Du kannst nicht mehr als 25 Themen auswählen
Themen müssen entweder mit einem Buchstaben oder einer Ziffer beginnen. Sie können Bindestriche („-“) enthalten und bis zu 35 Zeichen lang sein.
699 Zeilen
18 KiB
699 Zeilen
18 KiB
// 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.
|
|
|
|
#include <dirent.h>
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <pthread.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <sys/mman.h>
|
|
#include <sys/resource.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/time.h>
|
|
#include <sys/types.h>
|
|
#include <time.h>
|
|
#include <unistd.h>
|
|
#include <deque>
|
|
#include <limits>
|
|
#include <set>
|
|
#include "leveldb/env.h"
|
|
#include "leveldb/slice.h"
|
|
#include "port/port.h"
|
|
#include "util/logging.h"
|
|
#include "util/mutexlock.h"
|
|
#include "util/posix_logger.h"
|
|
#include "util/env_posix_test_helper.h"
|
|
|
|
namespace leveldb {
|
|
|
|
namespace {
|
|
|
|
static int open_read_only_file_limit = -1;
|
|
static int mmap_limit = -1;
|
|
|
|
static Status PosixError(const std::string& context, int err_number) {
|
|
if (err_number == ENOENT) {
|
|
return Status::NotFound(context, strerror(err_number));
|
|
} else {
|
|
return Status::IOError(context, strerror(err_number));
|
|
}
|
|
}
|
|
|
|
// Helper class to limit resource usage to avoid exhaustion.
|
|
// Currently used to limit read-only file descriptors and mmap file usage
|
|
// so that we do not end up running out of file descriptors, virtual memory,
|
|
// or running into kernel performance problems for very large databases.
|
|
class Limiter {
|
|
public:
|
|
// Limit maximum number of resources to |n|.
|
|
Limiter(intptr_t n) {
|
|
SetAllowed(n);
|
|
}
|
|
|
|
// If another resource is available, acquire it and return true.
|
|
// Else return false.
|
|
bool Acquire() {
|
|
if (GetAllowed() <= 0) {
|
|
return false;
|
|
}
|
|
MutexLock l(&mu_);
|
|
intptr_t x = GetAllowed();
|
|
if (x <= 0) {
|
|
return false;
|
|
} else {
|
|
SetAllowed(x - 1);
|
|
return true;
|
|
}
|
|
}
|
|
|
|
// Release a resource acquired by a previous call to Acquire() that returned
|
|
// true.
|
|
void Release() {
|
|
MutexLock l(&mu_);
|
|
SetAllowed(GetAllowed() + 1);
|
|
}
|
|
|
|
private:
|
|
port::Mutex mu_;
|
|
port::AtomicPointer allowed_;
|
|
|
|
intptr_t GetAllowed() const {
|
|
return reinterpret_cast<intptr_t>(allowed_.Acquire_Load());
|
|
}
|
|
|
|
// REQUIRES: mu_ must be held
|
|
void SetAllowed(intptr_t v) {
|
|
allowed_.Release_Store(reinterpret_cast<void*>(v));
|
|
}
|
|
|
|
Limiter(const Limiter&);
|
|
void operator=(const Limiter&);
|
|
};
|
|
|
|
class PosixSequentialFile: public SequentialFile {
|
|
private:
|
|
std::string filename_;
|
|
FILE* file_;
|
|
|
|
public:
|
|
PosixSequentialFile(const std::string& fname, FILE* f)
|
|
: filename_(fname), file_(f) { }
|
|
virtual ~PosixSequentialFile() { fclose(file_); }
|
|
|
|
virtual Status Read(size_t n, Slice* result, char* scratch) {
|
|
Status s;
|
|
size_t r = fread_unlocked(scratch, 1, n, file_);
|
|
*result = Slice(scratch, r);
|
|
if (r < n) {
|
|
if (feof(file_)) {
|
|
// We leave status as ok if we hit the end of the file
|
|
} else {
|
|
// A partial read with an error: return a non-ok status
|
|
s = PosixError(filename_, errno);
|
|
}
|
|
}
|
|
return s;
|
|
}
|
|
|
|
virtual Status Skip(uint64_t n) {
|
|
if (fseek(file_, n, SEEK_CUR)) {
|
|
return PosixError(filename_, errno);
|
|
}
|
|
return Status::OK();
|
|
}
|
|
};
|
|
|
|
// pread() based random-access
|
|
class PosixRandomAccessFile: public RandomAccessFile {
|
|
private:
|
|
std::string filename_;
|
|
bool temporary_fd_; // If true, fd_ is -1 and we open on every read.
