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hash: move the random generator out of bees-hash.cc

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We need random numbers in more places, so centralize the engines.
Initialize with a proper random seed so every worker thread gets
different behavior.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This commit is contained in:
Zygo Blaxell 2021-11-16 00:55:58 -05:00
parent 73f94750ec
commit ba694b4881
3 changed files with 14 additions and 4 deletions
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7
src/bees-hash.cc
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@ -5,7 +5,6 @@
#include "crucible/string.h"
#include <algorithm>
#include <random>
#include <sys/mman.h>
@ -538,6 +537,8 @@ BeesHashTable::push_front_hash_addr(HashType hash, AddrType addr)
return found;
}
thread_local uniform_int_distribution<size_t> BeesHashTable::tl_distribution(0, c_cells_per_bucket - 1);
/// Insert a hash entry at some unspecified point in the list.
/// If entry is already present in list, returns true and does not
/// modify list. If entry is not present in list, returns false and
@ -555,9 +556,7 @@ BeesHashTable::push_random_hash_addr(HashType hash, AddrType addr)
Cell *ip = find(er.first, er.second, mv);
bool found = (ip < er.second);
thread_local default_random_engine generator;
thread_local uniform_int_distribution<int> distribution(0, c_cells_per_bucket - 1);
auto pos = distribution(generator);
const auto pos = tl_distribution(bees_generator);
int case_cond = 0;
#if 0

7
src/bees.cc
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@ -268,6 +268,13 @@ bees_unreadahead(int const fd, off_t offset, size_t size)
BEESCOUNTADD(readahead_unread_ms, unreadahead_timer.age() * 1000);
}
thread_local random_device bees_random_device;
thread_local uniform_int_distribution<default_random_engine::result_type> bees_random_seed_dist(
numeric_limits<default_random_engine::result_type>::min(),
numeric_limits<default_random_engine::result_type>::max()
);
thread_local default_random_engine bees_generator(bees_random_seed_dist(bees_random_device));
BeesStringFile::BeesStringFile(Fd dir_fd, string name, size_t limit) :
m_dir_fd(dir_fd),
m_name(name),

4
src/bees.h
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@ -18,6 +18,7 @@
#include <list>
#include <mutex>
#include <string>
#include <random>
#include <thread>
#include <syslog.h>
@ -496,6 +497,8 @@ private:
BeesHashTable(const BeesHashTable &) = delete;
BeesHashTable &operator=(const BeesHashTable &) = delete;
static thread_local uniform_int_distribution<size_t> tl_distribution;
};
ostream &operator<<(ostream &os, const BeesHashTable::Cell &bhte);
@ -881,6 +884,7 @@ public:
extern int bees_log_level;
extern const char *BEES_USAGE;
extern const char *BEES_VERSION;
extern thread_local default_random_engine bees_generator;
string pretty(double d);
void bees_sync(int fd);
void bees_readahead(int fd, off_t offset, size_t size);