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rocksdb/env/io_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.
#ifdef ROCKSDB_LIB_IO_POSIX
#include "env/io_posix.h"
#include <errno.h>
#include <fcntl.h>
#include <algorithm>
#if defined(OS_LINUX)
#include <linux/fs.h>
#ifndef FALLOC_FL_KEEP_SIZE
#include <linux/falloc.h>
#endif
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#ifdef OS_LINUX
#include <sys/statfs.h>
#include <sys/syscall.h>
#include <sys/sysmacros.h>
#endif
#include "monitoring/iostats_context_imp.h"
#include "port/port.h"
#include "rocksdb/slice.h"
#include "test_util/sync_point.h"
#include "util/autovector.h"
#include "util/coding.h"
#include "util/string_util.h"
#if defined(OS_LINUX) && !defined(F_SET_RW_HINT)
#define F_LINUX_SPECIFIC_BASE 1024
#define F_SET_RW_HINT (F_LINUX_SPECIFIC_BASE + 12)
#endif
namespace ROCKSDB_NAMESPACE {
std::string IOErrorMsg(const std::string& context,
const std::string& file_name) {
if (file_name.empty()) {
return context;
}
return context + ": " + file_name;
}
// file_name can be left empty if it is not unkown.
IOStatus IOError(const std::string& context, const std::string& file_name,
int err_number) {
switch (err_number) {
case ENOSPC: {
IOStatus s = IOStatus::NoSpace(IOErrorMsg(context, file_name),
strerror(err_number));
s.SetRetryable(true);
return s;
}
case ESTALE:
return IOStatus::IOError(IOStatus::kStaleFile);
case ENOENT:
return IOStatus::PathNotFound(IOErrorMsg(context, file_name),
strerror(err_number));
default:
return IOStatus::IOError(IOErrorMsg(context, file_name),
strerror(err_number));
}
}
// A wrapper for fadvise, if the platform doesn't support fadvise,
// it will simply return 0.
int Fadvise(int fd, off_t offset, size_t len, int advice) {
#ifdef OS_LINUX
return posix_fadvise(fd, offset, len, advice);
#else
(void)fd;
(void)offset;
(void)len;
(void)advice;
return 0; // simply do nothing.
#endif
}
namespace {
// On MacOS (and probably *BSD), the posix write and pwrite calls do not support
// buffers larger than 2^31-1 bytes. These two wrappers fix this issue by
// cutting the buffer in 1GB chunks. We use this chunk size to be sure to keep
// the writes aligned.
bool PosixWrite(int fd, const char* buf, size_t nbyte) {
const size_t kLimit1Gb = 1UL << 30;
const char* src = buf;
size_t left = nbyte;
while (left != 0) {
size_t bytes_to_write = std::min(left, kLimit1Gb);
ssize_t done = write(fd, src, bytes_to_write);
if (done < 0) {
if (errno == EINTR) {
continue;
}
return false;
}
left -= done;
src += done;
}
return true;
}
bool PosixPositionedWrite(int fd, const char* buf, size_t nbyte, off_t offset) {
const size_t kLimit1Gb = 1UL << 30;
const char* src = buf;
size_t left = nbyte;
while (left != 0) {
size_t bytes_to_write = std::min(left, kLimit1Gb);
ssize_t done = pwrite(fd, src, bytes_to_write, offset);
if (done < 0) {
if (errno == EINTR) {
continue;
}
return false;
}
left -= done;
offset += done;
src += done;
}
return true;
}
#ifdef ROCKSDB_RANGESYNC_PRESENT
#if !defined(ZFS_SUPER_MAGIC)
// The magic number for ZFS was not exposed until recently. It should be fixed
// forever so we can just copy the magic number here.
#define ZFS_SUPER_MAGIC 0x2fc12fc1
#endif
bool IsSyncFileRangeSupported(int fd) {
// The approach taken in this function is to build a blacklist of cases where
// we know `sync_file_range` definitely will not work properly despite passing
// the compile-time check (`ROCKSDB_RANGESYNC_PRESENT`). If we are unsure, or
// if any of the checks fail in unexpected ways, we allow `sync_file_range` to
// be used. This way should minimize risk of impacting existing use cases.
struct statfs buf;
int ret = fstatfs(fd, &buf);
assert(ret == 0);
if (ret == 0 && buf.f_type == ZFS_SUPER_MAGIC) {
// Testing on ZFS showed the writeback did not happen asynchronously when
// `sync_file_range` was called, even though it returned success. Avoid it
// and use `fdatasync` instead to preserve the contract of `bytes_per_sync`,
// even though this'll incur extra I/O for metadata.
