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rocksdb/util/env_posix.cc
Dhruba Borthakur b4ad5e89ae Implement a compressed block cache. 
Summary:
Rocksdb can now support a uncompressed block cache, or a compressed
block cache or both. Lookups first look for a block in the
uncompressed cache, if it is not found only then it is looked up
in the compressed cache. If it is found in the compressed cache,
then it is uncompressed and inserted into the uncompressed cache.

It is possible that the same block resides in the compressed cache
as well as the uncompressed cache at the same time. Both caches
have their own individual LRU policy.

Test Plan: Unit test case attached.

Reviewers: kailiu, sdong, haobo, leveldb

Reviewed By: haobo

CC: xjin, haobo

Differential Revision: https://reviews.facebook.net/D12675
2013-11-01 14:31:35 -07:00

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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same 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.
#include <deque>
#include <set>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/vfs.h>
#include <time.h>
#include <unistd.h>
#if defined(OS_LINUX)
#include <linux/fs.h>
#include <fcntl.h>
#endif
#if defined(LEVELDB_PLATFORM_ANDROID)
#include <sys/stat.h>
#endif
#include "rocksdb/env.h"
#include "rocksdb/slice.h"
#include "port/port.h"
#include "util/coding.h"
#include "util/logging.h"
#include "util/posix_logger.h"
#include "util/random.h"
#include <signal.h>
#if !defined(TMPFS_MAGIC)
#define TMPFS_MAGIC 0x01021994
#endif
#if !defined(XFS_SUPER_MAGIC)
#define XFS_SUPER_MAGIC 0x58465342
#endif
#if !defined(EXT4_SUPER_MAGIC)
#define EXT4_SUPER_MAGIC 0xEF53
#endif
// This is only set from db_stress.cc and for testing only.
// If non-zero, kill at various points in source code with probability 1/this
int rocksdb_kill_odds = 0;
namespace rocksdb {
namespace {
// list of pathnames that are locked
static std::set<std::string> lockedFiles;
static port::Mutex mutex_lockedFiles;
static Status IOError(const std::string& context, int err_number) {
return Status::IOError(context, strerror(err_number));
}
#ifdef NDEBUG
// empty in release build
#define TEST_KILL_RANDOM(rocksdb_kill_odds)
#else
// Kill the process with probablity 1/odds for testing.
static void TestKillRandom(int odds, const std::string& srcfile,
int srcline) {
time_t curtime = time(nullptr);
Random r((uint32_t)curtime);
assert(odds > 0);
bool crash = r.OneIn(odds);
if (crash) {
fprintf(stdout, "Crashing at %s:%d\n", srcfile.c_str(), srcline);
fflush(stdout);
kill(getpid(), SIGTERM);
}
}
// To avoid crashing always at some frequently executed codepaths (during
// kill random test), use this factor to reduce odds
#define REDUCE_ODDS 2
#define REDUCE_ODDS2 4
#define TEST_KILL_RANDOM(rocksdb_kill_odds) { \
if (rocksdb_kill_odds > 0) { \
TestKillRandom(rocksdb_kill_odds, __FILE__, __LINE__); \
} \
}
#endif
#if defined(OS_LINUX)
namespace {
static size_t GetUniqueIdFromFile(int fd, char* id, size_t max_size) {
if (max_size < kMaxVarint64Length*3) {
return 0;
}
struct stat buf;
int result = fstat(fd, &buf);
if (result == -1) {
return 0;
}
long version = 0;
result = ioctl(fd, FS_IOC_GETVERSION, &version);
if (result == -1) {
return 0;
}
uint64_t uversion = (uint64_t)version;
char* rid = id;
rid = EncodeVarint64(rid, buf.st_dev);
rid = EncodeVarint64(rid, buf.st_ino);
rid = EncodeVarint64(rid, uversion);
assert(rid >= id);
return static_cast<size_t>(rid-id);
}
}
#endif
class PosixSequentialFile: public SequentialFile {
private:
std::string filename_;
FILE* file_;
int fd_;
bool use_os_buffer_;
public:
PosixSequentialFile(const std::string& fname, FILE* f,
const EnvOptions& options)
: filename_(fname), file_(f), fd_(fileno(f)),
use_os_buffer_(options.use_os_buffer) {
}
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 = IOError(filename_, errno);
}
}
if (!use_os_buffer_) {
// we need to fadvise away the entire range of pages because
// we do not want readahead pages to be cached.
