| // Copyright 2020 The Abseil Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include "absl/strings/cord.h" |
| |
| #include <algorithm> |
| #include <atomic> |
| #include <cstddef> |
| #include <cstdio> |
| #include <cstdlib> |
| #include <iomanip> |
| #include <iostream> |
| #include <limits> |
| #include <ostream> |
| #include <sstream> |
| #include <type_traits> |
| #include <unordered_set> |
| #include <vector> |
| |
| #include "absl/base/casts.h" |
| #include "absl/base/internal/raw_logging.h" |
| #include "absl/base/macros.h" |
| #include "absl/base/port.h" |
| #include "absl/container/fixed_array.h" |
| #include "absl/container/inlined_vector.h" |
| #include "absl/strings/escaping.h" |
| #include "absl/strings/internal/cord_internal.h" |
| #include "absl/strings/internal/cord_rep_flat.h" |
| #include "absl/strings/internal/cord_rep_ring.h" |
| #include "absl/strings/internal/cordz_statistics.h" |
| #include "absl/strings/internal/cordz_update_scope.h" |
| #include "absl/strings/internal/cordz_update_tracker.h" |
| #include "absl/strings/internal/resize_uninitialized.h" |
| #include "absl/strings/str_cat.h" |
| #include "absl/strings/str_format.h" |
| #include "absl/strings/str_join.h" |
| #include "absl/strings/string_view.h" |
| |
| namespace absl { |
| ABSL_NAMESPACE_BEGIN |
| |
| using ::absl::cord_internal::CordRep; |
| using ::absl::cord_internal::CordRepConcat; |
| using ::absl::cord_internal::CordRepExternal; |
| using ::absl::cord_internal::CordRepFlat; |
| using ::absl::cord_internal::CordRepRing; |
| using ::absl::cord_internal::CordRepSubstring; |
| using ::absl::cord_internal::CordzUpdateTracker; |
| using ::absl::cord_internal::InlineData; |
| using ::absl::cord_internal::kMaxFlatLength; |
| using ::absl::cord_internal::kMinFlatLength; |
| |
| using ::absl::cord_internal::CONCAT; |
| using ::absl::cord_internal::EXTERNAL; |
| using ::absl::cord_internal::FLAT; |
| using ::absl::cord_internal::RING; |
| using ::absl::cord_internal::SUBSTRING; |
| |
| using ::absl::cord_internal::kInlinedVectorSize; |
| using ::absl::cord_internal::kMaxBytesToCopy; |
| |
| constexpr uint64_t Fibonacci(unsigned char n, uint64_t a = 0, uint64_t b = 1) { |
| return n == 0 ? a : Fibonacci(n - 1, b, a + b); |
| } |
| |
| static_assert(Fibonacci(63) == 6557470319842, |
| "Fibonacci values computed incorrectly"); |
| |
| // Minimum length required for a given depth tree -- a tree is considered |
| // balanced if |
| // length(t) >= min_length[depth(t)] |
| // The root node depth is allowed to become twice as large to reduce rebalancing |
| // for larger strings (see IsRootBalanced). |
| static constexpr uint64_t min_length[] = { |
| Fibonacci(2), Fibonacci(3), Fibonacci(4), Fibonacci(5), |
| Fibonacci(6), Fibonacci(7), Fibonacci(8), Fibonacci(9), |
| Fibonacci(10), Fibonacci(11), Fibonacci(12), Fibonacci(13), |
| Fibonacci(14), Fibonacci(15), Fibonacci(16), Fibonacci(17), |
| Fibonacci(18), Fibonacci(19), Fibonacci(20), Fibonacci(21), |
| Fibonacci(22), Fibonacci(23), Fibonacci(24), Fibonacci(25), |
| Fibonacci(26), Fibonacci(27), Fibonacci(28), Fibonacci(29), |
| Fibonacci(30), Fibonacci(31), Fibonacci(32), Fibonacci(33), |
| Fibonacci(34), Fibonacci(35), Fibonacci(36), Fibonacci(37), |
| Fibonacci(38), Fibonacci(39), Fibonacci(40), Fibonacci(41), |
| Fibonacci(42), Fibonacci(43), Fibonacci(44), Fibonacci(45), |
| Fibonacci(46), Fibonacci(47), |
| 0xffffffffffffffffull, // Avoid overflow |
| }; |
| |
| static const int kMinLengthSize = ABSL_ARRAYSIZE(min_length); |
| |
| static inline bool cord_ring_enabled() { |
| return cord_internal::cord_ring_buffer_enabled.load( |
| std::memory_order_relaxed); |
| } |
| |
| static inline bool IsRootBalanced(CordRep* node) { |
| if (node->tag != CONCAT) { |
| return true; |
| } else if (node->concat()->depth() <= 15) { |
| return true; |
| } else if (node->concat()->depth() > kMinLengthSize) { |
| return false; |
| } else { |
| // Allow depth to become twice as large as implied by fibonacci rule to |
| // reduce rebalancing for larger strings. |
| return (node->length >= min_length[node->concat()->depth() / 2]); |
| } |
| } |
| |
| static CordRep* Rebalance(CordRep* node); |
| static void DumpNode(CordRep* rep, bool include_data, std::ostream* os, |
| int indent = 0); |
| static bool VerifyNode(CordRep* root, CordRep* start_node, |
| bool full_validation); |
| |
| static inline CordRep* VerifyTree(CordRep* node) { |
| // Verification is expensive, so only do it in debug mode. |
| // Even in debug mode we normally do only light validation. |
| // If you are debugging Cord itself, you should define the |
| // macro EXTRA_CORD_VALIDATION, e.g. by adding |
| // --copt=-DEXTRA_CORD_VALIDATION to the blaze line. |
| #ifdef EXTRA_CORD_VALIDATION |
| assert(node == nullptr || VerifyNode(node, node, /*full_validation=*/true)); |
| #else // EXTRA_CORD_VALIDATION |
| assert(node == nullptr || VerifyNode(node, node, /*full_validation=*/false)); |
| #endif // EXTRA_CORD_VALIDATION |
| static_cast<void>(&VerifyNode); |
| |
| return node; |
| } |
| |
| // Return the depth of a node |
| static int Depth(const CordRep* rep) { |
| if (rep->tag == CONCAT) { |
| return rep->concat()->depth(); |
| } else { |
| return 0; |
| } |
| } |
| |
| static void SetConcatChildren(CordRepConcat* concat, CordRep* left, |
| CordRep* right) { |
| concat->left = left; |
| concat->right = right; |
| |
| concat->length = left->length + right->length; |
| concat->set_depth(1 + std::max(Depth(left), Depth(right))); |
| } |
| |
| // Create a concatenation of the specified nodes. |
| // Does not change the refcounts of "left" and "right". |
| // The returned node has a refcount of 1. |
| static CordRep* RawConcat(CordRep* left, CordRep* right) { |
| // Avoid making degenerate concat nodes (one child is empty) |
| if (left == nullptr) return right; |
| if (right == nullptr) return left; |
| if (left->length == 0) { |
| CordRep::Unref(left); |
| return right; |
| } |
| if (right->length == 0) { |
| CordRep::Unref(right); |
| return left; |
| } |
| |
| CordRepConcat* rep = new CordRepConcat(); |
| rep->tag = CONCAT; |
| SetConcatChildren(rep, left, right); |
| |
| return rep; |
| } |
| |
| static CordRep* Concat(CordRep* left, CordRep* right) { |
| CordRep* rep = RawConcat(left, right); |
| if (rep != nullptr && !IsRootBalanced(rep)) { |
| rep = Rebalance(rep); |
| } |
| return VerifyTree(rep); |
| } |
| |
| // Make a balanced tree out of an array of leaf nodes. |
| static CordRep* MakeBalancedTree(CordRep** reps, size_t n) { |
| // Make repeated passes over the array, merging adjacent pairs |
| // until we are left with just a single node. |
| while (n > 1) { |
| size_t dst = 0; |
| for (size_t src = 0; src < n; src += 2) { |
| if (src + 1 < n) { |
| reps[dst] = Concat(reps[src], reps[src + 1]); |
| } else { |
| reps[dst] = reps[src]; |
| } |
| dst++; |
| } |
| n = dst; |
| } |
| |
| return reps[0]; |
| } |
| |
| static CordRepFlat* CreateFlat(const char* data, size_t length, |
| size_t alloc_hint) { |
| CordRepFlat* flat = CordRepFlat::New(length + alloc_hint); |
| flat->length = length; |
| memcpy(flat->Data(), data, length); |
| return flat; |
| } |
| |
| // Creates a new flat or ringbuffer out of the specified array. |
| // The returned node has a refcount of 1. |
| static CordRep* RingNewTree(const char* data, size_t length, |
| size_t alloc_hint) { |
| if (length <= kMaxFlatLength) { |
| return CreateFlat(data, length, alloc_hint); |
| } |
| CordRepFlat* flat = CreateFlat(data, kMaxFlatLength, 0); |
| data += kMaxFlatLength; |
| length -= kMaxFlatLength; |
| size_t extra = (length - 1) / kMaxFlatLength + 1; |
| auto* root = CordRepRing::Create(flat, extra); |
| return CordRepRing::Append(root, {data, length}, alloc_hint); |
| } |
| |
| // Create a new tree out of the specified array. |
| // The returned node has a refcount of 1. |
| static CordRep* NewTree(const char* data, size_t length, size_t alloc_hint) { |
| if (length == 0) return nullptr; |
| if (cord_ring_enabled()) { |
| return RingNewTree(data, length, alloc_hint); |
| } |
| absl::FixedArray<CordRep*> reps((length - 1) / kMaxFlatLength + 1); |
| size_t n = 0; |
| do { |
| const size_t len = std::min(length, kMaxFlatLength); |
| CordRepFlat* rep = CordRepFlat::New(len + alloc_hint); |
| rep->length = len; |
| memcpy(rep->Data(), data, len); |
| reps[n++] = VerifyTree(rep); |
| data += len; |
| length -= len; |
| } while (length != 0); |
| return MakeBalancedTree(reps.data(), n); |
| } |
| |
| namespace cord_internal { |
| |