return false;
}
ret = sync_file_range(fd, 0 /* offset */, 0 /* nbytes */, 0 /* flags */);
assert(!(ret == -1 && errno != ENOSYS));
if (ret == -1 && errno == ENOSYS) {
// `sync_file_range` is not implemented on all platforms even if
// compile-time checks pass and a supported filesystem is in-use. For
// example, using ext4 on WSL (Windows Subsystem for Linux),
// `sync_file_range()` returns `ENOSYS`
// ("Function not implemented").
return false;
}
// None of the cases on the blacklist matched, so allow `sync_file_range` use.
return true;
}
#undef ZFS_SUPER_MAGIC
#endif // ROCKSDB_RANGESYNC_PRESENT
} // anonymous namespace
/*
* DirectIOHelper
*/
namespace {
bool IsSectorAligned(const size_t off, size_t sector_size) {
assert((sector_size & (sector_size - 1)) == 0);
return (off & (sector_size - 1)) == 0;
}
#ifndef NDEBUG
bool IsSectorAligned(const void* ptr, size_t sector_size) {
return uintptr_t(ptr) % sector_size == 0;
}
#endif
} // namespace
/*
* PosixSequentialFile
*/
PosixSequentialFile::PosixSequentialFile(const std::string& fname, FILE* file,
int fd, size_t logical_block_size,
const EnvOptions& options)
: filename_(fname),
file_(file),
fd_(fd),
use_direct_io_(options.use_direct_reads),
logical_sector_size_(logical_block_size) {
assert(!options.use_direct_reads || !options.use_mmap_reads);
}
PosixSequentialFile::~PosixSequentialFile() {
if (!use_direct_io()) {
assert(file_);
fclose(file_);
} else {
assert(fd_);
close(fd_);
}
}
IOStatus PosixSequentialFile::Read(size_t n, const IOOptions& /*opts*/,
Slice* result, char* scratch,
IODebugContext* /*dbg*/) {
assert(result != nullptr && !use_direct_io());
IOStatus s;
size_t r = 0;
do {
clearerr(file_);
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("While reading file sequentially", filename_, errno);
}
}
return s;
}
IOStatus PosixSequentialFile::PositionedRead(uint64_t offset, size_t n,
const IOOptions& /*opts*/,
Slice* result, char* scratch,
IODebugContext* /*dbg*/) {
assert(use_direct_io());
assert(IsSectorAligned(offset, GetRequiredBufferAlignment()));
assert(IsSectorAligned(n, GetRequiredBufferAlignment()));
assert(IsSectorAligned(scratch, GetRequiredBufferAlignment()));
IOStatus 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 (r == -1 && errno == EINTR) {
continue;
}
break;
}
ptr += r;
offset += r;
left -= r;
if (!IsSectorAligned(r, GetRequiredBufferAlignment())) {
// Bytes reads don't fill sectors. Should only happen at the end
// of the file.
break;
}
}
if (r < 0) {
// An error: return a non-ok status
s = IOError(
"While pread " + ToString(n) + " bytes from offset " + ToString(offset),
filename_, errno);
}
*result = Slice(scratch, (r < 0) ? 0 : n - left);
return s;
}
IOStatus PosixSequentialFile::Skip(uint64_t n) {
if (fseek(file_, static_cast<long int>(n), SEEK_CUR)) {
return IOError("While fseek to skip " + ToString(n) + " bytes", filename_,
errno);
}
return IOStatus::OK();
}
IOStatus PosixSequentialFile::InvalidateCache(size_t offset, size_t length) {
#ifndef OS_LINUX
(void)offset;
(void)length;
return IOStatus::OK();
#else
if (!use_direct_io()) {
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret != 0) {
return IOError("While fadvise NotNeeded offset " + ToString(offset) +
" len " + ToString(length),
filename_, errno);
}
}
return IOStatus::OK();
#endif
}
/*
* PosixRandomAccessFile
*/
#if defined(OS_LINUX)
size_t PosixHelper::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);
TEST_SYNC_POINT_CALLBACK("GetUniqueIdFromFile:FS_IOC_GETVERSION", &result);
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
#if defined(OS_MACOSX) || defined(OS_AIX)
size_t PosixHelper::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;
}
char* rid = id;
rid = EncodeVarint64(rid, buf.st_dev);
rid = EncodeVarint64(rid, buf.st_ino);
rid = EncodeVarint64(rid, buf.st_gen);
assert(rid >= id);
return static_cast<size_t>(rid - id);
}
#endif
#ifdef OS_LINUX
std::string RemoveTrailingSlash(const std::string& path) {
std::string p = path;
if (p.size() > 1 && p.back() == '/') {
p.pop_back();
}
return p;
}
Status LogicalBlockSizeCache::RefAndCacheLogicalBlockSize(
const std::vector<std::string>& directories) {
std::vector<std::string> dirs;
dirs.reserve(directories.size());
