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Export of internal Abseil changes

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--
91ca367a7548270155721bdda74611aeea2a2153 by Abseil Team <absl-team@google.com>:

Replace the only usage of btree_node::swap with simpler logic using transfers and delete btree_node::swap.

Add a benchmark for constructing small containers.

PiperOrigin-RevId: 301169874

--
ff9d73a7125b7f8ab5733cda877204dfbfac138e by Derek Mauro <dmauro@google.com>:

Ensure ABSL_CXX_STANDARD is set.
Fixes #640

PiperOrigin-RevId: 301160106

--
14ca0beee8c109e532134e7e9da7b072da1bf911 by Abseil Team <absl-team@google.com>:

Rollback the change to make Cord iterators a fixed size.  That change increased the iterator size, which can cause a deep recursion call to hit the stack memory limit, in turn causing a signal 11 failure.

PiperOrigin-RevId: 301084915

--
619e3cd9e56408bdb8b3b5a1e08dda1e95242264 by Matthew Brown <matthewbr@google.com>:

Internal Change

PiperOrigin-RevId: 300832828

--
64f8d62ab4c4c78077dbe85a9595a8eeb6d16608 by Gennadiy Rozental <rogeeff@google.com>:

Fix for empty braces support.

We will call proper aggregate construction in case when {} is used as default value. In other words instead of "new T", we'll call "new T{}".

PiperOrigin-RevId: 300715686

--
db3f65594d6db8b104b01262f884dff465b696ef by Abseil Team <absl-team@google.com>:

Emscripten supports thread-local storage nowadays.

PiperOrigin-RevId: 300675185
GitOrigin-RevId: 91ca367a7548270155721bdda74611aeea2a2153
Change-Id: I3344f745f9c3fc78775532b1808442fabd98e34a
This commit is contained in:
Abseil Team 2020-03-16 09:06:23 -07:00 committed by vslashg
parent c6954897f7
commit 7853a7586c
12 changed files with 254 additions and 283 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
absl/base/config.h
View file

@ -262,13 +262,6 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
#endif
#endif // defined(__ANDROID__) && defined(__clang__)
// Emscripten doesn't yet support `thread_local` or `__thread`.
// https://github.com/emscripten-core/emscripten/issues/3502
#if defined(__EMSCRIPTEN__)
#undef ABSL_HAVE_TLS
#undef ABSL_HAVE_THREAD_LOCAL
#endif // defined(__EMSCRIPTEN__)
// ABSL_HAVE_INTRINSIC_INT128
//
// Checks whether the __int128 compiler extension for a 128-bit integral type is

22
absl/container/btree_benchmark.cc
View file

@ -134,6 +134,27 @@ void BM_InsertEnd(benchmark::State& state) {
}
}
// Benchmark inserting the first few elements in a container. In b-tree, this is
// when the root node grows.
template <typename T>
void BM_InsertSmall(benchmark::State& state) {
using V = typename remove_pair_const<typename T::value_type>::type;
const int kSize = 8;
std::vector<V> values = GenerateValues<V>(kSize);
T container;
while (state.KeepRunningBatch(kSize)) {
for (int i = 0; i < kSize; ++i) {
benchmark::DoNotOptimize(container.insert(values[i]));
}
state.PauseTiming();
// Do not measure the time it takes to clear the container.
container.clear();
state.ResumeTiming();
}
}
template <typename T>
void BM_LookupImpl(benchmark::State& state, bool sorted) {
using V = typename remove_pair_const<typename T::value_type>::type;
@ -493,6 +514,7 @@ BTREE_TYPES(Time);
MY_BENCHMARK4(type, Insert); \
MY_BENCHMARK4(type, InsertSorted); \
MY_BENCHMARK4(type, InsertEnd); \
MY_BENCHMARK4(type, InsertSmall); \
MY_BENCHMARK4(type, Lookup); \
MY_BENCHMARK4(type, FullLookup); \
MY_BENCHMARK4(type, Delete); \