|
|
int fd_;
|
|
Limiter* limiter_;
|
|
|
|
public:
|
|
PosixRandomAccessFile(const std::string& fname, int fd, Limiter* limiter)
|
|
: filename_(fname), fd_(fd), limiter_(limiter) {
|
|
temporary_fd_ = !limiter->Acquire();
|
|
if (temporary_fd_) {
|
|
// Open file on every access.
|
|
close(fd_);
|
|
fd_ = -1;
|
|
}
|
|
}
|
|
|
|
virtual ~PosixRandomAccessFile() {
|
|
if (!temporary_fd_) {
|
|
close(fd_);
|
|
limiter_->Release();
|
|
}
|
|
}
|
|
|
|
virtual Status Read(uint64_t offset, size_t n, Slice* result,
|
|
char* scratch) const {
|
|
int fd = fd_;
|
|
if (temporary_fd_) {
|
|
fd = open(filename_.c_str(), O_RDONLY);
|
|
if (fd < 0) {
|
|
return PosixError(filename_, errno);
|
|
}
|
|
}
|
|
|
|
Status s;
|
|
ssize_t r = pread(fd, scratch, n, static_cast<off_t>(offset));
|
|
*result = Slice(scratch, (r < 0) ? 0 : r);
|
|
if (r < 0) {
|
|
// An error: return a non-ok status
|
|
s = PosixError(filename_, errno);
|
|
}
|
|
if (temporary_fd_) {
|
|
// Close the temporary file descriptor opened earlier.
|
|
close(fd);
|
|
}
|
|
return s;
|
|
}
|
|
};
|
|
|
|
// mmap() based random-access
|
|
class PosixMmapReadableFile: public RandomAccessFile {
|
|
private:
|
|
std::string filename_;
|
|
void* mmapped_region_;
|
|
size_t length_;
|
|
Limiter* limiter_;
|
|
|
|
public:
|
|
// base[0,length-1] contains the mmapped contents of the file.
|
|
PosixMmapReadableFile(const std::string& fname, void* base, size_t length,
|
|
Limiter* limiter)
|
|
: filename_(fname), mmapped_region_(base), length_(length),
|
|
limiter_(limiter) {
|
|
}
|
|
|
|
virtual ~PosixMmapReadableFile() {
|
|
munmap(mmapped_region_, length_);
|
|
limiter_->Release();
|
|
}
|
|
|
|
virtual Status Read(uint64_t offset, size_t n, Slice* result,
|
|
char* scratch) const {
|
|
Status s;
|
|
if (offset + n > length_) {
|
|
*result = Slice();
|
|
s = PosixError(filename_, EINVAL);
|
|
} else {
|
|
*result = Slice(reinterpret_cast<char*>(mmapped_region_) + offset, n);
|
|
}
|
|
return s;
|
|
}
|
|
};
|
|
|
|
class PosixWritableFile : public WritableFile {
|
|
private:
|
|
std::string filename_;
|
|
FILE* file_;
|
|
|
|
public:
|
|
PosixWritableFile(const std::string& fname, FILE* f)
|
|
: filename_(fname), file_(f) { }
|
|
|
|
~PosixWritableFile() {
|
|
if (file_ != NULL) {
|
|
// Ignoring any potential errors
|
|
fclose(file_);
|
|
}
|
|
}
|
|
|
|
virtual Status Append(const Slice& data) {
|
|
size_t r = fwrite_unlocked(data.data(), 1, data.size(), file_);
|
|
if (r != data.size()) {
|
|
return PosixError(filename_, errno);
|
|
}
|
|
return Status::OK();
|
|
}
|
|
|
|
virtual Status Close() {
|
|
Status result;
|
|
if (fclose(file_) != 0) {
|
|
result = PosixError(filename_, errno);
|
|
}
|
|
file_ = NULL;
|
|
return result;
|
|
}
|
|
|
|
virtual Status Flush() {
|
|
if (fflush_unlocked(file_) != 0) {
|
|
return PosixError(filename_, errno);
|
|
}
|
|
return Status::OK();
|
|
}
|
|
|
|
Status SyncDirIfManifest() {
|
|
const char* f = filename_.c_str();
|
