2 files changed, 25 insertions, 15 deletions

diff --git a/absl/profiling/internal/exponential_biased_test.cc b/absl/profiling/internal/exponential_biased_test.cc
index 6a6c317e..ebfbcad4 100644
--- a/absl/profiling/internal/exponential_biased_test.cc
+++ b/absl/profiling/internal/exponential_biased_test.cc
@@ -94,13 +94,14 @@ double AndersonDarlingPValue(int n, double z) {
 }
 
 double AndersonDarlingStatistic(const std::vector<double>& random_sample) {
-  int n = random_sample.size();
+  size_t n = random_sample.size();
   double ad_sum = 0;
-  for (int i = 0; i < n; i++) {
+  for (size_t i = 0; i < n; i++) {
     ad_sum += (2 * i + 1) *
               std::log(random_sample[i] * (1 - random_sample[n - 1 - i]));
   }
-  double ad_statistic = -n - 1 / static_cast<double>(n) * ad_sum;
+  const auto n_as_double = static_cast<double>(n);
+  double ad_statistic = -n_as_double - 1 / n_as_double * ad_sum;
   return ad_statistic;
 }
 
@@ -111,14 +112,15 @@ double AndersonDarlingStatistic(const std::vector<double>& random_sample) {
 // Marsaglia and Marsaglia for details.
 double AndersonDarlingTest(const std::vector<double>& random_sample) {
   double ad_statistic = AndersonDarlingStatistic(random_sample);
-  double p = AndersonDarlingPValue(random_sample.size(), ad_statistic);
+  double p = AndersonDarlingPValue(static_cast<int>(random_sample.size()),
+                                   ad_statistic);
   return p;
 }
 
 TEST(ExponentialBiasedTest, CoinTossDemoWithGetSkipCount) {
   ExponentialBiased eb;
   for (int runs = 0; runs < 10; ++runs) {
-    for (int flips = eb.GetSkipCount(1); flips > 0; --flips) {
+    for (int64_t flips = eb.GetSkipCount(1); flips > 0; --flips) {
       printf("head...");
     }
     printf("tail\n");
@@ -132,7 +134,7 @@ TEST(ExponentialBiasedTest, CoinTossDemoWithGetSkipCount) {
 
 TEST(ExponentialBiasedTest, SampleDemoWithStride) {
   ExponentialBiased eb;
-  int stride = eb.GetStride(10);
+  int64_t stride = eb.GetStride(10);
   int samples = 0;
   for (int i = 0; i < 10000000; ++i) {
     if (--stride == 0) {
@@ -147,7 +149,7 @@ TEST(ExponentialBiasedTest, SampleDemoWithStride) {
 // Testing that NextRandom generates uniform random numbers. Applies the
 // Anderson-Darling test for uniformity
 TEST(ExponentialBiasedTest, TestNextRandom) {
-  for (auto n : std::vector<int>({
+  for (auto n : std::vector<size_t>({
            10,  // Check short-range correlation
            100, 1000,
            10000  // Make sure there's no systemic error
@@ -161,7 +163,7 @@ TEST(ExponentialBiasedTest, TestNextRandom) {
     }
     std::vector<uint64_t> int_random_sample(n);
     // Collect samples
-    for (int i = 0; i < n; i++) {
+    for (size_t i = 0; i < n; i++) {
       int_random_sample[i] = x;
       x = ExponentialBiased::NextRandom(x);
     }
@@ -169,7 +171,7 @@ TEST(ExponentialBiasedTest, TestNextRandom) {
     std::sort(int_random_sample.begin(), int_random_sample.end());
     std::vector<double> random_sample(n);
     // Convert them to uniform randoms (in the range [0,1])
-    for (int i = 0; i < n; i++) {
+    for (size_t i = 0; i < n; i++) {
       random_sample[i] =
           static_cast<double>(int_random_sample[i]) / max_prng_value;
     }
diff --git a/absl/profiling/internal/sample_recorder.h b/absl/profiling/internal/sample_recorder.h
index 5f65983b..371f6c47 100644
--- a/absl/profiling/internal/sample_recorder.h
+++ b/absl/profiling/internal/sample_recorder.h
@@ -77,8 +77,8 @@ class SampleRecorder {
   // samples that have been dropped.
   int64_t Iterate(const std::function<void(const T& stack)>& f);
 
-  int32_t GetMaxSamples() const;
-  void SetMaxSamples(int32_t max);
+  size_t GetMaxSamples() const;
+  void SetMaxSamples(size_t max);
 
  private:
   void PushNew(T* sample);
@@ -88,7 +88,7 @@ class SampleRecorder {
 
   std::atomic<size_t> dropped_samples_;
   std::atomic<size_t> size_estimate_;
-  std::atomic<int32_t> max_samples_{1 << 20};
+  std::atomic<size_t> max_samples_{1 << 20};
 
   // Intrusive lock free linked lists for tracking samples.
   //
@@ -186,7 +186,7 @@ T* SampleRecorder<T>::PopDead(Targs... args) {
 template <typename T>
 template <typename... Targs>
 T* SampleRecorder<T>::Register(Targs&&... args) {
-  int64_t size = size_estimate_.fetch_add(1, std::memory_order_relaxed);
+  size_t size = size_estimate_.fetch_add(1, std::memory_order_relaxed);
   if (size > max_samples_.load(std::memory_order_relaxed)) {
     size_estimate_.fetch_sub(1, std::memory_order_relaxed);
     dropped_samples_.fetch_add(1, std::memory_order_relaxed);
@@ -199,6 +199,14 @@ T* SampleRecorder<T>::Register(Targs&&... args) {
     sample = new T();
     {
       absl::MutexLock sample_lock(&sample->init_mu);
+      // If flag initialization happens to occur (perhaps in another thread)
+      // while in this block, it will lock `graveyard_` which is usually always
+      // locked before any sample. This will appear as a lock inversion.
+      // However, this code is run exactly once per sample, and this sample
+      // cannot be accessed until after it is returned from this method.  This
+      // means that this lock state can never be recreated, so we can safely
+      // inform the deadlock detector to ignore it.
+      sample->init_mu.ForgetDeadlockInfo();
       sample->PrepareForSampling(std::forward<Targs>(args)...);
     }
     PushNew(sample);
@@ -229,12 +237,12 @@ int64_t SampleRecorder<T>::Iterate(
 }
 
 template <typename T>
-void SampleRecorder<T>::SetMaxSamples(int32_t max) {
+void SampleRecorder<T>::SetMaxSamples(size_t max) {
   max_samples_.store(max, std::memory_order_release);
 }
 
 template <typename T>
-int32_t SampleRecorder<T>::GetMaxSamples() const {
+size_t SampleRecorder<T>::GetMaxSamples() const {
   return max_samples_.load(std::memory_order_acquire);
 }