for (auto& d : directories) {
dirs.emplace_back(RemoveTrailingSlash(d));
}
std::map<std::string, size_t> dir_sizes;
{
ReadLock lock(&cache_mutex_);
for (const auto& dir : dirs) {
if (cache_.find(dir) == cache_.end()) {
dir_sizes.emplace(dir, 0);
}
}
}
Status s;
for (auto& dir_size : dir_sizes) {
s = get_logical_block_size_of_directory_(dir_size.first, &dir_size.second);
if (!s.ok()) {
return s;
}
}
WriteLock lock(&cache_mutex_);
for (const auto& dir : dirs) {
auto& v = cache_[dir];
v.ref++;
auto dir_size = dir_sizes.find(dir);
if (dir_size != dir_sizes.end()) {
v.size = dir_size->second;
}
}
return s;
}
void LogicalBlockSizeCache::UnrefAndTryRemoveCachedLogicalBlockSize(
const std::vector<std::string>& directories) {
std::vector<std::string> dirs;
dirs.reserve(directories.size());
for (auto& dir : directories) {
dirs.emplace_back(RemoveTrailingSlash(dir));
}
WriteLock lock(&cache_mutex_);
for (const auto& dir : dirs) {
auto it = cache_.find(dir);
if (it != cache_.end() && !(--(it->second.ref))) {
cache_.erase(it);
}
}
}
size_t LogicalBlockSizeCache::GetLogicalBlockSize(const std::string& fname,
int fd) {
std::string dir = fname.substr(0, fname.find_last_of("/"));
if (dir.empty()) {
dir = "/";
}
{
ReadLock lock(&cache_mutex_);
auto it = cache_.find(dir);
if (it != cache_.end()) {
return it->second.size;
}
}
return get_logical_block_size_of_fd_(fd);
}
#endif
Status PosixHelper::GetLogicalBlockSizeOfDirectory(const std::string& directory,
size_t* size) {
int fd = open(directory.c_str(), O_DIRECTORY | O_RDONLY);
if (fd == -1) {
close(fd);
return Status::IOError("Cannot open directory " + directory);
}
*size = PosixHelper::GetLogicalBlockSizeOfFd(fd);
close(fd);
return Status::OK();
}
size_t PosixHelper::GetLogicalBlockSizeOfFd(int fd) {
#ifdef OS_LINUX
struct stat buf;
int result = fstat(fd, &buf);
if (result == -1) {
return kDefaultPageSize;
}
if (major(buf.st_dev) == 0) {
// Unnamed devices (e.g. non-device mounts), reserved as null device number.
// These don't have an entry in /sys/dev/block/. Return a sensible default.
return kDefaultPageSize;
}
// Reading queue/logical_block_size does not require special permissions.
const int kBufferSize = 100;
char path[kBufferSize];
char real_path[PATH_MAX + 1];
snprintf(path, kBufferSize, "/sys/dev/block/%u:%u", major(buf.st_dev),
minor(buf.st_dev));
if (realpath(path, real_path) == nullptr) {
return kDefaultPageSize;
}
std::string device_dir(real_path);
if (!device_dir.empty() && device_dir.back() == '/') {
device_dir.pop_back();
}
// NOTE: sda3 and nvme0n1p1 do not have a `queue/` subdir, only the parent sda
// and nvme0n1 have it.
// $ ls -al '/sys/dev/block/8:3'
// lrwxrwxrwx. 1 root root 0 Jun 26 01:38 /sys/dev/block/8:3 ->
// ../../block/sda/sda3
// $ ls -al '/sys/dev/block/259:4'
// lrwxrwxrwx 1 root root 0 Jan 31 16:04 /sys/dev/block/259:4 ->
// ../../devices/pci0000:17/0000:17:00.0/0000:18:00.0/nvme/nvme0/nvme0n1/nvme0n1p1
size_t parent_end = device_dir.rfind('/', device_dir.length() - 1);
if (parent_end == std::string::npos) {
return kDefaultPageSize;
}
size_t parent_begin = device_dir.rfind('/', parent_end - 1);
if (parent_begin == std::string::npos) {
return kDefaultPageSize;
}
std::string parent =
device_dir.substr(parent_begin + 1, parent_end - parent_begin - 1);
std::string child = device_dir.substr(parent_end + 1, std::string::npos);
if (parent != "block" &&
(child.compare(0, 4, "nvme") || child.find('p') != std::string::npos)) {
device_dir = device_dir.substr(0, parent_end);
}
std::string fname = device_dir + "/queue/logical_block_size";
FILE* fp;
size_t size = 0;
fp = fopen(fname.c_str(), "r");
if (fp != nullptr) {
char* line = nullptr;
size_t len = 0;
if (getline(&line, &len, fp) != -1) {
sscanf(line, "%zu", &size);
}
free(line);
fclose(fp);
}
if (size != 0 && (size & (size - 1)) == 0) {
return size;
}
#endif
(void)fd;
return kDefaultPageSize;
}
/*
* PosixRandomAccessFile
*
* pread() based random-access
*/
PosixRandomAccessFile::PosixRandomAccessFile(
const std::string& fname, int fd, size_t logical_block_size,
const EnvOptions& options
#if defined(ROCKSDB_IOURING_PRESENT)
,
ThreadLocalPtr* thread_local_io_urings
#endif
)
: filename_(fname),
fd_(fd),
use_direct_io_(options.use_direct_reads),