76
absl/container/internal/btree.h
View file

@ -776,9 +776,6 @@ class btree_node {
// delimiting key in the parent node onto itself.
void merge(btree_node *src, allocator_type *alloc);
// Swaps the contents of `this` and `other`.
void swap(btree_node *other, allocator_type *alloc);
// Node allocation/deletion routines.
void init_leaf(btree_node *parent, int max_count) {
set_parent(parent);
@ -820,6 +817,14 @@ class btree_node {
absl::container_internal::SanitizerPoisonObject(slot(i));
}
// Transfers value from slot `src_i` in `src` to slot `dest_i` in `this`.
void transfer(const size_type dest_i, const size_type src_i, btree_node *src,
allocator_type *alloc) {
absl::container_internal::SanitizerUnpoisonObject(slot(dest_i));
params_type::transfer(alloc, slot(dest_i), src->slot(src_i));
absl::container_internal::SanitizerPoisonObject(src->slot(src_i));
}
// Move n values starting at value i in this node into the values starting at
// value j in dest_node.
void uninitialized_move_n(const size_type n, const size_type i,
@ -1752,54 +1757,6 @@ void btree_node<P>::merge(btree_node *src, allocator_type *alloc) {
parent()->remove_value(position(), alloc);
}
template <typename P>
void btree_node<P>::swap(btree_node *other, allocator_type *alloc) {
using std::swap;
assert(leaf() == other->leaf());
// Determine which is the smaller/larger node.
btree_node *smaller = this, *larger = other;
if (smaller->count() > larger->count()) {
swap(smaller, larger);
}
// Swap the values.
for (slot_type *a = smaller->start_slot(), *b = larger->start_slot(),
*end = smaller->finish_slot();
a != end; ++a, ++b) {
params_type::swap(alloc, a, b);
}
// Move values that can't be swapped.
const size_type to_move = larger->count() - smaller->count();
larger->uninitialized_move_n(to_move, smaller->finish(), smaller->finish(),
smaller, alloc);
larger->value_destroy_n(smaller->finish(), to_move, alloc);
if (!leaf()) {
// Swap the child pointers.
std::swap_ranges(&smaller->mutable_child(smaller->start()),
&smaller->mutable_child(smaller->finish() + 1),
&larger->mutable_child(larger->start()));
// Update swapped children's parent pointers.
int i = smaller->start();
int j = larger->start();
for (; i <= smaller->finish(); ++i, ++j) {
smaller->child(i)->set_parent(smaller);
larger->child(j)->set_parent(larger);
}
// Move the child pointers that couldn't be swapped.
for (; j <= larger->finish(); ++i, ++j) {
smaller->init_child(i, larger->child(j));
larger->clear_child(j);
}
}
// Swap the `finish`s.
// TODO(ezb): with floating storage, will also need to swap starts.
swap(mutable_finish(), other->mutable_finish());
}
////
// btree_iterator methods
template <typename N, typename R, typename P>
@ -2492,6 +2449,7 @@ inline auto btree<P>::internal_emplace(iterator iter, Args &&... args)
++iter.position;
}
const int max_count = iter.node->max_count();
allocator_type *alloc = mutable_allocator();
if (iter.node->count() == max_count) {
// Make room in the leaf for the new item.
if (max_count < kNodeValues) {
@ -2500,15 +2458,21 @@ inline auto btree<P>::internal_emplace(iterator iter, Args &&... args)
assert(iter.node == root());
iter.node =
new_leaf_root_node((std::min<int>)(kNodeValues, 2 * max_count));
iter.node->swap(root(), mutable_allocator());
delete_leaf_node(root());
mutable_root() = rightmost_ = iter.node;
// Transfer the values from the old root to the new root.
node_type *old_root = root();
node_type *new_root = iter.node;
for (int i = old_root->start(), f = old_root->finish(); i < f; ++i) {
new_root->transfer(i, i, old_root, alloc);
}
new_root->set_finish(old_root->finish());
old_root->set_finish(old_root->start());
delete_leaf_node(old_root);
mutable_root() = rightmost_ = new_root;
} else {
rebalance_or_split(&iter);
}
}
iter.node->emplace_value(iter.position, mutable_allocator(),
std::forward<Args>(args)...);
iter.node->emplace_value(iter.position, alloc, std::forward<Args>(args)...);
++size_;
return iter;
}

