Export of internal Abseil changes

--
e7f53dfbf809812e84770217777f81b6308a3084 by Abseil Team <absl-team@google.com>:

Add a parameter pack to absl profile to allow profiles to separate
dynamic data from static data that is available at constructor-time.

Background: `inline_element_size` is effectively constant, but there
is a data race between its initialization and its access. We had fixed that race by making
inline_element_size atomic.  This CL changes `inline_element_size`
back to a non-atomic integer, and provides a way for all profiles to
provide Register()-time values.
PiperOrigin-RevId: 413960559

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70234c5943f8e37e17c1d9c54d8ed61d39880abf by Chris Kennelly <ckennelly@google.com>:

Document that absl::FunctionRef does not allocate.

PiperOrigin-RevId: 413946831

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3308ae571412c4be3cc32d088c6edac98ff2d1ed by Samuel Benzaquen <sbenza@google.com>:

Internal change

PiperOrigin-RevId: 413933619

--
1617093a730d055edcf7bc04fdd6509783f5f75d by Martijn Vels <mvels@google.com>:

Internal Change

PiperOrigin-RevId: 413778735

--
03ad683f059c806a6c8b04f5b79b2662c3df8c73 by Evan Brown <ezb@google.com>:

Unify btree erase_if definitions and optimize them so that we only do rebalancing once per leaf node.

PiperOrigin-RevId: 413757280

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5ba402f70801938178e486617063f01c7862525d by Martijn Vels <mvels@google.com>:

Cleanup up cord sampling internals

PiperOrigin-RevId: 413755011

--
522da8f9d3e0f11630d89fb41952004742bc335a by Evan Brown <ezb@google.com>:

Add b-tree benchmark for erase_if.

Since this benchmark doesn't work for std:: containers before C++20, disable it for them.

PiperOrigin-RevId: 413740844

--
a690ea42de8ed4a761d00235d8b2fb7548ba9732 by Andy Getzendanner <durandal@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 413735737
GitOrigin-RevId: e7f53dfbf809812e84770217777f81b6308a3084
Change-Id: I4f9f9039ba92831bc48971964aa063244c9fed72

1 files changed, 14 insertions, 6 deletions

diff --git a/absl/profiling/internal/sample_recorder.h b/absl/profiling/internal/sample_recorder.h
index 6c146210..fc269bdd 100644
--- a/absl/profiling/internal/sample_recorder.h
+++ b/absl/profiling/internal/sample_recorder.h
@@ -59,7 +59,8 @@ class SampleRecorder {
   ~SampleRecorder();
 
   // Registers for sampling.  Returns an opaque registration info.
-  T* Register();
+  template <typename... Targs>
+  T* Register(Targs&&... args);
 
   // Unregisters the sample.
   void Unregister(T* sample);
@@ -81,7 +82,8 @@ class SampleRecorder {
  private:
   void PushNew(T* sample);
   void PushDead(T* sample);
-  T* PopDead();
+  template <typename... Targs>
+  T* PopDead(Targs... args);
 
   std::atomic<size_t> dropped_samples_;
   std::atomic<size_t> size_estimate_;
@@ -163,7 +165,8 @@ void SampleRecorder<T>::PushDead(T* sample) {
 }
 
 template <typename T>
-T* SampleRecorder<T>::PopDead() {
+template <typename... Targs>
+T* SampleRecorder<T>::PopDead(Targs... args) {
   absl::MutexLock graveyard_lock(&graveyard_.init_mu);
 
   // The list is circular, so eventually it collapses down to
@@ -175,12 +178,13 @@ T* SampleRecorder<T>::PopDead() {
   absl::MutexLock sample_lock(&sample->init_mu);
   graveyard_.dead = sample->dead;
   sample->dead = nullptr;
-  sample->PrepareForSampling();
+  sample->PrepareForSampling(std::forward<Targs>(args)...);
   return sample;
 }
 
 template <typename T>
-T* SampleRecorder<T>::Register() {
+template <typename... Targs>
+T* SampleRecorder<T>::Register(Targs&&... args) {
   int64_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);
@@ -188,10 +192,14 @@ T* SampleRecorder<T>::Register() {
     return nullptr;
   }
 
-  T* sample = PopDead();
+  T* sample = PopDead(args...);
   if (sample == nullptr) {
     // Resurrection failed.  Hire a new warlock.
     sample = new T();
+    {
+      absl::MutexLock sample_lock(&sample->init_mu);
+      sample->PrepareForSampling(std::forward<Targs>(args)...);
+    }
     PushNew(sample);
   }