364 lines
8.5 KiB
C++
364 lines
8.5 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
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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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#pragma once
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#include "td/utils/format.h"
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#include "td/utils/List.h"
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#include "td/utils/MovableValue.h"
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#include "td/utils/Observer.h"
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#include "td/utils/port/detail/NativeFd.h"
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#include "td/utils/SpinLock.h"
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#include "td/utils/Status.h"
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#include <atomic>
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namespace td {
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class ObserverBase;
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class PollFlags {
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public:
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using Raw = int32;
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bool can_read() const {
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return has_flags(Read());
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}
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bool can_write() const {
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return has_flags(Write());
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}
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bool can_close() const {
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return has_flags(Close());
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}
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bool has_pending_error() const {
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return has_flags(Error());
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}
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void remove_flags(PollFlags flags) {
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remove_flags(flags.raw());
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}
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bool add_flags(PollFlags flags) {
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auto old_flags = flags_;
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add_flags(flags.raw());
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return old_flags != flags_;
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}
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bool has_flags(PollFlags flags) const {
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return has_flags(flags.raw());
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}
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bool empty() const {
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return flags_ == 0;
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}
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Raw raw() const {
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return flags_;
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}
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static PollFlags from_raw(Raw raw) {
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return PollFlags(raw);
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}
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PollFlags() = default;
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bool operator==(const PollFlags &other) const {
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return flags_ == other.flags_;
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}
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bool operator!=(const PollFlags &other) const {
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return !(*this == other);
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}
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PollFlags operator|(const PollFlags other) const {
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return from_raw(raw() | other.raw());
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}
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static PollFlags Write() {
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return PollFlags(Flag::Write);
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}
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static PollFlags Error() {
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return PollFlags(Flag::Error);
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}
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static PollFlags Close() {
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return PollFlags(Flag::Close);
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}
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static PollFlags Read() {
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return PollFlags(Flag::Read);
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}
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static PollFlags ReadWrite() {
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return Read() | Write();
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}
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private:
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enum class Flag : Raw { Write = 0x001, Read = 0x002, Close = 0x004, Error = 0x008, None = 0 };
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Raw flags_{static_cast<Raw>(Flag::None)};
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explicit PollFlags(Raw raw) : flags_(raw) {
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}
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explicit PollFlags(Flag flag) : PollFlags(static_cast<Raw>(flag)) {
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}
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PollFlags &add_flags(Raw flags) {
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flags_ |= flags;
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return *this;
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}
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PollFlags &remove_flags(Raw flags) {
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flags_ &= ~flags;
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return *this;
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}
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bool has_flags(Raw flags) const {
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return (flags_ & flags) == flags;
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}
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};
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inline StringBuilder &operator<<(StringBuilder &sb, PollFlags flags) {
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sb << "[";
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if (flags.can_read()) {
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sb << "R";
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}
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if (flags.can_write()) {
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sb << "W";
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}
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if (flags.can_close()) {
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sb << "C";
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}
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if (flags.has_pending_error()) {
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sb << "E";
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}
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return sb << "]";
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}
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class PollFlagsSet {
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public:
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// write flags from any thread
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// this is the only function that should be called from other threads
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bool write_flags(PollFlags flags);
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bool write_flags_local(PollFlags flags);
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bool flush() const;
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PollFlags read_flags() const;
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PollFlags read_flags_local() const;
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void clear_flags(PollFlags flags);
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void clear();
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private:
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mutable std::atomic<PollFlags::Raw> to_write_{0};
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mutable PollFlags flags_;
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};
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class PollableFdInfo;
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class PollableFdInfoUnlock {
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public:
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void operator()(PollableFdInfo *ptr);
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};
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class PollableFd;
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class PollableFdRef {
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public:
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explicit PollableFdRef(ListNode *list_node) : list_node_(list_node) {
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}
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PollableFd lock();
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private:
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ListNode *list_node_;
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};
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class PollableFd {
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public:
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// Interface for kqueue, epoll and e.t.c.
