112 lines
2.8 KiB
C++
112 lines
2.8 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#include "td/utils/port/MemoryMapping.h"
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#include "td/utils/logging.h"
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#include "td/utils/misc.h"
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// TODO:
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// windows,
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// anonymous maps,
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// huge pages?
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#if TD_WINDOWS
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#else
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#include <sys/mman.h>
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#include <unistd.h>
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#endif
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namespace td {
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class MemoryMapping::Impl {
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public:
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Impl(MutableSlice data, int64 offset) : data_(data), offset_(offset) {
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}
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Slice as_slice() const {
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return data_.substr(narrow_cast<size_t>(offset_));
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}
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MutableSlice as_mutable_slice() const {
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return {};
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}
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private:
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MutableSlice data_;
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int64 offset_;
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};
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static Result<int64> get_page_size() {
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#if TD_WINDOWS
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return Status::Error("Unimplemented");
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#else
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static Result<int64> page_size = []() -> Result<int64> {
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auto page_size = sysconf(_SC_PAGESIZE);
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if (page_size < 0) {
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return OS_ERROR("Can't load page size from sysconf");
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}
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return page_size;
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}();
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return page_size.clone();
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#endif
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}
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Result<MemoryMapping> MemoryMapping::create_anonymous(const MemoryMapping::Options &options) {
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return Status::Error("Unsupported yet");
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}
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Result<MemoryMapping> MemoryMapping::create_from_file(const FileFd &file_fd, const MemoryMapping::Options &options) {
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#if TD_WINDOWS
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return Status::Error("Unsupported yet");
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#else
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if (file_fd.empty()) {
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return Status::Error("Can't create memory mapping: file is empty");
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}
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TRY_RESULT(stat, file_fd.stat());
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auto fd = file_fd.get_native_fd().fd();
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auto begin = options.offset;
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if (begin < 0) {
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return Status::Error(PSLICE() << "Can't create memory mapping: negative offset " << options.offset);
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}
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int64 end;
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if (options.size < 0) {
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end = stat.size_;
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} else {
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end = begin + stat.size_;
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}
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TRY_RESULT(page_size, get_page_size());
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auto fixed_begin = begin / page_size * page_size;
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auto data_offset = begin - fixed_begin;
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auto data_size = narrow_cast<size_t>(end - fixed_begin);
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void *data = mmap(nullptr, data_size, PROT_READ, MADV_MERGEABLE, fd, narrow_cast<off_t>(fixed_begin));
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if (data == MAP_FAILED) {
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return OS_ERROR("mmap call failed");
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}
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return MemoryMapping(make_unique<Impl>(MutableSlice(static_cast<char *>(data), data_size), data_offset));
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#endif
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}
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MemoryMapping::MemoryMapping(MemoryMapping &&other) = default;
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MemoryMapping &MemoryMapping::operator=(MemoryMapping &&other) = default;
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MemoryMapping::~MemoryMapping() = default;
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MemoryMapping::MemoryMapping(unique_ptr<Impl> impl) : impl_(std::move(impl)) {
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}
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Slice MemoryMapping::as_slice() const {
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return impl_->as_slice();
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}
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MutableSlice MemoryMapping::as_mutable_slice() {
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return impl_->as_mutable_slice();
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}
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} // namespace td
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