posix_fadvise(fd_, 0, 0, POSIX_FADV_DONTNEED); // free OS pages
}
return s;
}
virtual Status Skip(uint64_t n) {
if (fseek(file_, n, SEEK_CUR)) {
return IOError(filename_, errno);
}
return Status::OK();
}
virtual Status InvalidateCache(size_t offset, size_t length) {
// free OS pages
int ret = posix_fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
}
};
// pread() based random-access
class PosixRandomAccessFile: public RandomAccessFile {
private:
std::string filename_;
int fd_;
bool use_os_buffer_;
public:
PosixRandomAccessFile(const std::string& fname, int fd,
const EnvOptions& options)
: filename_(fname), fd_(fd), use_os_buffer_(options.use_os_buffer) {
assert(!options.use_mmap_reads);
}
virtual ~PosixRandomAccessFile() { close(fd_); }
virtual Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const {
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 = IOError(filename_, errno);
}
if (!use_os_buffer_) {
// we need to fadvise away the entire range of pages because
// we do not want readahead pages to be cached.
posix_fadvise(fd_, 0, 0, POSIX_FADV_DONTNEED); // free OS pages
}
return s;
}
#if defined(OS_LINUX)
virtual size_t GetUniqueId(char* id, size_t max_size) const {
return GetUniqueIdFromFile(fd_, id, max_size);
}
#endif
virtual void Hint(AccessPattern pattern) {
switch(pattern) {
case NORMAL:
posix_fadvise(fd_, 0, 0, POSIX_FADV_NORMAL);
break;
case RANDOM:
posix_fadvise(fd_, 0, 0, POSIX_FADV_RANDOM);
break;
case SEQUENTIAL:
posix_fadvise(fd_, 0, 0, POSIX_FADV_SEQUENTIAL);
break;
case WILLNEED:
posix_fadvise(fd_, 0, 0, POSIX_FADV_WILLNEED);
break;
case DONTNEED:
posix_fadvise(fd_, 0, 0, POSIX_FADV_DONTNEED);
break;
default:
assert(false);
break;
}
}
virtual Status InvalidateCache(size_t offset, size_t length) {
// free OS pages
int ret = posix_fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
}
};
// mmap() based random-access
class PosixMmapReadableFile: public RandomAccessFile {
private:
int fd_;
std::string filename_;
void* mmapped_region_;
size_t length_;
public:
// base[0,length-1] contains the mmapped contents of the file.
PosixMmapReadableFile(const int fd, const std::string& fname,
void* base, size_t length,
const EnvOptions& options)
: fd_(fd), filename_(fname), mmapped_region_(base), length_(length) {
assert(options.use_mmap_reads);
assert(options.use_os_buffer);
}
virtual ~PosixMmapReadableFile() { munmap(mmapped_region_, length_); }
virtual Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const {
Status s;
if (offset + n > length_) {
*result = Slice();
s = IOError(filename_, EINVAL);
} else {
*result = Slice(reinterpret_cast<char*>(mmapped_region_) + offset, n);
}
return s;
}
virtual Status InvalidateCache(size_t offset, size_t length) {
// free OS pages
int ret = posix_fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
}
};
// We preallocate up to an extra megabyte and use memcpy to append new
// data to the file. This is safe since we either properly close the
// file before reading from it, or for log files, the reading code
// knows enough to skip zero suffixes.
class PosixMmapFile : public WritableFile {
private:
std::string filename_;
int fd_;
size_t page_size_;
size_t map_size_; // How much extra memory to map at a time
char* base_; // The mapped region
char* limit_; // Limit of the mapped region
char* dst_; // Where to write next (in range [base_,limit_])
char* last_sync_; // Where have we synced up to
uint64_t file_offset_; // Offset of base_ in file
// Have we done an munmap of unsynced data?
