|
| 1 | +/** |
| 2 | + * Copyright (c) 2017-present, Facebook, Inc. |
| 3 | + * All rights reserved. |
| 4 | + * |
| 5 | + * This source code is licensed under the BSD-style license found in the |
| 6 | + * LICENSE file in the root directory of this source tree. |
| 7 | + */ |
| 8 | + |
| 9 | +#pragma once |
| 10 | + |
| 11 | +#include <functional> |
| 12 | +#include <memory> |
| 13 | + |
| 14 | +#include <gloo/transport/tcp/error.h> |
| 15 | +#include <gloo/transport/tcp/loop.h> |
| 16 | +#include <gloo/transport/tcp/socket.h> |
| 17 | + |
| 18 | +namespace gloo { |
| 19 | +namespace transport { |
| 20 | +namespace tcp { |
| 21 | + |
| 22 | +// ReadValueOperation asynchronously reads a value of type T from the |
| 23 | +// socket specified at construction. Upon completion or error, the |
| 24 | +// callback is called. Its lifetime is coupled with completion of the |
| 25 | +// operation, so the called doesn't need to hold on to the instance. |
| 26 | +// It does so by storing a shared_ptr to itself (effectively a leak) |
| 27 | +// until the event loop calls back. |
| 28 | +template <typename T> |
| 29 | +class ReadValueOperation final |
| 30 | + : public Handler, |
| 31 | + public std::enable_shared_from_this<ReadValueOperation<T>> { |
| 32 | + public: |
| 33 | + using callback_t = |
| 34 | + std::function<void(std::shared_ptr<Socket>, const Error& error, T&& t)>; |
| 35 | + |
| 36 | + ReadValueOperation( |
| 37 | + std::shared_ptr<Loop> loop, |
| 38 | + std::shared_ptr<Socket> socket, |
| 39 | + callback_t fn) |
| 40 | + : loop_(std::move(loop)), |
| 41 | + socket_(std::move(socket)), |
| 42 | + fn_(std::move(fn)) {} |
| 43 | + |
| 44 | + void run() { |
| 45 | + // Cannot initialize leak until after the object has been |
| 46 | + // constructed, because the std::make_shared initialization |
| 47 | + // doesn't run after construction of the underlying object. |
| 48 | + leak_ = this->shared_from_this(); |
| 49 | + // Register with loop only after we've leaked the shared_ptr, |
| 50 | + // because we unleak it when the event loop thread calls. |
| 51 | + loop_->registerDescriptor(socket_->fd(), EPOLLIN | EPOLLONESHOT, this); |
| 52 | + } |
| 53 | + |
| 54 | + void handleEvents(int events) override { |
| 55 | + // Move leaked shared_ptr to the stack so that this object |
| 56 | + // destroys itself once this function returns. |
| 57 | + auto self = std::move(this->leak_); |
| 58 | + |
| 59 | + // Read T. |
| 60 | + auto rv = socket_->read(&t_, sizeof(t_)); |
| 61 | + if (rv == -1) { |
| 62 | + fn_(socket_, SystemError("read", errno), std::move(t_)); |
| 63 | + return; |
| 64 | + } |
| 65 | + |
| 66 | + // Check for short read (assume we can read in a single call). |
| 67 | + if (rv < sizeof(t_)) { |
| 68 | + fn_(socket_, ShortReadError(rv, sizeof(t_)), std::move(t_)); |
| 69 | + return; |
| 70 | + } |
| 71 | + |
| 72 | + fn_(socket_, Error::kSuccess, std::move(t_)); |
| 73 | + } |
| 74 | + |
| 75 | + private: |
| 76 | + std::shared_ptr<Loop> loop_; |
| 77 | + std::shared_ptr<Socket> socket_; |
| 78 | + callback_t fn_; |
| 79 | + std::shared_ptr<ReadValueOperation<T>> leak_; |
| 80 | + |
| 81 | + T t_; |
| 82 | +}; |
| 83 | + |
| 84 | +template <typename T> |
| 85 | +void read( |
| 86 | + std::shared_ptr<Loop> loop, |
| 87 | + std::shared_ptr<Socket> socket, |
