot_array = common.slots_; - const size_t capacity = common.capacity_; + void* slot_array = common.slots_ptr(); + const size_t capacity = common.capacity(); assert(IsValidCapacity(capacity)); assert(!is_small(capacity)); // Algorithm: @@ -150,7 +151,7 @@ // swap current element with target element // mark target as FULL // repeat procedure for current slot with moved from element (target) - ctrl_t* ctrl = common.control_; + ctrl_t* ctrl = common.control(); ConvertDeletedToEmptyAndFullToDeleted(ctrl, capacity); auto hasher = policy.hash_slot; auto transfer = policy.transfer; @@ -210,11 +211,11 @@ void EraseMetaOnly(CommonFields& c, ctrl_t* it, size_t slot_size) { assert(IsFull(*it) && "erasing a dangling iterator"); - --c.size_; - const auto index = static_cast<size_t>(it - c.control_); - const size_t index_before = (index - Group::kWidth) & c.capacity_; + c.set_size(c.size() - 1); + const auto index = static_cast<size_t>(it - c.control()); + const size_t index_before = (index - Group::kWidth) & c.capacity(); const auto empty_after = Group(it).MaskEmpty(); - const auto empty_before = Group(c.control_ + index_before).MaskEmpty(); + const auto empty_before = Group(c.control() + index_before).MaskEmpty(); // We count how many consecutive non empties we have to the right and to the // left of `it`. If the sum is >= kWidth then there is at least one probe @@ -226,26 +227,26 @@ SetCtrl(c, index, was_never_full ? ctrl_t::kEmpty : ctrl_t::kDeleted, slot_size); - c.growth_left() += (was_never_full ? 1 : 0); + c.set_growth_left(c.growth_left() + (was_never_full ? 1 : 0)); c.infoz().RecordErase(); } void ClearBackingArray(CommonFields& c, const PolicyFunctions& policy, bool reuse) { - c.size_ = 0; + c.set_size(0); if (reuse) { ResetCtrl(c, policy.slot_size); - c.infoz().RecordStorageChanged(0, c.capacity_); + c.infoz().RecordStorageChanged(0, c.capacity()); } else { void* set = &c; - (*policy.dealloc)(set, policy, c.control_, c.slots_, c.capacity_); - c.control_ = EmptyGroup(); + (*policy.dealloc)(set, policy, c.control(), c.slots_ptr(), c.capacity()); + c.set_control(EmptyGroup()); c.set_generation_ptr(EmptyGeneration()); - c.slots_ = nullptr; - c.capacity_ = 0; - c.growth_left() = 0; + c.set_slots(nullptr); + c.set_capacity(0); + c.set_growth_left(0); c.infoz().RecordClearedReservation(); - assert(c.size_ == 0); + assert(c.size() == 0); c.infoz().RecordStorageChanged(0, 0); } }
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h index 2880af7..970016f 100644 --- a/absl/container/internal/raw_hash_set.h +++ b/absl/container/internal/raw_hash_set.h
@@ -889,6 +889,11 @@ using HashSetIteratorGenerationInfo = HashSetIteratorGenerationInfoDisabled; #endif +// Returns whether `n` is a valid capacity (i.e., number of slots). +// +// A valid capacity is a non-zero integer `2^m - 1`. +inline bool IsValidCapacity(size_t n) { return ((n + 1) & n) == 0 && n > 0; } + // CommonFields hold the fields in raw_hash_set that do not depend // on template parameters. This allows us to conveniently pass all // of this state to helper functions as a single argument. @@ -906,21 +911,35 @@ std::move(static_cast<CommonFieldsGenerationInfo&&>(that))), // Explicitly copying fields into "this" and then resetting "that" // fields generates less code then calling absl::exchange per field. - control_(that.control_), - slots_(that.slots_), - size_(that.size_), - capacity_(that.capacity_), + control_(that.control()), + slots_(that.slots_ptr()), + size_(that.size()), + capacity_(that.capacity()), compressed_tuple_(that.growth_left(), std::move(that.infoz())) { - that.control_ = EmptyGroup(); - that.slots_ = nullptr; - that.size_ = 0; - that.capacity_ = 0; - that.growth_left() = 0; + that.set_control(EmptyGroup()); + that.set_slots(nullptr); + that.set_size(0); + that.set_capacity(0); + that.set_growth_left(0); } CommonFields& operator=(CommonFields&&) = default; + ctrl_t* control() const { return control_; } + void set_control(ctrl_t* c) { control_ = c; } + // Note: we can't use slots() because Qt defines "slots" as a macro. + void* slots_ptr() const { return slots_; } + void set_slots(void* s) { slots_ = s; } + size_t size() const { return size_; } + void set_size(size_t s) { size_ = s; } + size_t capacity() const { return capacity_; } + void set_capacity(size_t c) { + assert(c == 0 || IsValidCapacity(c)); + capacity_ = c; + } + // The number of slots we can still fill without