2
absl/copts/AbseilConfigureCopts.cmake
View file

@ -63,3 +63,5 @@ else()
set(ABSL_DEFAULT_COPTS "")
set(ABSL_TEST_COPTS "")
endif()
set(ABSL_CXX_STANDARD "${CMAKE_CXX_STANDARD}")

67
absl/flags/flag_test.cc
View file

@ -293,6 +293,18 @@ TEST_F(FlagTest, TestFlagDefinition) {
// --------------------------------------------------------------------
TEST_F(FlagTest, TestDefault) {
EXPECT_EQ(FLAGS_test_flag_01.DefaultValue(), "true");
EXPECT_EQ(FLAGS_test_flag_02.DefaultValue(), "1234");
EXPECT_EQ(FLAGS_test_flag_03.DefaultValue(), "-34");
EXPECT_EQ(FLAGS_test_flag_04.DefaultValue(), "189");
EXPECT_EQ(FLAGS_test_flag_05.DefaultValue(), "10765");
EXPECT_EQ(FLAGS_test_flag_06.DefaultValue(), "40000");
EXPECT_EQ(FLAGS_test_flag_07.DefaultValue(), "-1234567");
EXPECT_EQ(FLAGS_test_flag_08.DefaultValue(), "9876543");
EXPECT_EQ(FLAGS_test_flag_09.DefaultValue(), "-9.876e-50");
EXPECT_EQ(FLAGS_test_flag_10.DefaultValue(), "1.234e+12");
EXPECT_EQ(FLAGS_test_flag_11.DefaultValue(), "");
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_01), true);
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_02), 1234);
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_03), -34);
@ -308,6 +320,61 @@ TEST_F(FlagTest, TestDefault) {
// --------------------------------------------------------------------
struct NonTriviallyCopyableAggregate {
NonTriviallyCopyableAggregate() = default;
NonTriviallyCopyableAggregate(const NonTriviallyCopyableAggregate& rhs)
: value(rhs.value) {}
NonTriviallyCopyableAggregate& operator=(
const NonTriviallyCopyableAggregate& rhs) {
value = rhs.value;
return *this;
}
int value;
};
bool AbslParseFlag(absl::string_view src, NonTriviallyCopyableAggregate* f,
std::string* e) {
return absl::ParseFlag(src, &f->value, e);
}
std::string AbslUnparseFlag(const NonTriviallyCopyableAggregate& ntc) {
return absl::StrCat(ntc.value);
}
bool operator==(const NonTriviallyCopyableAggregate& ntc1,
const NonTriviallyCopyableAggregate& ntc2) {
return ntc1.value == ntc2.value;
}
} // namespace
ABSL_FLAG(bool, test_flag_eb_01, {}, "");
ABSL_FLAG(int32_t, test_flag_eb_02, {}, "");
ABSL_FLAG(int64_t, test_flag_eb_03, {}, "");
ABSL_FLAG(double, test_flag_eb_04, {}, "");
ABSL_FLAG(std::string, test_flag_eb_05, {}, "");
ABSL_FLAG(NonTriviallyCopyableAggregate, test_flag_eb_06, {}, "");
namespace {
TEST_F(FlagTest, TestEmptyBracesDefault) {
EXPECT_EQ(FLAGS_test_flag_eb_01.DefaultValue(), "false");
EXPECT_EQ(FLAGS_test_flag_eb_02.DefaultValue(), "0");
EXPECT_EQ(FLAGS_test_flag_eb_03.DefaultValue(), "0");
EXPECT_EQ(FLAGS_test_flag_eb_04.DefaultValue(), "0");
EXPECT_EQ(FLAGS_test_flag_eb_05.DefaultValue(), "");
EXPECT_EQ(FLAGS_test_flag_eb_06.DefaultValue(), "0");
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_01), false);
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_02), 0);
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_03), 0);
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_04), 0.0);
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_05), "");
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_eb_06),
NonTriviallyCopyableAggregate{});
}
// --------------------------------------------------------------------
TEST_F(FlagTest, TestGetSet) {
absl::SetFlag(&FLAGS_test_flag_01, false);
EXPECT_EQ(absl::GetFlag(FLAGS_test_flag_01), false);