| void InitializeCordRepExternal(absl::string_view data, CordRepExternal* rep) { |
| assert(!data.empty()); |
| rep->length = data.size(); |
| rep->tag = EXTERNAL; |
| rep->base = data.data(); |
| VerifyTree(rep); |
| } |
| |
| } // namespace cord_internal |
| |
| static CordRep* NewSubstring(CordRep* child, size_t offset, size_t length) { |
| // Never create empty substring nodes |
| if (length == 0) { |
| CordRep::Unref(child); |
| return nullptr; |
| } else { |
| CordRepSubstring* rep = new CordRepSubstring(); |
| assert((offset + length) <= child->length); |
| rep->length = length; |
| rep->tag = SUBSTRING; |
| rep->start = offset; |
| rep->child = child; |
| return VerifyTree(rep); |
| } |
| } |
| |
| // Creates a CordRep from the provided string. If the string is large enough, |
| // and not wasteful, we move the string into an external cord rep, preserving |
| // the already allocated string contents. |
| // Requires the provided string length to be larger than `kMaxInline`. |
| static CordRep* CordRepFromString(std::string&& src) { |
| assert(src.length() > cord_internal::kMaxInline); |
| if ( |
| // String is short: copy data to avoid external block overhead. |
| src.size() <= kMaxBytesToCopy || |
| // String is wasteful: copy data to avoid pinning too much unused memory. |
| src.size() < src.capacity() / 2 |
| ) { |
| return NewTree(src.data(), src.size(), 0); |
| } |
| |
| struct StringReleaser { |
| void operator()(absl::string_view /* data */) {} |
| std::string data; |
| }; |
| const absl::string_view original_data = src; |
| auto* rep = |
| static_cast<::absl::cord_internal::CordRepExternalImpl<StringReleaser>*>( |
| absl::cord_internal::NewExternalRep(original_data, |
| StringReleaser{std::move(src)})); |
| // Moving src may have invalidated its data pointer, so adjust it. |
| rep->base = rep->template get<0>().data.data(); |
| return rep; |
| } |
| |
| // -------------------------------------------------------------------- |
| // Cord::InlineRep functions |
| |
| constexpr unsigned char Cord::InlineRep::kMaxInline; |
| |
| inline void Cord::InlineRep::set_data(const char* data, size_t n, |
| bool nullify_tail) { |
| static_assert(kMaxInline == 15, "set_data is hard-coded for a length of 15"); |
| |
| cord_internal::SmallMemmove(data_.as_chars(), data, n, nullify_tail); |
| set_inline_size(n); |
| } |
| |
| inline char* Cord::InlineRep::set_data(size_t n) { |
| assert(n <= kMaxInline); |
| ResetToEmpty(); |
| set_inline_size(n); |
| return data_.as_chars(); |
| } |
| |
| inline void Cord::InlineRep::reduce_size(size_t n) { |
| size_t tag = inline_size(); |
| assert(tag <= kMaxInline); |
| assert(tag >= n); |
| tag -= n; |
| memset(data_.as_chars() + tag, 0, n); |
| set_inline_size(static_cast<char>(tag)); |
| } |
| |
| inline void Cord::InlineRep::remove_prefix(size_t n) { |
| cord_internal::SmallMemmove(data_.as_chars(), data_.as_chars() + n, |
| inline_size() - n); |
| reduce_size(n); |
| } |
| |
| // Returns `rep` converted into a CordRepRing. |
| // Directly returns `rep` if `rep` is already a CordRepRing. |
| static CordRepRing* ForceRing(CordRep* rep, size_t extra) { |
| return (rep->tag == RING) ? rep->ring() : CordRepRing::Create(rep, extra); |
| } |
| |
| void Cord::InlineRep::AppendTreeToInlined(CordRep* tree, |
| MethodIdentifier method) { |
| assert(!is_tree()); |
| if (!data_.is_empty()) { |
| CordRepFlat* flat = MakeFlatWithExtraCapacity(0); |
| if (cord_ring_enabled()) { |
| tree = CordRepRing::Append(CordRepRing::Create(flat, 1), tree); |
| } else { |
| tree = Concat(flat, tree); |
| } |
| } |
| EmplaceTree(tree, method); |
| } |
| |
| void Cord::InlineRep::AppendTreeToTree(CordRep* tree, MethodIdentifier method) { |
| assert(is_tree()); |
| const CordzUpdateScope scope(data_.cordz_info(), method); |
| if (cord_ring_enabled()) { |
| tree = CordRepRing::Append(ForceRing(data_.as_tree(), 1), tree); |
| } else { |
| tree = Concat(data_.as_tree(), tree); |
| } |
| SetTree(tree, scope); |
| } |
| |
| void Cord::InlineRep::AppendTree(CordRep* tree, MethodIdentifier method) { |
| if (tree == nullptr) return; |
| if (data_.is_tree()) { |
| AppendTreeToTree(tree, method); |
| } else { |
| AppendTreeToInlined(tree, method); |
| } |
| } |
| |
| void Cord::InlineRep::PrependTreeToInlined(CordRep* tree, |
| MethodIdentifier method) { |
| assert(!is_tree()); |
| if (!data_.is_empty()) { |
| CordRepFlat* flat = MakeFlatWithExtraCapacity(0); |
| if (cord_ring_enabled()) { |
| tree = CordRepRing::Prepend(CordRepRing::Create(flat, 1), tree); |
| } else { |
| tree = Concat(tree, flat); |
| } |
| } |
| EmplaceTree(tree, method); |
| } |
| |
| void Cord::InlineRep::PrependTreeToTree(CordRep* tree, |
| MethodIdentifier method) { |
| assert(is_tree()); |
| const CordzUpdateScope scope(data_.cordz_info(), method); |
| if (cord_ring_enabled()) { |
| tree = CordRepRing::Prepend(ForceRing(data_.as_tree(), 1), tree); |
| } else { |
| tree = Concat(tree, data_.as_tree()); |
| } |
| SetTree(tree, scope); |
| } |
| |
| void Cord::InlineRep::PrependTree(CordRep* tree, MethodIdentifier method) { |
| assert(tree != nullptr); |
| if (data_.is_tree()) { |
| PrependTreeToTree(tree, method); |
| } else { |
| PrependTreeToInlined(tree, method); |
| } |
| } |
| |
| // Searches for a non-full flat node at the rightmost leaf of the tree. If a |
| // suitable leaf is found, the function will update the length field for all |
| // nodes to account for the size increase. The append region address will be |
| // written to region and the actual size increase will be written to size. |
| static inline bool PrepareAppendRegion(CordRep* root, char** region, |
| size_t* size, size_t max_length) { |
| if (root->tag == RING && root->refcount.IsOne()) { |
| Span<char> span = root->ring()->GetAppendBuffer(max_length); |
| if (!span.empty()) { |
| *region = span.data(); |
| *size = span.size(); |
| return true; |
| } |
| } |
| |
| // Search down the right-hand path for a non-full FLAT node. |
| CordRep* dst = root; |
| while (dst->tag == CONCAT && dst->refcount.IsOne()) { |
| dst = dst->concat()->right; |
| } |
| |
| if (dst->tag < FLAT || !dst->refcount.IsOne()) { |
| *region = nullptr; |
| *size = 0; |
| return false; |
| } |
| |
| const size_t in_use = dst->length; |
| const size_t capacity = dst->flat()->Capacity(); |
| if (in_use == capacity) { |
| *region = nullptr; |
| *size = 0; |
| return false; |
| } |
| |
| size_t size_increase = std::min(capacity - in_use, max_length); |
| |
| // We need to update the length fields for all nodes, including the leaf node. |
| for (CordRep* rep = root; rep != dst; rep = rep->concat()->right) { |
| rep->length += size_increase; |
| } |
| dst->length += size_increase; |
| |
| *region = dst->flat()->Data() + in_use; |
| *size = size_increase; |
| return true; |
| } |
| |
| template <bool has_length> |
| void Cord::InlineRep::GetAppendRegion(char** region, size_t* size, |
| size_t length) { |
| auto constexpr method = CordzUpdateTracker::kGetAppendRegion; |
| |
| CordRep* root = tree(); |
| size_t sz = root ? root->length : inline_size(); |
| if (root == nullptr) { |
| size_t available = kMaxInline - sz; |
| if (available >= (has_length ? length : 1)) { |
| *region = data_.as_chars() + sz; |
| *size = has_length ? length : available; |
| set_inline_size(has_length ? sz + length : kMaxInline); |
| return; |
| } |
| } |
| |
| size_t extra = has_length ? length : (std::max)(sz, kMinFlatLength); |
| CordRep* rep = root ? root : MakeFlatWithExtraCapacity(extra); |
| CordzUpdateScope scope(root ? data_.cordz_info() : nullptr, method); |
| if (PrepareAppendRegion(rep, region, size, length)) { |
| CommitTree(root, rep, scope, method); |
| return; |
| } |
| |
| // Allocate new node. |
| CordRepFlat* new_node = CordRepFlat::New(extra); |
| new_node->length = std::min(new_node->Capacity(), length); |
| *region = new_node->Data(); |
| *size = new_node->length; |
| |
| if (cord_ring_enabled()) { |
| rep = CordRepRing::Append(ForceRing(rep, 1), new_node); |
| } else { |
| rep = Concat(rep, new_node); |
| } |
| CommitTree(root, rep, scope, method); |
| } |
| |
| // If the rep is a leaf, this will increment the value at total_mem_usage and |
| // will return true. |
| static bool RepMemoryUsageLeaf(const CordRep* rep, size_t* total_mem_usage) { |
| if (rep->tag >= FLAT) { |
| *total_mem_usage += rep->flat()->AllocatedSize(); |
| return true; |
| } |
| if (rep->tag == EXTERNAL) { |
| // We don't know anything about the embedded / bound data, but we can safely |
