rocksdb/port/port_posix.cc

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#if !defined(OS_WIN)
#include "port/port_posix.h"
#include <assert.h>
support for concurrent adds to memtable Summary: This diff adds support for concurrent adds to the skiplist memtable implementations. Memory allocation is made thread-safe by the addition of a spinlock, with small per-core buffers to avoid contention. Concurrent memtable writes are made via an additional method and don't impose a performance overhead on the non-concurrent case, so parallelism can be selected on a per-batch basis. Write thread synchronization is an increasing bottleneck for higher levels of concurrency, so this diff adds --enable_write_thread_adaptive_yield (default off). This feature causes threads joining a write batch group to spin for a short time (default 100 usec) using sched_yield, rather than going to sleep on a mutex. If the timing of the yield calls indicates that another thread has actually run during the yield then spinning is avoided. This option improves performance for concurrent situations even without parallel adds, although it has the potential to increase CPU usage (and the heuristic adaptation is not yet mature). Parallel writes are not currently compatible with inplace updates, update callbacks, or delete filtering. Enable it with --allow_concurrent_memtable_write (and --enable_write_thread_adaptive_yield). Parallel memtable writes are performance neutral when there is no actual parallelism, and in my experiments (SSD server-class Linux and varying contention and key sizes for fillrandom) they are always a performance win when there is more than one thread. Statistics are updated earlier in the write path, dropping the number of DB mutex acquisitions from 2 to 1 for almost all cases. This diff was motivated and inspired by Yahoo's cLSM work. It is more conservative than cLSM: RocksDB's write batch group leader role is preserved (along with all of the existing flush and write throttling logic) and concurrent writers are blocked until all memtable insertions have completed and the sequence number has been advanced, to preserve linearizability. My test config is "db_bench -benchmarks=fillrandom -threads=$T -batch_size=1 -memtablerep=skip_list -value_size=100 --num=1000000/$T -level0_slowdown_writes_trigger=9999 -level0_stop_writes_trigger=9999 -disable_auto_compactions --max_write_buffer_number=8 -max_background_flushes=8 --disable_wal --write_buffer_size=160000000 --block_size=16384 --allow_concurrent_memtable_write" on a two-socket Xeon E5-2660 @ 2.2Ghz with lots of memory and an SSD hard drive. With 1 thread I get ~440Kops/sec. Peak performance for 1 socket (numactl -N1) is slightly more than 1Mops/sec, at 16 threads. Peak performance across both sockets happens at 30 threads, and is ~900Kops/sec, although with fewer threads there is less performance loss when the system has background work. Test Plan: 1. concurrent stress tests for InlineSkipList and DynamicBloom 2. make clean; make check 3. make clean; DISABLE_JEMALLOC=1 make valgrind_check; valgrind db_bench 4. make clean; COMPILE_WITH_TSAN=1 make all check; db_bench 5. make clean; COMPILE_WITH_ASAN=1 make all check; db_bench 6. make clean; OPT=-DROCKSDB_LITE make check 7. verify no perf regressions when disabled Reviewers: igor, sdong Reviewed By: sdong Subscribers: MarkCallaghan, IslamAbdelRahman, anthony, yhchiang, rven, sdong, guyg8, kradhakrishnan, dhruba Differential Revision: https://reviews.facebook.net/D50589
2015-08-15 01:59:07 +02:00
#if defined(__i386__) || defined(__x86_64__)
#include <cpuid.h>
#endif
#include <errno.h>
#include <sched.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <unistd.h>
#include <cstdlib>
