Export of internal Abseil changes

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730bb88bee556aa11fa19aa33e1434cb6fa78985 by Evan Brown <ezb@google.com>:

Support missing allocator-related constructors in b-tree. See [reference](https://en.cppreference.com/w/cpp/container/set/set).

Also use allocator_traits::select_on_container_copy_construction() to get allocator for copy construction.

PiperOrigin-RevId: 339058322

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b6cc121689ae3e452d1db2d66122cb198d25142b by Derek Mauro <dmauro@google.com>:

Fix more sign-compare warnings

PiperOrigin-RevId: 339057920

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0e2c62da1dcaf6529abab952bdcc96c6de2d9506 by Abseil Team <absl-team@google.com>:

Add missing <limits> include

PiperOrigin-RevId: 339054753

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d5a9ec2d1e40fe6359e720942e4955009ee415ec by Derek Mauro <dmauro@google.com>:

Stop disabling sign-compare warnings for non-test targets.
Our users complain about these.

This does not catch issues in header-only libraries (like btree.h)
but we may work on those in the future

PiperOrigin-RevId: 338967089

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0c062c542a4c61ea0f65d25811827c0858e3adde by Abseil Team <absl-team@google.com>:

Improve cache-locality for ThreadIdentity and PerThreadSynch.

This is a change based on an observation in RPC benchmarks that shows
significant cycles being spent in waking up a thread, 99.8% of which
was on cache misses. Investigating this a bit more, it turns out to
be due to sharing the cache line with the waiter state.

To fix this issue, the following changes are introduced:
- Reorder fields in PerThreadSync so that it fits in a single cache line
  The size of this structure was 80 bytes before this change.
  Note: Manually inspected all booleans to make sure they are not modified by
        multiple threads concurrently.

PiperOrigin-RevId: 338852058

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a90d6f2b2346385017e32dd8ae1b5ca691a5863f by Derek Mauro <dmauro@google.com>:

Delete GCC 4.9 test script. It is no longer supported

PiperOrigin-RevId: 338779452

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7274008d4757e88869110be9db39d03d911ae2b5 by Abseil Team <absl-team@google.com>:

Fix the usage example in which SetFlag should take a pointer.

PiperOrigin-RevId: 338744529
GitOrigin-RevId: 730bb88bee556aa11fa19aa33e1434cb6fa78985
Change-Id: Iff99594c4022e60e482a392d334b376c7ae8883e

1 files changed, 23 insertions, 19 deletions

diff --git a/absl/container/internal/btree.h b/absl/container/internal/btree.h
index a82b5177..8547d68e 100644
--- a/absl/container/internal/btree.h
+++ b/absl/container/internal/btree.h
@@ -1141,21 +1141,35 @@ class btree {
   // before this method is called. This method is used in copy construction,
   // copy assignment, and move assignment.
   template <typename Btree>
-  void copy_or_move_values_in_order(Btree *other);
+  void copy_or_move_values_in_order(Btree &other);
 
   // Validates that various assumptions/requirements are true at compile time.
   constexpr static bool static_assert_validation();
 
  public:
-  btree(const key_compare &comp, const allocator_type &alloc);
+  btree(const key_compare &comp, const allocator_type &alloc)
+      : root_(comp, alloc, EmptyNode()), rightmost_(EmptyNode()), size_(0) {}
 
-  btree(const btree &other);
+  btree(const btree &other) : btree(other, other.allocator()) {}
+  btree(const btree &other, const allocator_type &alloc)
+      : btree(other.key_comp(), alloc) {
+    copy_or_move_values_in_order(other);
+  }
   btree(btree &&other) noexcept
       : root_(std::move(other.root_)),
         rightmost_(absl::exchange(other.rightmost_, EmptyNode())),
         size_(absl::exchange(other.size_, 0)) {
     other.mutable_root() = EmptyNode();
   }
+  btree(btree &&other, const allocator_type &alloc)
+      : btree(other.key_comp(), alloc) {
+    if (alloc == other.allocator()) {
+      swap(other);
+    } else {
+      // Move values from `other` one at a time when allocators are different.
+      copy_or_move_values_in_order(other);
+    }
+  }
 
   ~btree() {
     // Put static_asserts in destructor to avoid triggering them before the type
@@ -1851,7 +1865,7 @@ void btree_iterator<N, R, P>::decrement_slow() {
 // btree methods
 template <typename P>
 template <typename Btree>
-void btree<P>::copy_or_move_values_in_order(Btree *other) {
+void btree<P>::copy_or_move_values_in_order(Btree &other) {
   static_assert(std::is_same<btree, Btree>::value ||
                     std::is_same<const btree, Btree>::value,
                 "Btree type must be same or const.");
@@ -1859,11 +1873,11 @@ void btree<P>::copy_or_move_values_in_order(Btree *other) {
 
   // We can avoid key comparisons because we know the order of the
   // values is the same order we'll store them in.
-  auto iter = other->begin();
-  if (iter == other->end()) return;
+  auto iter = other.begin();
+  if (iter == other.end()) return;
   insert_multi(maybe_move_from_iterator(iter));
   ++iter;
-  for (; iter != other->end(); ++iter) {
+  for (; iter != other.end(); ++iter) {
     // If the btree is not empty, we can just insert the new value at the end
     // of the tree.
     internal_emplace(end(), maybe_move_from_iterator(iter));
@@ -1902,16 +1916,6 @@ constexpr bool btree<P>::static_assert_validation() {
 }
 
 template <typename P>
-btree<P>::btree(const key_compare &comp, const allocator_type &alloc)
-    : root_(comp, alloc, EmptyNode()), rightmost_(EmptyNode()), size_(0) {}
-
-template <typename P>
-btree<P>::btree(const btree &other)
-    : btree(other.key_comp(), other.allocator()) {
-  copy_or_move_values_in_order(&other);
-}
-
-template <typename P>
 template <typename K>
 auto btree<P>::equal_range(const K &key) -> std::pair<iterator, iterator> {
   const iterator lower = lower_bound(key);
@@ -2068,7 +2072,7 @@ auto btree<P>::operator=(const btree &other) -> btree & {
       *mutable_allocator() = other.allocator();
     }
 
-    copy_or_move_values_in_order(&other);
+    copy_or_move_values_in_order(other);
   }
   return *this;
 }
@@ -2098,7 +2102,7 @@ auto btree<P>::operator=(btree &&other) noexcept -> btree & {
         // comparator while moving the values so we can't swap the key
         // comparators.
         *mutable_key_comp() = other.key_comp();
-        copy_or_move_values_in_order(&other);
+        copy_or_move_values_in_order(other);
       }
     }
   }