|
const char* sep = strrchr(f, '/');
|
|
Slice basename;
|
|
std::string dir;
|
|
if (sep == NULL) {
|
|
dir = ".";
|
|
basename = f;
|
|
} else {
|
|
dir = std::string(f, sep - f);
|
|
basename = sep + 1;
|
|
}
|
|
Status s;
|
|
if (basename.starts_with("MANIFEST")) {
|
|
int fd = open(dir.c_str(), O_RDONLY);
|
|
if (fd < 0) {
|
|
s = PosixError(dir, errno);
|
|
} else {
|
|
if (fsync(fd) < 0) {
|
|
s = PosixError(dir, errno);
|
|
}
|
|
close(fd);
|
|
}
|
|
}
|
|
return s;
|
|
}
|
|
|
|
virtual Status Sync() {
|
|
// Ensure new files referred to by the manifest are in the filesystem.
|
|
Status s = SyncDirIfManifest();
|
|
if (!s.ok()) {
|
|
return s;
|
|
}
|
|
if (fflush_unlocked(file_) != 0 ||
|
|
fdatasync(fileno(file_)) != 0) {
|
|
s = Status::IOError(filename_, strerror(errno));
|
|
}
|
|
return s;
|
|
}
|
|
};
|
|
|
|
static int LockOrUnlock(int fd, bool lock) {
|
|
errno = 0;
|
|
struct flock f;
|
|
memset(&f, 0, sizeof(f));
|
|
f.l_type = (lock ? F_WRLCK : F_UNLCK);
|
|
f.l_whence = SEEK_SET;
|
|
f.l_start = 0;
|
|
f.l_len = 0; // Lock/unlock entire file
|
|
return fcntl(fd, F_SETLK, &f);
|
|
}
|
|
|
|
class PosixFileLock : public FileLock {
|
|
public:
|
|
int fd_;
|
|
std::string name_;
|
|
};
|
|
|
|
// Set of locked files. We keep a separate set instead of just
|
|
// relying on fcntrl(F_SETLK) since fcntl(F_SETLK) does not provide
|
|
// any protection against multiple uses from the same process.
|
|
class PosixLockTable {
|
|
private:
|
|
port::Mutex mu_;
|
|
std::set<std::string> locked_files_;
|
|
public:
|
|
bool Insert(const std::string& fname) {
|
|
MutexLock l(&mu_);
|
|
return locked_files_.insert(fname).second;
|
|
}
|
|
void Remove(const std::string& fname) {
|
|
MutexLock l(&mu_);
|
|
locked_files_.erase(fname);
|
|
}
|
|
};
|
|
|
|
class PosixEnv : public Env {
|
|
public:
|
|
PosixEnv();
|
|
virtual ~PosixEnv() {
|
|
char msg[] = "Destroying Env::Default()\n";
|
|
fwrite(msg, 1, sizeof(msg), stderr);
|
|
abort();
|
|
}
|
|
|
|
virtual Status NewSequentialFile(const std::string& fname,
|
|
SequentialFile** result) {
|
|
FILE* f = fopen(fname.c_str(), "r");
|
|
if (f == NULL) {
|
|
*result = NULL;
|
|
return PosixError(fname, errno);
|
|
} else {
|
|
*result = new PosixSequentialFile(fname, f);
|
|
return Status::OK();
|
|
}
|
|
}
|
|
|
|
virtual Status NewRandomAccessFile(const std::string& fname,
|
|
RandomAccessFile** result) {
|
|
*result = NULL;
|
|
Status s;
|
|
int fd = open(fname.c_str(), O_RDONLY);
|
|
if (fd < 0) {
|
|
s = PosixError(fname, errno);
|
|
} else if (mmap_limit_.Acquire()) {
|
|
uint64_t size;
|
|
s = GetFileSize(fname, &size);
|
|
if (s.ok()) {
|
|
void* base = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
|
|
if (base != MAP_FAILED) {
|
|
*result = new PosixMmapReadableFile(fname, base, size, &mmap_limit_);
|
|
} else {
|
|
s = PosixError(fname, errno);
|
|
}
|
|
}
|
|
close(fd);
|
|
if (!s.ok()) {
|
|
mmap_limit_.Release();
|
|
}
|
|
} else {
|
|