bool pending_sync_;
// Roundup x to a multiple of y
static size_t Roundup(size_t x, size_t y) {
return ((x + y - 1) / y) * y;
}
size_t TruncateToPageBoundary(size_t s) {
s -= (s & (page_size_ - 1));
assert((s % page_size_) == 0);
return s;
}
bool UnmapCurrentRegion() {
bool result = true;
TEST_KILL_RANDOM(rocksdb_kill_odds);
if (base_ != nullptr) {
if (last_sync_ < limit_) {
// Defer syncing this data until next Sync() call, if any
pending_sync_ = true;
}
if (munmap(base_, limit_ - base_) != 0) {
result = false;
}
file_offset_ += limit_ - base_;
base_ = nullptr;
limit_ = nullptr;
last_sync_ = nullptr;
dst_ = nullptr;
// Increase the amount we map the next time, but capped at 1MB
if (map_size_ < (1<<20)) {
map_size_ *= 2;
}
}
return result;
}
Status MapNewRegion() {
assert(base_ == nullptr);
TEST_KILL_RANDOM(rocksdb_kill_odds);
int alloc_status = posix_fallocate(fd_, file_offset_, map_size_);
if (alloc_status != 0) {
return Status::IOError("Error allocating space to file : " + filename_ +
"Error : " + strerror(alloc_status));
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
void* ptr = mmap(nullptr, map_size_, PROT_READ | PROT_WRITE, MAP_SHARED,
fd_, file_offset_);
if (ptr == MAP_FAILED) {
return Status::IOError("MMap failed on " + filename_);
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
base_ = reinterpret_cast<char*>(ptr);
limit_ = base_ + map_size_;
dst_ = base_;
last_sync_ = base_;
return Status::OK();
}
public:
PosixMmapFile(const std::string& fname, int fd, size_t page_size,
const EnvOptions& options)
: filename_(fname),
fd_(fd),
page_size_(page_size),
map_size_(Roundup(65536, page_size)),
base_(nullptr),
limit_(nullptr),
dst_(nullptr),
last_sync_(nullptr),
file_offset_(0),
pending_sync_(false) {
assert((page_size & (page_size - 1)) == 0);
assert(options.use_mmap_writes);
}
~PosixMmapFile() {
if (fd_ >= 0) {
PosixMmapFile::Close();
}
}
virtual Status Append(const Slice& data) {
const char* src = data.data();
size_t left = data.size();
TEST_KILL_RANDOM(rocksdb_kill_odds * REDUCE_ODDS);
PrepareWrite(GetFileSize(), left);
while (left > 0) {
assert(base_ <= dst_);
assert(dst_ <= limit_);
size_t avail = limit_ - dst_;
if (avail == 0) {
if (UnmapCurrentRegion()) {
Status s = MapNewRegion();
if (!s.ok()) {
return s;
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
}
}
size_t n = (left <= avail) ? left : avail;
memcpy(dst_, src, n);
dst_ += n;
src += n;
left -= n;
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
return Status::OK();
}
virtual Status Close() {
Status s;
size_t unused = limit_ - dst_;
TEST_KILL_RANDOM(rocksdb_kill_odds);
if (!UnmapCurrentRegion()) {
s = IOError(filename_, errno);
} else if (unused > 0) {
// Trim the extra space at the end of the file
if (ftruncate(fd_, file_offset_ - unused) < 0) {
s = IOError(filename_, errno);
}
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
if (close(fd_) < 0) {
if (s.ok()) {
s = IOError(filename_, errno);
}
}
fd_ = -1;
base_ = nullptr;
limit_ = nullptr;
return s;
}
virtual Status Flush() {
TEST_KILL_RANDOM(rocksdb_kill_odds);
return Status::OK();
}
virtual Status Sync() {
Status s;
if (pending_sync_) {
// Some unmapped data was not synced
TEST_KILL_RANDOM(rocksdb_kill_odds);
pending_sync_ = false;
if (fdatasync(fd_) < 0) {
s = IOError(filename_, errno);
}
TEST_KILL_RANDOM(rocksdb_kill_odds * REDUCE_ODDS);
}
if (dst_ > last_sync_) {
// Find the beginnings of the pages that contain the first and last
// bytes to be synced.
size_t p1 = TruncateToPageBoundary(last_sync_ - base_);
size_t p2 = TruncateToPageBoundary(dst_ - base_ - 1);
last_sync_ = dst_;
TEST_KILL_RANDOM(rocksdb_kill_odds);
if (msync(base_ + p1, p2 - p1 + page_size_, MS_SYNC) < 0) {
s = IOError(filename_, errno);
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
}
return s;
}
/**
* Flush data as well as metadata to stable storage.
*/
virtual Status Fsync() {
if (pending_sync_) {
// Some unmapped data was not synced
TEST_KILL_RANDOM(rocksdb_kill_odds);
pending_sync_ = false;
if (fsync(fd_) < 0) {
return IOError(filename_, errno);
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
}
// This invocation to Sync will not issue the call to
// fdatasync because pending_sync_ has already been cleared.
return Sync();
}
/**
* Get the size of valid data in the file. This will not match the
* size that is returned from the filesystem because we use mmap
* to extend file by map_size every time.
