Export of internal Abseil changes

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93c607726d663800b4bfa472cba043fd3f5d0e97 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 389158822

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55b3bb50bbc168567c6ba25d07df2c2c39e864af by Martijn Vels <mvels@google.com>:

Change CordRepRing alternative implementation to CordRepBtree alternative.

This changes makes CordRepBtree (BTREE) the alternative to CordRepConcat (CONCAT) trees, enabled through the internal / experimental 'cord_btree_enabled' latch.

PiperOrigin-RevId: 389030571

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d6fc346143606c096bca8eb5029e4c429ac6e305 by Todd Lipcon <tlipcon@google.com>:

Fix a small typo in SequenceLock doc comment

PiperOrigin-RevId: 388972936

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e46f9245dce8b4150e3ca2664e0cf42b75f90a83 by Martijn Vels <mvels@google.com>:

Add 'shallow' validation mode to CordRepBtree which will be the default for internal assertions.

PiperOrigin-RevId: 388753606

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b5e74f163b490beb006f848ace67bb650433fe13 by Martijn Vels <mvels@google.com>:

Add btree statistics to CordzInfo, and reduce rounding errors

PiperOrigin-RevId: 388715878

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105bcbf80de649937e693b29b18220f9e6841a51 by Evan Brown <ezb@google.com>:

Skip length checking when constructing absl::string_view from `const char*`.
The length check causes unnecessary code bloat.

PiperOrigin-RevId: 388271741

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bed595158f24839efe49c65ae483f797d79fe0ae by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 387713428
GitOrigin-RevId: 93c607726d663800b4bfa472cba043fd3f5d0e97
Change-Id: I2a4840f5ffcd7f70b7d7d45cce66f23c42cf565f

1 files changed, 19 insertions, 18 deletions

diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index e758f1cd..ac1832f0 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -79,8 +79,9 @@
 #include "absl/functional/function_ref.h"
 #include "absl/meta/type_traits.h"
 #include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_btree.h"
+#include "absl/strings/internal/cord_rep_btree_reader.h"
 #include "absl/strings/internal/cord_rep_ring.h"
-#include "absl/strings/internal/cord_rep_ring_reader.h"
 #include "absl/strings/internal/cordz_functions.h"
 #include "absl/strings/internal/cordz_info.h"
 #include "absl/strings/internal/cordz_statistics.h"
@@ -370,8 +371,8 @@ class Cord {
 
    private:
     using CordRep = absl::cord_internal::CordRep;
-    using CordRepRing = absl::cord_internal::CordRepRing;
-    using CordRepRingReader = absl::cord_internal::CordRepRingReader;
+    using CordRepBtree = absl::cord_internal::CordRepBtree;
+    using CordRepBtreeReader = absl::cord_internal::CordRepBtreeReader;
 
     // Stack of right children of concat nodes that we have to visit.
     // Keep this at the end of the structure to avoid cache-thrashing.
@@ -397,9 +398,9 @@ class Cord {
     // Stack specific operator++
     ChunkIterator& AdvanceStack();
 
-    // Ring buffer specific operator++
-    ChunkIterator& AdvanceRing();
-    void AdvanceBytesRing(size_t n);
+    // Btree specific operator++
+    ChunkIterator& AdvanceBtree();
+    void AdvanceBytesBtree(size_t n);
 
     // Iterates `n` bytes, where `n` is expected to be greater than or equal to
     // `current_chunk_.size()`.
@@ -415,8 +416,8 @@ class Cord {
     // The number of bytes left in the `Cord` over which we are iterating.
     size_t bytes_remaining_ = 0;
 
-    // Cord reader for ring buffers. Empty if not traversing a ring buffer.
-    CordRepRingReader ring_reader_;
+    // Cord reader for cord btrees. Empty if not traversing a btree.
+    CordRepBtreeReader btree_reader_;
 
     // See 'Stack' alias definition.
     Stack stack_of_right_children_;
@@ -1247,8 +1248,8 @@ inline bool Cord::StartsWith(absl::string_view rhs) const {
 }
 
 inline void Cord::ChunkIterator::InitTree(cord_internal::CordRep* tree) {
-  if (tree->tag == cord_internal::RING) {
-    current_chunk_ = ring_reader_.Reset(tree->ring());
+  if (tree->tag == cord_internal::BTREE) {
+    current_chunk_ = btree_reader_.Init(tree->btree());
     return;
   }
 
@@ -1271,20 +1272,20 @@ inline Cord::ChunkIterator::ChunkIterator(const Cord* cord)
   }
 }
 
-inline Cord::ChunkIterator& Cord::ChunkIterator::AdvanceRing() {
-  current_chunk_ = ring_reader_.Next();
+inline Cord::ChunkIterator& Cord::ChunkIterator::AdvanceBtree() {
+  current_chunk_ = btree_reader_.Next();
   return *this;
 }
 
-inline void Cord::ChunkIterator::AdvanceBytesRing(size_t n) {
+inline void Cord::ChunkIterator::AdvanceBytesBtree(size_t n) {
   assert(n >= current_chunk_.size());
   bytes_remaining_ -= n;
   if (bytes_remaining_) {
     if (n == current_chunk_.size()) {
-      current_chunk_ = ring_reader_.Next();
+      current_chunk_ = btree_reader_.Next();
     } else {
-      size_t offset = ring_reader_.length() - bytes_remaining_;
-      current_chunk_ = ring_reader_.Seek(offset);
+      size_t offset = btree_reader_.length() - bytes_remaining_;
+      current_chunk_ = btree_reader_.Seek(offset);
     }
   } else {
     current_chunk_ = {};
@@ -1297,7 +1298,7 @@ inline Cord::ChunkIterator& Cord::ChunkIterator::operator++() {
   assert(bytes_remaining_ >= current_chunk_.size());
   bytes_remaining_ -= current_chunk_.size();
   if (bytes_remaining_ > 0) {
-    return ring_reader_ ? AdvanceRing() : AdvanceStack();
+    return btree_reader_ ? AdvanceBtree() : AdvanceStack();
   } else {
     current_chunk_ = {};
   }
@@ -1339,7 +1340,7 @@ inline void Cord::ChunkIterator::AdvanceBytes(size_t n) {
   if (ABSL_PREDICT_TRUE(n < current_chunk_.size())) {
     RemoveChunkPrefix(n);
   } else if (n != 0) {
-    ring_reader_ ? AdvanceBytesRing(n) : AdvanceBytesSlowPath(n);
+    btree_reader_ ? AdvanceBytesBtree(n) : AdvanceBytesSlowPath(n);
   }
 }