| 88 | + typename ReadValueOperation<T>::callback_t fn) { |
| 89 | + auto x = std::make_shared<ReadValueOperation<T>>( |
| 90 | + std::move(loop), std::move(socket), std::move(fn)); |
| 91 | + x->run(); |
| 92 | +} |
| 93 | + |
| 94 | +// WriteValueOperation asynchronously writes a value of type T to the |
| 95 | +// socket specified at construction. Upon completion or error, the |
| 96 | +// callback is called. Its lifetime is coupled with completion of the |
| 97 | +// operation, so the called doesn't need to hold on to the instance. |
| 98 | +// It does so by storing a shared_ptr to itself (effectively a leak) |
| 99 | +// until the event loop calls back. |
| 100 | +template <typename T> |
| 101 | +class WriteValueOperation final |
| 102 | + : public Handler, |
| 103 | + public std::enable_shared_from_this<WriteValueOperation<T>> { |
| 104 | + public: |
| 105 | + using callback_t = |
| 106 | + std::function<void(std::shared_ptr<Socket>, const Error& error)>; |
| 107 | + |
| 108 | + WriteValueOperation( |
| 109 | + std::shared_ptr<Loop> loop, |
| 110 | + std::shared_ptr<Socket> socket, |
| 111 | + T t, |
| 112 | + callback_t fn) |
| 113 | + : loop_(std::move(loop)), |
| 114 | + socket_(std::move(socket)), |
| 115 | + fn_(std::move(fn)), |
| 116 | + t_(std::move(t)) {} |
| 117 | + |
| 118 | + void run() { |
| 119 | + // Cannot initialize leak until after the object has been |
| 120 | + // constructed, because the std::make_shared initialization |
| 121 | + // doesn't run after construction of the underlying object. |
| 122 | + leak_ = this->shared_from_this(); |
| 123 | + // Register with loop only after we've leaked the shared_ptr, |
| 124 | + // because we unleak it when the event loop thread calls. |
| 125 | + loop_->registerDescriptor(socket_->fd(), EPOLLOUT | EPOLLONESHOT, this); |
| 126 | + } |
| 127 | + |
| 128 | + void handleEvents(int events) override { |
| 129 | + // Move leaked shared_ptr to the stack so that this object |
| 130 | + // destroys itself once this function returns. |
| 131 | + auto leak = std::move(this->leak_); |
| 132 | + |
| 133 | + // Write T. |
| 134 | + auto rv = socket_->write(&t_, sizeof(t_)); |
| 135 | + if (rv == -1) { |
| 136 | + fn_(socket_, SystemError("write", errno)); |
| 137 | + return; |
| 138 | + } |
| 139 | + |
| 140 | + // Check for short write (assume we can write in a single call). |
| 141 | + if (rv < sizeof(t_)) { |
| 142 | + fn_(socket_, ShortWriteError(rv, sizeof(t_))); |
| 143 | + return; |
| 144 | + } |
| 145 | + |
| 146 | + fn_(socket_, Error::kSuccess); |
| 147 | + } |
| 148 | + |
| 149 | + private: |
| 150 | + std::shared_ptr<Loop> loop_; |
| 151 | + std::shared_ptr<Socket> socket_; |
| 152 | + callback_t fn_; |
| 153 | + std::shared_ptr<WriteValueOperation<T>> leak_; |
| 154 | + |
| 155 | + T t_; |
| 156 | +}; |
| 157 | + |
| 158 | +template <typename T> |
| 159 | +void write( |
| 160 | + std::shared_ptr<Loop> loop, |
| 161 | + std::shared_ptr<Socket> socket, |
| 162 | + T t, |
| 163 | + typename WriteValueOperation<T>::callback_t fn) { |
| 164 | + auto x = std::make_shared<WriteValueOperation<T>>( |
| 165 | + std::move(loop), std::move(socket), std::move(t), std::move(fn)); |
| 166 | + x->run(); |
| 167 | +} |
| 168 | + |
| 169 | +} // namespace tcp |
| 170 | +} // namespace transport |
| 171 | +} // namespace gloo |
0 commit comments