*result = new PosixRandomAccessFile(fname, fd, &fd_limit_);
|
|
}
|
|
return s;
|
|
}
|
|
|
|
virtual Status NewWritableFile(const std::string& fname,
|
|
WritableFile** result) {
|
|
Status s;
|
|
FILE* f = fopen(fname.c_str(), "w");
|
|
if (f == NULL) {
|
|
*result = NULL;
|
|
s = PosixError(fname, errno);
|
|
} else {
|
|
*result = new PosixWritableFile(fname, f);
|
|
}
|
|
return s;
|
|
}
|
|
|
|
virtual Status NewAppendableFile(const std::string& fname,
|
|
WritableFile** result) {
|
|
Status s;
|
|
FILE* f = fopen(fname.c_str(), "a");
|
|
if (f == NULL) {
|
|
*result = NULL;
|
|
s = PosixError(fname, errno);
|
|
} else {
|
|
*result = new PosixWritableFile(fname, f);
|
|
}
|
|
return s;
|
|
}
|
|
|
|
virtual bool FileExists(const std::string& fname) {
|
|
return access(fname.c_str(), F_OK) == 0;
|
|
}
|
|
|
|
virtual Status GetChildren(const std::string& dir,
|
|
std::vector<std::string>* result) {
|
|
result->clear();
|
|
DIR* d = opendir(dir.c_str());
|
|
if (d == NULL) {
|
|
return PosixError(dir, errno);
|
|
}
|
|
struct dirent* entry;
|
|
while ((entry = readdir(d)) != NULL) {
|
|
result->push_back(entry->d_name);
|
|
}
|
|
closedir(d);
|
|
return Status::OK();
|
|
}
|
|
|
|
virtual Status DeleteFile(const std::string& fname) {
|
|
Status result;
|
|
if (unlink(fname.c_str()) != 0) {
|
|
result = PosixError(fname, errno);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
virtual Status CreateDir(const std::string& name) {
|
|
Status result;
|
|
if (mkdir(name.c_str(), 0755) != 0) {
|
|
result = PosixError(name, errno);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
virtual Status DeleteDir(const std::string& name) {
|
|
Status result;
|
|
if (rmdir(name.c_str()) != 0) {
|
|
result = PosixError(name, errno);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
virtual Status GetFileSize(const std::string& fname, uint64_t* size) {
|
|
Status s;
|
|
struct stat sbuf;
|
|
if (stat(fname.c_str(), &sbuf) != 0) {
|
|
*size = 0;
|
|
s = PosixError(fname, errno);
|
|
} else {
|
|
*size = sbuf.st_size;
|
|
}
|
|
return s;
|
|
}
|
|
|
|
virtual Status RenameFile(const std::string& src, const std::string& target) {
|
|
Status result;
|
|
if (rename(src.c_str(), target.c_str()) != 0) {
|
|
result = PosixError(src, errno);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
virtual Status LockFile(const std::string& fname, FileLock** lock) {
|
|
*lock = NULL;
|
|
Status result;
|
|
int fd = open(fname.c_str(), O_RDWR | O_CREAT, 0644);
|
|
if (fd < 0) {
|
|
result = PosixError(fname, errno);
|
|
} else if (!locks_.Insert(fname)) {
|
|
close(fd);
|
|
result = Status::IOError("lock " + fname, "already held by process");
|
|
} else if (LockOrUnlock(fd, true) == -1) {
|
|
result = PosixError("lock " + fname, errno);
|
|
close(fd);
|
|
locks_.Remove(fname);
|
|
} else {
|
|
PosixFileLock* my_lock = new PosixFileLock;
|
|
my_lock->fd_ = fd;
|
|
my_lock->name_ = fname;
|
|
*lock = my_lock;
|
|
}
|
|
return result;
|