logical_sector_size_(logical_block_size)
#if defined(ROCKSDB_IOURING_PRESENT)
,
thread_local_io_urings_(thread_local_io_urings)
#endif
{
assert(!options.use_direct_reads || !options.use_mmap_reads);
assert(!options.use_mmap_reads || sizeof(void*) < 8);
}
PosixRandomAccessFile::~PosixRandomAccessFile() { close(fd_); }
IOStatus PosixRandomAccessFile::Read(uint64_t offset, size_t n,
const IOOptions& /*opts*/, Slice* result,
char* scratch,
IODebugContext* /*dbg*/) const {
if (use_direct_io()) {
assert(IsSectorAligned(offset, GetRequiredBufferAlignment()));
assert(IsSectorAligned(n, GetRequiredBufferAlignment()));
assert(IsSectorAligned(scratch, GetRequiredBufferAlignment()));
}
IOStatus 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 (r == -1 && errno == EINTR) {
continue;
}
break;
}
ptr += r;
offset += r;
left -= r;
if (use_direct_io() &&
r % static_cast<ssize_t>(GetRequiredBufferAlignment()) != 0) {
// Bytes reads don't fill sectors. Should only happen at the end
// of the file.
break;
}
}
if (r < 0) {
// An error: return a non-ok status
s = IOError(
"While pread offset " + ToString(offset) + " len " + ToString(n),
filename_, errno);
}
*result = Slice(scratch, (r < 0) ? 0 : n - left);
return s;
}
IOStatus PosixRandomAccessFile::MultiRead(FSReadRequest* reqs,
size_t num_reqs,
const IOOptions& options,
IODebugContext* dbg) {
if (use_direct_io()) {
for (size_t i = 0; i < num_reqs; i++) {
assert(IsSectorAligned(reqs[i].offset, GetRequiredBufferAlignment()));
assert(IsSectorAligned(reqs[i].len, GetRequiredBufferAlignment()));
assert(IsSectorAligned(reqs[i].scratch, GetRequiredBufferAlignment()));
}
}
#if defined(ROCKSDB_IOURING_PRESENT)
struct io_uring* iu = nullptr;
if (thread_local_io_urings_) {
iu = static_cast<struct io_uring*>(thread_local_io_urings_->Get());
if (iu == nullptr) {
iu = CreateIOUring();
if (iu != nullptr) {
thread_local_io_urings_->Reset(iu);
}
}
}
// Init failed, platform doesn't support io_uring. Fall back to
// serialized reads
if (iu == nullptr) {
return FSRandomAccessFile::MultiRead(reqs, num_reqs, options, dbg);
}
struct WrappedReadRequest {
FSReadRequest* req;
struct iovec iov;
size_t finished_len;
explicit WrappedReadRequest(FSReadRequest* r) : req(r), finished_len(0) {}
};
autovector<WrappedReadRequest, 32> req_wraps;
autovector<WrappedReadRequest*, 4> incomplete_rq_list;
for (size_t i = 0; i < num_reqs; i++) {
req_wraps.emplace_back(&reqs[i]);
}
size_t reqs_off = 0;
while (num_reqs > reqs_off || !incomplete_rq_list.empty()) {
size_t this_reqs = (num_reqs - reqs_off) + incomplete_rq_list.size();
// If requests exceed depth, split it into batches
if (this_reqs > kIoUringDepth) this_reqs = kIoUringDepth;
assert(incomplete_rq_list.size() <= this_reqs);
for (size_t i = 0; i < this_reqs; i++) {
WrappedReadRequest* rep_to_submit;
if (i < incomplete_rq_list.size()) {
rep_to_submit = incomplete_rq_list[i];
} else {
rep_to_submit = &req_wraps[reqs_off++];
}
assert(rep_to_submit->req->len > rep_to_submit->finished_len);
rep_to_submit->iov.iov_base =
rep_to_submit->req->scratch + rep_to_submit->finished_len;
rep_to_submit->iov.iov_len =
rep_to_submit->req->len - rep_to_submit->finished_len;
struct io_uring_sqe* sqe;
sqe = io_uring_get_sqe(iu);
io_uring_prep_readv(
sqe, fd_, &rep_to_submit->iov, 1,
rep_to_submit->req->offset + rep_to_submit->finished_len);
io_uring_sqe_set_data(sqe, rep_to_submit);
}
incomplete_rq_list.clear();
ssize_t ret =
io_uring_submit_and_wait(iu, static_cast<unsigned int>(this_reqs));
if (static_cast<size_t>(ret) != this_reqs) {
fprintf(stderr, "ret = %ld this_reqs: %ld\n", (long)ret, (long)this_reqs);
}
assert(static_cast<size_t>(ret) == this_reqs);
for (size_t i = 0; i < this_reqs; i++) {
struct io_uring_cqe* cqe;
WrappedReadRequest* req_wrap;
// We could use the peek variant here, but this seems safer in terms
// of our initial wait not reaping all completions
ret = io_uring_wait_cqe(iu, &cqe);
assert(!ret);
req_wrap = static_cast<WrappedReadRequest*>(io_uring_cqe_get_data(cqe));
FSReadRequest* req = req_wrap->req;
if (cqe->res < 0) {
req->result = Slice(req->scratch, 0);
req->status = IOError("Req failed", filename_, cqe->res);
} else {
size_t bytes_read = static_cast<size_t>(cqe->res);
