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<title>Asynchronous I/O in Windows for Unix Programmers</title> |
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<body> |
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<h1>Asynchronous I/O in Windows for Unix Programmers</h1> |
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|
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<p>Ryan Dahl ryan@joyent.com |
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|
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<p>This document assumes you are familiar with how non-blocking socket I/O |
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is done in Unix. |
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|
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<p>The syscall |
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<a href="http://msdn.microsoft.com/en-us/library/ms740141(v=VS.85).aspx"><code>select</code> |
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is available in Windows</a> |
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but <code>select</code> processing is O(n) in the number of file descriptors |
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unlike the modern constant-time multiplexers like epoll which makes select |
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unacceptable for high-concurrency servers. |
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This document will describe how high-concurrency programs are |
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designed in Windows. |
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|
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<p> |
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Instead of <a href="http://en.wikipedia.org/wiki/Epoll">epoll</a> |
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or |
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<a href="http://en.wikipedia.org/wiki/Kqueue">kqueue</a>, |
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Windows has its own I/O multiplexer called |
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<a href="http://msdn.microsoft.com/en-us/library/aa365198(VS.85).aspx">I/O completion ports</a> |
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(IOCPs). IOCPs are the objects used to poll |
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<a href="http://msdn.microsoft.com/en-us/library/ms686358(v=vs.85).aspx">overlapped I/O</a> |
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for completion. IOCP polling is constant time (REF?). |
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|
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<p> |
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The fundamental variation is that in a Unix you generally ask the kernel to |
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wait for state change in a file descriptor's readability or writablity. With |
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overlapped I/O and IOCPs the programmers waits for asynchronous function |
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calls to complete. |
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For example, instead of waiting for a socket to become writable and then |
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using <a |
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href="http://www.kernel.org/doc/man-pages/online/pages/man2/send.2.html"><code>send(2)</code></a> |
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on it, as you commonly would do in a Unix, with overlapped I/O you |
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would rather <a |
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href="http://msdn.microsoft.com/en-us/library/ms742203(v=vs.85).aspx"><code>WSASend()</code></a> |
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the data and then wait for it to have been sent. |
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|
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<p> Unix non-blocking I/O is not beautiful. A principle abstraction in Unix |
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is the unified treatment of many things as files (or more precisely as file |
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descriptors). <code>write(2)</code>, <code>read(2)</code>, and |
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<code>close(2)</code> work with TCP sockets just as they do on regular |
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files. Well—kind of. Synchronous operations work similarly on different |
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types of file descriptors but once demands on performance drive you to world of |
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<code>O_NONBLOCK</code> various types of file descriptors can act quite |
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different for even the most basic operations. In particular, |
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regular file system files do <i>not</i> support non-blocking operations. |
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|
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(Disturbingly no man page mentions this rather important fact.) |
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|
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For example, one cannot poll on a regular file FD for readability expecting |
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it to indicate when it is safe to do a non-blocking read. |
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|
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Regular file are always readable and <code>read(2)</code> calls |
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<i>always</i> have the possibility of blocking the calling thread for an |
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unknown amount of time. |
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|
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<p>POSIX has defined <a |
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href="http://pubs.opengroup.org/onlinepubs/007908799/xsh/aio.h.html">an |
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asynchronous interface</a> for some operations but implementations for |
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many Unixes have unclear status. On Linux the |
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<code>aio_*</code> routines are implemented in userland in GNU libc using |
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pthreads. |
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<a |
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href="http://www.kernel.org/doc/man-pages/online/pages/man2/io_submit.2.html"><code>io_submit(2)</code></a> |
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does not have a GNU libc wrapper and has been reported <a |
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href="http://voinici.ceata.org/~sana/blog/?p=248"> to be very slow and |
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possibly blocking</a>. <a |
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href="http://download.oracle.com/docs/cd/E19253-01/816-5171/aio-write-3rt/index.html">Solaris |
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has real kernel AIO</a> but it's unclear what its performance |
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characteristics are for socket I/O as opposed to disk I/O. |
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Contemporary high-performance Unix socket programs use non-blocking |
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file descriptors with a I/O multiplexer—not POSIX AIO. |
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Common practice for accessing the disk asynchronously is still done using custom |
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userland thread pools—not POSIX AIO. |
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|
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<p>Windows IOCPs does support both sockets and regular file I/O which |
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greatly simplifies the handling of disks. For example, |
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<a href="http://msdn.microsoft.com/en-us/library/aa365468(v=VS.85).aspx"><code>ReadFileEx()</code></a> |
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operates on both. |
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As a first example let's look at how <code>ReadFile()</code> works. |
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|
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<pre> |
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typedef void* HANDLE; |
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|
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BOOL ReadFile(HANDLE file, |
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void* buffer, |
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DWORD numberOfBytesToRead, |
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DWORD* numberOfBytesRead, |
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OVERLAPPED* overlapped); |
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</pre> |
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|
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<p> |
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The function has the possibility of executing the read synchronously |
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or asynchronously. A synchronous operation is indicated by |
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returning 0 and <a |
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href="http://msdn.microsoft.com/en-us/library/ms741580(v=VS.85).aspx">WSAGetLastError()</code></a> |
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returning <code>WSA_IO_PENDING</code>. |
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When <code>ReadFile()</code> operates asynchronously the |
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the user-supplied <a |
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href="http://msdn.microsoft.com/en-us/library/ms741665(v=VS.85).aspx"><code>OVERLAPPED*</code></a> |
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is a handle to the incomplete operation. |
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|
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<pre> |
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typedef struct { |
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unsigned long* Internal; |
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unsigned long* InternalHigh; |
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union { |
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struct { |
