/usr/include/kj/async-io.h is in libcapnp-dev 0.4.0-1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 | // Copyright (c) 2013, Kenton Varda <temporal@gmail.com>
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef KJ_ASYNC_IO_H_
#define KJ_ASYNC_IO_H_
#include "async.h"
#include "function.h"
#include "thread.h"
namespace kj {
class AsyncInputStream {
// Asynchronous equivalent of InputStream (from io.h).
public:
virtual Promise<size_t> read(void* buffer, size_t minBytes, size_t maxBytes) = 0;
virtual Promise<size_t> tryRead(void* buffer, size_t minBytes, size_t maxBytes) = 0;
Promise<void> read(void* buffer, size_t bytes);
};
class AsyncOutputStream {
// Asynchronous equivalent of OutputStream (from io.h).
public:
virtual Promise<void> write(const void* buffer, size_t size) = 0;
virtual Promise<void> write(ArrayPtr<const ArrayPtr<const byte>> pieces) = 0;
};
class AsyncIoStream: public AsyncInputStream, public AsyncOutputStream {
// A combination input and output stream.
public:
virtual void shutdownWrite() = 0;
// Cleanly shut down just the write end of the stream, while keeping the read end open.
};
class ConnectionReceiver {
// Represents a server socket listening on a port.
public:
virtual Promise<Own<AsyncIoStream>> accept() = 0;
// Accept the next incoming connection.
virtual uint getPort() = 0;
// Gets the port number, if applicable (i.e. if listening on IP). This is useful if you didn't
// specify a port when constructing the LocalAddress -- one will have been assigned automatically.
};
class NetworkAddress {
// Represents a remote address to which the application can connect.
public:
virtual Promise<Own<AsyncIoStream>> connect() = 0;
// Make a new connection to this address.
//
// The address must not be a wildcard ("*"). If it is an IP address, it must have a port number.
virtual Own<ConnectionReceiver> listen() = 0;
// Listen for incoming connections on this address.
//
// The address must be local.
virtual String toString() = 0;
// Produce a human-readable string which hopefully can be passed to Network::parseRemoteAddress()
// to reproduce this address, although whether or not that works of course depends on the Network
// implementation. This should be called only to display the address to human users, who will
// hopefully know what they are able to do with it.
};
class LocalAddress {
// Represents a local address on which the application can potentially accept connections.
public:
virtual String toString() = 0;
// Produce a human-readable string which hopefully can be passed to Network::parseRemoteAddress()
// to reproduce this address, although whether or not that works of course depends on the Network
// implementation. This should be called only to display the address to human users, who will
// hopefully know what they are able to do with it.
};
class Network {
// Factory for LocalAddress and RemoteAddress instances, representing the network services
// offered by the operating system.
//
// This interface typically represents broad authority, and well-designed code should limit its
// use to high-level startup code and user interaction. Low-level APIs should accept
// LocalAddress and/or RemoteAddress instances directly and work from there, if at all possible.
public:
virtual Promise<Own<NetworkAddress>> parseAddress(StringPtr addr, uint portHint = 0) = 0;
// Construct a network address from a user-provided string. The format of the address
// strings is not specified at the API level, and application code should make no assumptions
// about them. These strings should always be provided by humans, and said humans will know
// what format to use in their particular context.
//
// `portHint`, if provided, specifies the "standard" IP port number for the application-level
// service in play. If the address turns out to be an IP address (v4 or v6), and it lacks a
// port number, this port will be used. If `addr` lacks a port number *and* `portHint` is
// omitted, then the returned address will only support listen() (not connect()), and a port
// will be chosen when listen() is called.
virtual Own<NetworkAddress> getSockaddr(const void* sockaddr, uint len) = 0;
// Construct a network address from a legacy struct sockaddr.
};
struct OneWayPipe {
// A data pipe with an input end and an output end. (Typically backed by pipe() system call.)
Own<AsyncInputStream> in;
Own<AsyncOutputStream> out;
};
struct TwoWayPipe {
// A data pipe that supports sending in both directions. Each end's output sends data to the
// other end's input. (Typically backed by socketpair() system call.)
Own<AsyncIoStream> ends[2];
};
class AsyncIoProvider {
// Class which constructs asynchronous wrappers around the operating system's I/O facilities.
//
// Generally, the implementation of this interface must integrate closely with a particular
// `EventLoop` implementation. Typically, the EventLoop implementation itself will provide
// an AsyncIoProvider.
public:
virtual OneWayPipe newOneWayPipe() = 0;
// Creates an input/output stream pair representing the ends of a one-way pipe (e.g. created with
// the pipe(2) system call).
virtual TwoWayPipe newTwoWayPipe() = 0;
// Creates two AsyncIoStreams representing the two ends of a two-way pipe (e.g. created with
// socketpair(2) system call). Data written to one end can be read from the other.
virtual Network& getNetwork() = 0;
// Creates a new `Network` instance representing the networks exposed by the operating system.
//
// DO NOT CALL THIS except at the highest levels of your code, ideally in the main() function. If
// you call this from low-level code, then you are preventing higher-level code from injecting an
// alternative implementation. Instead, if your code needs to use network functionality, it
// should ask for a `Network` as a constructor or method parameter, so that higher-level code can
// chose what implementation to use. The system network is essentially a singleton. See:
// http://www.object-oriented-security.org/lets-argue/singletons
//
// Code that uses the system network should not make any assumptions about what kinds of
// addresses it will parse, as this could differ across platforms. String addresses should come
// strictly from the user, who will know how to write them correctly for their system.