*/
virtual uint64_t GetFileSize() {
size_t used = dst_ - base_;
return file_offset_ + used;
}
virtual Status InvalidateCache(size_t offset, size_t length) {
// free OS pages
int ret = posix_fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
}
#ifdef OS_LINUX
virtual Status Allocate(off_t offset, off_t len) {
TEST_KILL_RANDOM(rocksdb_kill_odds);
if (!fallocate(fd_, FALLOC_FL_KEEP_SIZE, offset, len)) {
return Status::OK();
} else {
return IOError(filename_, errno);
}
}
#endif
};
// Use posix write to write data to a file.
class PosixWritableFile : public WritableFile {
private:
const std::string filename_;
int fd_;
size_t cursize_; // current size of cached data in buf_
size_t capacity_; // max size of buf_
unique_ptr<char[]> buf_; // a buffer to cache writes
uint64_t filesize_;
bool pending_sync_;
bool pending_fsync_;
uint64_t last_sync_size_;
uint64_t bytes_per_sync_;
public:
PosixWritableFile(const std::string& fname, int fd, size_t capacity,
const EnvOptions& options) :
filename_(fname),
fd_(fd),
cursize_(0),
capacity_(capacity),
buf_(new char[capacity]),
filesize_(0),
pending_sync_(false),
pending_fsync_(false),
last_sync_size_(0),
bytes_per_sync_(options.bytes_per_sync) {
assert(!options.use_mmap_writes);
}
~PosixWritableFile() {
if (fd_ >= 0) {
PosixWritableFile::Close();
}
}
virtual Status Append(const Slice& data) {
const char* src = data.data();
size_t left = data.size();
Status s;
pending_sync_ = true;
pending_fsync_ = true;
TEST_KILL_RANDOM(rocksdb_kill_odds * REDUCE_ODDS2);
PrepareWrite(GetFileSize(), left);
// if there is no space in the cache, then flush
if (cursize_ + left > capacity_) {
s = Flush();
if (!s.ok()) {
return s;
}
// Increase the buffer size, but capped at 1MB
if (capacity_ < (1<<20)) {
capacity_ *= 2;
buf_.reset(new char[capacity_]);
}
assert(cursize_ == 0);
}
// if the write fits into the cache, then write to cache
// otherwise do a write() syscall to write to OS buffers.
if (cursize_ + left <= capacity_) {
memcpy(buf_.get()+cursize_, src, left);
cursize_ += left;
} else {
while (left != 0) {
ssize_t done = write(fd_, src, left);
if (done < 0) {
return IOError(filename_, errno);
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
left -= done;
src += done;
}
}
filesize_ += data.size();
return Status::OK();
}
virtual Status Close() {
Status s;
s = Flush(); // flush cache to OS
if (!s.ok()) {
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
if (close(fd_) < 0) {
if (s.ok()) {
s = IOError(filename_, errno);
}
}
fd_ = -1;
return s;
}
// write out the cached data to the OS cache
virtual Status Flush() {
TEST_KILL_RANDOM(rocksdb_kill_odds * REDUCE_ODDS2);
size_t left = cursize_;
char* src = buf_.get();
while (left != 0) {
ssize_t done = write(fd_, src, left);
if (done < 0) {
return IOError(filename_, errno);
}
TEST_KILL_RANDOM(rocksdb_kill_odds * REDUCE_ODDS2);
left -= done;
src += done;
}
cursize_ = 0;
// sync OS cache to disk for every bytes_per_sync_
// TODO: give log file and sst file different options (log
// files could be potentially cached in OS for their whole
// life time, thus we might not want to flush at all).