Built-in support for generating unique IDs, bug fix (#8708) Summary: Env::GenerateUniqueId() works fine on Windows and on POSIX where /proc/sys/kernel/random/uuid exists. Our other implementation is flawed and easily produces collision in a new multi-threaded test. As we rely more heavily on DB session ID uniqueness, this becomes a serious issue. This change combines several individually suitable entropy sources for reliable generation of random unique IDs, with goal of uniqueness and portability, not cryptographic strength nor maximum speed. Specifically: * Moves code for getting UUIDs from the OS to port::GenerateRfcUuid rather than in Env implementation details. Callers are now told whether the operation fails or succeeds. * Adds an internal API GenerateRawUniqueId for generating high-quality 128-bit unique identifiers, by combining entropy from three "tracks": * Lots of info from default Env like time, process id, and hostname. * std::random_device * port::GenerateRfcUuid (when working) * Built-in implementations of Env::GenerateUniqueId() will now always produce an RFC 4122 UUID string, either from platform-specific API or by converting the output of GenerateRawUniqueId. DB session IDs now use GenerateRawUniqueId while DB IDs (not as critical) try to use port::GenerateRfcUuid but fall back on GenerateRawUniqueId with conversion to an RFC 4122 UUID. GenerateRawUniqueId is declared and defined under env/ rather than util/ or even port/ because of the Env dependency. Likely follow-up: enhance GenerateRawUniqueId to be faster after the first call and to guarantee uniqueness within the lifetime of a single process (imparting the same property onto DB session IDs). Pull Request resolved: https://github.com/facebook/rocksdb/pull/8708 Test Plan: A new mini-stress test in env_test checks the various public and internal APIs for uniqueness, including each track of GenerateRawUniqueId individually. We can't hope to verify anywhere close to 128 bits of entropy, but it can at least detect flaws as bad as the old code. Serial execution of the new tests takes about 350 ms on my machine. Reviewed By: zhichao-cao, mrambacher Differential Revision: D30563780 Pulled By: pdillinger fbshipit-source-id: de4c9ff4b2f581cf784fcedb5f39f16e5185c364
2021-08-31 00:19:39 +02:00
#include <fstream>
#include <string>
#include "util/string_util.h"
namespace ROCKSDB_NAMESPACE {
// We want to give users opportunity to default all the mutexes to adaptive if
// not specified otherwise. This enables a quick way to conduct various
// performance related experiements.
//
// NB! Support for adaptive mutexes is turned on by definining
// ROCKSDB_PTHREAD_ADAPTIVE_MUTEX during the compilation. If you use RocksDB
// build environment then this happens automatically; otherwise it's up to the
// consumer to define the identifier.
#ifdef ROCKSDB_DEFAULT_TO_ADAPTIVE_MUTEX
extern const bool kDefaultToAdaptiveMutex = true;
#else
extern const bool kDefaultToAdaptiveMutex = false;
#endif
namespace port {
static int PthreadCall(const char* label, int result) {
if (result != 0 && result != ETIMEDOUT && result != EBUSY) {
fprintf(stderr, "pthread %s: %s\n", label, errnoStr(result).c_str());
abort();
}
return result;
}
Mutex::Mutex(bool adaptive) {
(void) adaptive;
#ifdef ROCKSDB_PTHREAD_ADAPTIVE_MUTEX
if (!adaptive) {
PthreadCall("init mutex", pthread_mutex_init(&mu_, nullptr));
} else {
pthread_mutexattr_t mutex_attr;
PthreadCall("init mutex attr", pthread_mutexattr_init(&mutex_attr));
PthreadCall("set mutex attr",
pthread_mutexattr_settype(&mutex_attr,
PTHREAD_MUTEX_ADAPTIVE_NP));
PthreadCall("init mutex", pthread_mutex_init(&mu_, &mutex_attr));
PthreadCall("destroy mutex attr",
pthread_mutexattr_destroy(&mutex_attr));
}
#else
PthreadCall("init mutex", pthread_mutex_init(&mu_, nullptr));
#endif // ROCKSDB_PTHREAD_ADAPTIVE_MUTEX
}
Mutex::~Mutex() { PthreadCall("destroy mutex", pthread_mutex_destroy(&mu_)); }
void Mutex::Lock() {
PthreadCall("lock", pthread_mutex_lock(&mu_));
#ifndef NDEBUG
locked_ = true;
#endif
}
void Mutex::Unlock() {
#ifndef NDEBUG
locked_ = false;
#endif
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
}
bool Mutex::TryLock() {
bool ret = PthreadCall("trylock", pthread_mutex_trylock(&mu_)) == 0;
#ifndef NDEBUG
if (ret) {
locked_ = true;
}
#endif
return ret;
}
void Mutex::AssertHeld() {
#ifndef NDEBUG
assert(locked_);
#endif
}
CondVar::CondVar(Mutex* mu)
: mu_(mu) {
PthreadCall("init cv", pthread_cond_init(&cv_, nullptr));
}
CondVar::~CondVar() { PthreadCall("destroy cv", pthread_cond_destroy(&cv_)); }
void CondVar::Wait() {
#ifndef NDEBUG
mu_->locked_ = false;
#endif
PthreadCall("wait", pthread_cond_wait(&cv_, &mu_->mu_));
#ifndef NDEBUG
mu_->locked_ = true;
#endif
}
bool CondVar::TimedWait(uint64_t abs_time_us) {
struct timespec ts;
