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rocksdb/util/io_posix.cc

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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.
#ifdef ROCKSDB_LIB_IO_POSIX
#include "posix/io_posix.h"
namespace rocksdb {
// A wrapper for fadvise, if the platform doesn't support fadvise,
// it will simply return Status::NotSupport.
int Fadvise(int fd, off_t offset, size_t len, int advice) {
#ifdef OS_LINUX
return posix_fadvise(fd, offset, len, advice);
#else
return 0; // simply do nothing.
#endif
}
/*
* PosixSequentialFile
*/
PosixSequentialFile::PosixSequentialFile(const std::string& fname, FILE* f,
const EnvOptions& options)
: filename_(fname),
file_(f),
fd_(fileno(f)),
use_os_buffer_(options.use_os_buffer) {}
PosixSequentialFile::~PosixSequentialFile() { fclose(file_); }
Status PosixSequentialFile::Read(size_t n, Slice* result, char* scratch) {
Status s;
size_t r = 0;
do {
r = fread_unlocked(scratch, 1, n, file_);
} while (r == 0 && ferror(file_) && errno == EINTR);
*result = Slice(scratch, r);
if (r < n) {
if (feof(file_)) {
// We leave status as ok if we hit the end of the file
// We also clear the error so that the reads can continue
// if a new data is written to the file
clearerr(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.
Fadvise(fd_, 0, 0, POSIX_FADV_DONTNEED); // free OS pages
}
return s;
}
Status PosixSequentialFile::Skip(uint64_t n) {
if (fseek(file_, static_cast<long int>(n), SEEK_CUR)) {
return IOError(filename_, errno);
}
return Status::OK();
}
Status PosixSequentialFile::InvalidateCache(size_t offset, size_t length) {
#ifndef OS_LINUX
return Status::OK();
#else
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
#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
/*
* PosixRandomAccessFile
*
* pread() based random-access
*/
PosixRandomAccessFile::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 || sizeof(void*) < 8);
}
PosixRandomAccessFile::~PosixRandomAccessFile() { close(fd_); }
Status PosixRandomAccessFile::Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const {
Status s;
ssize_t r = -1;
size_t left = n;
char* ptr = scratch;
while (left > 0) {
r = pread(fd_, ptr, left, static_cast<off_t>(offset));
if (r <= 0) {
if (errno == EINTR) {
continue;
}
break;
}
ptr += r;
offset += r;
left -= r;
}
*result = Slice(scratch, (r < 0) ? 0 : n - left);
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.
Fadvise(fd_, 0, 0, POSIX_FADV_DONTNEED); // free OS pages
}
return s;
}
#ifdef OS_LINUX
size_t PosixRandomAccessFile::GetUniqueId(char* id, size_t max_size) const {
return GetUniqueIdFromFile(fd_, id, max_size);
}
#endif
void PosixRandomAccessFile::Hint(AccessPattern pattern) {
switch (pattern) {
case NORMAL:
Fadvise(fd_, 0, 0, POSIX_FADV_NORMAL);
break;
case RANDOM:
Fadvise(fd_, 0, 0, POSIX_FADV_RANDOM);
break;
case SEQUENTIAL:
Fadvise(fd_, 0, 0, POSIX_FADV_SEQUENTIAL);
break;
case WILLNEED:
Fadvise(fd_, 0, 0, POSIX_FADV_WILLNEED);
break;
case DONTNEED:
Fadvise(fd_, 0, 0, POSIX_FADV_DONTNEED);
break;
default:
assert(false);
break;
}
}
Status PosixRandomAccessFile::InvalidateCache(size_t offset, size_t length) {
#ifndef OS_LINUX
return Status::OK();
#else
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
#endif
}
/*
* PosixMmapReadableFile
*
* mmap() based random-access
*/
// base[0,length-1] contains the mmapped contents of the file.
PosixMmapReadableFile::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) {
fd_ = fd_ + 0; // suppress the warning for used variables
assert(options.use_mmap_reads);
assert(options.use_os_buffer);
}
PosixMmapReadableFile::~PosixMmapReadableFile() {
int ret = munmap(mmapped_region_, length_);
if (ret != 0) {
fprintf(stdout, "failed to munmap %p length %" ROCKSDB_PRIszt " \n",
mmapped_region_, length_);
}
}
Status PosixMmapReadableFile::Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const {
Status s;
if (offset > length_) {
*result = Slice();
return IOError(filename_, EINVAL);
} else if (offset + n > length_) {
n = static_cast<size_t>(length_ - offset);
}
*result = Slice(reinterpret_cast<char*>(mmapped_region_) + offset, n);
return s;
}
Status PosixMmapReadableFile::InvalidateCache(size_t offset, size_t length) {
#ifndef OS_LINUX
return Status::OK();
#else
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
#endif
}
/*
* PosixMmapFile
*
* 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.
