ShardedAtomicInt Struct Reference

Public Member Functions
void	inc (int64_t val=1)
int64_t	readFast ()
int64_t	readFull ()

Public Attributes
std::atomic< int64_t >	ints_ [kBuckets_]

Static Public Attributes
static const int64_t	kBuckets_ = 2048

Detailed Description

Definition at line 303 of file ThreadCachedIntTest.cpp.

Member Function Documentation

void ShardedAtomicInt::inc ( int64_t  val = 1 )

inline

Definition at line 307 of file ThreadCachedIntTest.cpp.

References folly::getCurrentThreadID(), folly::hash::twang_mix64(), and val.

                                   {
    int buck = hash::twang_mix64(folly::getCurrentThreadID()) & (kBuckets_ - 1);
    std::atomic_fetch_add(&ints_[buck], val);
  }

int64_t ShardedAtomicInt::readFast ( )

inline

Definition at line 313 of file ThreadCachedIntTest.cpp.

References FOR_EACH_RANGE, i, and int64_t.

Referenced by BENCHMARK().

                     {
    int64_t ret = 0;
    static const int numToRead = 8;
    FOR_EACH_RANGE (i, 0, numToRead) {
      ret += ints_[i].load(std::memory_order_relaxed);
    }
    return ret * (kBuckets_ / numToRead);
  }

int64_t ShardedAtomicInt::readFull ( )

inline

Definition at line 323 of file ThreadCachedIntTest.cpp.

References i, and int64_t.

Referenced by BENCHMARK().

                     {
    int64_t ret = 0;
    for (auto& i : ints_) {
      // Fun fact - using memory_order_consume below reduces perf 30-40% in high
      // contention benchmarks.
      ret += i.load(std::memory_order_relaxed);
    }
    return ret;
  }

Member Data Documentation

std::atomic<int64_t> ShardedAtomicInt::ints_[kBuckets_]

Definition at line 305 of file ThreadCachedIntTest.cpp.

const int64_t ShardedAtomicInt::kBuckets_ = 2048

static

Definition at line 304 of file ThreadCachedIntTest.cpp.

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The documentation for this struct was generated from the following file:

• proxygen/folly/folly/test/ThreadCachedIntTest.cpp