TEST_SYNC_POINT_CALLBACK(
"PosixRandomAccessFile::MultiRead:io_uring_result", &bytes_read);
if (bytes_read == req_wrap->iov.iov_len) {
req->result = Slice(req->scratch, req->len);
req->status = IOStatus::OK();
} else if (bytes_read == 0) {
// cqe->res == 0 can means EOF, or can mean partial results. See
// comment
// https://github.com/facebook/rocksdb/pull/6441#issuecomment-589843435
// Fall back to pread in this case.
if (use_direct_io() &&
!IsSectorAligned(req_wrap->finished_len,
GetRequiredBufferAlignment())) {
// Bytes reads don't fill sectors. Should only happen at the end
// of the file.
req->result = Slice(req->scratch, req_wrap->finished_len);
req->status = IOStatus::OK();
} else {
Slice tmp_slice;
req->status =
Read(req->offset + req_wrap->finished_len,
req->len - req_wrap->finished_len, options, &tmp_slice,
req->scratch + req_wrap->finished_len, dbg);
req->result =
Slice(req->scratch, req_wrap->finished_len + tmp_slice.size());
}
} else if (bytes_read < req_wrap->iov.iov_len) {
assert(bytes_read > 0);
assert(bytes_read + req_wrap->finished_len < req->len);
req_wrap->finished_len += bytes_read;
incomplete_rq_list.push_back(req_wrap);
} else {
req->result = Slice(req->scratch, 0);
req->status = IOError("Req returned more bytes than requested",
filename_, cqe->res);
}
}
io_uring_cqe_seen(iu, cqe);
}
}
return IOStatus::OK();
#else
return FSRandomAccessFile::MultiRead(reqs, num_reqs, options, dbg);
#endif
}
IOStatus PosixRandomAccessFile::Prefetch(uint64_t offset, size_t n,
const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
IOStatus s;
if (!use_direct_io()) {
ssize_t r = 0;
#ifdef OS_LINUX
r = readahead(fd_, offset, n);
#endif
#ifdef OS_MACOSX
radvisory advice;
advice.ra_offset = static_cast<off_t>(offset);
advice.ra_count = static_cast<int>(n);
r = fcntl(fd_, F_RDADVISE, &advice);
#endif
if (r == -1) {
s = IOError("While prefetching offset " + ToString(offset) + " len " +
ToString(n),
filename_, errno);
}
}
return s;
}
#if defined(OS_LINUX) || defined(OS_MACOSX) || defined(OS_AIX)
size_t PosixRandomAccessFile::GetUniqueId(char* id, size_t max_size) const {
return PosixHelper::GetUniqueIdFromFile(fd_, id, max_size);
}
#endif
void PosixRandomAccessFile::Hint(AccessPattern pattern) {
if (use_direct_io()) {
return;
}
switch (pattern) {
case kNormal:
Fadvise(fd_, 0, 0, POSIX_FADV_NORMAL);
break;
case kRandom:
Fadvise(fd_, 0, 0, POSIX_FADV_RANDOM);
break;
case kSequential:
Fadvise(fd_, 0, 0, POSIX_FADV_SEQUENTIAL);
break;
case kWillNeed:
Fadvise(fd_, 0, 0, POSIX_FADV_WILLNEED);
break;
case kWontNeed:
Fadvise(fd_, 0, 0, POSIX_FADV_DONTNEED);
break;
default:
assert(false);
break;
}
}
IOStatus PosixRandomAccessFile::InvalidateCache(size_t offset, size_t length) {
if (use_direct_io()) {
return IOStatus::OK();
}
#ifndef OS_LINUX
(void)offset;
(void)length;
return IOStatus::OK();
#else
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return IOStatus::OK();
}
return IOError("While fadvise NotNeeded offset " + ToString(offset) +
" len " + ToString(length),
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) {
#ifdef NDEBUG
(void)options;
#endif
fd_ = fd_ + 0; // suppress the warning for used variables
assert(options.use_mmap_reads);
assert(!options.use_direct_reads);
}
PosixMmapReadableFile::~PosixMmapReadableFile() {
int ret = munmap(mmapped_region_, length_);
if (ret != 0) {
fprintf(stdout, "failed to munmap %p length %" ROCKSDB_PRIszt " \n",
mmapped_region_, length_);
}
close(fd_);
}
IOStatus PosixMmapReadableFile::Read(uint64_t offset, size_t n,
const IOOptions& /*opts*/, Slice* result,
char* /*scratch*/,
IODebugContext* /*dbg*/) const {
IOStatus s;
if (offset > length_) {
*result = Slice();
return IOError("While mmap read offset " + ToString(offset) +
" larger than file length " + ToString(length_),
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;
}
IOStatus PosixMmapReadableFile::InvalidateCache(size_t offset, size_t length) {
#ifndef OS_LINUX
(void)offset;
(void)length;
return IOStatus::OK();
#else
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return IOStatus::OK();
}
return IOError("While fadvise not needed. Offset " + ToString(offset) +
" len" + ToString(length),
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.
