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remove constexpr from util/random.h for MSVC compat

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Summary:
Scoped anonymous enums seem to be better supported than static
constexpr at the moment, so this diff replaces the latter with the former.
Also, this diff removes an incorrect inclusion of pthread.h.  MSVC build
was broken starting with D50439.

Test Plan:
1. build
2. observe proper skiplist behavior by absence of pathological slowdown
3. push diff to tmp_try_windows branch to tickle AppVeyor
4. wait for contbuild before committing to master

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D50517
This commit is contained in:
Nathan Bronson 2015-11-10 12:50:09 -08:00
parent b81b430987
commit 505accda38
2 changed files with 11 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
util/random.cc
View File

@ -6,9 +6,10 @@
#include "util/random.h" #include "util/random.h"
#include <pthread.h>
#include <stdint.h> #include <stdint.h>
#include <string.h> #include <string.h>
#include <thread>
#include <utility>
#include "port/likely.h" #include "port/likely.h"
#include "util/thread_local.h" #include "util/thread_local.h"
@ -27,10 +28,8 @@ Random* Random::GetTLSInstance() {
auto rv = tls_instance; auto rv = tls_instance;
if (UNLIKELY(rv == nullptr)) { if (UNLIKELY(rv == nullptr)) {
const pthread_t self = pthread_self(); size_t seed = std::hash<std::thread::id>()(std::this_thread::get_id());
uint32_t seed = 0; rv = new (&tls_instance_bytes) Random((uint32_t)seed);
memcpy(&seed, &self, sizeof(seed));
rv = new (&tls_instance_bytes) Random(seed);
tls_instance = rv; tls_instance = rv;
} }
return rv; return rv;

10
util/random.h
View File

@ -18,8 +18,12 @@ namespace rocksdb {
// package. // package.
class Random { class Random {
private: private:
static constexpr uint32_t M = 2147483647L; // 2^31-1 enum : uint32_t {
static constexpr uint64_t A = 16807; // bits 14, 8, 7, 5, 2, 1, 0 M = 2147483647L // 2^31-1
};
enum : uint64_t {
A = 16807 // bits 14, 8, 7, 5, 2, 1, 0
};
uint32_t seed_; uint32_t seed_;
@ -27,7 +31,7 @@ class Random {
public: public:
// This is the largest value that can be returned from Next() // This is the largest value that can be returned from Next()
static constexpr uint32_t kMaxNext = M; enum : uint32_t { kMaxNext = M };
explicit Random(uint32_t s) : seed_(GoodSeed(s)) {} explicit Random(uint32_t s) : seed_(GoodSeed(s)) {}