| // assume it is 'at least' a word / pointer to data. In the future we may |
| // choose to use the 'data' byte as a tag to identify the types of some |
| // well-known externals, such as a std::string instance. |
| *total_mem_usage += |
| sizeof(cord_internal::CordRepExternalImpl<intptr_t>) + rep->length; |
| return true; |
| } |
| return false; |
| } |
| |
| void Cord::InlineRep::AssignSlow(const Cord::InlineRep& src) { |
| assert(&src != this); |
| assert(is_tree() || src.is_tree()); |
| auto constexpr method = CordzUpdateTracker::kAssignCord; |
| if (ABSL_PREDICT_TRUE(!is_tree())) { |
| EmplaceTree(CordRep::Ref(src.as_tree()), src.data_, method); |
| return; |
| } |
| |
| // See b/187581164: unsample cord if already sampled |
| // TODO(b/117940323): continuously 'assigned to' cords would reach 100% |
| // sampling probability. Imagine a cord x in some cache: |
| // cache.SetCord(const Cord& foo) { |
| // x = foo; |
| // } |
| // CordzInfo::MaybeTrackCord does: |
| // x.profiled = foo.profiled | x.profiled | random(cordz_mean_interval) |
| // Which means it will on the long run converge to 'always samples' |
| // The real fix is in CordzMaybeTrackCord, but the below is a low risk |
| // forward fix for b/187581164 and similar BT benchmark regressions. |
| if (ABSL_PREDICT_FALSE(is_profiled())) { |
| cordz_info()->Untrack(); |
| clear_cordz_info(); |
| } |
| |
| CordRep* tree = as_tree(); |
| if (CordRep* src_tree = src.tree()) { |
| data_.set_tree(CordRep::Ref(src_tree)); |
| CordzInfo::MaybeTrackCord(data_, src.data_, method); |
| } else { |
| CordzInfo::MaybeUntrackCord(data_.cordz_info()); |
| data_ = src.data_; |
| } |
| CordRep::Unref(tree); |
| } |
| |
| void Cord::InlineRep::UnrefTree() { |
| if (is_tree()) { |
| CordzInfo::MaybeUntrackCord(data_.cordz_info()); |
| CordRep::Unref(tree()); |
| } |
| } |
| |
| // -------------------------------------------------------------------- |
| // Constructors and destructors |
| |
| Cord::Cord(absl::string_view src, MethodIdentifier method) |
| : contents_(InlineData::kDefaultInit) { |
| const size_t n = src.size(); |
| if (n <= InlineRep::kMaxInline) { |
| contents_.set_data(src.data(), n, true); |
| } else { |
| CordRep* rep = NewTree(src.data(), n, 0); |
| contents_.EmplaceTree(rep, method); |
| } |
| } |
| |
| template <typename T, Cord::EnableIfString<T>> |
| Cord::Cord(T&& src) : contents_(InlineData::kDefaultInit) { |
| if (src.size() <= InlineRep::kMaxInline) { |
| contents_.set_data(src.data(), src.size(), true); |
| } else { |
| CordRep* rep = CordRepFromString(std::forward<T>(src)); |
| contents_.EmplaceTree(rep, CordzUpdateTracker::kConstructorString); |
| } |
| } |
| |
| template Cord::Cord(std::string&& src); |
| |
| // The destruction code is separate so that the compiler can determine |
| // that it does not need to call the destructor on a moved-from Cord. |
| void Cord::DestroyCordSlow() { |
| assert(contents_.is_tree()); |
| CordzInfo::MaybeUntrackCord(contents_.cordz_info()); |
| CordRep::Unref(VerifyTree(contents_.as_tree())); |
| } |
| |
| // -------------------------------------------------------------------- |
| // Mutators |
| |
| void Cord::Clear() { |
| if (CordRep* tree = contents_.clear()) { |
| CordRep::Unref(tree); |
| } |
| } |
| |
| Cord& Cord::AssignLargeString(std::string&& src) { |
| auto constexpr method = CordzUpdateTracker::kAssignString; |
| assert(src.size() > kMaxBytesToCopy); |
| CordRep* rep = CordRepFromString(std::move(src)); |
| if (CordRep* tree = contents_.tree()) { |
| CordzUpdateScope scope(contents_.cordz_info(), method); |
| contents_.SetTree(rep, scope); |
| CordRep::Unref(tree); |
| } else { |
| contents_.EmplaceTree(rep, method); |
| } |
| return *this; |
| } |
| |
| Cord& Cord::operator=(absl::string_view src) { |
| auto constexpr method = CordzUpdateTracker::kAssignString; |
| const char* data = src.data(); |
| size_t length = src.size(); |
| CordRep* tree = contents_.tree(); |
| if (length <= InlineRep::kMaxInline) { |
| // Embed into this->contents_, which is somewhat subtle: |
| // - MaybeUntrackCord must be called before Unref(tree). |
| // - MaybeUntrackCord must be called before set_data() clobbers cordz_info. |
| // - set_data() must be called before Unref(tree) as it may reference tree. |
| if (tree != nullptr) CordzInfo::MaybeUntrackCord(contents_.cordz_info()); |
| contents_.set_data(data, length, true); |
| if (tree != nullptr) CordRep::Unref(tree); |
| return *this; |
| } |
| if (tree != nullptr) { |
| CordzUpdateScope scope(contents_.cordz_info(), method); |
| if (tree->tag >= FLAT && tree->flat()->Capacity() >= length && |
| tree->refcount.IsOne()) { |
| // Copy in place if the existing FLAT node is reusable. |
| memmove(tree->flat()->Data(), data, length); |
| tree->length = length; |
| VerifyTree(tree); |
| return *this; |
| } |
| contents_.SetTree(NewTree(data, length, 0), scope); |
| CordRep::Unref(tree); |
| } else { |
| contents_.EmplaceTree(NewTree(data, length, 0), method); |
| } |
| return *this; |
| } |
| |
| // TODO(sanjay): Move to Cord::InlineRep section of file. For now, |
| // we keep it here to make diffs easier. |
| void Cord::InlineRep::AppendArray(absl::string_view src, |
| MethodIdentifier method) { |
| if (src.empty()) return; // memcpy(_, nullptr, 0) is undefined. |
| |
| size_t appended = 0; |
| CordRep* rep = tree(); |
| const CordRep* const root = rep; |
| CordzUpdateScope scope(root ? cordz_info() : nullptr, method); |
| if (root != nullptr) { |
| char* region; |
| if (PrepareAppendRegion(rep, ®ion, &appended, src.size())) { |
| memcpy(region, src.data(), appended); |
| } |
| } else { |
| // Try to fit in the inline buffer if possible. |
| size_t inline_length = inline_size(); |
| if (src.size() <= kMaxInline - inline_length) { |
| // Append new data to embedded array |
| memcpy(data_.as_chars() + inline_length, src.data(), src.size()); |
| set_inline_size(inline_length + src.size()); |
| return; |
| } |
| |
| // Note: we don't concern ourselves if src aliases data stored in the |
| // inlined data of 'this', as we update the InlineData only at the end. |
| // We are going from an inline size to beyond inline size. Make the new size |
| // either double the inlined size, or the added size + 10%. |
| const size_t size1 = inline_length * 2 + src.size(); |
| const size_t size2 = inline_length + src.size() / 10; |
| rep = CordRepFlat::New(std::max<size_t>(size1, size2)); |
| appended = std::min(src.size(), rep->flat()->Capacity() - inline_length); |
| memcpy(rep->flat()->Data(), data_.as_chars(), inline_length); |
| memcpy(rep->flat()->Data() + inline_length, src.data(), appended); |
| rep->length = inline_length + appended; |
| } |
| |
| src.remove_prefix(appended); |
| if (src.empty()) { |
| CommitTree(root, rep, scope, method); |
| return; |
| } |
| |
| if (cord_ring_enabled()) { |
| rep = ForceRing(rep, (src.size() - 1) / kMaxFlatLength + 1); |
| rep = CordRepRing::Append(rep->ring(), src); |
| } else { |
| // Use new block(s) for any remaining bytes that were not handled above. |
| // Alloc extra memory only if the right child of the root of the new tree |
| // is going to be a FLAT node, which will permit further inplace appends. |
| size_t length = src.size(); |
| if (src.size() < kMaxFlatLength) { |
| // The new length is either |
| // - old size + 10% |
| // - old_size + src.size() |
| // This will cause a reasonable conservative step-up in size that is |
| // still large enough to avoid excessive amounts of small fragments |
| // being added. |
| length = std::max<size_t>(rep->length / 10, src.size()); |
| } |
| rep = Concat(rep, NewTree(src.data(), src.size(), length - src.size())); |
| } |
| CommitTree(root, rep, scope, method); |
| } |
| |
| inline CordRep* Cord::TakeRep() const& { |
| return CordRep::Ref(contents_.tree()); |
| } |
| |
| inline CordRep* Cord::TakeRep() && { |
| CordRep* rep = contents_.tree(); |
| contents_.clear(); |
| return rep; |
| } |
| |
| template <typename C> |
| inline void Cord::AppendImpl(C&& src) { |
| auto constexpr method = CordzUpdateTracker::kAppendCord; |
| if (empty()) { |
| // Since destination is empty, we can avoid allocating a node, |
| if (src.contents_.is_tree()) { |
| // by taking the tree directly |
| CordRep* rep = std::forward<C>(src).TakeRep(); |
| contents_.EmplaceTree(rep, method); |
| } else { |
| // or copying over inline data |
| contents_.data_ = src.contents_.data_; |
| } |
| return; |
| } |
| |
| // For short cords, it is faster to copy data if there is room in dst. |
| const size_t src_size = src.contents_.size(); |