*/
IOStatus 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("While munmap", 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 IOStatus::OK();
}
IOStatus 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 IOStatus::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 IOStatus::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 IOStatus::OK();
#else
return IOStatus::NotSupported("This platform doesn't support fallocate()");
#endif
}
IOStatus PosixMmapFile::Msync() {
if (dst_ == last_sync_) {
return IOStatus::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("While msync", filename_, errno);
}
return IOStatus::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;
#else
(void)options;
#endif
assert((page_size & (page_size - 1)) == 0);
assert(options.use_mmap_writes);
assert(!options.use_direct_writes);
}
PosixMmapFile::~PosixMmapFile() {
if (fd_ >= 0) {
PosixMmapFile::Close(IOOptions(), nullptr);
}
}
IOStatus PosixMmapFile::Append(const Slice& data, const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
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) {
IOStatus 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;
assert(dst_);
memcpy(dst_, src, n);
dst_ += n;
src += n;
left -= n;
}
return IOStatus::OK();
}
IOStatus PosixMmapFile::Close(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
IOStatus s;
size_t unused = limit_ - dst_;
s = UnmapCurrentRegion();
if (!s.ok()) {
s = IOError("While closing mmapped file", 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("While ftruncating mmaped file", filename_, errno);
}
}
if (close(fd_) < 0) {
if (s.ok()) {
s = IOError("While closing mmapped file", filename_, errno);
}
}
fd_ = -1;
base_ = nullptr;
limit_ = nullptr;
return s;
}
IOStatus PosixMmapFile::Flush(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
return IOStatus::OK();
}
IOStatus PosixMmapFile::Sync(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
if (fdatasync(fd_) < 0) {
return IOError("While fdatasync mmapped file", filename_, errno);
}
return Msync();
}
/**
* Flush data as well as metadata to stable storage.
*/
IOStatus PosixMmapFile::Fsync(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
if (fsync(fd_) < 0) {
return IOError("While fsync mmaped file", 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(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
size_t used = dst_ - base_;
return file_offset_ + used;
}
IOStatus PosixMmapFile::InvalidateCache(size_t offset, size_t length) {
#ifndef OS_LINUX
(void)offset;
(void)length;
return IOStatus::OK();
#else
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return IOStatus::OK();
}
return IOError("While fadvise NotNeeded mmapped file", filename_, errno);
#endif
}
#ifdef ROCKSDB_FALLOCATE_PRESENT
IOStatus PosixMmapFile::Allocate(uint64_t offset, uint64_t len,
const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
assert(offset <= static_cast<uint64_t>(std::numeric_limits<off_t>::max()));
assert(len <= static_cast<uint64_t>(std::numeric_limits<off_t>::max()));
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,
static_cast<off_t>(offset), static_cast<off_t>(len));
}
if (alloc_status == 0) {
return IOStatus::OK();
} else {
return IOError(
"While fallocate offset " + ToString(offset) + " len " + ToString(len),
filename_, errno);
}
}
#endif
/*
* PosixWritableFile
*
* Use posix write to write data to a file.