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const NativeFd &native_fd() const;
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ListNode *release_as_list_node();
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PollableFdRef ref();
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static PollableFd from_list_node(ListNode *node);
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void add_flags(PollFlags flags);
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PollFlags get_flags_unsafe() const;
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private:
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std::unique_ptr<PollableFdInfo, PollableFdInfoUnlock> fd_info_;
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friend class PollableFdInfo;
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explicit PollableFd(std::unique_ptr<PollableFdInfo, PollableFdInfoUnlock> fd_info) : fd_info_(std::move(fd_info)) {
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}
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};
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inline PollableFd PollableFdRef::lock() {
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return PollableFd::from_list_node(list_node_);
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}
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class PollableFdInfo : private ListNode {
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public:
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PollableFdInfo() = default;
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PollableFd extract_pollable_fd(ObserverBase *observer) {
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VLOG(fd) << native_fd() << " extract pollable fd " << tag("observer", observer);
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CHECK(!empty());
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bool was_locked = lock_.test_and_set(std::memory_order_acquire);
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CHECK(!was_locked);
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set_observer(observer);
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return PollableFd{std::unique_ptr<PollableFdInfo, PollableFdInfoUnlock>{this}};
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}
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PollableFdRef get_pollable_fd_ref() {
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CHECK(!empty());
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bool was_locked = lock_.test_and_set(std::memory_order_acquire);
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CHECK(was_locked);
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return PollableFdRef{as_list_node()};
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}
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void add_flags(PollFlags flags) {
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flags_.write_flags_local(flags);
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}
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void clear_flags(PollFlags flags) {
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flags_.clear_flags(flags);
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}
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PollFlags get_flags() const {
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return flags_.read_flags();
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}
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PollFlags get_flags_local() const {
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return flags_.read_flags_local();
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}
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bool empty() const {
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return !fd_;
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}
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void set_native_fd(NativeFd new_native_fd) {
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if (fd_) {
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CHECK(!new_native_fd);
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bool was_locked = lock_.test_and_set(std::memory_order_acquire);
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CHECK(!was_locked);
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lock_.clear(std::memory_order_release);
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}
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fd_ = std::move(new_native_fd);
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}
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explicit PollableFdInfo(NativeFd native_fd) {
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set_native_fd(std::move(native_fd));
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}
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const NativeFd &native_fd() const {
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//CHECK(!empty());
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return fd_;
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}
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NativeFd move_as_native_fd() {
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return std::move(fd_);
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}
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~PollableFdInfo() {
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VLOG(fd) << native_fd() << " destroy PollableFdInfo";
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bool was_locked = lock_.test_and_set(std::memory_order_acquire);
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CHECK(!was_locked);
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}
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void add_flags_from_poll(PollFlags flags) {
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VLOG(fd) << native_fd() << " add flags from poll " << flags;
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if (flags_.write_flags(flags)) {
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notify_observer();
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}
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}
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private:
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NativeFd fd_{};
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std::atomic_flag lock_{false};
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PollFlagsSet flags_;
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#if TD_PORT_WINDOWS
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SpinLock observer_lock_;
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#endif
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ObserverBase *observer_{nullptr};
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friend class PollableFd;
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friend class PollableFdInfoUnlock;
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void set_observer(ObserverBase *observer) {
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#if TD_PORT_WINDOWS
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auto lock = observer_lock_.lock();
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#endif
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CHECK(!observer_);
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observer_ = observer;
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}
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void clear_observer() {
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#if TD_PORT_WINDOWS
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auto lock = observer_lock_.lock();
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#endif
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observer_ = nullptr;
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}
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void notify_observer() {
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#if TD_PORT_WINDOWS
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auto lock = observer_lock_.lock();
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#endif
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VLOG(fd) << native_fd() << " notify " << tag("observer", observer_);
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if (observer_) {
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observer_->notify();
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}
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}
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void unlock() {
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clear_observer();
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lock_.clear(std::memory_order_release);
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as_list_node()->remove();
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}
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ListNode *as_list_node() {
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return static_cast<ListNode *>(this);
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}
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static PollableFdInfo *from_list_node(ListNode *list_node) {
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return static_cast<PollableFdInfo *>(list_node);
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}
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};
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inline void PollableFdInfoUnlock::operator()(PollableFdInfo *ptr) {
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ptr->unlock();
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}
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inline ListNode *PollableFd::release_as_list_node() {
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return fd_info_.release()->as_list_node();
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}
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inline PollableFdRef PollableFd::ref() {
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return PollableFdRef{fd_info_->as_list_node()};
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}
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inline PollableFd PollableFd::from_list_node(ListNode *node) {
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return PollableFd(std::unique_ptr<PollableFdInfo, PollableFdInfoUnlock>(PollableFdInfo::from_list_node(node)));
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}
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inline void PollableFd::add_flags(PollFlags flags) {
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fd_info_->add_flags_from_poll(flags);
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}
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inline PollFlags PollableFd::get_flags_unsafe() const {
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return fd_info_->get_flags_local();
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}
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inline const NativeFd &PollableFd::native_fd() const {
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return fd_info_->native_fd();
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}
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#if TD_PORT_POSIX
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template <class F>
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auto skip_eintr(F &&f) {
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decltype(f()) res;
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static_assert(std::is_integral<decltype(res)>::value, "integral type expected");
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do {
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errno = 0; // just in case
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res = f();
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} while (res < 0 && errno == EINTR);
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return res;
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}
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template <class F>
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auto skip_eintr_cstr(F &&f) {
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char *res;
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do {
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errno = 0; // just in case
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res = f();
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} while (res == nullptr && errno == EINTR);
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return res;
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}
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#endif
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template <class FdT>
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bool can_read(const FdT &fd) {
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return fd.get_poll_info().get_flags().can_read() || fd.get_poll_info().get_flags().has_pending_error();
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}
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template <class FdT>
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bool can_write(const FdT &fd) {
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return fd.get_poll_info().get_flags().can_write();
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}
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template <class FdT>
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bool can_close(const FdT &fd) {
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return fd.get_poll_info().get_flags().can_close();
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}
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} // namespace td
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