From 6af91b35109cb35ae53cfe908e31a0c31c4a47f3 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Fri, 11 Sep 2020 07:15:05 -0700
Subject: Export of internal Abseil changes

--
0e6d5abe305df4e943e0bc0256c67afc00956691 by Abseil Team <absl-team@google.com>:

Ensure that Hashtablez does not pull in absl::Mutex dependency when turned off at compile time.

PiperOrigin-RevId: 331142625
GitOrigin-RevId: 0e6d5abe305df4e943e0bc0256c67afc00956691
Change-Id: I984d6d3436e4825a7b20758c45b3142c0f3bb45a
---
 absl/container/internal/hashtablez_sampler.h       | 22 ++++++++++++++++++++--
 absl/container/internal/hashtablez_sampler_test.cc | 13 +++++++++++--
 absl/container/internal/raw_hash_set_test.cc       |  4 ++--
 3 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/absl/container/internal/hashtablez_sampler.h b/absl/container/internal/hashtablez_sampler.h
index b2a30c9a..394348da 100644
--- a/absl/container/internal/hashtablez_sampler.h
+++ b/absl/container/internal/hashtablez_sampler.h
@@ -139,6 +139,11 @@ inline void RecordEraseSlow(HashtablezInfo* info) {
 HashtablezInfo* SampleSlow(int64_t* next_sample);
 void UnsampleSlow(HashtablezInfo* info);
 
+#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
+#error ABSL_INTERNAL_HASHTABLEZ_SAMPLE cannot be directly set
+#endif  // defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
+
+#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
 class HashtablezInfoHandle {
  public:
   explicit HashtablezInfoHandle() : info_(nullptr) {}
@@ -190,9 +195,22 @@ class HashtablezInfoHandle {
   friend class HashtablezInfoHandlePeer;
   HashtablezInfo* info_;
 };
+#else
+// Ensure that when Hashtablez is turned off at compile time, HashtablezInfo can
+// be removed by the linker, in order to reduce the binary size.
+class HashtablezInfoHandle {
+ public:
+  explicit HashtablezInfoHandle() = default;
+  explicit HashtablezInfoHandle(std::nullptr_t) {}
 
-#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
-#error ABSL_INTERNAL_HASHTABLEZ_SAMPLE cannot be directly set
+  inline void RecordStorageChanged(size_t /*size*/, size_t /*capacity*/) {}
+  inline void RecordRehash(size_t /*total_probe_length*/) {}
+  inline void RecordInsert(size_t /*hash*/, size_t /*distance_from_desired*/) {}
+  inline void RecordErase() {}
+
+  friend inline void swap(HashtablezInfoHandle& /*lhs*/,
+                          HashtablezInfoHandle& /*rhs*/) {}
+};
 #endif  // defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
 
 #if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
diff --git a/absl/container/internal/hashtablez_sampler_test.cc b/absl/container/internal/hashtablez_sampler_test.cc
index 04a26cb7..8d10a1e9 100644
--- a/absl/container/internal/hashtablez_sampler_test.cc
+++ b/absl/container/internal/hashtablez_sampler_test.cc
@@ -38,6 +38,7 @@ constexpr int kProbeLength = 8;
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace container_internal {
+#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
 class HashtablezInfoHandlePeer {
  public:
   static bool IsSampled(const HashtablezInfoHandle& h) {
@@ -46,6 +47,13 @@ class HashtablezInfoHandlePeer {
 
   static HashtablezInfo* GetInfo(HashtablezInfoHandle* h) { return h->info_; }
 };
+#else
+class HashtablezInfoHandlePeer {
+ public:
+  static bool IsSampled(const HashtablezInfoHandle&) { return false; }
+  static HashtablezInfo* GetInfo(HashtablezInfoHandle*) { return nullptr; }
+};
+#endif  // defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
 
 namespace {
 using ::absl::synchronization_internal::ThreadPool;
@@ -172,7 +180,7 @@ TEST(HashtablezInfoTest, RecordRehash) {
   EXPECT_EQ(info.num_rehashes.load(), 1);
 }
 
-#if defined(ABSL_HASHTABLEZ_SAMPLE)
+#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
 TEST(HashtablezSamplerTest, SmallSampleParameter) {
   SetHashtablezEnabled(true);
   SetHashtablezSampleParameter(100);
@@ -216,7 +224,6 @@ TEST(HashtablezSamplerTest, Sample) {
   }
   EXPECT_NEAR(sample_rate, 0.01, 0.005);
 }
-#endif
 
 TEST(HashtablezSamplerTest, Handle) {
   auto& sampler = HashtablezSampler::Global();
@@ -246,6 +253,8 @@ TEST(HashtablezSamplerTest, Handle) {
   });
   EXPECT_FALSE(found);
 }
+#endif
+
 
 TEST(HashtablezSamplerTest, Registration) {
   HashtablezSampler sampler;
diff --git a/absl/container/internal/raw_hash_set_test.cc b/absl/container/internal/raw_hash_set_test.cc
index e3279301..f5ae83c4 100644
--- a/absl/container/internal/raw_hash_set_test.cc
+++ b/absl/container/internal/raw_hash_set_test.cc
@@ -1796,7 +1796,7 @@ TEST(TableDeathTest, EraseOfEndAsserts) {
   EXPECT_DEATH_IF_SUPPORTED(t.erase(t.end()), kDeathMsg);
 }
 
-#if defined(ABSL_HASHTABLEZ_SAMPLE)
+#if defined(ABSL_INTERNAL_HASHTABLEZ_SAMPLE)
 TEST(RawHashSamplerTest, Sample) {
   // Enable the feature even if the prod default is off.
   SetHashtablezEnabled(true);
@@ -1817,7 +1817,7 @@ TEST(RawHashSamplerTest, Sample) {
   EXPECT_NEAR((end_size - start_size) / static_cast<double>(tables.size()),
               0.01, 0.005);
 }
-#endif  // ABSL_HASHTABLEZ_SAMPLER
+#endif  // ABSL_INTERNAL_HASHTABLEZ_SAMPLE
 
 TEST(RawHashSamplerTest, DoNotSampleCustomAllocators) {
   // Enable the feature even if the prod default is off.
-- 
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