if (bytes_per_sync_ &&
filesize_ - last_sync_size_ >= bytes_per_sync_) {
RangeSync(last_sync_size_, filesize_ - last_sync_size_);
last_sync_size_ = filesize_;
}
return Status::OK();
}
virtual Status Sync() {
TEST_KILL_RANDOM(rocksdb_kill_odds);
if (pending_sync_ && fdatasync(fd_) < 0) {
return IOError(filename_, errno);
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
pending_sync_ = false;
return Status::OK();
}
virtual Status Fsync() {
TEST_KILL_RANDOM(rocksdb_kill_odds);
if (pending_fsync_ && fsync(fd_) < 0) {
return IOError(filename_, errno);
}
TEST_KILL_RANDOM(rocksdb_kill_odds);
pending_fsync_ = false;
pending_sync_ = false;
return Status::OK();
}
virtual uint64_t GetFileSize() {
return filesize_;
}
virtual Status InvalidateCache(size_t offset, size_t length) {
// free OS pages
int ret = posix_fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
}
#ifdef OS_LINUX
virtual Status Allocate(off_t offset, off_t len) {
TEST_KILL_RANDOM(rocksdb_kill_odds);
if (!fallocate(fd_, FALLOC_FL_KEEP_SIZE, offset, len)) {
return Status::OK();
} else {
return IOError(filename_, errno);
}
}
virtual Status RangeSync(off64_t offset, off64_t nbytes) {
if (sync_file_range(fd_, offset, nbytes, SYNC_FILE_RANGE_WRITE) == 0) {
return Status::OK();
} else {
return IOError(filename_, errno);
}
}
virtual size_t GetUniqueId(char* id, size_t max_size) const {
return GetUniqueIdFromFile(fd_, id, max_size);
}
#endif
};
class PosixRandomRWFile : public RandomRWFile {
private:
const std::string filename_;
int fd_;
bool pending_sync_;
bool pending_fsync_;
public:
PosixRandomRWFile(const std::string& fname, int fd,
const EnvOptions& options) :
filename_(fname),
fd_(fd),
pending_sync_(false),
pending_fsync_(false) {
assert(!options.use_mmap_writes && !options.use_mmap_reads);
}
~PosixRandomRWFile() {
if (fd_ >= 0) {
Close();
}
}
virtual Status Write(uint64_t offset, const Slice& data) {
const char* src = data.data();
size_t left = data.size();
Status s;
pending_sync_ = true;
pending_fsync_ = true;
while (left != 0) {
ssize_t done = pwrite(fd_, src, left, offset);
if (done < 0) {
return IOError(filename_, errno);
}
left -= done;
src += done;
offset += done;
}
return Status::OK();
}
virtual Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const {
Status s;
ssize_t r = pread(fd_, scratch, n, static_cast<off_t>(offset));
*result = Slice(scratch, (r < 0) ? 0 : r);
if (r < 0) {
s = IOError(filename_, errno);
}
return s;
}
virtual Status Close() {
Status s = Status::OK();
if (fd_ >= 0 && close(fd_) < 0) {
s = IOError(filename_, errno);
}
fd_ = -1;
return s;
}
virtual Status Sync() {
if (pending_sync_ && fdatasync(fd_) < 0) {
return IOError(filename_, errno);
}
pending_sync_ = false;
return Status::OK();
}
virtual Status Fsync() {
if (pending_fsync_ && fsync(fd_) < 0) {
return IOError(filename_, errno);
}
pending_fsync_ = false;
pending_sync_ = false;
return Status::OK();
}
#ifdef OS_LINUX
virtual Status Allocate(off_t offset, off_t len) {
if (!fallocate(fd_, FALLOC_FL_KEEP_SIZE, offset, len)) {
return Status::OK();
} else {
return IOError(filename_, errno);
}
}
#endif
};
static int LockOrUnlock(const std::string& fname, int fd, bool lock) {
mutex_lockedFiles.Lock();
if (lock) {
// If it already exists in the lockedFiles set, then it is already locked,
// and fail this lock attempt. Otherwise, insert it into lockedFiles.
// This check is needed because fcntl() does not detect lock conflict
// if the fcntl is issued by the same thread that earlier acquired
// this lock.
if (lockedFiles.insert(fname).second == false) {
mutex_lockedFiles.Unlock();
errno = ENOLCK;
return -1;
}
} else {
// If we are unlocking, then verify that we had locked it earlier,
// it should already exist in lockedFiles. Remove it from lockedFiles.