ts.tv_sec = static_cast<time_t>(abs_time_us / 1000000);
ts.tv_nsec = static_cast<suseconds_t>((abs_time_us % 1000000) * 1000);
#ifndef NDEBUG
mu_->locked_ = false;
#endif
int err = pthread_cond_timedwait(&cv_, &mu_->mu_, &ts);
#ifndef NDEBUG
mu_->locked_ = true;
#endif
if (err == ETIMEDOUT) {
return true;
}
if (err != 0) {
PthreadCall("timedwait", err);
}
return false;
}
void CondVar::Signal() {
PthreadCall("signal", pthread_cond_signal(&cv_));
}
void CondVar::SignalAll() {
PthreadCall("broadcast", pthread_cond_broadcast(&cv_));
}
RWMutex::RWMutex() {
PthreadCall("init mutex", pthread_rwlock_init(&mu_, nullptr));
}
RWMutex::~RWMutex() { PthreadCall("destroy mutex", pthread_rwlock_destroy(&mu_)); }
void RWMutex::ReadLock() { PthreadCall("read lock", pthread_rwlock_rdlock(&mu_)); }
void RWMutex::WriteLock() { PthreadCall("write lock", pthread_rwlock_wrlock(&mu_)); }
void RWMutex::ReadUnlock() { PthreadCall("read unlock", pthread_rwlock_unlock(&mu_)); }
void RWMutex::WriteUnlock() { PthreadCall("write unlock", pthread_rwlock_unlock(&mu_)); }
int PhysicalCoreID() {
#if defined(ROCKSDB_SCHED_GETCPU_PRESENT) && defined(__x86_64__) && \
(__GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 22))
// sched_getcpu uses VDSO getcpu() syscall since 2.22. I believe Linux offers VDSO
// support only on x86_64. This is the fastest/preferred method if available.
int cpuno = sched_getcpu();
if (cpuno < 0) {
return -1;
}
return cpuno;
#elif defined(__x86_64__) || defined(__i386__)
// clang/gcc both provide cpuid.h, which defines __get_cpuid(), for x86_64 and i386.
support for concurrent adds to memtable Summary: This diff adds support for concurrent adds to the skiplist memtable implementations. Memory allocation is made thread-safe by the addition of a spinlock, with small per-core buffers to avoid contention. Concurrent memtable writes are made via an additional method and don't impose a performance overhead on the non-concurrent case, so parallelism can be selected on a per-batch basis. Write thread synchronization is an increasing bottleneck for higher levels of concurrency, so this diff adds --enable_write_thread_adaptive_yield (default off). This feature causes threads joining a write batch group to spin for a short time (default 100 usec) using sched_yield, rather than going to sleep on a mutex. If the timing of the yield calls indicates that another thread has actually run during the yield then spinning is avoided. This option improves performance for concurrent situations even without parallel adds, although it has the potential to increase CPU usage (and the heuristic adaptation is not yet mature). Parallel writes are not currently compatible with inplace updates, update callbacks, or delete filtering. Enable it with --allow_concurrent_memtable_write (and --enable_write_thread_adaptive_yield). Parallel memtable writes are performance neutral when there is no actual parallelism, and in my experiments (SSD server-class Linux and varying contention and key sizes for fillrandom) they are always a performance win when there is more than one thread. Statistics are updated earlier in the write path, dropping the number of DB mutex acquisitions from 2 to 1 for almost all cases. This diff was motivated and inspired by Yahoo's cLSM work. It is more conservative than cLSM: RocksDB's write batch group leader role is preserved (along with all of the existing flush and write throttling logic) and concurrent writers are blocked until all memtable insertions have completed and the sequence number has been advanced, to preserve linearizability. My test config is "db_bench -benchmarks=fillrandom -threads=$T -batch_size=1 -memtablerep=skip_list -value_size=100 --num=1000000/$T -level0_slowdown_writes_trigger=9999 -level0_stop_writes_trigger=9999 -disable_auto_compactions --max_write_buffer_number=8 -max_background_flushes=8 --disable_wal --write_buffer_size=160000000 --block_size=16384 --allow_concurrent_memtable_write" on a two-socket Xeon E5-2660 @ 2.2Ghz with lots of memory and an SSD hard drive. With 1 thread I get ~440Kops/sec. Peak performance for 1 socket (numactl -N1) is slightly more than 1Mops/sec, at 16 threads. Peak performance across both sockets happens at 30 threads, and is ~900Kops/sec, although with fewer