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tdutils/td/utils/port/detail/PollableFd.h

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+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#pragma once
+
+#include "td/utils/common.h"
+#include "td/utils/format.h"
+#include "td/utils/List.h"
+#include "td/utils/logging.h"
+#include "td/utils/Observer.h"
+#include "td/utils/port/detail/NativeFd.h"
+#include "td/utils/port/PollFlags.h"
+#include "td/utils/SpinLock.h"
+
+#include <atomic>
+#include <memory>
+#include <type_traits>
+
+namespace td {
+
+class PollableFdInfo;
+class PollableFdInfoUnlock {
+ public:
+  void operator()(PollableFdInfo *ptr);
+};
+
+class PollableFd;
+class PollableFdRef {
+ public:
+  explicit PollableFdRef(ListNode *list_node) : list_node_(list_node) {
+  }
+  PollableFd lock();
+
+ private:
+  ListNode *list_node_;
+};
+
+class PollableFd {
+ public:
+  // Interface for kqueue, epoll and e.t.c.
+  const NativeFd &native_fd() const;
+
+  ListNode *release_as_list_node();
+  PollableFdRef ref();
+  static PollableFd from_list_node(ListNode *node);
+  void add_flags(PollFlags flags);
+  PollFlags get_flags_unsafe() const;
+
+ private:
+  std::unique_ptr<PollableFdInfo, PollableFdInfoUnlock> fd_info_;
+  friend class PollableFdInfo;
+
+  explicit PollableFd(std::unique_ptr<PollableFdInfo, PollableFdInfoUnlock> fd_info) : fd_info_(std::move(fd_info)) {
+  }
+};
+
+inline PollableFd PollableFdRef::lock() {
+  return PollableFd::from_list_node(list_node_);
+}
+
+class PollableFdInfo : private ListNode {
+ public:
+  PollableFdInfo() = default;
+  PollableFdInfo(const PollableFdInfo &) = delete;
+  PollableFdInfo &operator=(const PollableFdInfo &) = delete;
+  PollableFdInfo(PollableFdInfo &&) = delete;
+  PollableFdInfo &operator=(PollableFdInfo &&) = delete;
+
+  PollableFd extract_pollable_fd(ObserverBase *observer) {
+    VLOG(fd) << native_fd() << " extract pollable fd " << tag("observer", observer);
+    CHECK(!empty());
+    bool was_locked = lock_.test_and_set(std::memory_order_acquire);
+    CHECK(!was_locked);
+    set_observer(observer);
+    return PollableFd{std::unique_ptr<PollableFdInfo, PollableFdInfoUnlock>{this}};
+  }
+  PollableFdRef get_pollable_fd_ref() {
+    CHECK(!empty());
+    bool was_locked = lock_.test_and_set(std::memory_order_acquire);
+    CHECK(was_locked);
+    return PollableFdRef{as_list_node()};
+  }
+
+  void add_flags(PollFlags flags) {
+    flags_.write_flags_local(flags);
+  }
+
+  void clear_flags(PollFlags flags) {
+    flags_.clear_flags(flags);
+  }
+  PollFlags get_flags() const {
+    return flags_.read_flags();
+  }
+  PollFlags get_flags_local() const {
+    return flags_.read_flags_local();
+  }
+
+  bool empty() const {
+    return !fd_;
+  }
+
+  void set_native_fd(NativeFd new_native_fd) {
+    if (fd_) {
+      CHECK(!new_native_fd);
+      bool was_locked = lock_.test_and_set(std::memory_order_acquire);
+      CHECK(!was_locked);
+      lock_.clear(std::memory_order_release);
+    }
+
+    fd_ = std::move(new_native_fd);
+  }
+  explicit PollableFdInfo(NativeFd native_fd) {
+    set_native_fd(std::move(native_fd));
+  }
+  const NativeFd &native_fd() const {
+    //CHECK(!empty());
+    return fd_;
+  }