if (lockedFiles.erase(fname) != 1) {
mutex_lockedFiles.Unlock();
errno = ENOLCK;
return -1;
}
}
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
int value = fcntl(fd, F_SETLK, &f);
if (value == -1 && lock) {
// if there is an error in locking, then remove the pathname from lockedfiles
lockedFiles.erase(fname);
}
mutex_lockedFiles.Unlock();
return value;
}
class PosixFileLock : public FileLock {
public:
int fd_;
std::string filename;
};
namespace {
void PthreadCall(const char* label, int result) {
if (result != 0) {
fprintf(stderr, "pthread %s: %s\n", label, strerror(result));
exit(1);
}
}
}
class PosixEnv : public Env {
public:
PosixEnv();
virtual ~PosixEnv(){
for (const auto tid : threads_to_join_) {
pthread_join(tid, nullptr);
}
}
void SetFD_CLOEXEC(int fd, const EnvOptions* options) {
if ((options == nullptr || options->set_fd_cloexec) && fd > 0) {
fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
}
}
virtual Status NewSequentialFile(const std::string& fname,
unique_ptr<SequentialFile>* result,
const EnvOptions& options) {
result->reset();
FILE* f = fopen(fname.c_str(), "r");
if (f == nullptr) {
*result = nullptr;
return IOError(fname, errno);
} else {
int fd = fileno(f);
SetFD_CLOEXEC(fd, &options);
result->reset(new PosixSequentialFile(fname, f, options));
return Status::OK();
}
}
virtual Status NewRandomAccessFile(const std::string& fname,
unique_ptr<RandomAccessFile>* result,
const EnvOptions& options) {
result->reset();
Status s;
int fd = open(fname.c_str(), O_RDONLY);
SetFD_CLOEXEC(fd, &options);
if (fd < 0) {
s = IOError(fname, errno);
} else if (options.use_mmap_reads && sizeof(void*) >= 8) {
// Use of mmap for random reads has been removed because it
// kills performance when storage is fast.
// Use mmap when virtual address-space is plentiful.
uint64_t size;
s = GetFileSize(fname, &size);
if (s.ok()) {
void* base = mmap(nullptr, size, PROT_READ, MAP_SHARED, fd, 0);
if (base != MAP_FAILED) {
result->reset(new PosixMmapReadableFile(fd, fname, base,
size, options));
} else {
s = IOError(fname, errno);
}
}
close(fd);
} else {
result->reset(new PosixRandomAccessFile(fname, fd, options));
}
return s;
}
virtual Status NewWritableFile(const std::string& fname,
unique_ptr<WritableFile>* result,
const EnvOptions& options) {
result->reset();
Status s;
const int fd = open(fname.c_str(), O_CREAT | O_RDWR | O_TRUNC, 0644);
if (fd < 0) {
s = IOError(fname, errno);
} else {
SetFD_CLOEXEC(fd, &options);
if (options.use_mmap_writes) {
if (!checkedDiskForMmap_) {
// this will be executed once in the program's lifetime.
// do not use mmapWrite on non ext-3/xfs/tmpfs systems.
if (!SupportsFastAllocate(fname)) {
forceMmapOff = true;
}
checkedDiskForMmap_ = true;
}
}
if (options.use_mmap_writes && !forceMmapOff) {
result->reset(new PosixMmapFile(fname, fd, page_size_, options));
} else {
result->reset(new PosixWritableFile(fname, fd, 65536, options));
}
}
return s;
}
virtual Status NewRandomRWFile(const std::string& fname,
unique_ptr<RandomRWFile>* result,
const EnvOptions& options) {
result->reset();
Status s;
const int fd = open(fname.c_str(), O_CREAT | O_RDWR, 0644);
if (fd < 0) {
s = IOError(fname, errno);
} else {
SetFD_CLOEXEC(fd, &options);
// no support for mmap yet
if (options.use_mmap_writes || options.use_mmap_reads) {
return Status::NotSupported("No support for mmap read/write yet");
}
result->reset(new PosixRandomRWFile(fname, fd, options));
}
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 == nullptr) {
return IOError(dir, errno);
}
struct dirent* entry;
while ((entry = readdir(d)) != nullptr) {
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 = IOError(fname, errno);
}
return result;
};
virtual Status CreateDir(const std::string& name) {
Status result;
if (mkdir(name.c_str(), 0755) != 0) {
result = IOError(name, errno);
}
return result;
};
virtual Status CreateDirIfMissing(const std::string& name) {
Status result;
if (mkdir(name.c_str(), 0755) != 0) {
if (errno != EEXIST) {
result = IOError(name, errno);
} else if (!DirExists(name)) { // Check that name is actually a
// directory.