| if (src_size <= kMaxBytesToCopy) { |
| CordRep* src_tree = src.contents_.tree(); |
| if (src_tree == nullptr) { |
| // src has embedded data. |
| contents_.AppendArray({src.contents_.data(), src_size}, method); |
| return; |
| } |
| if (src_tree->tag >= FLAT) { |
| // src tree just has one flat node. |
| contents_.AppendArray({src_tree->flat()->Data(), src_size}, method); |
| return; |
| } |
| if (&src == this) { |
| // ChunkIterator below assumes that src is not modified during traversal. |
| Append(Cord(src)); |
| return; |
| } |
| // TODO(mec): Should we only do this if "dst" has space? |
| for (absl::string_view chunk : src.Chunks()) { |
| Append(chunk); |
| } |
| return; |
| } |
| |
| // Guaranteed to be a tree (kMaxBytesToCopy > kInlinedSize) |
| CordRep* rep = std::forward<C>(src).TakeRep(); |
| contents_.AppendTree(rep, CordzUpdateTracker::kAppendCord); |
| } |
| |
| void Cord::Append(const Cord& src) { AppendImpl(src); } |
| |
| void Cord::Append(Cord&& src) { AppendImpl(std::move(src)); } |
| |
| template <typename T, Cord::EnableIfString<T>> |
| void Cord::Append(T&& src) { |
| if (src.size() <= kMaxBytesToCopy) { |
| Append(absl::string_view(src)); |
| } else { |
| CordRep* rep = CordRepFromString(std::forward<T>(src)); |
| contents_.AppendTree(rep, CordzUpdateTracker::kAppendString); |
| } |
| } |
| |
| template void Cord::Append(std::string&& src); |
| |
| void Cord::Prepend(const Cord& src) { |
| CordRep* src_tree = src.contents_.tree(); |
| if (src_tree != nullptr) { |
| CordRep::Ref(src_tree); |
| contents_.PrependTree(src_tree, CordzUpdateTracker::kPrependCord); |
| return; |
| } |
| |
| // `src` cord is inlined. |
| absl::string_view src_contents(src.contents_.data(), src.contents_.size()); |
| return Prepend(src_contents); |
| } |
| |
| void Cord::Prepend(absl::string_view src) { |
| if (src.empty()) return; // memcpy(_, nullptr, 0) is undefined. |
| if (!contents_.is_tree()) { |
| size_t cur_size = contents_.inline_size(); |
| if (cur_size + src.size() <= InlineRep::kMaxInline) { |
| // Use embedded storage. |
| char data[InlineRep::kMaxInline + 1] = {0}; |
| memcpy(data, src.data(), src.size()); |
| memcpy(data + src.size(), contents_.data(), cur_size); |
| memcpy(contents_.data_.as_chars(), data, InlineRep::kMaxInline + 1); |
| contents_.set_inline_size(cur_size + src.size()); |
| return; |
| } |
| } |
| CordRep* rep = NewTree(src.data(), src.size(), 0); |
| contents_.PrependTree(rep, CordzUpdateTracker::kPrependString); |
| } |
| |
| template <typename T, Cord::EnableIfString<T>> |
| inline void Cord::Prepend(T&& src) { |
| if (src.size() <= kMaxBytesToCopy) { |
| Prepend(absl::string_view(src)); |
| } else { |
| CordRep* rep = CordRepFromString(std::forward<T>(src)); |
| contents_.PrependTree(rep, CordzUpdateTracker::kPrependString); |
| } |
| } |
| |
| template void Cord::Prepend(std::string&& src); |
| |
| static CordRep* RemovePrefixFrom(CordRep* node, size_t n) { |
| if (n >= node->length) return nullptr; |
| if (n == 0) return CordRep::Ref(node); |
| absl::InlinedVector<CordRep*, kInlinedVectorSize> rhs_stack; |
| |
| while (node->tag == CONCAT) { |
| assert(n <= node->length); |
| if (n < node->concat()->left->length) { |
| // Push right to stack, descend left. |
| rhs_stack.push_back(node->concat()->right); |
| node = node->concat()->left; |
| } else { |
| // Drop left, descend right. |
| n -= node->concat()->left->length; |
| node = node->concat()->right; |
| } |
| } |
| assert(n <= node->length); |
| |
| if (n == 0) { |
| CordRep::Ref(node); |
| } else { |
| size_t start = n; |
| size_t len = node->length - n; |
| if (node->tag == SUBSTRING) { |
| // Consider in-place update of node, similar to in RemoveSuffixFrom(). |
| start += node->substring()->start; |
| node = node->substring()->child; |
| } |
| node = NewSubstring(CordRep::Ref(node), start, len); |
| } |
| while (!rhs_stack.empty()) { |
| node = Concat(node, CordRep::Ref(rhs_stack.back())); |
| rhs_stack.pop_back(); |
| } |
| return node; |
| } |
| |
| // RemoveSuffixFrom() is very similar to RemovePrefixFrom(), with the |
| // exception that removing a suffix has an optimization where a node may be |
| // edited in place iff that node and all its ancestors have a refcount of 1. |
| static CordRep* RemoveSuffixFrom(CordRep* node, size_t n) { |
| if (n >= node->length) return nullptr; |
| if (n == 0) return CordRep::Ref(node); |
| absl::InlinedVector<CordRep*, kInlinedVectorSize> lhs_stack; |
| bool inplace_ok = node->refcount.IsOne(); |
| |
| while (node->tag == CONCAT) { |
| assert(n <= node->length); |
| if (n < node->concat()->right->length) { |
| // Push left to stack, descend right. |
| lhs_stack.push_back(node->concat()->left); |
| node = node->concat()->right; |
| } else { |
| // Drop right, descend left. |
| n -= node->concat()->right->length; |
| node = node->concat()->left; |
| } |
| inplace_ok = inplace_ok && node->refcount.IsOne(); |
| } |
| assert(n <= node->length); |
| |
| if (n == 0) { |
| CordRep::Ref(node); |
| } else if (inplace_ok && node->tag != EXTERNAL) { |
| // Consider making a new buffer if the current node capacity is much |
| // larger than the new length. |
| CordRep::Ref(node); |
| node->length -= n; |
| } else { |
| size_t start = 0; |
| size_t len = node->length - n; |
| if (node->tag == SUBSTRING) { |
| start = node->substring()->start; |
| node = node->substring()->child; |
| } |
| node = NewSubstring(CordRep::Ref(node), start, len); |
| } |
| while (!lhs_stack.empty()) { |
| node = Concat(CordRep::Ref(lhs_stack.back()), node); |
| lhs_stack.pop_back(); |
| } |
| return node; |
| } |
| |
| void Cord::RemovePrefix(size_t n) { |
| ABSL_INTERNAL_CHECK(n <= size(), |
| absl::StrCat("Requested prefix size ", n, |
| " exceeds Cord's size ", size())); |
| CordRep* tree = contents_.tree(); |
| if (tree == nullptr) { |
| contents_.remove_prefix(n); |
| } else { |
| auto constexpr method = CordzUpdateTracker::kRemovePrefix; |
| CordzUpdateScope scope(contents_.cordz_info(), method); |
| if (tree->tag == RING) { |
| tree = CordRepRing::RemovePrefix(tree->ring(), n); |
| } else { |
| CordRep* newrep = RemovePrefixFrom(tree, n); |
| CordRep::Unref(tree); |
| tree = VerifyTree(newrep); |
| } |
| contents_.SetTreeOrEmpty(tree, scope); |
| } |
| } |
| |
| void Cord::RemoveSuffix(size_t n) { |
| ABSL_INTERNAL_CHECK(n <= size(), |
| absl::StrCat("Requested suffix size ", n, |
| " exceeds Cord's size ", size())); |
| CordRep* tree = contents_.tree(); |
| if (tree == nullptr) { |
| contents_.reduce_size(n); |
| } else { |
| auto constexpr method = CordzUpdateTracker::kRemoveSuffix; |
| CordzUpdateScope scope(contents_.cordz_info(), method); |
| if (tree->tag == RING) { |
| tree = CordRepRing::RemoveSuffix(tree->ring(), n); |
| } else { |
| CordRep* newrep = RemoveSuffixFrom(tree, n); |
| CordRep::Unref(tree); |
| tree = VerifyTree(newrep); |
| } |
| contents_.SetTreeOrEmpty(tree, scope); |
| } |
| } |
| |
| // Work item for NewSubRange(). |
| struct SubRange { |
| SubRange(CordRep* a_node, size_t a_pos, size_t a_n) |
| : node(a_node), pos(a_pos), n(a_n) {} |
| CordRep* node; // nullptr means concat last 2 results. |
| size_t pos; |
| size_t n; |
| }; |
| |
| static CordRep* NewSubRange(CordRep* node, size_t pos, size_t n) { |
| absl::InlinedVector<CordRep*, kInlinedVectorSize> results; |
| absl::InlinedVector<SubRange, kInlinedVectorSize> todo; |
| todo.push_back(SubRange(node, pos, n)); |
| do { |
| const SubRange& sr = todo.back(); |
| node = sr.node; |
| pos = sr.pos; |
| n = sr.n; |
| todo.pop_back(); |
| |
| if (node == nullptr) { |
| assert(results.size() >= 2); |
| CordRep* right = results.back(); |
| results.pop_back(); |
| CordRep* left = results.back(); |
| results.pop_back(); |
| results.push_back(Concat(left, right)); |
| } else if (pos == 0 && n == node->length) { |
| results.push_back(CordRep::Ref(node)); |
| } else if (node->tag != CONCAT) { |
| if (node->tag == SUBSTRING) { |
| pos += node->substring()->start; |
| node = node->substring()->child; |
| } |
| results.push_back(NewSubstring(CordRep::Ref(node), pos, n)); |
| } else if (pos + n <= node->concat()->left->length) { |
| todo.push_back(SubRange(node->concat()->left, pos, n)); |
| } else if (pos >= node->concat()->left->length) { |
| pos -= node->concat()->left->length; |
| todo.push_back(SubRange(node->concat()->right, pos, n)); |
| } else { |
| size_t left_n = node->concat()->left->length - pos; |
| todo.push_back(SubRange(nullptr, 0, 0)); // Concat() |