threads there is less performance loss when the system has background work. Test Plan: 1. concurrent stress tests for InlineSkipList and DynamicBloom 2. make clean; make check 3. make clean; DISABLE_JEMALLOC=1 make valgrind_check; valgrind db_bench 4. make clean; COMPILE_WITH_TSAN=1 make all check; db_bench 5. make clean; COMPILE_WITH_ASAN=1 make all check; db_bench 6. make clean; OPT=-DROCKSDB_LITE make check 7. verify no perf regressions when disabled Reviewers: igor, sdong Reviewed By: sdong Subscribers: MarkCallaghan, IslamAbdelRahman, anthony, yhchiang, rven, sdong, guyg8, kradhakrishnan, dhruba Differential Revision: https://reviews.facebook.net/D50589
2015-08-15 01:59:07 +02:00
unsigned eax, ebx = 0, ecx, edx;
if (!__get_cpuid(1, &eax, &ebx, &ecx, &edx)) {
return -1;
}
support for concurrent adds to memtable Summary: This diff adds support for concurrent adds to the skiplist memtable implementations. Memory allocation is made thread-safe by the addition of a spinlock, with small per-core buffers to avoid contention. Concurrent memtable writes are made via an additional method and don't impose a performance overhead on the non-concurrent case, so parallelism can be selected on a per-batch basis. Write thread synchronization is an increasing bottleneck for higher levels of concurrency, so this diff adds --enable_write_thread_adaptive_yield (default off). This feature causes threads joining a write batch group to spin for a short time (default 100 usec) using sched_yield, rather than going to sleep on a mutex. If the timing of the yield calls indicates that another thread has actually run during the yield then spinning is avoided. This option improves performance for concurrent situations even without parallel adds, although it has the potential to increase CPU usage (and the heuristic adaptation is not yet mature). Parallel writes are not currently compatible with inplace updates, update callbacks, or delete filtering. Enable it with --allow_concurrent_memtable_write (and --enable_write_thread_adaptive_yield). Parallel memtable writes are performance neutral when there is no actual parallelism, and in my experiments (SSD server-class Linux and varying contention and key sizes for fillrandom) they are always a performance win when there is more than one thread. Statistics are updated earlier in the write path, dropping the number of DB mutex acquisitions from 2 to 1 for almost all cases. This diff was motivated and inspired by Yahoo's cLSM work. It is more conservative than cLSM: RocksDB's write batch group leader role is preserved (along with all of the existing flush and write throttling logic) and concurrent writers are blocked until all memtable insertions have completed and the sequence number has been advanced, to preserve linearizability. My test config is "db_bench -benchmarks=fillrandom -threads=$T -batch_size=1 -memtablerep=skip_list -value_size=100 --num=1000000/$T -level0_slowdown_writes_trigger=9999 -level0_stop_writes_trigger=9999 -disable_auto_compactions --max_write_buffer_number=8 -max_background_flushes=8 --disable_wal --write_buffer_size=160000000 --block_size=16384 --allow_concurrent_memtable_write" on a two-socket Xeon E5-2660 @ 2.2Ghz with lots of memory and an SSD hard drive. With 1 thread I get ~440Kops/sec. Peak performance for 1 socket (numactl -N1) is slightly more than 1Mops/sec, at 16 threads. Peak performance across both sockets happens at 30 threads, and is ~900Kops/sec, although with fewer threads there is less performance loss when the system has background work. Test Plan: 1. concurrent stress tests for InlineSkipList and DynamicBloom 2. make clean; make check 3. make clean; DISABLE_JEMALLOC=1 make valgrind_check; valgrind db_bench 4. make clean; COMPILE_WITH_TSAN=1 make all check; db_bench 5. make clean; COMPILE_WITH_ASAN=1 make all check; db_bench 6. make clean; OPT=-DROCKSDB_LITE make check 7. verify no perf regressions when disabled Reviewers: igor, sdong Reviewed By: sdong Subscribers: MarkCallaghan, IslamAbdelRahman, anthony, yhchiang, rven, sdong, guyg8, kradhakrishnan, dhruba Differential Revision: https://reviews.facebook.net/D50589
2015-08-15 01:59:07 +02:00
return ebx >> 24;
#else
// give up, the caller can generate a random number or something.