2
absl/flags/internal/flag.h
View file

@ -647,7 +647,7 @@ T* MakeFromDefaultValue(T t) {
template <typename T>
T* MakeFromDefaultValue(EmptyBraces) {
return new T;
return new T{};
}
} // namespace flags_internal

241
absl/strings/cord.cc
View file

@ -30,6 +30,7 @@
#include "absl/base/internal/raw_logging.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/resize_uninitialized.h"
@ -131,14 +132,6 @@ inline const CordRepExternal* CordRep::external() const {
return static_cast<const CordRepExternal*>(this);
}
using CordTreeConstPath = CordTreePath<const CordRep*, MaxCordDepth()>;
// This type is used to store the list of pending nodes during re-balancing.
// Its maximum size is 2 * MaxCordDepth() because the tree has a maximum
// possible depth of MaxCordDepth() and every concat node along a tree path
// could theoretically be split during rebalancing.
using RebalancingStack = CordTreePath<CordRep*, 2 * MaxCordDepth()>;
} // namespace cord_internal
static const size_t kFlatOverhead = offsetof(CordRep, data);
@ -187,78 +180,98 @@ static constexpr size_t TagToLength(uint8_t tag) {
// Enforce that kMaxFlatSize maps to a well-known exact tag value.
static_assert(TagToAllocatedSize(224) == kMaxFlatSize, "Bad tag logic");
constexpr size_t Fibonacci(uint8_t n, const size_t a = 0, const size_t b = 1) {
return n == 0
? a
: n == 1 ? b
: Fibonacci(n - 1, b,
(a > (size_t(-1) - b)) ? size_t(-1) : a + b);
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) >= kMinLength[depth(t)]
// The node depth is allowed to become larger to reduce rebalancing
// for larger strings (see ShouldRebalance).
constexpr size_t kMinLength[] = {
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), Fibonacci(48), Fibonacci(49), Fibonacci(50), Fibonacci(51),
Fibonacci(52), Fibonacci(53), Fibonacci(54), Fibonacci(55), Fibonacci(56),
Fibonacci(57), Fibonacci(58), Fibonacci(59), Fibonacci(60), Fibonacci(61),
Fibonacci(62), Fibonacci(63), Fibonacci(64), Fibonacci(65), Fibonacci(66),
Fibonacci(67), Fibonacci(68), Fibonacci(69), Fibonacci(70), Fibonacci(71),
Fibonacci(72), Fibonacci(73), Fibonacci(74), Fibonacci(75), Fibonacci(76),
Fibonacci(77), Fibonacci(78), Fibonacci(79), Fibonacci(80), Fibonacci(81),
Fibonacci(82), Fibonacci(83), Fibonacci(84), Fibonacci(85), Fibonacci(86),
Fibonacci(87), Fibonacci(88), Fibonacci(89), Fibonacci(90), Fibonacci(91),
Fibonacci(92), Fibonacci(93), Fibonacci(94), Fibonacci(95)};
// 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_assert(sizeof(kMinLength) / sizeof(size_t) >=
(cord_internal::MaxCordDepth() + 1),
"Not enough elements in kMinLength array to cover all the "
"supported Cord depth(s)");
static const int kMinLengthSize = ABSL_ARRAYSIZE(min_length);
inline bool ShouldRebalance(const CordRep* node) {
if (node->tag != CONCAT) return false;
// The inlined size to use with absl::InlinedVector.
//
// Note: The InlinedVectors in this file (and in cord.h) do not need to use
// the same value for their inlined size. The fact that they do is historical.
// It may be desirable for each to use a different inlined size optimized for
// that InlinedVector's usage.
//
// TODO(jgm): Benchmark to see if there's a more optimal value than 47 for
// the inlined vector size (47 exists for backward compatibility).
static const int kInlinedVectorSize = 47;
size_t node_depth = node->concat()->depth();
if (node_depth <= 15) return false;
// Rebalancing Cords is expensive, so we reduce how often rebalancing occurs
// by allowing shallow Cords to have twice the depth that the Fibonacci rule
// would otherwise imply. Deep Cords need to follow the rule more closely,
// however to ensure algorithm correctness. We implement this with linear
// interpolation. Cords of depth 16 are treated as though they have a depth
// of 16 * 1/2, and Cords of depth MaxCordDepth() interpolate to
// MaxCordDepth() * 1.
return node->length <
kMinLength[(node_depth * (cord_internal::MaxCordDepth() - 16)) /