*/
Status PosixMmapFile::UnmapCurrentRegion() {
TEST_KILL_RANDOM("PosixMmapFile::UnmapCurrentRegion:0", rocksdb_kill_odds);
if (base_ != nullptr) {
int munmap_status = munmap(base_, limit_ - base_);
if (munmap_status != 0) {
return IOError(filename_, munmap_status);
}
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 Status::OK();
}
Status PosixMmapFile::MapNewRegion() {
#ifdef ROCKSDB_FALLOCATE_PRESENT
assert(base_ == nullptr);
TEST_KILL_RANDOM("PosixMmapFile::UnmapCurrentRegion:0", rocksdb_kill_odds);
// we can't fallocate with FALLOC_FL_KEEP_SIZE here
if (allow_fallocate_) {
IOSTATS_TIMER_GUARD(allocate_nanos);
int alloc_status = fallocate(fd_, 0, file_offset_, map_size_);
if (alloc_status != 0) {
// fallback to posix_fallocate
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("PosixMmapFile::Append:1", 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("PosixMmapFile::Append:2", rocksdb_kill_odds);
base_ = reinterpret_cast<char*>(ptr);
limit_ = base_ + map_size_;
dst_ = base_;
last_sync_ = base_;
return Status::OK();
#else
return Status::NotSupported("This platform doesn't support fallocate()");
#endif
}
Status PosixMmapFile::Msync() {
if (dst_ == last_sync_) {
return Status::OK();
}
// 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("PosixMmapFile::Msync:0", rocksdb_kill_odds);
if (msync(base_ + p1, p2 - p1 + page_size_, MS_SYNC) < 0) {
return IOError(filename_, errno);
}
return Status::OK();
}
PosixMmapFile::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) {
#ifdef ROCKSDB_FALLOCATE_PRESENT
allow_fallocate_ = options.allow_fallocate;
fallocate_with_keep_size_ = options.fallocate_with_keep_size;
#endif
assert((page_size & (page_size - 1)) == 0);
assert(options.use_mmap_writes);
}
PosixMmapFile::~PosixMmapFile() {
if (fd_ >= 0) {
PosixMmapFile::Close();
}
}
Status PosixMmapFile::Append(const Slice& data) {
const char* src = data.data();
size_t left = data.size();
while (left > 0) {
assert(base_ <= dst_);
assert(dst_ <= limit_);
size_t avail = limit_ - dst_;
if (avail == 0) {
Status s = UnmapCurrentRegion();
if (!s.ok()) {
return s;
}
s = MapNewRegion();
if (!s.ok()) {
return s;
}
TEST_KILL_RANDOM("PosixMmapFile::Append:0", rocksdb_kill_odds);
}
size_t n = (left <= avail) ? left : avail;
memcpy(dst_, src, n);
dst_ += n;
src += n;
left -= n;
}
return Status::OK();
}
Status PosixMmapFile::Close() {
Status s;
size_t unused = limit_ - dst_;
s = UnmapCurrentRegion();
if (!s.ok()) {
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);
}
}
if (close(fd_) < 0) {
if (s.ok()) {
s = IOError(filename_, errno);
}
}
fd_ = -1;
base_ = nullptr;
limit_ = nullptr;
return s;
}
Status PosixMmapFile::Flush() { return Status::OK(); }
Status PosixMmapFile::Sync() {
if (fdatasync(fd_) < 0) {
return IOError(filename_, errno);
}
return Msync();
}
/**
* Flush data as well as metadata to stable storage.
*/
Status PosixMmapFile::Fsync() {
if (fsync(fd_) < 0) {
return IOError(filename_, errno);
}
return Msync();
}
/**
* 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.
*/
uint64_t PosixMmapFile::GetFileSize() {
size_t used = dst_ - base_;
return file_offset_ + used;
}
Status PosixMmapFile::InvalidateCache(size_t offset, size_t length) {
#ifndef OS_LINUX
return Status::OK();
#else
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
#endif
}
#ifdef ROCKSDB_FALLOCATE_PRESENT
Status PosixMmapFile::Allocate(off_t offset, off_t len) {
TEST_KILL_RANDOM("PosixMmapFile::Allocate:0", rocksdb_kill_odds);
int alloc_status = 0;
if (allow_fallocate_) {
alloc_status = fallocate(
fd_, fallocate_with_keep_size_ ? FALLOC_FL_KEEP_SIZE : 0, offset, len);
}
if (alloc_status == 0) {
return Status::OK();
} else {
return IOError(filename_, errno);
}
}
#endif
/*
* PosixWritableFile
*
* Use posix write to write data to a file.
