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authorGravatar Abseil Team <absl-team@google.com>2018-01-10 11:46:09 -0800
committerGravatar Derek Mauro <dmauro@google.com>2018-01-10 15:36:31 -0500
commitc742b72354a84958b6a061755249822eeef87d06 (patch)
treebf7c3480e1b7396124625c49ccc103bb7bdc6008
parent98bff8b2bc53aa271c0dd0dff1b33730b4df8481 (diff)
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
-rw-r--r--absl/container/inlined_vector.h36
-rw-r--r--absl/container/inlined_vector_test.cc77
-rw-r--r--absl/numeric/int128.h11
3 files changed, 117 insertions, 7 deletions
diff --git a/absl/container/inlined_vector.h b/absl/container/inlined_vector.h
index 4bf9c18a..feba87b5 100644
--- a/absl/container/inlined_vector.h
+++ b/absl/container/inlined_vector.h
@@ -573,6 +573,42 @@ class InlinedVector {
}
}
+ // InlinedVector::shrink_to_fit()
+ //
+ // Reduces memory usage by freeing unused memory.
+ // After this call `capacity()` will be equal to `max(N, size())`.
+ //
+ // If `size() <= N` and the elements are currently stored on the heap, they
+ // will be moved to the inlined storage and the heap memory deallocated.
+ // If `size() > N` and `size() < capacity()` the elements will be moved to
+ // a reallocated storage on heap.
+ void shrink_to_fit() {
+ const auto s = size();
+ if (!allocated() || s == capacity()) {
+ // There's nothing to deallocate.
+ return;
+ }
+
+ if (s <= N) {
+ // Move the elements to the inlined storage.
+ // We have to do this using a temporary, because inlined_storage and
+ // allocation_storage are in a union field.
+ auto temp = std::move(*this);
+ assign(std::make_move_iterator(temp.begin()),
+ std::make_move_iterator(temp.end()));
+ return;
+ }
+
+ // Reallocate storage and move elements.
+ // We can't simply use the same approach as above, because assign() would
+ // call into reserve() internally and reserve larger capacity than we need.
+ Allocation new_allocation(allocator(), s);
+ UninitializedCopy(std::make_move_iterator(allocated_space()),
+ std::make_move_iterator(allocated_space() + s),
+ new_allocation.buffer());
+ ResetAllocation(new_allocation, s);
+ }
+
// InlinedVector::swap()
//
// Swaps the contents of this inlined vector with the contents of `other`.
diff --git a/absl/container/inlined_vector_test.cc b/absl/container/inlined_vector_test.cc
index 8527ba1a..0e39855b 100644
--- a/absl/container/inlined_vector_test.cc
+++ b/absl/container/inlined_vector_test.cc
@@ -407,6 +407,69 @@ TEST(InlinedVectorTest, EmplaceBack) {
EXPECT_EQ(allocated_element.second, 1729);
}
+TEST(InlinedVectorTest, ShrinkToFitGrowingVector) {
+ absl::InlinedVector<std::pair<std::string, int>, 1> v;
+
+ v.shrink_to_fit();
+ EXPECT_EQ(v.capacity(), 1);
+
+ v.emplace_back("answer", 42);
+ v.shrink_to_fit();
+ EXPECT_EQ(v.capacity(), 1);
+
+ v.emplace_back("taxicab", 1729);
+ EXPECT_GE(v.capacity(), 2);
+ v.shrink_to_fit();
+ EXPECT_EQ(v.capacity(), 2);
+
+ v.reserve(100);
+ EXPECT_GE(v.capacity(), 100);
+ v.shrink_to_fit();
+ EXPECT_EQ(v.capacity(), 2);
+}
+
+TEST(InlinedVectorTest, ShrinkToFitEdgeCases) {
+ {
+ absl::InlinedVector<std::pair<std::string, int>, 1> v;
+ v.emplace_back("answer", 42);
+ v.emplace_back("taxicab", 1729);
+ EXPECT_GE(v.capacity(), 2);
+ v.pop_back();
+ v.shrink_to_fit();
+ EXPECT_EQ(v.capacity(), 1);
+ EXPECT_EQ(v[0].first, "answer");
+ EXPECT_EQ(v[0].second, 42);
+ }
+
+ {
+ absl::InlinedVector<std::string, 2> v(100);
+ v.resize(0);
+ v.shrink_to_fit();
+ EXPECT_EQ(v.capacity(), 2); // inlined capacity
+ }
+
+ {
+ absl::InlinedVector<std::string, 2> v(100);
+ v.resize(1);
+ v.shrink_to_fit();
+ EXPECT_EQ(v.capacity(), 2); // inlined capacity
+ }
+
+ {
+ absl::InlinedVector<std::string, 2> v(100);
+ v.resize(2);
+ v.shrink_to_fit();
+ EXPECT_EQ(v.capacity(), 2);
+ }
+
+ {
+ absl::InlinedVector<std::string, 2> v(100);
+ v.resize(3);
+ v.shrink_to_fit();
+ EXPECT_EQ(v.capacity(), 3);
+ }
+}
+
TEST(IntVec, Insert) {
for (int len = 0; len < 20; len++) {
for (int pos = 0; pos <= len; pos++) {
@@ -1589,6 +1652,20 @@ TEST(AllocatorSupportTest, CountAllocations) {
AllocVec v3(std::move(v), alloc3);
EXPECT_THAT(allocated3, v3.size() * sizeof(int));
}
+ EXPECT_EQ(allocated, 0);
+ {
+ // Test shrink_to_fit deallocations.
+ AllocVec v(8, 2, alloc);
+ EXPECT_EQ(allocated, 8 * sizeof(int));
+ v.resize(5);
+ EXPECT_EQ(allocated, 8 * sizeof(int));
+ v.shrink_to_fit();
+ EXPECT_EQ(allocated, 5 * sizeof(int));
+ v.resize(4);
+ EXPECT_EQ(allocated, 5 * sizeof(int));
+ v.shrink_to_fit();
+ EXPECT_EQ(allocated, 0);
+ }
}
TEST(AllocatorSupportTest, SwapBothAllocated) {
diff --git a/absl/numeric/int128.h b/absl/numeric/int128.h
index f42a4aa3..a204ac4d 100644
--- a/absl/numeric/int128.h
+++ b/absl/numeric/int128.h
@@ -460,13 +460,10 @@ inline bool operator>=(uint128 lhs, uint128 rhs) {
// Unary operators.
inline uint128 operator-(uint128 val) {
- const uint64_t hi_flip = ~Uint128High64(val);
- const uint64_t lo_flip = ~Uint128Low64(val);
- const uint64_t lo_add = lo_flip + 1;
- if (lo_add < lo_flip) {
- return MakeUint128(hi_flip + 1, lo_add);
- }
- return MakeUint128(hi_flip, lo_add);
+ uint64_t hi = ~Uint128High64(val);
+ uint64_t lo = ~Uint128Low64(val) + 1;
+ if (lo == 0) ++hi; // carry
+ return MakeUint128(hi, lo);
}
inline bool operator!(uint128 val) {