| todo.push_back(SubRange(node->concat()->right, 0, n - left_n)); |
| todo.push_back(SubRange(node->concat()->left, pos, left_n)); |
| } |
| } while (!todo.empty()); |
| assert(results.size() == 1); |
| return results[0]; |
| } |
| |
| Cord Cord::Subcord(size_t pos, size_t new_size) const { |
| Cord sub_cord; |
| size_t length = size(); |
| if (pos > length) pos = length; |
| if (new_size > length - pos) new_size = length - pos; |
| if (new_size == 0) return sub_cord; |
| |
| CordRep* tree = contents_.tree(); |
| if (tree == nullptr) { |
| // sub_cord is newly constructed, no need to re-zero-out the tail of |
| // contents_ memory. |
| sub_cord.contents_.set_data(contents_.data() + pos, new_size, false); |
| return sub_cord; |
| } |
| |
| if (new_size <= InlineRep::kMaxInline) { |
| char* dest = sub_cord.contents_.data_.as_chars(); |
| Cord::ChunkIterator it = chunk_begin(); |
| it.AdvanceBytes(pos); |
| size_t remaining_size = new_size; |
| while (remaining_size > it->size()) { |
| cord_internal::SmallMemmove(dest, it->data(), it->size()); |
| remaining_size -= it->size(); |
| dest += it->size(); |
| ++it; |
| } |
| cord_internal::SmallMemmove(dest, it->data(), remaining_size); |
| sub_cord.contents_.set_inline_size(new_size); |
| return sub_cord; |
| } |
| |
| if (tree->tag == RING) { |
| CordRepRing* ring = CordRep::Ref(tree)->ring(); |
| tree = CordRepRing::SubRing(ring, pos, new_size); |
| } else { |
| tree = NewSubRange(tree, pos, new_size); |
| } |
| sub_cord.contents_.EmplaceTree(tree, contents_.data_, |
| CordzUpdateTracker::kSubCord); |
| return sub_cord; |
| } |
| |
| // -------------------------------------------------------------------- |
| // Balancing |
| |
| class CordForest { |
| public: |
| explicit CordForest(size_t length) |
| : root_length_(length), trees_(kMinLengthSize, nullptr) {} |
| |
| void Build(CordRep* cord_root) { |
| std::vector<CordRep*> pending = {cord_root}; |
| |
| while (!pending.empty()) { |
| CordRep* node = pending.back(); |
| pending.pop_back(); |
| CheckNode(node); |
| if (ABSL_PREDICT_FALSE(node->tag != CONCAT)) { |
| AddNode(node); |
| continue; |
| } |
| |
| CordRepConcat* concat_node = node->concat(); |
| if (concat_node->depth() >= kMinLengthSize || |
| concat_node->length < min_length[concat_node->depth()]) { |
| pending.push_back(concat_node->right); |
| pending.push_back(concat_node->left); |
| |
| if (concat_node->refcount.IsOne()) { |
| concat_node->left = concat_freelist_; |
| concat_freelist_ = concat_node; |
| } else { |
| CordRep::Ref(concat_node->right); |
| CordRep::Ref(concat_node->left); |
| CordRep::Unref(concat_node); |
| } |
| } else { |
| AddNode(node); |
| } |
| } |
| } |
| |
| CordRep* ConcatNodes() { |
| CordRep* sum = nullptr; |
| for (auto* node : trees_) { |
| if (node == nullptr) continue; |
| |
| sum = PrependNode(node, sum); |
| root_length_ -= node->length; |
| if (root_length_ == 0) break; |
| } |
| ABSL_INTERNAL_CHECK(sum != nullptr, "Failed to locate sum node"); |
| return VerifyTree(sum); |
| } |
| |
| private: |
| CordRep* AppendNode(CordRep* node, CordRep* sum) { |
| return (sum == nullptr) ? node : MakeConcat(sum, node); |
| } |
| |
| CordRep* PrependNode(CordRep* node, CordRep* sum) { |
| return (sum == nullptr) ? node : MakeConcat(node, sum); |
| } |
| |
| void AddNode(CordRep* node) { |
| CordRep* sum = nullptr; |
| |
| // Collect together everything with which we will merge with node |
| int i = 0; |
| for (; node->length > min_length[i + 1]; ++i) { |
| auto& tree_at_i = trees_[i]; |
| |
| if (tree_at_i == nullptr) continue; |
| sum = PrependNode(tree_at_i, sum); |
| tree_at_i = nullptr; |
| } |
| |
| sum = AppendNode(node, sum); |
| |
| // Insert sum into appropriate place in the forest |
| for (; sum->length >= min_length[i]; ++i) { |
| auto& tree_at_i = trees_[i]; |
| if (tree_at_i == nullptr) continue; |
| |
| sum = MakeConcat(tree_at_i, sum); |
| tree_at_i = nullptr; |
| } |
| |
| // min_length[0] == 1, which means sum->length >= min_length[0] |
| assert(i > 0); |
| trees_[i - 1] = sum; |
| } |
| |
| // Make concat node trying to resue existing CordRepConcat nodes we |
| // already collected in the concat_freelist_. |
| CordRep* MakeConcat(CordRep* left, CordRep* right) { |
| if (concat_freelist_ == nullptr) return RawConcat(left, right); |
| |
| CordRepConcat* rep = concat_freelist_; |
| if (concat_freelist_->left == nullptr) { |
| concat_freelist_ = nullptr; |
| } else { |
| concat_freelist_ = concat_freelist_->left->concat(); |
| } |
| SetConcatChildren(rep, left, right); |
| |
| return rep; |
| } |
| |
| static void CheckNode(CordRep* node) { |
| ABSL_INTERNAL_CHECK(node->length != 0u, ""); |
| if (node->tag == CONCAT) { |
| ABSL_INTERNAL_CHECK(node->concat()->left != nullptr, ""); |
| ABSL_INTERNAL_CHECK(node->concat()->right != nullptr, ""); |
| ABSL_INTERNAL_CHECK(node->length == (node->concat()->left->length + |
| node->concat()->right->length), |
| ""); |
| } |
| } |
| |
| size_t root_length_; |
| |
| // use an inlined vector instead of a flat array to get bounds checking |
| absl::InlinedVector<CordRep*, kInlinedVectorSize> trees_; |
| |
| // List of concat nodes we can re-use for Cord balancing. |
| CordRepConcat* concat_freelist_ = nullptr; |
| }; |
| |
| static CordRep* Rebalance(CordRep* node) { |
| VerifyTree(node); |
| assert(node->tag == CONCAT); |
| |
| if (node->length == 0) { |
| return nullptr; |
| } |
| |
| CordForest forest(node->length); |
| forest.Build(node); |
| return forest.ConcatNodes(); |
| } |
| |
| // -------------------------------------------------------------------- |
| // Comparators |
| |
| namespace { |
| |
| int ClampResult(int memcmp_res) { |
| return static_cast<int>(memcmp_res > 0) - static_cast<int>(memcmp_res < 0); |
| } |
| |
| int CompareChunks(absl::string_view* lhs, absl::string_view* rhs, |
| size_t* size_to_compare) { |
| size_t compared_size = std::min(lhs->size(), rhs->size()); |
| assert(*size_to_compare >= compared_size); |
| *size_to_compare -= compared_size; |
| |
| int memcmp_res = ::memcmp(lhs->data(), rhs->data(), compared_size); |
| if (memcmp_res != 0) return memcmp_res; |
| |
| lhs->remove_prefix(compared_size); |
| rhs->remove_prefix(compared_size); |
| |
| return 0; |
| } |
| |
| // This overload set computes comparison results from memcmp result. This |
| // interface is used inside GenericCompare below. Differet implementations |
| // are specialized for int and bool. For int we clamp result to {-1, 0, 1} |
| // set. For bool we just interested in "value == 0". |
| template <typename ResultType> |
| ResultType ComputeCompareResult(int memcmp_res) { |
| return ClampResult(memcmp_res); |
| } |
| template <> |
| bool ComputeCompareResult<bool>(int memcmp_res) { |
| return memcmp_res == 0; |
| } |
| |
| } // namespace |
| |
| // Helper routine. Locates the first flat chunk of the Cord without |
| // initializing the iterator. |
| inline absl::string_view Cord::InlineRep::FindFlatStartPiece() const { |
| if (!is_tree()) { |
| return absl::string_view(data_.as_chars(), data_.inline_size()); |
| } |
| |
| CordRep* node = tree(); |
| if (node->tag >= FLAT) { |
| return absl::string_view(node->flat()->Data(), node->length); |
| } |
| |
| if (node->tag == EXTERNAL) { |
| return absl::string_view(node->external()->base, node->length); |
| } |
| |
| if (node->tag == RING) { |
| return node->ring()->entry_data(node->ring()->head()); |
| } |
| |
| // Walk down the left branches until we hit a non-CONCAT node. |
| while (node->tag == CONCAT) { |
| node = node->concat()->left; |
| } |
| |
| // Get the child node if we encounter a SUBSTRING. |
| size_t offset = 0; |
| size_t length = node->length; |
| assert(length != 0); |
| |
| if (node->tag == SUBSTRING) { |
| offset = node->substring()->start; |
| node = node->substring()->child; |
| } |
| |
| if (node->tag >= FLAT) { |
| return absl::string_view(node->flat()->Data() + offset, length); |
| } |
| |
| assert((node->tag == EXTERNAL) && "Expect FLAT or EXTERNAL node here"); |
| |
| return absl::string_view(node->external()->base + offset, length); |
| } |
| |
| inline int Cord::CompareSlowPath(absl::string_view rhs, size_t compared_size, |
| size_t size_to_compare) const { |
| auto advance = [](Cord::ChunkIterator* it, absl::string_view* chunk) { |
| if (!chunk->empty()) return true; |
| ++*it; |
| if (it->bytes_remaining_ == 0) return false; |
| *chunk = **it; |
| return true; |
| }; |
| |
| Cord::ChunkIterator lhs_it = chunk_begin(); |
| |
| // compared_size is inside first chunk. |
| absl::string_view lhs_chunk = |