(2 * cord_internal::MaxCordDepth() - 16 - node_depth)];
}
// Unlike root balancing condition this one is part of the re-balancing
// algorithm and has to be always matching against right depth for
// algorithm to be correct.
inline bool IsNodeBalanced(const CordRep* node) {
if (node->tag != CONCAT) return true;
size_t node_depth = node->concat()->depth();
return node->length >= kMinLength[node_depth];
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(const CordRep* rep, bool include_data, std::ostream* os);
static bool VerifyNode(const CordRep* root, const CordRep* start_node,
static void DumpNode(CordRep* rep, bool include_data, std::ostream* os);
static bool VerifyNode(CordRep* root, CordRep* start_node,
bool full_validation);
static inline CordRep* VerifyTree(CordRep* node) {
@ -305,8 +318,7 @@ __attribute__((preserve_most))
static void UnrefInternal(CordRep* rep) {
assert(rep != nullptr);
cord_internal::RebalancingStack pending;
absl::InlinedVector<CordRep*, kInlinedVectorSize> pending;
while (true) {
if (rep->tag == CONCAT) {
CordRepConcat* rep_concat = rep->concat();
@ -388,11 +400,6 @@ static void SetConcatChildren(CordRepConcat* concat, CordRep* left,
concat->length = left->length + right->length;
concat->set_depth(1 + std::max(Depth(left), Depth(right)));
ABSL_INTERNAL_CHECK(concat->depth() <= cord_internal::MaxCordDepth(),
"Cord depth exceeds max");
ABSL_INTERNAL_CHECK(concat->length >= left->length, "Cord is too long");
ABSL_INTERNAL_CHECK(concat->length >= right->length, "Cord is too long");
}
// Create a concatenation of the specified nodes.
@ -418,7 +425,7 @@ static CordRep* RawConcat(CordRep* left, CordRep* right) {
static CordRep* Concat(CordRep* left, CordRep* right) {
CordRep* rep = RawConcat(left, right);
if (rep != nullptr && ShouldRebalance(rep)) {
if (rep != nullptr && !IsRootBalanced(rep)) {
rep = Rebalance(rep);
}
return VerifyTree(rep);
@ -909,7 +916,7 @@ void Cord::Prepend(absl::string_view src) {
static CordRep* RemovePrefixFrom(CordRep* node, size_t n) {
if (n >= node->length) return nullptr;
if (n == 0) return Ref(node);
cord_internal::CordTreeMutablePath rhs_stack;
absl::InlinedVector<CordRep*, kInlinedVectorSize> rhs_stack;
while (node->tag == CONCAT) {
assert(n <= node->length);
@ -950,7 +957,7 @@ static CordRep* RemovePrefixFrom(CordRep* node, size_t n) {
static CordRep* RemoveSuffixFrom(CordRep* node, size_t n) {
if (n >= node->length) return nullptr;
if (n == 0) return Ref(node);
absl::cord_internal::CordTreeMutablePath lhs_stack;
absl::InlinedVector<CordRep*, kInlinedVectorSize> lhs_stack;
bool inplace_ok = node->refcount.IsOne();
while (node->tag == CONCAT) {
@ -1021,7 +1028,6 @@ void Cord::RemoveSuffix(size_t n) {
// Work item for NewSubRange().
struct SubRange {
SubRange() = default;
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.
@ -1030,11 +1036,8 @@ struct SubRange {
};
static CordRep* NewSubRange(CordRep* node, size_t pos, size_t n) {
cord_internal::CordTreeMutablePath results;
// The algorithm below in worst case scenario adds up to 3 nodes to the `todo`
// list, but we also pop one out on every cycle. If original tree has depth d
// todo list can grew up to 2*d in size.
cord_internal::CordTreePath<SubRange, 2 * cord_internal::MaxCordDepth()> todo;
absl::InlinedVector<CordRep*, kInlinedVectorSize> results;
absl::InlinedVector<SubRange, kInlinedVectorSize> todo;
todo.push_back(SubRange(node, pos, n));
do {
const SubRange& sr = todo.back();
@ -1071,7 +1074,7 @@ static CordRep* NewSubRange(CordRep* node, size_t pos, size_t n) {
}
} while (!todo.empty());
assert(results.size() == 1);
return results.back();
return results[0];
}
Cord Cord::Subcord(size_t pos, size_t new_size) const {
@ -1110,12 +1113,11 @@ Cord Cord::Subcord(size_t pos, size_t new_size) const {
class CordForest {
public:
explicit CordForest(size_t length) : root_length_(length), trees_({}) {}
explicit CordForest(size_t length)
: root_length_(length), trees_(kMinLengthSize, nullptr) {}
void Build(CordRep* cord_root) {