+  NativeFd move_as_native_fd() {
+    return std::move(fd_);
+  }
+
+  ~PollableFdInfo() {
+    VLOG(fd) << native_fd() << " destroy PollableFdInfo";
+    bool was_locked = lock_.test_and_set(std::memory_order_acquire);
+    CHECK(!was_locked);
+  }
+
+  void add_flags_from_poll(PollFlags flags) {
+    VLOG(fd) << native_fd() << " add flags from poll " << flags;
+    if (flags_.write_flags(flags)) {
+      notify_observer();
+    }
+  }
+
+ private:
+  NativeFd fd_{};
+  std::atomic_flag lock_ = ATOMIC_FLAG_INIT;
+  PollFlagsSet flags_;
+#if TD_PORT_WINDOWS
+  SpinLock observer_lock_;
+#endif
+  ObserverBase *observer_{nullptr};
+
+  friend class PollableFd;
+  friend class PollableFdInfoUnlock;
+
+  void set_observer(ObserverBase *observer) {
+#if TD_PORT_WINDOWS
+    auto lock = observer_lock_.lock();
+#endif
+    CHECK(!observer_);
+    observer_ = observer;
+  }
+  void clear_observer() {
+#if TD_PORT_WINDOWS
+    auto lock = observer_lock_.lock();
+#endif
+    observer_ = nullptr;
+  }
+  void notify_observer() {
+#if TD_PORT_WINDOWS
+    auto lock = observer_lock_.lock();
+#endif
+    VLOG(fd) << native_fd() << " notify " << tag("observer", observer_);
+    if (observer_) {
+      observer_->notify();
+    }
+  }
+
+  void unlock() {
+    clear_observer();
+    lock_.clear(std::memory_order_release);
+    as_list_node()->remove();
+  }
+
+  ListNode *as_list_node() {
+    return static_cast<ListNode *>(this);
+  }
+  static PollableFdInfo *from_list_node(ListNode *list_node) {
+    return static_cast<PollableFdInfo *>(list_node);
+  }
+};
+inline void PollableFdInfoUnlock::operator()(PollableFdInfo *ptr) {
+  ptr->unlock();
+}
+
+inline ListNode *PollableFd::release_as_list_node() {
+  return fd_info_.release()->as_list_node();
+}
+inline PollableFdRef PollableFd::ref() {
+  return PollableFdRef{fd_info_->as_list_node()};
+}
+inline PollableFd PollableFd::from_list_node(ListNode *node) {
+  return PollableFd(std::unique_ptr<PollableFdInfo, PollableFdInfoUnlock>(PollableFdInfo::from_list_node(node)));
+}
+
+inline void PollableFd::add_flags(PollFlags flags) {
+  fd_info_->add_flags_from_poll(flags);
+}
+inline PollFlags PollableFd::get_flags_unsafe() const {
+  return fd_info_->get_flags_local();
+}
+inline const NativeFd &PollableFd::native_fd() const {
+  return fd_info_->native_fd();
+}
+
+#if TD_PORT_POSIX
+namespace detail {
+template <class F>
+auto skip_eintr(F &&f) {
+  decltype(f()) res;
+  static_assert(std::is_integral<decltype(res)>::value, "integral type expected");
+  do {
+    errno = 0;  // just in case
+    res = f();
+  } while (res < 0 && errno == EINTR);
+  return res;
+}
+template <class F>
+auto skip_eintr_cstr(F &&f) {
+  char *res;
+  do {
+    errno = 0;  // just in case
+    res = f();
+  } while (res == nullptr && errno == EINTR);
+  return res;
+}
+}  // namespace detail
+#endif
+
+template <class FdT>
+bool can_read(const FdT &fd) {
+  return fd.get_poll_info().get_flags().can_read() || fd.get_poll_info().get_flags().has_pending_error();
+}
+
+template <class FdT>
+bool can_write(const FdT &fd) {
+  return fd.get_poll_info().get_flags().can_write();
+}
+
+template <class FdT>
+bool can_close(const FdT &fd) {
+  return fd.get_poll_info().get_flags().can_close();
+}
+
+}  // namespace td