| (lhs_it.bytes_remaining_ != 0) ? *lhs_it : absl::string_view(); |
| assert(compared_size <= lhs_chunk.size()); |
| assert(compared_size <= rhs.size()); |
| lhs_chunk.remove_prefix(compared_size); |
| rhs.remove_prefix(compared_size); |
| size_to_compare -= compared_size; // skip already compared size. |
| |
| while (advance(&lhs_it, &lhs_chunk) && !rhs.empty()) { |
| int comparison_result = CompareChunks(&lhs_chunk, &rhs, &size_to_compare); |
| if (comparison_result != 0) return comparison_result; |
| if (size_to_compare == 0) return 0; |
| } |
| |
| return static_cast<int>(rhs.empty()) - static_cast<int>(lhs_chunk.empty()); |
| } |
| |
| inline int Cord::CompareSlowPath(const Cord& rhs, size_t compared_size, |
| size_t size_to_compare) const { |
| auto advance = [](Cord::ChunkIterator* it, absl::string_view* chunk) { |
| if (!chunk->empty()) return true; |
| ++*it; |
| if (it->bytes_remaining_ == 0) return false; |
| *chunk = **it; |
| return true; |
| }; |
| |
| Cord::ChunkIterator lhs_it = chunk_begin(); |
| Cord::ChunkIterator rhs_it = rhs.chunk_begin(); |
| |
| // compared_size is inside both first chunks. |
| absl::string_view lhs_chunk = |
| (lhs_it.bytes_remaining_ != 0) ? *lhs_it : absl::string_view(); |
| absl::string_view rhs_chunk = |
| (rhs_it.bytes_remaining_ != 0) ? *rhs_it : absl::string_view(); |
| assert(compared_size <= lhs_chunk.size()); |
| assert(compared_size <= rhs_chunk.size()); |
| lhs_chunk.remove_prefix(compared_size); |
| rhs_chunk.remove_prefix(compared_size); |
| size_to_compare -= compared_size; // skip already compared size. |
| |
| while (advance(&lhs_it, &lhs_chunk) && advance(&rhs_it, &rhs_chunk)) { |
| int memcmp_res = CompareChunks(&lhs_chunk, &rhs_chunk, &size_to_compare); |
| if (memcmp_res != 0) return memcmp_res; |
| if (size_to_compare == 0) return 0; |
| } |
| |
| return static_cast<int>(rhs_chunk.empty()) - |
| static_cast<int>(lhs_chunk.empty()); |
| } |
| |
| inline absl::string_view Cord::GetFirstChunk(const Cord& c) { |
| return c.contents_.FindFlatStartPiece(); |
| } |
| inline absl::string_view Cord::GetFirstChunk(absl::string_view sv) { |
| return sv; |
| } |
| |
| // Compares up to 'size_to_compare' bytes of 'lhs' with 'rhs'. It is assumed |
| // that 'size_to_compare' is greater that size of smallest of first chunks. |
| template <typename ResultType, typename RHS> |
| ResultType GenericCompare(const Cord& lhs, const RHS& rhs, |
| size_t size_to_compare) { |
| absl::string_view lhs_chunk = Cord::GetFirstChunk(lhs); |
| absl::string_view rhs_chunk = Cord::GetFirstChunk(rhs); |
| |
| size_t compared_size = std::min(lhs_chunk.size(), rhs_chunk.size()); |
| assert(size_to_compare >= compared_size); |
| int memcmp_res = ::memcmp(lhs_chunk.data(), rhs_chunk.data(), compared_size); |
| if (compared_size == size_to_compare || memcmp_res != 0) { |
| return ComputeCompareResult<ResultType>(memcmp_res); |
| } |
| |
| return ComputeCompareResult<ResultType>( |
| lhs.CompareSlowPath(rhs, compared_size, size_to_compare)); |
| } |
| |
| bool Cord::EqualsImpl(absl::string_view rhs, size_t size_to_compare) const { |
| return GenericCompare<bool>(*this, rhs, size_to_compare); |
| } |
| |
| bool Cord::EqualsImpl(const Cord& rhs, size_t size_to_compare) const { |
| return GenericCompare<bool>(*this, rhs, size_to_compare); |
| } |
| |
| template <typename RHS> |
| inline int SharedCompareImpl(const Cord& lhs, const RHS& rhs) { |
| size_t lhs_size = lhs.size(); |
| size_t rhs_size = rhs.size(); |
| if (lhs_size == rhs_size) { |
| return GenericCompare<int>(lhs, rhs, lhs_size); |
| } |
| if (lhs_size < rhs_size) { |
| auto data_comp_res = GenericCompare<int>(lhs, rhs, lhs_size); |
| return data_comp_res == 0 ? -1 : data_comp_res; |
| } |
| |
| auto data_comp_res = GenericCompare<int>(lhs, rhs, rhs_size); |
| return data_comp_res == 0 ? +1 : data_comp_res; |
| } |
| |
| int Cord::Compare(absl::string_view rhs) const { |
| return SharedCompareImpl(*this, rhs); |
| } |
| |
| int Cord::CompareImpl(const Cord& rhs) const { |
| return SharedCompareImpl(*this, rhs); |
| } |
| |
| bool Cord::EndsWith(absl::string_view rhs) const { |
| size_t my_size = size(); |
| size_t rhs_size = rhs.size(); |
| |
| if (my_size < rhs_size) return false; |
| |
| Cord tmp(*this); |
| tmp.RemovePrefix(my_size - rhs_size); |
| return tmp.EqualsImpl(rhs, rhs_size); |
| } |
| |
| bool Cord::EndsWith(const Cord& rhs) const { |
| size_t my_size = size(); |
| size_t rhs_size = rhs.size(); |
| |
| if (my_size < rhs_size) return false; |
| |
| Cord tmp(*this); |
| tmp.RemovePrefix(my_size - rhs_size); |
| return tmp.EqualsImpl(rhs, rhs_size); |
| } |
| |
| // -------------------------------------------------------------------- |
| // Misc. |
| |
| Cord::operator std::string() const { |
| std::string s; |
| absl::CopyCordToString(*this, &s); |
| return s; |
| } |
| |
| void CopyCordToString(const Cord& src, std::string* dst) { |
| if (!src.contents_.is_tree()) { |
| src.contents_.CopyTo(dst); |
| } else { |
| absl::strings_internal::STLStringResizeUninitialized(dst, src.size()); |
| src.CopyToArraySlowPath(&(*dst)[0]); |
| } |
| } |
| |
| void Cord::CopyToArraySlowPath(char* dst) const { |
| assert(contents_.is_tree()); |
| absl::string_view fragment; |
| if (GetFlatAux(contents_.tree(), &fragment)) { |
| memcpy(dst, fragment.data(), fragment.size()); |
| return; |
| } |
| for (absl::string_view chunk : Chunks()) { |
| memcpy(dst, chunk.data(), chunk.size()); |
| dst += chunk.size(); |
| } |
| } |
| |
| Cord::ChunkIterator& Cord::ChunkIterator::AdvanceStack() { |
| auto& stack_of_right_children = stack_of_right_children_; |
| if (stack_of_right_children.empty()) { |
| assert(!current_chunk_.empty()); // Called on invalid iterator. |
| // We have reached the end of the Cord. |
| return *this; |
| } |
| |
| // Process the next node on the stack. |
| CordRep* node = stack_of_right_children.back(); |
| stack_of_right_children.pop_back(); |
| |
| // Walk down the left branches until we hit a non-CONCAT node. Save the |
| // right children to the stack for subsequent traversal. |
| while (node->tag == CONCAT) { |
| stack_of_right_children.push_back(node->concat()->right); |
| node = node->concat()->left; |
| } |
| |
| // Get the child node if we encounter a SUBSTRING. |
| size_t offset = 0; |
| size_t length = node->length; |
| if (node->tag == SUBSTRING) { |
| offset = node->substring()->start; |
| node = node->substring()->child; |
| } |
| |
| assert(node->tag == EXTERNAL || node->tag >= FLAT); |
| assert(length != 0); |
| const char* data = |
| node->tag == EXTERNAL ? node->external()->base : node->flat()->Data(); |
| current_chunk_ = absl::string_view(data + offset, length); |
| current_leaf_ = node; |
| return *this; |
| } |
| |
| Cord Cord::ChunkIterator::AdvanceAndReadBytes(size_t n) { |
| ABSL_HARDENING_ASSERT(bytes_remaining_ >= n && |
| "Attempted to iterate past `end()`"); |
| Cord subcord; |
| auto constexpr method = CordzUpdateTracker::kCordReader; |
| |
| if (n <= InlineRep::kMaxInline) { |
| // Range to read fits in inline data. Flatten it. |
| char* data = subcord.contents_.set_data(n); |
| while (n > current_chunk_.size()) { |
| memcpy(data, current_chunk_.data(), current_chunk_.size()); |
| data += current_chunk_.size(); |
| n -= current_chunk_.size(); |
| ++*this; |
| } |
| memcpy(data, current_chunk_.data(), n); |
| if (n < current_chunk_.size()) { |
| RemoveChunkPrefix(n); |
| } else if (n > 0) { |
| ++*this; |
| } |
| return subcord; |
| } |
| |
| if (ring_reader_) { |
| size_t chunk_size = current_chunk_.size(); |
| if (n <= chunk_size && n <= kMaxBytesToCopy) { |
| subcord = Cord(current_chunk_.substr(0, n), method); |
| } else { |
| auto* ring = CordRep::Ref(ring_reader_.ring())->ring(); |
| size_t offset = ring_reader_.length() - bytes_remaining_; |
| CordRep* rep = CordRepRing::SubRing(ring, offset, n); |
| subcord.contents_.EmplaceTree(rep, method); |
| } |
| if (n < chunk_size) { |
| bytes_remaining_ -= n; |
| current_chunk_.remove_prefix(n); |
| } else { |
| AdvanceBytesRing(n); |
| } |
| return subcord; |
| } |
| |
| auto& stack_of_right_children = stack_of_right_children_; |
| if (n < current_chunk_.size()) { |
| // Range to read is a proper subrange of the current chunk. |
| assert(current_leaf_ != nullptr); |
| CordRep* subnode = CordRep::Ref(current_leaf_); |
| const char* data = subnode->tag == EXTERNAL ? subnode->external()->base |
| : subnode->flat()->Data(); |
| subnode = NewSubstring(subnode, current_chunk_.data() - data, n); |
| subcord.contents_.EmplaceTree(VerifyTree(subnode), method); |