//
// With that said, KJ currently supports the following string address formats:
// - IPv4: "1.2.3.4", "1.2.3.4:80"
// - IPv6: "1234:5678::abcd", "[1234:5678::abcd]:80"
// - Local IP wildcard (covers both v4 and v6): "*", "*:80"
// - Symbolic names: "example.com", "example.com:80", "example.com:http", "1.2.3.4:http"
// - Unix domain: "unix:/path/to/socket"
struct PipeThread {
// A combination of a thread and a two-way pipe that communicates with that thread.
//
// The fields are intentionally ordered so that the pipe will be destroyed (and therefore
// disconnected) before the thread is destroyed (and therefore joined). Thus if the thread
// arranges to exit when it detects disconnect, destruction should be clean.
Own<Thread> thread;
Own<AsyncIoStream> pipe;
};
virtual PipeThread newPipeThread(
Function<void(AsyncIoProvider&, AsyncIoStream&, WaitScope&)> startFunc) = 0;
// Create a new thread and set up a two-way pipe (socketpair) which can be used to communicate
// with it. One end of the pipe is passed to the thread's start function and the other end of
// the pipe is returned. The new thread also gets its own `AsyncIoProvider` instance and will
// already have an active `EventLoop` when `startFunc` is called.
//
// TODO(someday): I'm not entirely comfortable with this interface. It seems to be doing too
// much at once but I'm not sure how to cleanly break it down.
};
class LowLevelAsyncIoProvider {
// Similar to `AsyncIoProvider`, but represents a lower-level interface that may differ on
// different operating systems. You should prefer to use `AsyncIoProvider` over this interface
// whenever possible, as `AsyncIoProvider` is portable and friendlier to dependency-injection.
//
// On Unix, this interface can be used to import native file descriptors into the async framework.
// Different implementations of this interface might work on top of different event handling
// primitives, such as poll vs. epoll vs. kqueue vs. some higher-level event library.
//
// On Windows, this interface can be used to import native HANDLEs into the async framework.
// Different implementations of this interface might work on top of different event handling
// primitives, such as I/O completion ports vs. completion routines.
//
// TODO(port): Actually implement Windows support.
public:
// ---------------------------------------------------------------------------
// Unix-specific stuff
enum Flags {
// Flags controlling how to wrap a file descriptor.
TAKE_OWNERSHIP = 1 << 0,
// The returned object should own the file descriptor, automatically closing it when destroyed.
// The close-on-exec flag will be set on the descriptor if it is not already.
//
// If this flag is not used, then the file descriptor is not automatically closed and the
// close-on-exec flag is not modified.
ALREADY_CLOEXEC = 1 << 1,
// Indicates that the close-on-exec flag is known already to be set, so need not be set again.
// Only relevant when combined with TAKE_OWNERSHIP.
//
// On Linux, all system calls which yield new file descriptors have flags or variants which
// set the close-on-exec flag immediately. Unfortunately, other OS's do not.
ALREADY_NONBLOCK = 1 << 2
// Indicates that the file descriptor is known already to be in non-blocking mode, so the flag
// need not be set again. Otherwise, all wrap*Fd() methods will enable non-blocking mode
// automatically.
//
// On Linux, all system calls which yield new file descriptors have flags or variants which
// enable non-blocking mode immediately. Unfortunately, other OS's do not.
};
virtual Own<AsyncInputStream> wrapInputFd(int fd, uint flags = 0) = 0;
// Create an AsyncInputStream wrapping a file descriptor.
//
// `flags` is a bitwise-OR of the values of the `Flags` enum.
virtual Own<AsyncOutputStream> wrapOutputFd(int fd, uint flags = 0) = 0;
// Create an AsyncOutputStream wrapping a file descriptor.
//
// `flags` is a bitwise-OR of the values of the `Flags` enum.
virtual Own<AsyncIoStream> wrapSocketFd(int fd, uint flags = 0) = 0;
// Create an AsyncIoStream wrapping a socket file descriptor.
//
// `flags` is a bitwise-OR of the values of the `Flags` enum.
virtual Promise<Own<AsyncIoStream>> wrapConnectingSocketFd(int fd, uint flags = 0) = 0;
// Create an AsyncIoStream wrapping a socket that is in the process of connecting. The returned
// promise should not resolve until connection has completed -- traditionally indicated by the
// descriptor becoming writable.
//
// `flags` is a bitwise-OR of the values of the `Flags` enum.
virtual Own<ConnectionReceiver> wrapListenSocketFd(int fd, uint flags = 0) = 0;
// Create an AsyncIoStream wrapping a listen socket file descriptor. This socket should already
// have had `bind()` and `listen()` called on it, so it's ready for `accept()`.
//
// `flags` is a bitwise-OR of the values of the `Flags` enum.
};
Own<AsyncIoProvider> newAsyncIoProvider(LowLevelAsyncIoProvider& lowLevel);
// Make a new AsyncIoProvider wrapping a `LowLevelAsyncIoProvider`.
struct AsyncIoContext {
Own<LowLevelAsyncIoProvider> lowLevelProvider;
Own<AsyncIoProvider> provider;
WaitScope& waitScope;
};
AsyncIoContext setupAsyncIo();
// Convenience method which sets up the current thread with everything it needs to do async I/O.
// The returned objects contain an `EventLoop` which is wrapping an appropriate `EventPort` for
// doing I/O on the host system, so everything is ready for the thread to start making async calls
// and waiting on promises.
//
// You would typically call this in your main() loop or in the start function of a thread.
// Example:
//
// int main() {
// auto ioContext = kj::setupAsyncIo();
//
// // Now we can call an async function.
// Promise<String> textPromise = getHttp(*ioContext.provider, "http://example.com");
//
// // And we can wait for the promise to complete. Note that you can only use `wait()`
// // from the top level, not from inside a promise callback.
// String text = textPromise.wait();
// print(text);
// return 0;
// }
} // namespace kj
#endif // KJ_ASYNC_IO_H_
|