return -1;
support for concurrent adds to memtable Summary: This diff adds support for concurrent adds to the skiplist memtable implementations. Memory allocation is made thread-safe by the addition of a spinlock, with small per-core buffers to avoid contention. Concurrent memtable writes are made via an additional method and don't impose a performance overhead on the non-concurrent case, so parallelism can be selected on a per-batch basis. Write thread synchronization is an increasing bottleneck for higher levels of concurrency, so this diff adds --enable_write_thread_adaptive_yield (default off). This feature causes threads joining a write batch group to spin for a short time (default 100 usec) using sched_yield, rather than going to sleep on a mutex. If the timing of the yield calls indicates that another thread has actually run during the yield then spinning is avoided. This option improves performance for concurrent situations even without parallel adds, although it has the potential to increase CPU usage (and the heuristic adaptation is not yet mature). Parallel writes are not currently compatible with inplace updates, update callbacks, or delete filtering. Enable it with --allow_concurrent_memtable_write (and --enable_write_thread_adaptive_yield). Parallel memtable writes are performance neutral when there is no actual parallelism, and in my experiments (SSD server-class Linux and varying contention and key sizes for fillrandom) they are always a performance win when there is more than one thread. Statistics are updated earlier in the write path, dropping the number of DB mutex acquisitions from 2 to 1 for almost all cases. This diff was motivated and inspired by Yahoo's cLSM work. It is more conservative than cLSM: RocksDB's write batch group leader role is preserved (along with all of the existing flush and write throttling logic) and concurrent writers are blocked until all memtable insertions have completed and the sequence number has been advanced, to preserve linearizability. My test config is "db_bench -benchmarks=fillrandom -threads=$T -batch_size=1 -memtablerep=skip_list -value_size=100 --num=1000000/$T -level0_slowdown_writes_trigger=9999 -level0_stop_writes_trigger=9999 -disable_auto_compactions --max_write_buffer_number=8 -max_background_flushes=8 --disable_wal --write_buffer_size=160000000 --block_size=16384 --allow_concurrent_memtable_write" on a two-socket Xeon E5-2660 @ 2.2Ghz with lots of memory and an SSD hard drive. With 1 thread I get ~440Kops/sec. Peak performance for 1 socket (numactl -N1) is slightly more than 1Mops/sec, at 16 threads. Peak performance across both sockets happens at 30 threads, and is ~900Kops/sec, although with fewer threads there is less performance loss when the system has background work. Test Plan: 1. concurrent stress tests for InlineSkipList and DynamicBloom 2. make clean; make check 3. make clean; DISABLE_JEMALLOC=1 make valgrind_check; valgrind db_bench 4. make clean; COMPILE_WITH_TSAN=1 make all check; db_bench 5. make clean; COMPILE_WITH_ASAN=1 make all check; db_bench 6. make clean; OPT=-DROCKSDB_LITE make check 7. verify no perf regressions when disabled Reviewers: igor, sdong Reviewed By: sdong Subscribers: MarkCallaghan, IslamAbdelRahman, anthony, yhchiang, rven, sdong, guyg8, kradhakrishnan, dhruba Differential Revision: https://reviews.facebook.net/D50589
2015-08-15 01:59:07 +02:00
#endif
}
void InitOnce(OnceType* once, void (*initializer)()) {
PthreadCall("once", pthread_once(once, initializer));
}
void Crash(const std::string& srcfile, int srcline) {
fprintf(stdout, "Crashing at %s:%d\n", srcfile.c_str(), srcline);
fflush(stdout);
kill(getpid(), SIGTERM);
}
int GetMaxOpenFiles() {
#if defined(RLIMIT_NOFILE)
struct rlimit no_files_limit;
if (getrlimit(RLIMIT_NOFILE, &no_files_limit) != 0) {
return -1;
}
// protect against overflow
if (static_cast<uintmax_t>(no_files_limit.rlim_cur) >=
static_cast<uintmax_t>(std::numeric_limits<int>::max())) {