|
}
|
|
|
|
virtual Status UnlockFile(FileLock* lock) {
|
|
PosixFileLock* my_lock = reinterpret_cast<PosixFileLock*>(lock);
|
|
Status result;
|
|
if (LockOrUnlock(my_lock->fd_, false) == -1) {
|
|
result = PosixError("unlock", errno);
|
|
}
|
|
locks_.Remove(my_lock->name_);
|
|
close(my_lock->fd_);
|
|
delete my_lock;
|
|
return result;
|
|
}
|
|
|
|
virtual void Schedule(void (*function)(void*), void* arg);
|
|
|
|
virtual void StartThread(void (*function)(void* arg), void* arg);
|
|
|
|
virtual Status GetTestDirectory(std::string* result) {
|
|
const char* env = getenv("TEST_TMPDIR");
|
|
if (env && env[0] != '\0') {
|
|
*result = env;
|
|
} else {
|
|
char buf[100];
|
|
snprintf(buf, sizeof(buf), "/tmp/leveldbtest-%d", int(geteuid()));
|
|
*result = buf;
|
|
}
|
|
// Directory may already exist
|
|
CreateDir(*result);
|
|
return Status::OK();
|
|
}
|
|
|
|
static uint64_t gettid() {
|
|
pthread_t tid = pthread_self();
|
|
uint64_t thread_id = 0;
|
|
memcpy(&thread_id, &tid, std::min(sizeof(thread_id), sizeof(tid)));
|
|
return thread_id;
|
|
}
|
|
|
|
virtual Status NewLogger(const std::string& fname, Logger** result) {
|
|
FILE* f = fopen(fname.c_str(), "w");
|
|
if (f == NULL) {
|
|
*result = NULL;
|
|
return PosixError(fname, errno);
|
|
} else {
|
|
*result = new PosixLogger(f, &PosixEnv::gettid);
|
|
return Status::OK();
|
|
}
|
|
}
|
|
|
|
virtual uint64_t NowMicros() {
|
|
struct timeval tv;
|
|
gettimeofday(&tv, NULL);
|
|
return static_cast<uint64_t>(tv.tv_sec) * 1000000 + tv.tv_usec;
|
|
}
|
|
|
|
virtual void SleepForMicroseconds(int micros) {
|
|
usleep(micros);
|
|
}
|
|
|
|
private:
|
|
void PthreadCall(const char* label, int result) {
|
|
if (result != 0) {
|
|
fprintf(stderr, "pthread %s: %s\n", label, strerror(result));
|
|
abort();
|
|
}
|
|
}
|
|
|
|
// BGThread() is the body of the background thread
|
|
void BGThread();
|
|
static void* BGThreadWrapper(void* arg) {
|
|
reinterpret_cast<PosixEnv*>(arg)->BGThread();
|
|
return NULL;
|
|
}
|
|
|
|
pthread_mutex_t mu_;
|
|
pthread_cond_t bgsignal_;
|
|
pthread_t bgthread_;
|
|
bool started_bgthread_;
|
|
|
|
// Entry per Schedule() call
|
|
struct BGItem { void* arg; void (*function)(void*); };
|
|
typedef std::deque<BGItem> BGQueue;
|
|
BGQueue queue_;
|
|
|
|
PosixLockTable locks_;
|
|
Limiter mmap_limit_;
|
|
Limiter fd_limit_;
|
|
};
|
|
|
|
// Return the maximum number of concurrent mmaps.
|
|
static int MaxMmaps() {
|
|
if (mmap_limit >= 0) {
|
|
return mmap_limit;
|
|
}
|
|
// Up to 1000 mmaps for 64-bit binaries; none for smaller pointer sizes.
|
|
mmap_limit = sizeof(void*) >= 8 ? 1000 : 0;
|
|
return mmap_limit;
|
|
}
|
|
|
|
// Return the maximum number of read-only files to keep open.
|
|
static intptr_t MaxOpenFiles() {
|
|
if (open_read_only_file_limit >= 0) {
|
|
return open_read_only_file_limit;
|
|
}
|
|
struct rlimit rlim;
|
|
if (getrlimit(RLIMIT_NOFILE, &rlim)) {
|
|
// getrlimit failed, fallback to hard-coded default.