*/
PosixWritableFile::PosixWritableFile(const std::string& fname, int fd,
const EnvOptions& options)
: filename_(fname), fd_(fd), filesize_(0) {
#ifdef ROCKSDB_FALLOCATE_PRESENT
allow_fallocate_ = options.allow_fallocate;
fallocate_with_keep_size_ = options.fallocate_with_keep_size;
#endif
assert(!options.use_mmap_writes);
}
PosixWritableFile::~PosixWritableFile() {
if (fd_ >= 0) {
PosixWritableFile::Close();
}
}
Status PosixWritableFile::Append(const Slice& data) {
const char* src = data.data();
size_t left = data.size();
while (left != 0) {
ssize_t done = write(fd_, src, left);
if (done < 0) {
if (errno == EINTR) {
continue;
}
return IOError(filename_, errno);
}
left -= done;
src += done;
}
filesize_ += data.size();
return Status::OK();
}
Status PosixWritableFile::Close() {
Status s;
size_t block_size;
size_t last_allocated_block;
GetPreallocationStatus(&block_size, &last_allocated_block);
if (last_allocated_block > 0) {
// trim the extra space preallocated at the end of the file
// NOTE(ljin): we probably don't want to surface failure as an IOError,
// but it will be nice to log these errors.
int dummy __attribute__((unused));
dummy = ftruncate(fd_, filesize_);
#ifdef ROCKSDB_FALLOCATE_PRESENT
// in some file systems, ftruncate only trims trailing space if the
// new file size is smaller than the current size. Calling fallocate
// with FALLOC_FL_PUNCH_HOLE flag to explicitly release these unused
// blocks. FALLOC_FL_PUNCH_HOLE is supported on at least the following
// filesystems:
// XFS (since Linux 2.6.38)
// ext4 (since Linux 3.0)
// Btrfs (since Linux 3.7)
// tmpfs (since Linux 3.5)
// We ignore error since failure of this operation does not affect
// correctness.
IOSTATS_TIMER_GUARD(allocate_nanos);
if (allow_fallocate_) {
fallocate(fd_, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, filesize_,
block_size * last_allocated_block - filesize_);
}
#endif
}
if (close(fd_) < 0) {
s = IOError(filename_, errno);
}
fd_ = -1;
return s;
}
// write out the cached data to the OS cache
Status PosixWritableFile::Flush() { return Status::OK(); }
Status PosixWritableFile::Sync() {
if (fdatasync(fd_) < 0) {
return IOError(filename_, errno);
}
return Status::OK();
}
Status PosixWritableFile::Fsync() {
if (fsync(fd_) < 0) {
return IOError(filename_, errno);
}
return Status::OK();
}
bool PosixWritableFile::IsSyncThreadSafe() const { return true; }
uint64_t PosixWritableFile::GetFileSize() { return filesize_; }
Status PosixWritableFile::InvalidateCache(size_t offset, size_t length) {
#ifndef OS_LINUX
return Status::OK();
#else
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return Status::OK();
}
return IOError(filename_, errno);
#endif
}
#ifdef ROCKSDB_FALLOCATE_PRESENT
Status PosixWritableFile::Allocate(off_t offset, off_t len) {
TEST_KILL_RANDOM("PosixWritableFile::Allocate:0", rocksdb_kill_odds);
IOSTATS_TIMER_GUARD(allocate_nanos);
int alloc_status = 0;
if (allow_fallocate_) {
alloc_status = fallocate(
fd_, fallocate_with_keep_size_ ? FALLOC_FL_KEEP_SIZE : 0, offset, len);
}
if (alloc_status == 0) {
return Status::OK();
} else {
return IOError(filename_, errno);
}
}
Status PosixWritableFile::RangeSync(off_t offset, off_t nbytes) {
if (sync_file_range(fd_, offset, nbytes, SYNC_FILE_RANGE_WRITE) == 0) {
return Status::OK();
} else {
return IOError(filename_, errno);
}
}
size_t PosixWritableFile::GetUniqueId(char* id, size_t max_size) const {
return GetUniqueIdFromFile(fd_, id, max_size);
}
#endif
} // namespace rocksdb
#endif