// We are adding up to two nodes to the `pending` list, but we also popping
// one, so the size of `pending` will never exceed `MaxCordDepth()`.
cord_internal::CordTreeMutablePath pending(cord_root);
std::vector<CordRep*> pending = {cord_root};
while (!pending.empty()) {
CordRep* node = pending.back();
@ -1127,20 +1129,21 @@ class CordForest {
}
CordRepConcat* concat_node = node->concat();
if (IsNodeBalanced(concat_node)) {
AddNode(node);
continue;
}
pending.push_back(concat_node->right);
pending.push_back(concat_node->left);
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;
if (concat_node->refcount.IsOne()) {
concat_node->left = concat_freelist_;
concat_freelist_ = concat_node;
} else {
Ref(concat_node->right);
Ref(concat_node->left);
Unref(concat_node);
}
} else {
Ref(concat_node->right);
Ref(concat_node->left);
Unref(concat_node);
AddNode(node);
}
}
}
@ -1172,7 +1175,7 @@ class CordForest {
// Collect together everything with which we will merge with node
int i = 0;
for (; node->length >= kMinLength[i + 1]; ++i) {
for (; node->length > min_length[i + 1]; ++i) {
auto& tree_at_i = trees_[i];
if (tree_at_i == nullptr) continue;
@ -1183,7 +1186,7 @@ class CordForest {
sum = AppendNode(node, sum);
// Insert sum into appropriate place in the forest
for (; sum->length >= kMinLength[i]; ++i) {
for (; sum->length >= min_length[i]; ++i) {
auto& tree_at_i = trees_[i];
if (tree_at_i == nullptr) continue;
@ -1191,7 +1194,7 @@ class CordForest {
tree_at_i = nullptr;
}
// kMinLength[0] == 1, which means sum->length >= kMinLength[0]
// min_length[0] == 1, which means sum->length >= min_length[0]
assert(i > 0);
trees_[i - 1] = sum;
}
@ -1224,7 +1227,9 @@ class CordForest {
}
size_t root_length_;
std::array<cord_internal::CordRep*, cord_internal::MaxCordDepth()> trees_;
// 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;
@ -1836,18 +1841,18 @@ absl::string_view Cord::FlattenSlowPath() {
}
}
static void DumpNode(const CordRep* rep, bool include_data, std::ostream* os) {
static void DumpNode(CordRep* rep, bool include_data, std::ostream* os) {
const int kIndentStep = 1;
int indent = 0;
cord_internal::CordTreeConstPath stack;
cord_internal::CordTreePath<int, cord_internal::MaxCordDepth()> indents;
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<const void*>(rep);
if (include_data) *os << static_cast<void*>(rep);
*os << "]";
*os << " " << (IsNodeBalanced(rep) ? 'b' : 'u');
*os << " " << (IsRootBalanced(rep) ? 'b' : 'u');
*os << " " << std::setw(indent) << "";
if (rep->tag == CONCAT) {
*os << "CONCAT depth=" << Depth(rep) << "\n";
@ -1868,7 +1873,7 @@ static void DumpNode(const CordRep* rep, bool include_data, std::ostream* os) {
} else {
*os << "FLAT cap=" << TagToLength(rep->tag) << " [";
if (include_data)
*os << absl::CEscape(absl::string_view(rep->data, rep->length));
*os << absl::CEscape(std::string(rep->data, rep->length));
*os << "]\n";
}
if (stack.empty()) break;
@ -1881,19 +1886,19 @@ static void DumpNode(const CordRep* rep, bool include_data, std::ostream* os) {
ABSL_INTERNAL_CHECK(indents.empty(), "");
}
static std::string ReportError(const CordRep* root, const CordRep* node) {
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(const CordRep* root, const CordRep* start_node,
static bool VerifyNode(CordRep* root, CordRep* start_node,
bool full_validation) {
cord_internal::CordTreeConstPath worklist;
absl::InlinedVector<CordRep*, 2> worklist;
worklist.push_back(start_node);
do {
const CordRep* node = worklist.back();
CordRep* node = worklist.back();
worklist.pop_back();
ABSL_INTERNAL_CHECK(node != nullptr, ReportError(root, node));
@ -1943,7 +1948,7 @@ static bool VerifyNode(const CordRep* root, const CordRep* start_node,
// 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.
cord_internal::CordTreeConstPath tree_stack;
absl::InlinedVector<const CordRep*, kInlinedVectorSize> tree_stack;
const CordRep* cur_node = rep;
while (true) {
const CordRep* next_node = nullptr;