needing to rehash. - size_t& growth_left() { return compressed_tuple_.template get<0>(); } + size_t growth_left() const { return compressed_tuple_.template get<0>(); } + void set_growth_left(size_t gl) { compressed_tuple_.template get<0>() = gl; } HashtablezInfoHandle& infoz() { return compressed_tuple_.template get<1>(); } const HashtablezInfoHandle& infoz() const { @@ -929,15 +948,17 @@ bool should_rehash_for_bug_detection_on_insert() const { return CommonFieldsGenerationInfo:: - should_rehash_for_bug_detection_on_insert(control_, capacity_); + should_rehash_for_bug_detection_on_insert(control(), capacity()); } void reset_reserved_growth(size_t reservation) { CommonFieldsGenerationInfo::reset_reserved_growth(reservation, size_); } + private: // TODO(b/259599413): Investigate removing some of these fields: // - control/slots can be derived from each other - // - size can be moved into the slot array + // - growth_left can be moved into the slot array + // - we can use 6 bits for capacity since it's always a power of two minus 1 // The control bytes (and, also, a pointer to the base of the backing array). // @@ -971,11 +992,6 @@ template <class Policy, class Hash, class Eq, class Alloc> class raw_hash_set; -// Returns whether `n` is a valid capacity (i.e., number of slots). -// -// A valid capacity is a non-zero integer `2^m - 1`. -inline bool IsValidCapacity(size_t n) { return ((n + 1) & n) == 0 && n > 0; } - // Returns the next valid capacity after `n`. inline size_t NextCapacity(size_t n) { assert(IsValidCapacity(n) || n == 0); @@ -1216,7 +1232,7 @@ return probe_seq<Group::kWidth>(H1(hash, ctrl), capacity); } inline probe_seq<Group::kWidth> probe(const CommonFields& common, size_t hash) { - return probe(common.control_, common.capacity_, hash); + return probe(common.control(), common.capacity(), hash); } // Probes an array of control bits using a probe sequence derived from `hash`, @@ -1229,7 +1245,7 @@ template <typename = void> inline FindInfo find_first_non_full(const CommonFields& common, size_t hash) { auto seq = probe(common, hash); - const ctrl_t* ctrl = common.control_; + const ctrl_t* ctrl = common.control(); while (true) { Group g{ctrl + seq.offset()}; auto mask = g.MaskEmptyOrDeleted(); @@ -1239,14 +1255,14 @@ // In debug build we will randomly insert in either the front or back of // the group. // TODO(kfm,sbenza): revisit after we do unconditional mixing - if (!is_small(common.capacity_) && ShouldInsertBackwards(hash, ctrl)) { + if (!is_small(common.capacity()) && ShouldInsertBackwards(hash, ctrl)) { return {seq.offset(mask.HighestBitSet()), seq.index()}; } #endif return {seq.offset(mask.LowestBitSet()), seq.index()}; } seq.next(); - assert(seq.index() <= common.capacity_ && "full table!"); + assert(seq.index() <= common.capacity() && "full table!"); } } @@ -1260,18 +1276,18 @@ FindInfo find_first_non_full_outofline(const CommonFields&, size_t); inline void ResetGrowthLeft(CommonFields& common) { - common.growth_left() = CapacityToGrowth(common.capacity_) - common.size_; + common.set_growth_left(CapacityToGrowth(common.capacity()) - common.size()); } // Sets `ctrl` to `{kEmpty, kSentinel, ..., kEmpty}`, marking the entire // array as marked as empty. inline void ResetCtrl(CommonFields& common, size_t slot_size) { - const size_t capacity = common.capacity_; - ctrl_t* ctrl = common.control_; + const size_t capacity = common.capacity(); + ctrl_t* ctrl = common.control(); std::memset(ctrl, static_cast<int8_t>(ctrl_t::kEmpty), capacity + 1 + NumClonedBytes()); ctrl[capacity] = ctrl_t::kSentinel; - SanitizerPoisonMemoryRegion(common.slots_, slot_size * capacity); + SanitizerPoisonMemoryRegion(common.slots_ptr(), slot_size * capacity); ResetGrowthLeft(common); } @@ -1281,17 +1297,17 @@ // mirror the value to the cloned tail if necessary. inline void SetCtrl(const CommonFields& common, size_t i, ctrl_t h, size_t slot_size) { - const size_t capacity = common.capacity_; + const size_t capacity = common.capacity(); assert(i < capacity); - auto* slot_i = static_cast<const char*>(common.slots_) + i * slot_size; + auto* slot_i = static_cast<const char*>(common.slots_ptr()) + i * slot_size; if (IsFull(h)) { SanitizerUnpoisonMemoryRegion(slot_i, slot_size); } else { SanitizerPoisonMemoryRegion(slot_i, slot_size); } - ctrl_t* ctrl = common.control_; + ctrl_t* ctrl = common.control(); ctrl[i] = h; ctrl[((i - NumClonedBytes()) & capacity) + (NumClonedBytes() & capacity)] = h; } @@ -1327,31 +1343,32 @@ template <typename Alloc, size_t SizeOfSlot, size_t AlignOfSlot> ABSL_ATTRIBUTE_NOINLINE void InitializeSlots(CommonFields& c, Alloc alloc) { - assert(c.capacity_); + assert(c.capacity()); // Folks with custom allocators often make unwarranted assumptions about the // behavior of their classes vis-a-vis trivial destructability and what // calls they will or won't make. Avoid sampling for people with custom // allocators to get us out of this mess. This is not a hard guarantee but // a workaround while we plan the exact guarantee we want to provide. const size_t sample_size = - (std::is_same<Alloc, std::allocator<char>>::value && c.slots_ == nullptr) + (std::is_same<Alloc, std::allocator<char>>::value && + c.slots_ptr() == nullptr) ? SizeOfSlot : 0; - const size_t cap = c.capacity_; + const size_t cap = c.capacity(); char* mem = static_cast<char*>( Allocate<AlignOfSlot>(&alloc, AllocSize(cap, SizeOfSlot, AlignOfSlot))); const GenerationType old_generation = c.generation(); c.set_generation_ptr( reinterpret_cast<GenerationType*>(mem + GenerationOffset(cap))); c.set_generation(NextGeneration(old_generation)); - c.control_ = reinterpret_cast<ctrl_t*>(mem); - c.slots_ = mem + SlotOffset(cap, AlignOfSlot); + c.set_control(reinterpret_cast<ctrl_t*>(mem)); + c.set_slots(mem + SlotOffset(cap, AlignOfSlot)); ResetCtrl(c, SizeOfSlot); if (sample_size) { c.infoz() = Sample(sample_size); } - c.infoz().RecordStorageChanged(c.size_, cap); + c.infoz().RecordStorageChanged(c.size(), cap); } // PolicyFunctions bundles together some information for a particular @@ -1654,7 +1671,7 @@ const allocator_type& alloc = allocator_type()) : settings_(CommonFields{}, hash, eq, alloc) { if (bucket_count) { - common().capacity_ = NormalizeCapacity(bucket_count); + common().set_capacity(NormalizeCapacity(bucket_count)); initialize_slots(); } } @@ -1767,8 +1784,8 @@ common().maybe_increment_generation_on_insert(); infoz().RecordInsert(hash, target.probe_length); } - common().size_ = that.size(); - growth_left() -= that.size(); + common().set_size(that.size()); + set_growth_left(growth_left() - that.size()); } ABSL_ATTRIBUTE_NOINLINE raw_hash_set(raw_hash_set&& that) noexcept( @@ -1849,8 +1866,8 @@ const_iterator cend() const ABSL_ATTRIBUTE_LIFETIME_BOUND { return end(); } bool empty() const { return !size(); } - size_t size() const { return common().size_; } - size_t capacity() const { return common().capacity_; } + size_t size() const { return common().size(); } + size_t capacity() const { return common().capacity(); } size_t max_size() const { return (std::numeric_limits<size_t>::max)(); } ABSL_ATTRIBUTE_REINITIALIZES void clear() { @@ -2432,8 +2449,8 @@ assert(IsValidCapacity(new_capacity)); auto* old_ctrl = control(); auto* old_slots = slot_array(); - const size_t old_capacity = common().capacity_; - common().capacity_ = new_capacity; + const size_t old_capacity = common().capacity(); + common().set_capacity(new_capacity); initialize_slots(); auto* new_slots = slot_array(); @@ -2600,8 +2617,8 @@ rehash_and_grow_if_necessary(); target = find_first_non_full(common(), hash); } - ++common().size_; - growth_left() -= IsEmpty(control()[target.offset]); + common().set_size(common().size() + 1); + set_growth_left(growth_left() - IsEmpty(control()[target.offset])); SetCtrl(common(), target.offset, H2(hash), sizeof(slot_type)); common().maybe_increment_generation_on_insert(); infoz().RecordInsert(hash, target.probe_length); @@ -2646,7 +2663,8 @@ // side-effect. // // See `CapacityToGrowth()`. - size_t& growth_left() { return common().growth_left(); } + size_t growth_left() const { return common().growth_left(); } + void set_growth_left(size_t gl) { return common().set_growth_left(gl); } // Prefetch the heap-allocated memory region to resolve potential TLB and // cache misses. This is intended to overlap with execution of calculating the @@ -2660,9 +2678,9 @@ CommonFields& common() { return settings_.template get<0>(); } const CommonFields& common() const { return settings_.template get<0>(); } - ctrl_t* control() const { return common().control_; } + ctrl_t* control() const { return common().control(); } slot_type* slot_array() const { - return static_cast<slot_type*>(common().slots_); + return static_cast<slot_type*>(common().slots_ptr()); } HashtablezInfoHandle& infoz() { return common().infoz(); }