| RemoveChunkPrefix(n); |
| return subcord; |
| } |
| |
| // Range to read begins with a proper subrange of the current chunk. |
| assert(!current_chunk_.empty()); |
| assert(current_leaf_ != nullptr); |
| CordRep* subnode = CordRep::Ref(current_leaf_); |
| if (current_chunk_.size() < subnode->length) { |
| const char* data = subnode->tag == EXTERNAL ? subnode->external()->base |
| : subnode->flat()->Data(); |
| subnode = NewSubstring(subnode, current_chunk_.data() - data, |
| current_chunk_.size()); |
| } |
| n -= current_chunk_.size(); |
| bytes_remaining_ -= current_chunk_.size(); |
| |
| // Process the next node(s) on the stack, reading whole subtrees depending on |
| // their length and how many bytes we are advancing. |
| CordRep* node = nullptr; |
| while (!stack_of_right_children.empty()) { |
| node = stack_of_right_children.back(); |
| stack_of_right_children.pop_back(); |
| if (node->length > n) break; |
| // TODO(qrczak): This might unnecessarily recreate existing concat nodes. |
| // Avoiding that would need pretty complicated logic (instead of |
| // current_leaf, keep current_subtree_ which points to the highest node |
| // such that the current leaf can be found on the path of left children |
| // starting from current_subtree_; delay creating subnode while node is |
| // below current_subtree_; find the proper node along the path of left |
| // children starting from current_subtree_ if this loop exits while staying |
| // below current_subtree_; etc.; alternatively, push parents instead of |
| // right children on the stack). |
| subnode = Concat(subnode, CordRep::Ref(node)); |
| n -= node->length; |
| bytes_remaining_ -= node->length; |
| node = nullptr; |
| } |
| |
| if (node == nullptr) { |
| // We have reached the end of the Cord. |
| assert(bytes_remaining_ == 0); |
| subcord.contents_.EmplaceTree(VerifyTree(subnode), method); |
| return subcord; |
| } |
| |
| // Walk down the appropriate branches until we hit a non-CONCAT node. Save the |
| // right children to the stack for subsequent traversal. |
| while (node->tag == CONCAT) { |
| if (node->concat()->left->length > n) { |
| // Push right, descend left. |
| stack_of_right_children.push_back(node->concat()->right); |
| node = node->concat()->left; |
| } else { |
| // Read left, descend right. |
| subnode = Concat(subnode, CordRep::Ref(node->concat()->left)); |
| n -= node->concat()->left->length; |
| bytes_remaining_ -= node->concat()->left->length; |
| node = node->concat()->right; |
| } |
| } |
| |
| // Get the child node if we encounter a SUBSTRING. |
| size_t offset = 0; |
| size_t length = node->length; |
| if (node->tag == SUBSTRING) { |
| offset = node->substring()->start; |
| node = node->substring()->child; |
| } |
| |
| // Range to read ends with a proper (possibly empty) subrange of the current |
| // chunk. |
| assert(node->tag == EXTERNAL || node->tag >= FLAT); |
| assert(length > n); |
| if (n > 0) { |
| subnode = Concat(subnode, NewSubstring(CordRep::Ref(node), offset, n)); |
| } |
| const char* data = |
| node->tag == EXTERNAL ? node->external()->base : node->flat()->Data(); |
| current_chunk_ = absl::string_view(data + offset + n, length - n); |
| current_leaf_ = node; |
| bytes_remaining_ -= n; |
| subcord.contents_.EmplaceTree(VerifyTree(subnode), method); |
| return subcord; |
| } |
| |
| void Cord::ChunkIterator::AdvanceBytesSlowPath(size_t n) { |
| assert(bytes_remaining_ >= n && "Attempted to iterate past `end()`"); |
| assert(n >= current_chunk_.size()); // This should only be called when |
| // iterating to a new node. |
| |
| n -= current_chunk_.size(); |
| bytes_remaining_ -= current_chunk_.size(); |
| |
| if (stack_of_right_children_.empty()) { |
| // We have reached the end of the Cord. |
| assert(bytes_remaining_ == 0); |
| return; |
| } |
| |
| // Process the next node(s) on the stack, skipping whole subtrees depending on |
| // their length and how many bytes we are advancing. |
| CordRep* node = nullptr; |
| auto& stack_of_right_children = stack_of_right_children_; |
| while (!stack_of_right_children.empty()) { |
| node = stack_of_right_children.back(); |
| stack_of_right_children.pop_back(); |
| if (node->length > n) break; |
| n -= node->length; |
| bytes_remaining_ -= node->length; |
| node = nullptr; |
| } |
| |
| if (node == nullptr) { |
| // We have reached the end of the Cord. |
| assert(bytes_remaining_ == 0); |
| return; |
| } |
| |
| // Walk down the appropriate branches until we hit a non-CONCAT node. Save the |
| // right children to the stack for subsequent traversal. |
| while (node->tag == CONCAT) { |
| if (node->concat()->left->length > n) { |
| // Push right, descend left. |
| stack_of_right_children.push_back(node->concat()->right); |
| node = node->concat()->left; |
| } else { |
| // Skip left, descend right. |
| n -= node->concat()->left->length; |
| bytes_remaining_ -= node->concat()->left->length; |
| node = node->concat()->right; |
| } |
| } |
| |
| // Get the child node if we encounter a SUBSTRING. |
| size_t offset = 0; |
| size_t length = node->length; |
| if (node->tag == SUBSTRING) { |
| offset = node->substring()->start; |
| node = node->substring()->child; |
| } |
| |
| assert(node->tag == EXTERNAL || node->tag >= FLAT); |
| assert(length > n); |
| const char* data = |
| node->tag == EXTERNAL ? node->external()->base : node->flat()->Data(); |
| current_chunk_ = absl::string_view(data + offset + n, length - n); |
| current_leaf_ = node; |
| bytes_remaining_ -= n; |
| } |
| |
| char Cord::operator[](size_t i) const { |
| ABSL_HARDENING_ASSERT(i < size()); |
| size_t offset = i; |
| const CordRep* rep = contents_.tree(); |
| if (rep == nullptr) { |
| return contents_.data()[i]; |
| } |
| while (true) { |
| assert(rep != nullptr); |
| assert(offset < rep->length); |
| if (rep->tag >= FLAT) { |
| // Get the "i"th character directly from the flat array. |
| return rep->flat()->Data()[offset]; |
| } else if (rep->tag == RING) { |
| return rep->ring()->GetCharacter(offset); |
| } else if (rep->tag == EXTERNAL) { |
| // Get the "i"th character from the external array. |
| return rep->external()->base[offset]; |
| } else if (rep->tag == CONCAT) { |
| // Recursively branch to the side of the concatenation that the "i"th |
| // character is on. |
| size_t left_length = rep->concat()->left->length; |
| if (offset < left_length) { |
| rep = rep->concat()->left; |
| } else { |
| offset -= left_length; |
| rep = rep->concat()->right; |
| } |
| } else { |
| // This must be a substring a node, so bypass it to get to the child. |
| assert(rep->tag == SUBSTRING); |
| offset += rep->substring()->start; |
| rep = rep->substring()->child; |
| } |
| } |
| } |
| |
| absl::string_view Cord::FlattenSlowPath() { |
| assert(contents_.is_tree()); |
| size_t total_size = size(); |
| CordRep* new_rep; |
| char* new_buffer; |
| |
| // Try to put the contents into a new flat rep. If they won't fit in the |
| // biggest possible flat node, use an external rep instead. |
| if (total_size <= kMaxFlatLength) { |
| new_rep = CordRepFlat::New(total_size); |
| new_rep->length = total_size; |
| new_buffer = new_rep->flat()->Data(); |
| CopyToArraySlowPath(new_buffer); |
| } else { |
| new_buffer = std::allocator<char>().allocate(total_size); |
| CopyToArraySlowPath(new_buffer); |
| new_rep = absl::cord_internal::NewExternalRep( |
| absl::string_view(new_buffer, total_size), [](absl::string_view s) { |
| std::allocator<char>().deallocate(const_cast<char*>(s.data()), |
| s.size()); |
| }); |
| } |
| CordzUpdateScope scope(contents_.cordz_info(), CordzUpdateTracker::kFlatten); |
| CordRep::Unref(contents_.as_tree()); |
| contents_.SetTree(new_rep, scope); |
| return absl::string_view(new_buffer, total_size); |
| } |
| |
| /* static */ bool Cord::GetFlatAux(CordRep* rep, absl::string_view* fragment) { |
| assert(rep != nullptr); |
| if (rep->tag >= FLAT) { |
| *fragment = absl::string_view(rep->flat()->Data(), rep->length); |
| return true; |
| } else if (rep->tag == EXTERNAL) { |
| *fragment = absl::string_view(rep->external()->base, rep->length); |
| return true; |
| } else if (rep->tag == RING) { |
| return rep->ring()->IsFlat(fragment); |
| } else if (rep->tag == SUBSTRING) { |
| CordRep* child = rep->substring()->child; |
| if (child->tag >= FLAT) { |
| *fragment = absl::string_view( |
| child->flat()->Data() + rep->substring()->start, rep->length); |
| return true; |
| } else if (child->tag == EXTERNAL) { |
| *fragment = absl::string_view( |