53
absl/strings/cord.h
View file

@ -48,6 +48,7 @@
#include "absl/base/internal/per_thread_tls.h"
#include "absl/base/macros.h"
#include "absl/base/port.h"
#include "absl/container/inlined_vector.h"
#include "absl/functional/function_ref.h"
#include "absl/meta/type_traits.h"
#include "absl/strings/internal/cord_internal.h"
@ -67,55 +68,6 @@ template <typename H>
H HashFragmentedCord(H, const Cord&);
}
namespace cord_internal {
// It's expensive to keep a tree perfectly balanced, so instead we keep trees
// approximately balanced. A tree node N of depth D(N) that contains a string
// of L(N) characters is considered balanced if L >= Fibonacci(D + 2).
// The "+ 2" is used to ensure that every balanced leaf node contains at least
// one character. Here we presume that
// Fibonacci(0) = 0
// Fibonacci(1) = 1
// Fibonacci(2) = 1
// Fibonacci(3) = 2
// ...
// The algorithm is based on paper by Hans Boehm et al:
// https://www.cs.rit.edu/usr/local/pub/jeh/courses/QUARTERS/FP/Labs/CedarRope/rope-paper.pdf
// In this paper authors shows that rebalancing based on cord forest of already
// balanced subtrees can be proven to never produce tree of depth larger than
// largest Fibonacci number representable in the same integral type as cord size
// For 64 bit integers this is the 93rd Fibonacci number. For 32 bit integrals
// this is 47th Fibonacci number.
constexpr size_t MaxCordDepth() { return sizeof(size_t) == 8 ? 93 : 47; }
// This class models fixed max size stack of CordRep pointers.
// The elements are being pushed back and popped from the back.
template <typename CordRepPtr, size_t N>
class CordTreePath {
public:
CordTreePath() {}
explicit CordTreePath(CordRepPtr root) { push_back(root); }
bool empty() const { return size_ == 0; }
size_t size() const { return size_; }
void clear() { size_ = 0; }
CordRepPtr back() { return data_[size_ - 1]; }
void pop_back() {
--size_;
assert(size_ < N);
}
void push_back(CordRepPtr elem) { data_[size_++] = elem; }
private:
CordRepPtr data_[N];
size_t size_ = 0;
};
using CordTreeMutablePath = CordTreePath<CordRep*, MaxCordDepth()>;
} // namespace cord_internal
// A Cord is a sequence of characters.
class Cord {
private:
@ -333,7 +285,8 @@ class Cord {
absl::cord_internal::CordRep* current_leaf_ = nullptr;
// The number of bytes left in the `Cord` over which we are iterating.
size_t bytes_remaining_ = 0;
absl::cord_internal::CordTreeMutablePath stack_of_right_children_;
absl::InlinedVector<absl::cord_internal::CordRep*, 4>
stack_of_right_children_;
};
// Returns an iterator to the first chunk of the `Cord`.

