Changes imported from Abseil "staging" branch:
- f679f7de2957ac4dca0a862d04f1165d2f503525 Merge GitHub PR #78: Fix typo in thread_identity.h by Derek Mauro <dmauro@google.com> - 369cbefc9ebb8503e3c25b1516c856dab3bed7ac Minor refactor of operator-(uint128). by Alex Strelnikov <strel@google.com> - fba0f8c33b051d90936ad0fcaa4bea83f554bf8d Merge GitHub PR #75: Fix typo in per_thread_tls.h by Derek Mauro <dmauro@google.com> - 76d5d25a54ab93c1ea3bc74b5a28ba335b0f2bab Implement InlinedVector::shrink_to_fit() method. by Abseil Team <absl-team@google.com> GitOrigin-RevId: f679f7de2957ac4dca0a862d04f1165d2f503525 Change-Id: I03b39fdbd70c00a455d98d949d413dd7c8019578
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3 changed files with 117 additions and 7 deletions
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@ -573,6 +573,42 @@ class InlinedVector {
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}
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}
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// InlinedVector::shrink_to_fit()
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//
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// Reduces memory usage by freeing unused memory.
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// After this call `capacity()` will be equal to `max(N, size())`.
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//
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// If `size() <= N` and the elements are currently stored on the heap, they
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// will be moved to the inlined storage and the heap memory deallocated.
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// If `size() > N` and `size() < capacity()` the elements will be moved to
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// a reallocated storage on heap.
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void shrink_to_fit() {
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const auto s = size();
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if (!allocated() || s == capacity()) {
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// There's nothing to deallocate.
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return;
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}
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if (s <= N) {
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// Move the elements to the inlined storage.
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// We have to do this using a temporary, because inlined_storage and
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// allocation_storage are in a union field.
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auto temp = std::move(*this);
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assign(std::make_move_iterator(temp.begin()),
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std::make_move_iterator(temp.end()));
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return;
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}
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// Reallocate storage and move elements.
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// We can't simply use the same approach as above, because assign() would
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// call into reserve() internally and reserve larger capacity than we need.
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Allocation new_allocation(allocator(), s);
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UninitializedCopy(std::make_move_iterator(allocated_space()),
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std::make_move_iterator(allocated_space() + s),
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new_allocation.buffer());
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ResetAllocation(new_allocation, s);
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}
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// InlinedVector::swap()
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//
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// Swaps the contents of this inlined vector with the contents of `other`.
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@ -407,6 +407,69 @@ TEST(InlinedVectorTest, EmplaceBack) {
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EXPECT_EQ(allocated_element.second, 1729);
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}
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TEST(InlinedVectorTest, ShrinkToFitGrowingVector) {
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absl::InlinedVector<std::pair<std::string, int>, 1> v;
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v.shrink_to_fit();
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EXPECT_EQ(v.capacity(), 1);
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v.emplace_back("answer", 42);
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v.shrink_to_fit();
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EXPECT_EQ(v.capacity(), 1);
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v.emplace_back("taxicab", 1729);
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EXPECT_GE(v.capacity(), 2);
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v.shrink_to_fit();
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EXPECT_EQ(v.capacity(), 2);
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v.reserve(100);
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EXPECT_GE(v.capacity(), 100);
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v.shrink_to_fit();
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EXPECT_EQ(v.capacity(), 2);
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}
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TEST(InlinedVectorTest, ShrinkToFitEdgeCases) {
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{
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absl::InlinedVector<std::pair<std::string, int>, 1> v;
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v.emplace_back("answer", 42);
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v.emplace_back("taxicab", 1729);
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EXPECT_GE(v.capacity(), 2);
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v.pop_back();
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v.shrink_to_fit();
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EXPECT_EQ(v.capacity(), 1);
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EXPECT_EQ(v[0].first, "answer");
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EXPECT_EQ(v[0].second, 42);
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}
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{
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absl::InlinedVector<std::string, 2> v(100);
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v.resize(0);
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v.shrink_to_fit();
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EXPECT_EQ(v.capacity(), 2); // inlined capacity
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}
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{
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absl::InlinedVector<std::string, 2> v(100);
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v.resize(1);
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v.shrink_to_fit();
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EXPECT_EQ(v.capacity(), 2); // inlined capacity
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}
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{
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absl::InlinedVector<std::string, 2> v(100);
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v.resize(2);
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v.shrink_to_fit();
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EXPECT_EQ(v.capacity(), 2);
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}
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{
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absl::InlinedVector<std::string, 2> v(100);
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v.resize(3);
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v.shrink_to_fit();
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EXPECT_EQ(v.capacity(), 3);
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}
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}
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TEST(IntVec, Insert) {
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for (int len = 0; len < 20; len++) {
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for (int pos = 0; pos <= len; pos++) {
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@ -1589,6 +1652,20 @@ TEST(AllocatorSupportTest, CountAllocations) {
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AllocVec v3(std::move(v), alloc3);
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EXPECT_THAT(allocated3, v3.size() * sizeof(int));
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}
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EXPECT_EQ(allocated, 0);
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{
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// Test shrink_to_fit deallocations.
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AllocVec v(8, 2, alloc);
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EXPECT_EQ(allocated, 8 * sizeof(int));
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v.resize(5);
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EXPECT_EQ(allocated, 8 * sizeof(int));
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v.shrink_to_fit();
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EXPECT_EQ(allocated, 5 * sizeof(int));
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v.resize(4);
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EXPECT_EQ(allocated, 5 * sizeof(int));
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v.shrink_to_fit();
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EXPECT_EQ(allocated, 0);
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}
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}
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TEST(AllocatorSupportTest, SwapBothAllocated) {
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@ -460,13 +460,10 @@ inline bool operator>=(uint128 lhs, uint128 rhs) {
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// Unary operators.
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inline uint128 operator-(uint128 val) {
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const uint64_t hi_flip = ~Uint128High64(val);
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const uint64_t lo_flip = ~Uint128Low64(val);
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const uint64_t lo_add = lo_flip + 1;
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if (lo_add < lo_flip) {
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return MakeUint128(hi_flip + 1, lo_add);
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}
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return MakeUint128(hi_flip, lo_add);
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uint64_t hi = ~Uint128High64(val);
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uint64_t lo = ~Uint128Low64(val) + 1;
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if (lo == 0) ++hi; // carry
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return MakeUint128(hi, lo);
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}
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inline bool operator!(uint128 val) {
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