| child->external()->base + rep->substring()->start, rep->length); |
| return true; |
| } else if (child->tag == RING) { |
| return child->ring()->IsFlat(rep->substring()->start, rep->length, |
| fragment); |
| } |
| } |
| return false; |
| } |
| |
| /* static */ void Cord::ForEachChunkAux( |
| absl::cord_internal::CordRep* rep, |
| absl::FunctionRef<void(absl::string_view)> callback) { |
| if (rep->tag == RING) { |
| ChunkIterator it(rep), end; |
| while (it != end) { |
| callback(*it); |
| ++it; |
| } |
| return; |
| } |
| |
| assert(rep != nullptr); |
| int stack_pos = 0; |
| constexpr int stack_max = 128; |
| // Stack of right branches for tree traversal |
| absl::cord_internal::CordRep* stack[stack_max]; |
| absl::cord_internal::CordRep* current_node = rep; |
| while (true) { |
| if (current_node->tag == CONCAT) { |
| if (stack_pos == stack_max) { |
| // There's no more room on our stack array to add another right branch, |
| // and the idea is to avoid allocations, so call this function |
| // recursively to navigate this subtree further. (This is not something |
| // we expect to happen in practice). |
| ForEachChunkAux(current_node, callback); |
| |
| // Pop the next right branch and iterate. |
| current_node = stack[--stack_pos]; |
| continue; |
| } else { |
| // Save the right branch for later traversal and continue down the left |
| // branch. |
| stack[stack_pos++] = current_node->concat()->right; |
| current_node = current_node->concat()->left; |
| continue; |
| } |
| } |
| // This is a leaf node, so invoke our callback. |
| absl::string_view chunk; |
| bool success = GetFlatAux(current_node, &chunk); |
| assert(success); |
| if (success) { |
| callback(chunk); |
| } |
| if (stack_pos == 0) { |
| // end of traversal |
| return; |
| } |
| current_node = stack[--stack_pos]; |
| } |
| } |
| |
| static void DumpNode(CordRep* rep, bool include_data, std::ostream* os, |
| int indent) { |
| const int kIndentStep = 1; |
| absl::InlinedVector<CordRep*, kInlinedVectorSize> stack; |
| absl::InlinedVector<int, kInlinedVectorSize> indents; |
| for (;;) { |
| *os << std::setw(3) << rep->refcount.Get(); |
| *os << " " << std::setw(7) << rep->length; |
| *os << " ["; |
| if (include_data) *os << static_cast<void*>(rep); |
| *os << "]"; |
| *os << " " << (IsRootBalanced(rep) ? 'b' : 'u'); |
| *os << " " << std::setw(indent) << ""; |
| if (rep->tag == CONCAT) { |
| *os << "CONCAT depth=" << Depth(rep) << "\n"; |
| indent += kIndentStep; |
| indents.push_back(indent); |
| stack.push_back(rep->concat()->right); |
| rep = rep->concat()->left; |
| } else if (rep->tag == SUBSTRING) { |
| *os << "SUBSTRING @ " << rep->substring()->start << "\n"; |
| indent += kIndentStep; |
| rep = rep->substring()->child; |
| } else { // Leaf or ring |
| if (rep->tag == EXTERNAL) { |
| *os << "EXTERNAL ["; |
| if (include_data) |
| *os << absl::CEscape(std::string(rep->external()->base, rep->length)); |
| *os << "]\n"; |
| } else if (rep->tag >= FLAT) { |
| *os << "FLAT cap=" << rep->flat()->Capacity() << " ["; |
| if (include_data) |
| *os << absl::CEscape(std::string(rep->flat()->Data(), rep->length)); |
| *os << "]\n"; |
| } else { |
| assert(rep->tag == RING); |
| auto* ring = rep->ring(); |
| *os << "RING, entries = " << ring->entries() << "\n"; |
| CordRepRing::index_type head = ring->head(); |
| do { |
| DumpNode(ring->entry_child(head), include_data, os, |
| indent + kIndentStep); |
| head = ring->advance(head); |
| } while (head != ring->tail()); |
| } |
| if (stack.empty()) break; |
| rep = stack.back(); |
| stack.pop_back(); |
| indent = indents.back(); |
| indents.pop_back(); |
| } |
| } |
| ABSL_INTERNAL_CHECK(indents.empty(), ""); |
| } |
| |
| static std::string ReportError(CordRep* root, CordRep* node) { |
| std::ostringstream buf; |
| buf << "Error at node " << node << " in:"; |
| DumpNode(root, true, &buf); |
| return buf.str(); |
| } |
| |
| static bool VerifyNode(CordRep* root, CordRep* start_node, |
| bool full_validation) { |
| absl::InlinedVector<CordRep*, 2> worklist; |
| worklist.push_back(start_node); |
| do { |
| CordRep* node = worklist.back(); |
| worklist.pop_back(); |
| |
| ABSL_INTERNAL_CHECK(node != nullptr, ReportError(root, node)); |
| if (node != root) { |
| ABSL_INTERNAL_CHECK(node->length != 0, ReportError(root, node)); |
| } |
| |
| if (node->tag == CONCAT) { |
| ABSL_INTERNAL_CHECK(node->concat()->left != nullptr, |
| ReportError(root, node)); |
| ABSL_INTERNAL_CHECK(node->concat()->right != nullptr, |
| ReportError(root, node)); |
| ABSL_INTERNAL_CHECK((node->length == node->concat()->left->length + |
| node->concat()->right->length), |
| ReportError(root, node)); |
| if (full_validation) { |
| worklist.push_back(node->concat()->right); |
| worklist.push_back(node->concat()->left); |
| } |
| } else if (node->tag >= FLAT) { |
| ABSL_INTERNAL_CHECK(node->length <= node->flat()->Capacity(), |
| ReportError(root, node)); |
| } else if (node->tag == EXTERNAL) { |
| ABSL_INTERNAL_CHECK(node->external()->base != nullptr, |
| ReportError(root, node)); |
| } else if (node->tag == SUBSTRING) { |
| ABSL_INTERNAL_CHECK( |
| node->substring()->start < node->substring()->child->length, |
| ReportError(root, node)); |
| ABSL_INTERNAL_CHECK(node->substring()->start + node->length <= |
| node->substring()->child->length, |
| ReportError(root, node)); |
| } |
| } while (!worklist.empty()); |
| return true; |
| } |
| |
| // Traverses the tree and computes the total memory allocated. |
| /* static */ size_t Cord::MemoryUsageAux(const CordRep* rep) { |
| size_t total_mem_usage = 0; |
| |
| // Allow a quick exit for the common case that the root is a leaf. |
| if (RepMemoryUsageLeaf(rep, &total_mem_usage)) { |
| return total_mem_usage; |
| } |
| |
| // Iterate over the tree. cur_node is never a leaf node and leaf nodes will |
| // never be appended to tree_stack. This reduces overhead from manipulating |
| // tree_stack. |
| absl::InlinedVector<const CordRep*, kInlinedVectorSize> tree_stack; |
| const CordRep* cur_node = rep; |
| while (true) { |
| const CordRep* next_node = nullptr; |
| |
| if (cur_node->tag == CONCAT) { |
| total_mem_usage += sizeof(CordRepConcat); |
| const CordRep* left = cur_node->concat()->left; |
| if (!RepMemoryUsageLeaf(left, &total_mem_usage)) { |
| next_node = left; |
| } |
| |
| const CordRep* right = cur_node->concat()->right; |
| if (!RepMemoryUsageLeaf(right, &total_mem_usage)) { |
| if (next_node) { |
| tree_stack.push_back(next_node); |
| } |
| next_node = right; |
| } |
| } else if (cur_node->tag == RING) { |
| total_mem_usage += CordRepRing::AllocSize(cur_node->ring()->capacity()); |
| const CordRepRing* ring = cur_node->ring(); |
| CordRepRing::index_type pos = ring->head(), tail = ring->tail(); |
| do { |
| CordRep* node = ring->entry_child(pos); |
| assert(node->tag >= FLAT || node->tag == EXTERNAL); |
| RepMemoryUsageLeaf(node, &total_mem_usage); |
| } while ((pos = ring->advance(pos)) != tail); |
| } else { |
| // Since cur_node is not a leaf or a concat node it must be a substring. |
| assert(cur_node->tag == SUBSTRING); |
| total_mem_usage += sizeof(CordRepSubstring); |
| next_node = cur_node->substring()->child; |
| if (RepMemoryUsageLeaf(next_node, &total_mem_usage)) { |
| next_node = nullptr; |
| } |
| } |
| |
| if (!next_node) { |
| if (tree_stack.empty()) { |
| return total_mem_usage; |
| } |
| next_node = tree_stack.back(); |
| tree_stack.pop_back(); |
| } |
| cur_node = next_node; |
| } |
| } |
| |
| std::ostream& operator<<(std::ostream& out, const Cord& cord) { |
| for (absl::string_view chunk : cord.Chunks()) { |
| out.write(chunk.data(), chunk.size()); |
| } |
| return out; |
| } |
| |
| namespace strings_internal { |
| size_t CordTestAccess::FlatOverhead() { return cord_internal::kFlatOverhead; } |
| size_t CordTestAccess::MaxFlatLength() { return cord_internal::kMaxFlatLength; } |
| size_t CordTestAccess::FlatTagToLength(uint8_t tag) { |
| return cord_internal::TagToLength(tag); |
| } |
| uint8_t CordTestAccess::LengthToTag(size_t s) { |
| ABSL_INTERNAL_CHECK(s <= kMaxFlatLength, absl::StrCat("Invalid length ", s)); |
| return cord_internal::AllocatedSizeToTag(s + cord_internal::kFlatOverhead); |
| } |
| size_t CordTestAccess::SizeofCordRepConcat() { return sizeof(CordRepConcat); } |
| size_t CordTestAccess::SizeofCordRepExternal() { |
| return sizeof(CordRepExternal); |
| } |
| size_t CordTestAccess::SizeofCordRepSubstring() { |
| return sizeof(CordRepSubstring); |
| } |
| } // namespace strings_internal |
| ABSL_NAMESPACE_END |
| } // namespace absl |