47
absl/strings/cord_test.cc
View file

@ -1402,53 +1402,6 @@ TEST(CordChunkIterator, Operations) {
VerifyChunkIterator(subcords, 128);
}
TEST(CordChunkIterator, MaxLengthFullTree) {
// Start with a 1-byte cord, and then double its length in a loop. We should
// be able to do this until the point where we would overflow size_t.
absl::Cord cord;
size_t size = 1;
AddExternalMemory("x", &cord);
EXPECT_EQ(cord.size(), size);
const int kCordLengthDoublingLimit = std::numeric_limits<size_t>::digits - 1;
for (int i = 0; i < kCordLengthDoublingLimit; ++i) {
cord.Prepend(absl::Cord(cord));
size <<= 1;
EXPECT_EQ(cord.size(), size);
auto chunk_it = cord.chunk_begin();
EXPECT_EQ(*chunk_it, "x");
}
EXPECT_DEATH_IF_SUPPORTED(
(cord.Prepend(absl::Cord(cord)), *cord.chunk_begin()),
"Cord is too long");
}
TEST(CordChunkIterator, MaxDepth) {
// By reusing nodes, it's possible in pathological cases to build a Cord that
// exceeds both the maximum permissible length and depth. In this case, the
// violation of the maximum depth is reported.
absl::Cord left_child;
AddExternalMemory("x", &left_child);
absl::Cord root = left_child;
for (int i = 0; i < absl::cord_internal::MaxCordDepth() - 2; ++i) {
size_t new_size = left_child.size() + root.size();
root.Prepend(left_child);
EXPECT_EQ(root.size(), new_size);
auto chunk_it = root.chunk_begin();
EXPECT_EQ(*chunk_it, "x");
std::swap(left_child, root);
}
EXPECT_DEATH_IF_SUPPORTED(root.Prepend(left_child), "Cord is too long");
}
TEST(CordCharIterator, Traits) {
static_assert(std::is_copy_constructible<absl::Cord::CharIterator>::value,
"");

16
absl/strings/internal/str_format/extension.h
View file

@ -24,6 +24,7 @@
#include "absl/base/config.h"
#include "absl/base/port.h"
#include "absl/meta/type_traits.h"
#include "absl/strings/internal/str_format/output.h"
#include "absl/strings/string_view.h"
@ -365,11 +366,22 @@ constexpr FormatConversionCharSet operator|(FormatConversionCharSet a,
static_cast<uint64_t>(b));
}
// Overloaded conversion functions to support absl::ParsedFormat.
// Get a conversion with a single character in it.
constexpr FormatConversionCharSet ConversionCharToConv(char c) {
return FormatConversionCharSet(FormatConversionCharToConvValue(c));
constexpr FormatConversionCharSet ToFormatConversionCharSet(char c) {
return static_cast<FormatConversionCharSet>(
FormatConversionCharToConvValue(c));
}
// Get a conversion with a single character in it.
constexpr FormatConversionCharSet ToFormatConversionCharSet(
FormatConversionCharSet c) {
return c;
}
template <typename T>
void ToFormatConversionCharSet(T) = delete;
// Checks whether `c` exists in `set`.
constexpr bool Contains(FormatConversionCharSet set, char c) {
return (static_cast<uint64_t>(set) & FormatConversionCharToConvValue(c)) != 0;

2
absl/strings/str_format.h
View file

@ -285,7 +285,7 @@ using FormatSpec =
// }
template <char... Conv>
using ParsedFormat = str_format_internal::ExtendedParsedFormat<
str_format_internal::ConversionCharToConv(Conv)...>;
absl::str_format_internal::ToFormatConversionCharSet(Conv)...>;
// StrFormat()
//

2
ci/macos_xcode_cmake.sh
View file

@ -36,7 +36,7 @@ for compilation_mode in ${ABSL_CMAKE_BUILD_TYPES}; do
time cmake ${ABSEIL_ROOT} \
-GXcode \
-DCMAKE_BUILD_TYPE=${compilation_mode} \
-DCMAKE_CXX_FLAGS=-std=c++14 \
-DCMAKE_CXX_STANDARD=11 \
-DABSL_USE_GOOGLETEST_HEAD=ON \
-DABSL_RUN_TESTS=ON
time cmake --build .