*/
PosixWritableFile::PosixWritableFile(const std::string& fname, int fd,
size_t logical_block_size,
const EnvOptions& options)
: FSWritableFile(options),
filename_(fname),
use_direct_io_(options.use_direct_writes),
fd_(fd),
filesize_(0),
logical_sector_size_(logical_block_size) {
#ifdef ROCKSDB_FALLOCATE_PRESENT
allow_fallocate_ = options.allow_fallocate;
fallocate_with_keep_size_ = options.fallocate_with_keep_size;
#endif
#ifdef ROCKSDB_RANGESYNC_PRESENT
sync_file_range_supported_ = IsSyncFileRangeSupported(fd_);
#endif // ROCKSDB_RANGESYNC_PRESENT
assert(!options.use_mmap_writes);
}
PosixWritableFile::~PosixWritableFile() {
if (fd_ >= 0) {
PosixWritableFile::Close(IOOptions(), nullptr);
}
}
IOStatus PosixWritableFile::Append(const Slice& data, const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
if (use_direct_io()) {
assert(IsSectorAligned(data.size(), GetRequiredBufferAlignment()));
assert(IsSectorAligned(data.data(), GetRequiredBufferAlignment()));
}
const char* src = data.data();
size_t nbytes = data.size();
if (!PosixWrite(fd_, src, nbytes)) {
return IOError("While appending to file", filename_, errno);
}
filesize_ += nbytes;
return IOStatus::OK();
}
IOStatus PosixWritableFile::PositionedAppend(const Slice& data, uint64_t offset,
const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
if (use_direct_io()) {
assert(IsSectorAligned(offset, GetRequiredBufferAlignment()));
assert(IsSectorAligned(data.size(), GetRequiredBufferAlignment()));
assert(IsSectorAligned(data.data(), GetRequiredBufferAlignment()));
}
assert(offset <= static_cast<uint64_t>(std::numeric_limits<off_t>::max()));
const char* src = data.data();
size_t nbytes = data.size();
if (!PosixPositionedWrite(fd_, src, nbytes, static_cast<off_t>(offset))) {
return IOError("While pwrite to file at offset " + ToString(offset),
filename_, errno);
}
filesize_ = offset + nbytes;
return IOStatus::OK();
}
IOStatus PosixWritableFile::Truncate(uint64_t size, const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
IOStatus s;
int r = ftruncate(fd_, size);
if (r < 0) {
s = IOError("While ftruncate file to size " + ToString(size), filename_,
errno);
} else {
filesize_ = size;
}
return s;
}
IOStatus PosixWritableFile::Close(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
IOStatus 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_);
#if defined(ROCKSDB_FALLOCATE_PRESENT) && defined(FALLOC_FL_PUNCH_HOLE) && \
!defined(TRAVIS)
// 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.
// TRAVIS - this code does not work on TRAVIS filesystems.
// the FALLOC_FL_KEEP_SIZE option is expected to not change the size
// of the file, but it does. Simple strace report will show that.
// While we work with Travis-CI team to figure out if this is a
// quirk of Docker/AUFS, we will comment this out.
struct stat file_stats;
int result = fstat(fd_, &file_stats);
// After ftruncate, we check whether ftruncate has the correct behavior.
// If not, we should hack it with FALLOC_FL_PUNCH_HOLE
if (result == 0 &&
(file_stats.st_size + file_stats.st_blksize - 1) /
file_stats.st_blksize !=
file_stats.st_blocks / (file_stats.st_blksize / 512)) {
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("While closing file after writing", filename_, errno);
}
fd_ = -1;
return s;
}
// write out the cached data to the OS cache
IOStatus PosixWritableFile::Flush(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
return IOStatus::OK();
}
IOStatus PosixWritableFile::Sync(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
if (fdatasync(fd_) < 0) {
return IOError("While fdatasync", filename_, errno);
}
return IOStatus::OK();
}
IOStatus PosixWritableFile::Fsync(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
if (fsync(fd_) < 0) {
return IOError("While fsync", filename_, errno);
}
return IOStatus::OK();
}
bool PosixWritableFile::IsSyncThreadSafe() const { return true; }
uint64_t PosixWritableFile::GetFileSize(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
return filesize_;
}
void PosixWritableFile::SetWriteLifeTimeHint(Env::WriteLifeTimeHint hint) {
#ifdef OS_LINUX
// Suppress Valgrind "Unimplemented functionality" error.