|
|
open_read_only_file_limit = 50;
|
|
} else if (rlim.rlim_cur == RLIM_INFINITY) {
|
|
open_read_only_file_limit = std::numeric_limits<int>::max();
|
|
} else {
|
|
// Allow use of 20% of available file descriptors for read-only files.
|
|
open_read_only_file_limit = rlim.rlim_cur / 5;
|
|
}
|
|
return open_read_only_file_limit;
|
|
}
|
|
|
|
PosixEnv::PosixEnv()
|
|
: started_bgthread_(false),
|
|
mmap_limit_(MaxMmaps()),
|
|
fd_limit_(MaxOpenFiles()) {
|
|
PthreadCall("mutex_init", pthread_mutex_init(&mu_, NULL));
|
|
PthreadCall("cvar_init", pthread_cond_init(&bgsignal_, NULL));
|
|
}
|
|
|
|
void PosixEnv::Schedule(void (*function)(void*), void* arg) {
|
|
PthreadCall("lock", pthread_mutex_lock(&mu_));
|
|
|
|
// Start background thread if necessary
|
|
if (!started_bgthread_) {
|
|
started_bgthread_ = true;
|
|
PthreadCall(
|
|
"create thread",
|
|
pthread_create(&bgthread_, NULL, &PosixEnv::BGThreadWrapper, this));
|
|
}
|
|
|
|
// If the queue is currently empty, the background thread may currently be
|
|
// waiting.
|
|
if (queue_.empty()) {
|
|
PthreadCall("signal", pthread_cond_signal(&bgsignal_));
|
|
}
|
|
|
|
// Add to priority queue
|
|
queue_.push_back(BGItem());
|
|
queue_.back().function = function;
|
|
queue_.back().arg = arg;
|
|
|
|
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
|
|
}
|
|
|
|
void PosixEnv::BGThread() {
|
|
while (true) {
|
|
// Wait until there is an item that is ready to run
|
|
PthreadCall("lock", pthread_mutex_lock(&mu_));
|
|
while (queue_.empty()) {
|
|
PthreadCall("wait", pthread_cond_wait(&bgsignal_, &mu_));
|
|
}
|
|
|
|
void (*function)(void*) = queue_.front().function;
|
|
void* arg = queue_.front().arg;
|
|
queue_.pop_front();
|
|
|
|
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
|
|
(*function)(arg);
|
|
}
|
|
}
|
|
|
|
namespace {
|
|
struct StartThreadState {
|
|
void (*user_function)(void*);
|
|
void* arg;
|
|
};
|
|
}
|
|
static void* StartThreadWrapper(void* arg) {
|
|
StartThreadState* state = reinterpret_cast<StartThreadState*>(arg);
|
|
state->user_function(state->arg);
|
|
delete state;
|
|
return NULL;
|
|
}
|
|
|
|
void PosixEnv::StartThread(void (*function)(void* arg), void* arg) {
|
|
pthread_t t;
|
|
StartThreadState* state = new StartThreadState;
|
|
state->user_function = function;
|
|
state->arg = arg;
|
|
PthreadCall("start thread",
|
|
pthread_create(&t, NULL, &StartThreadWrapper, state));
|
|
}
|
|
|
|
} // namespace
|
|
|
|
static pthread_once_t once = PTHREAD_ONCE_INIT;
|
|
static Env* default_env;
|
|
static void InitDefaultEnv() { default_env = new PosixEnv; }
|
|
|
|
void EnvPosixTestHelper::SetReadOnlyFDLimit(int limit) {
|
|
assert(default_env == NULL);
|
|
open_read_only_file_limit = limit;
|
|
}
|
|
|
|
void EnvPosixTestHelper::SetReadOnlyMMapLimit(int limit) {
|
|
assert(default_env == NULL);
|
|
mmap_limit = limit;
|
|
}
|
|
|
|
Env* Env::Default() {
|
|
pthread_once(&once, InitDefaultEnv);
|
|
return default_env;
|
|
}
|
|
|
|
} // namespace leveldb
|