In sanitizer mode, detect when references become invalidated by randomly rehashing on insertions when there is no reserved growth.

PiperOrigin-RevId: 505807487
Change-Id: I9051a04f6a75e579d16e9ae8defd404bcc377fba

1 files changed, 15 insertions, 0 deletions

diff --git a/absl/container/internal/raw_hash_set.cc b/absl/container/internal/raw_hash_set.cc
index 3677ac59..5dc8b2fa 100644
--- a/absl/container/internal/raw_hash_set.cc
+++ b/absl/container/internal/raw_hash_set.cc
@@ -19,6 +19,7 @@
 #include <cstring>
 
 #include "absl/base/config.h"
+#include "absl/hash/hash.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
@@ -51,6 +52,20 @@ inline size_t RandomSeed() {
   return value ^ static_cast<size_t>(reinterpret_cast<uintptr_t>(&counter));
 }
 
+bool CommonFieldsGenerationInfoEnabled::
+    should_rehash_for_bug_detection_on_insert(const ctrl_t* ctrl,
+                                              size_t capacity) const {
+  if (reserved_growth_ == kReservedGrowthJustRanOut) return true;
+  if (reserved_growth_ > 0) return false;
+  // Note: we can't use the abseil-random library because abseil-random
+  // depends on swisstable. We want to return true with probability
+  // `min(1, RehashProbabilityConstant() / capacity())`. In order to do this,
+  // we probe based on a random hash and see if the offset is less than
+  // RehashProbabilityConstant().
+  return probe(ctrl, capacity, absl::HashOf(RandomSeed())).offset() <
+         RehashProbabilityConstant();
+}
+
 bool ShouldInsertBackwards(size_t hash, const ctrl_t* ctrl) {
   // To avoid problems with weak hashes and single bit tests, we use % 13.
   // TODO(kfm,sbenza): revisit after we do unconditional mixing