// Message is taken from mkdir
result = Status::IOError("`"+name+"' exists but is not a directory");
}
}
return result;
};
virtual Status DeleteDir(const std::string& name) {
Status result;
if (rmdir(name.c_str()) != 0) {
result = IOError(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 = IOError(fname, errno);
} else {
*size = sbuf.st_size;
}
return s;
}
virtual Status GetFileModificationTime(const std::string& fname,
uint64_t* file_mtime) {
struct stat s;
if (stat(fname.c_str(), &s) !=0) {
return IOError(fname, errno);
}
*file_mtime = static_cast<uint64_t>(s.st_mtime);
return Status::OK();
}
virtual Status RenameFile(const std::string& src, const std::string& target) {
Status result;
if (rename(src.c_str(), target.c_str()) != 0) {
result = IOError(src, errno);
}
return result;
}
virtual Status LockFile(const std::string& fname, FileLock** lock) {
*lock = nullptr;
Status result;
int fd = open(fname.c_str(), O_RDWR | O_CREAT, 0644);
if (fd < 0) {
result = IOError(fname, errno);
} else if (LockOrUnlock(fname, fd, true) == -1) {
result = IOError("lock " + fname, errno);
close(fd);
} else {
SetFD_CLOEXEC(fd, nullptr);
PosixFileLock* my_lock = new PosixFileLock;
my_lock->fd_ = fd;
my_lock->filename = fname;
*lock = my_lock;
}
return result;
}
virtual Status UnlockFile(FileLock* lock) {
PosixFileLock* my_lock = reinterpret_cast<PosixFileLock*>(lock);
Status result;
if (LockOrUnlock(my_lock->filename, my_lock->fd_, false) == -1) {
result = IOError("unlock", errno);
}
close(my_lock->fd_);
delete my_lock;
return result;
}
virtual void Schedule(void (*function)(void*), void* arg, Priority pri = LOW);
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/rocksdbtest-%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,
shared_ptr<Logger>* result) {
FILE* f = fopen(fname.c_str(), "w");
if (f == nullptr) {
result->reset();
return IOError(fname, errno);
} else {
int fd = fileno(f);
SetFD_CLOEXEC(fd, nullptr);
result->reset(new PosixLogger(f, &PosixEnv::gettid, this));
return Status::OK();
}
}
virtual uint64_t NowMicros() {
struct timeval tv;
gettimeofday(&tv, nullptr);
return static_cast<uint64_t>(tv.tv_sec) * 1000000 + tv.tv_usec;
}
virtual uint64_t NowNanos() {
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
return static_cast<uint64_t>(ts.tv_sec) * 1000000000 + ts.tv_nsec;
}
virtual void SleepForMicroseconds(int micros) {
usleep(micros);
}
virtual Status GetHostName(char* name, uint64_t len) {
int ret = gethostname(name, len);
if (ret < 0) {
if (errno == EFAULT || errno == EINVAL)
return Status::InvalidArgument(strerror(errno));
else
return IOError("GetHostName", errno);
}
return Status::OK();
}
virtual Status GetCurrentTime(int64_t* unix_time) {
time_t ret = time(nullptr);
if (ret == (time_t) -1) {
return IOError("GetCurrentTime", errno);
}
*unix_time = (int64_t) ret;
return Status::OK();
}
virtual Status GetAbsolutePath(const std::string& db_path,
std::string* output_path) {
if (db_path.find('/') == 0) {
*output_path = db_path;
return Status::OK();
}
char the_path[256];
char* ret = getcwd(the_path, 256);
if (ret == nullptr) {
return Status::IOError(strerror(errno));
}
*output_path = ret;
return Status::OK();
}
// Allow increasing the number of worker threads.
virtual void SetBackgroundThreads(int num, Priority pri) {
assert(pri >= Priority::LOW && pri <= Priority::HIGH);
thread_pools_[pri].SetBackgroundThreads(num);
}
virtual std::string TimeToString(uint64_t secondsSince1970) {
const time_t seconds = (time_t)secondsSince1970;
struct tm t;
int maxsize = 64;
std::string dummy;
dummy.reserve(maxsize);
dummy.resize(maxsize);
char* p = &dummy[0];
localtime_r(&seconds, &t);
snprintf(p, maxsize,
"%04d/%02d/%02d-%02d:%02d:%02d ",
t.tm_year + 1900,
t.tm_mon + 1,
t.tm_mday,
t.tm_hour,
t.tm_min,
t.tm_sec);
return dummy;
}
private:
bool checkedDiskForMmap_;
bool forceMmapOff; // do we override Env options?