return std::numeric_limits<int>::max();
}
return static_cast<int>(no_files_limit.rlim_cur);
#endif
return -1;
}
void *cacheline_aligned_alloc(size_t size) {
#if __GNUC__ < 5 && defined(__SANITIZE_ADDRESS__)
return malloc(size);
#elif ( _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600 || defined(__APPLE__))
void *m;
errno = posix_memalign(&m, CACHE_LINE_SIZE, size);
return errno ? nullptr : m;
#else
return malloc(size);
#endif
}
void cacheline_aligned_free(void *memblock) {
free(memblock);
}
static size_t GetPageSize() {
#if defined(OS_LINUX) || defined(_SC_PAGESIZE)
long v = sysconf(_SC_PAGESIZE);
if (v >= 1024) {
return static_cast<size_t>(v);
}
#endif
// Default assume 4KB
return 4U * 1024U;
}
const size_t kPageSize = GetPageSize();
void SetCpuPriority(ThreadId id, CpuPriority priority) {
#ifdef OS_LINUX
sched_param param;
param.sched_priority = 0;
switch (priority) {
case CpuPriority::kHigh:
sched_setscheduler(id, SCHED_OTHER, &param);
setpriority(PRIO_PROCESS, id, -20);
break;
case CpuPriority::kNormal:
sched_setscheduler(id, SCHED_OTHER, &param);
setpriority(PRIO_PROCESS, id, 0);
break;
case CpuPriority::kLow:
sched_setscheduler(id, SCHED_OTHER, &param);
setpriority(PRIO_PROCESS, id, 19);
break;
case CpuPriority::kIdle:
sched_setscheduler(id, SCHED_IDLE, &param);
break;
default:
assert(false);
}
#else
(void)id;
(void)priority;
#endif
}
int64_t GetProcessID() { return getpid(); }
Built-in support for generating unique IDs, bug fix (#8708) Summary: Env::GenerateUniqueId() works fine on Windows and on POSIX where /proc/sys/kernel/random/uuid exists. Our other implementation is flawed and easily produces collision in a new multi-threaded test. As we rely more heavily on DB session ID uniqueness, this becomes a serious issue. This change combines several individually suitable entropy sources for reliable generation of random unique IDs, with goal of uniqueness and portability, not cryptographic strength nor maximum speed. Specifically: * Moves code for getting UUIDs from the OS to port::GenerateRfcUuid rather than in Env implementation details. Callers are now told whether the operation fails or succeeds. * Adds an internal API GenerateRawUniqueId for generating high-quality 128-bit unique identifiers, by combining entropy from three "tracks": * Lots of info from default Env like time, process id, and hostname. * std::random_device * port::GenerateRfcUuid (when working) * Built-in implementations of Env::GenerateUniqueId() will now always produce an RFC 4122 UUID string, either from platform-specific API or by converting the output of GenerateRawUniqueId. DB session IDs now use GenerateRawUniqueId while DB IDs (not as critical) try to use port::GenerateRfcUuid but fall back on GenerateRawUniqueId with conversion to an RFC 4122 UUID. GenerateRawUniqueId is declared and defined under env/ rather than util/ or even port/ because of the Env dependency. Likely follow-up: enhance GenerateRawUniqueId to be faster after the first call and to guarantee uniqueness within the lifetime of a single process (imparting the same property onto DB session IDs). Pull Request resolved: https://github.com/facebook/rocksdb/pull/8708 Test Plan: A new mini-stress test in env_test checks the various public and internal APIs for uniqueness, including each track of GenerateRawUniqueId individually. We can't hope to verify anywhere close to 128 bits of entropy, but it can at least detect flaws as bad as the old code. Serial execution of the new tests takes about 350 ms on my machine. Reviewed By: zhichao-cao, mrambacher Differential Revision: D30563780 Pulled By: pdillinger fbshipit-source-id: de4c9ff4b2f581cf784fcedb5f39f16e5185c364
2021-08-31 00:19:39 +02:00
bool GenerateRfcUuid(std::string* output) {
output->clear();
std::ifstream f("/proc/sys/kernel/random/uuid");
std::getline(f, /*&*/ *output);
if (output->size() == 36) {
return true;
} else {
output->clear();
return false;
}
}
} // namespace port
} // namespace ROCKSDB_NAMESPACE
#endif