#ifndef ROCKSDB_VALGRIND_RUN
if (hint == write_hint_) {
return;
}
if (fcntl(fd_, F_SET_RW_HINT, &hint) == 0) {
write_hint_ = hint;
}
#else
(void)hint;
#endif // ROCKSDB_VALGRIND_RUN
#else
(void)hint;
#endif // OS_LINUX
}
IOStatus PosixWritableFile::InvalidateCache(size_t offset, size_t length) {
if (use_direct_io()) {
return IOStatus::OK();
}
#ifndef OS_LINUX
(void)offset;
(void)length;
return IOStatus::OK();
#else
// free OS pages
int ret = Fadvise(fd_, offset, length, POSIX_FADV_DONTNEED);
if (ret == 0) {
return IOStatus::OK();
}
return IOError("While fadvise NotNeeded", filename_, errno);
#endif
}
#ifdef ROCKSDB_FALLOCATE_PRESENT
IOStatus PosixWritableFile::Allocate(uint64_t offset, uint64_t len,
const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
assert(offset <= static_cast<uint64_t>(std::numeric_limits<off_t>::max()));
assert(len <= static_cast<uint64_t>(std::numeric_limits<off_t>::max()));
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,
static_cast<off_t>(offset), static_cast<off_t>(len));
}
if (alloc_status == 0) {
return IOStatus::OK();
} else {
return IOError(
"While fallocate offset " + ToString(offset) + " len " + ToString(len),
filename_, errno);
}
}
#endif
IOStatus PosixWritableFile::RangeSync(uint64_t offset, uint64_t nbytes,
const IOOptions& opts,
IODebugContext* dbg) {
#ifdef ROCKSDB_RANGESYNC_PRESENT
assert(offset <= static_cast<uint64_t>(std::numeric_limits<off_t>::max()));
assert(nbytes <= static_cast<uint64_t>(std::numeric_limits<off_t>::max()));
if (sync_file_range_supported_) {
int ret;
if (strict_bytes_per_sync_) {
// Specifying `SYNC_FILE_RANGE_WAIT_BEFORE` together with an offset/length
// that spans all bytes written so far tells `sync_file_range` to wait for
// any outstanding writeback requests to finish before issuing a new one.
ret =
sync_file_range(fd_, 0, static_cast<off_t>(offset + nbytes),
SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE);
} else {
ret = sync_file_range(fd_, static_cast<off_t>(offset),
static_cast<off_t>(nbytes), SYNC_FILE_RANGE_WRITE);
}
if (ret != 0) {
return IOError("While sync_file_range returned " + ToString(ret),
filename_, errno);
}
return IOStatus::OK();
}
#endif // ROCKSDB_RANGESYNC_PRESENT
return FSWritableFile::RangeSync(offset, nbytes, opts, dbg);
}
#ifdef OS_LINUX
size_t PosixWritableFile::GetUniqueId(char* id, size_t max_size) const {
return PosixHelper::GetUniqueIdFromFile(fd_, id, max_size);
}
#endif
/*
* PosixRandomRWFile
*/
PosixRandomRWFile::PosixRandomRWFile(const std::string& fname, int fd,
const EnvOptions& /*options*/)
: filename_(fname), fd_(fd) {}
PosixRandomRWFile::~PosixRandomRWFile() {
if (fd_ >= 0) {
Close(IOOptions(), nullptr);
}
}
IOStatus PosixRandomRWFile::Write(uint64_t offset, const Slice& data,
const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
const char* src = data.data();
size_t nbytes = data.size();
if (!PosixPositionedWrite(fd_, src, nbytes, static_cast<off_t>(offset))) {
return IOError(
"While write random read/write file at offset " + ToString(offset),
filename_, errno);
}
return IOStatus::OK();
}
IOStatus PosixRandomRWFile::Read(uint64_t offset, size_t n,
const IOOptions& /*opts*/, Slice* result,
char* scratch, IODebugContext* /*dbg*/) const {
size_t left = n;
char* ptr = scratch;
while (left > 0) {
ssize_t done = pread(fd_, ptr, left, offset);
if (done < 0) {
// error while reading from file
if (errno == EINTR) {
// read was interrupted, try again.
continue;
}
return IOError("While reading random read/write file offset " +
ToString(offset) + " len " + ToString(n),
filename_, errno);
} else if (done == 0) {
// Nothing more to read
break;
}
// Read `done` bytes
ptr += done;
offset += done;
left -= done;
}
*result = Slice(scratch, n - left);
return IOStatus::OK();
}
IOStatus PosixRandomRWFile::Flush(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
return IOStatus::OK();
}
IOStatus PosixRandomRWFile::Sync(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
if (fdatasync(fd_) < 0) {
return IOError("While fdatasync random read/write file", filename_, errno);
}
return IOStatus::OK();
}
IOStatus PosixRandomRWFile::Fsync(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
if (fsync(fd_) < 0) {
return IOError("While fsync random read/write file", filename_, errno);
}
return IOStatus::OK();
}
IOStatus PosixRandomRWFile::Close(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
if (close(fd_) < 0) {
return IOError("While close random read/write file", filename_, errno);
}
fd_ = -1;
return IOStatus::OK();
}
PosixMemoryMappedFileBuffer::~PosixMemoryMappedFileBuffer() {
// TODO should have error handling though not much we can do...
munmap(this->base_, length_);
}
/*
* PosixDirectory
*/
PosixDirectory::~PosixDirectory() { close(fd_); }
IOStatus PosixDirectory::Fsync(const IOOptions& /*opts*/,
IODebugContext* /*dbg*/) {
#ifndef OS_AIX
if (fsync(fd_) == -1) {
return IOError("While fsync", "a directory", errno);
}
#endif
return IOStatus::OK();
}
} // namespace ROCKSDB_NAMESPACE
#endif
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