// Returns true iff the named directory exists and is a directory.
virtual bool DirExists(const std::string& dname) {
struct stat statbuf;
if (stat(dname.c_str(), &statbuf) == 0) {
return S_ISDIR(statbuf.st_mode);
}
return false; // stat() failed return false
}
bool SupportsFastAllocate(const std::string& path) {
struct statfs s;
if (statfs(path.c_str(), &s)){
return false;
}
switch (s.f_type) {
case EXT4_SUPER_MAGIC:
return true;
case XFS_SUPER_MAGIC:
return true;
case TMPFS_MAGIC:
return true;
default:
return false;
}
}
size_t page_size_;
class ThreadPool {
public:
ThreadPool() :
total_threads_limit_(1),
bgthreads_(0),
queue_(),
exit_all_threads_(false) {
PthreadCall("mutex_init", pthread_mutex_init(&mu_, nullptr));
PthreadCall("cvar_init", pthread_cond_init(&bgsignal_, nullptr));
}
~ThreadPool() {
PthreadCall("lock", pthread_mutex_lock(&mu_));
assert(!exit_all_threads_);
exit_all_threads_ = true;
PthreadCall("signalall", pthread_cond_broadcast(&bgsignal_));
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
for (const auto tid : bgthreads_) {
pthread_join(tid, nullptr);
}
}
void BGThread() {
while (true) {
// Wait until there is an item that is ready to run
PthreadCall("lock", pthread_mutex_lock(&mu_));
while (queue_.empty() && !exit_all_threads_) {
PthreadCall("wait", pthread_cond_wait(&bgsignal_, &mu_));
}
if (exit_all_threads_) { // mechanism to let BG threads exit safely
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
break;
}
void (*function)(void*) = queue_.front().function;
void* arg = queue_.front().arg;
queue_.pop_front();
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
(*function)(arg);
}
}
static void* BGThreadWrapper(void* arg) {
reinterpret_cast<ThreadPool*>(arg)->BGThread();
return nullptr;
}
void SetBackgroundThreads(int num) {
PthreadCall("lock", pthread_mutex_lock(&mu_));
if (num > total_threads_limit_) {
total_threads_limit_ = num;
}
assert(total_threads_limit_ > 0);
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
}
void Schedule(void (*function)(void*), void* arg) {
PthreadCall("lock", pthread_mutex_lock(&mu_));
if (exit_all_threads_) {
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
return;
}
// Start background thread if necessary
while ((int)bgthreads_.size() < total_threads_limit_) {
pthread_t t;
PthreadCall(
"create thread",
pthread_create(&t,
nullptr,
&ThreadPool::BGThreadWrapper,
this));
fprintf(stdout, "Created bg thread 0x%lx\n", t);
bgthreads_.push_back(t);
}
// Add to priority queue
queue_.push_back(BGItem());
queue_.back().function = function;
queue_.back().arg = arg;
// always wake up at least one waiting thread.
PthreadCall("signal", pthread_cond_signal(&bgsignal_));
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
}
private:
// Entry per Schedule() call
struct BGItem { void* arg; void (*function)(void*); };
typedef std::deque<BGItem> BGQueue;
pthread_mutex_t mu_;
pthread_cond_t bgsignal_;
int total_threads_limit_;
std::vector<pthread_t> bgthreads_;
BGQueue queue_;
bool exit_all_threads_;
};
std::vector<ThreadPool> thread_pools_;
pthread_mutex_t mu_;
std::vector<pthread_t> threads_to_join_;
};
PosixEnv::PosixEnv() : checkedDiskForMmap_(false),
forceMmapOff(false),
page_size_(getpagesize()),
thread_pools_(Priority::TOTAL) {
PthreadCall("mutex_init", pthread_mutex_init(&mu_, nullptr));
}
void PosixEnv::Schedule(void (*function)(void*), void* arg, Priority pri) {
assert(pri >= Priority::LOW && pri <= Priority::HIGH);
thread_pools_[pri].Schedule(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 nullptr;
}
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, nullptr, &StartThreadWrapper, state));
PthreadCall("lock", pthread_mutex_lock(&mu_));
threads_to_join_.push_back(t);
PthreadCall("unlock", pthread_mutex_unlock(&mu_));
}
} // namespace
std::string Env::GenerateUniqueId() {
std::string uuid_file = "/proc/sys/kernel/random/uuid";
if (FileExists(uuid_file)) {
std::string uuid;
Status s = ReadFileToString(this, uuid_file, &uuid);
if (s.ok()) {
return uuid;
}
}
// Could not read uuid_file - generate uuid using "nanos-random"
Random64 r(time(nullptr));
uint64_t random_uuid_portion =
r.Uniform(std::numeric_limits<uint64_t>::max());
uint64_t nanos_uuid_portion = NowNanos();
char uuid2[200];
snprintf(uuid2, 200, "%lx-%lx", nanos_uuid_portion, random_uuid_portion);
return uuid2;
}
Env* Env::Default() {
static PosixEnv default_env;
return &default_env;
}
} // namespace rocksdb
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