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WORD Offset; |
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WORD OffsetHigh; |
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}; |
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void* Pointer; |
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}; |
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HANDLE hEvent; |
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} OVERLAPPED; |
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</pre> |
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|
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To poll on the completion of one of these functions, |
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use an IOCP, <code>overlapped->hEvent</code>, and |
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<a |
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href="http://msdn.microsoft.com/en-us/library/aa364986(v=vs.85).aspx"><code>GetQueuedCompletionStatus()</code></a>. |
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|
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<h3>Simple TCP Connection Example</h3> |
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|
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<p>To demonstrate the use of <code>GetQueuedCompletionStatus()</code> an |
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example of connecting to <code>localhost</code> at port 8000 is presented. |
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|
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<pre> |
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char* buffer[200]; |
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WSABUF b = { buffer, 200 }; |
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size_t bytes_recvd; |
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int r, total_events; |
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OVERLAPPED overlapped; |
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HANDLE port; |
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|
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port = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, NULL, 0); |
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if (!port) { |
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goto error; |
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} |
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|
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|
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r = WSARecv(socket, &b, 1, &bytes_recvd, NULL, &overlapped, NULL); |
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|
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CreateIoCompletionPort(port, &overlapped.hEvent, |
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|
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if (r == 0) { |
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if (WSAGetLastError() == WSA_IO_PENDING) { |
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/* Asynchronous */ |
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GetQueuedCompletionStatus() |
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|
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|
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if (r == WAIT_TIMEOUT) { |
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printf("Timeout\n"); |
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} else { |
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|
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} |
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|
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|
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} else { |
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/* Error */ |
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printf("Error %d\n", WSAGetLastError()); |
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} |
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} else { |
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/* Synchronous */ |
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printf("read %ld bytes from socket\n", bytes_recvd); |
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} |
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|
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|
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|
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</pre> |
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|
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<h3>Previous Work</h3> |
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|
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<p> Writing code that can take advantage of the best worlds on across Unix operating |
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systems and Windows is very difficult, requiring one to understand intricate |
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APIs and undocumented details from many different operating systems. There |
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are several projects which have made attempts to provide an abstraction |
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layer but in the author's opinion, none are completely satisfactory. |
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|
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<p><b>Marc Lehmann's |
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<a href="http://software.schmorp.de/pkg/libev.html">libev</a> and |
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<a href="http://software.schmorp.de/pkg/libeio.html">libeio</a>.</b> |
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libev is the perfect minimal abstraction of the Unix I/O multiplexers. It |
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includes several helpful tools like <code>ev_async</code>, which is for |
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asynchronous notification, but the main piece is the <code>ev_io</code>, |
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which informs the user about the state of file descriptors. As mentioned |
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before, in general it is not possible to get state changes for regular |
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files—and even if it were the <code>write(2)</code> and |
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<code>read(2)</code> calls do not guarantee that they won't block. |
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Therefore libeio is provided for calling various disk-related |
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syscalls in a managed thread pool. Unfortunately the abstraction layer |
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which libev targets is not appropriate for IOCPs—libev works strictly |
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with file descriptors and does not the concept of a <i>socket</i>. |
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Furthermore users on Unix will be using libeio for file I/O which is not |
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ideal for porting to Windows. On windows libev currently uses |
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<code>select()</code>—which is limited to 64 file descriptors per |
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thread. |
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|
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<p><b><a href="http://monkey.org/~provos/libevent/">libevent</a>.</b> |
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Somewhat bulkier than libev with code for RPC, DNS, and HTTP included. |
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Does not support file I/O. |
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libev was |
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created after Lehmann <a |
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href="http://www.mail-archive.com/libevent-users@monkey.org/msg00753.html">evaluated |
|||
libevent and rejected it</a>—it's interesting to read his reasons |
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why. <a |
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href="http://google-opensource.blogspot.com/2010/01/libevent-20x-like-libevent-14x-only.html">A |
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major rewrite</a> was done for version 2 to support Windows IOCPs but <a |
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href="http://www.mail-archive.com/libevent-users@monkey.org/msg01730.html">anecdotal |
|||
evidence</a> suggests that it is still not working correctly. |
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|
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<p><b><a |
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href="http://www.boost.org/doc/libs/1_43_0/doc/html/boost_asio.html">Boost |
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ASIO</a>.</b> It basically does what you want on Windows and Unix for |
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sockets. That is, epoll on Linux, kqueue on Macintosh, IOCPs on Windows. |
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It does not support file I/O. In the author's opinion is it too large |
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for a not extremely difficult problem (~300 files, ~12000 semicolons). |
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|
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|
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|
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<h2>File Types</h2> |
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<p> |
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Almost every socket operation that you're familiar with has an |
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overlapped counter-part. The following section tries to pair Windows |
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overlapped I/O syscalls with non-blocking Unix ones. |
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|
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|
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<h3>TCP Sockets</h3> |
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|
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TCP Sockets are by far the most important stream to get right. |
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Servers should expect to be handling tens of thousands of these |
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per thread, concurrently. This is possible with overlapped I/O in Windows if |
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one is careful to avoid Unix-ism like file descriptors. (Windows has a |
|||
hard limit of 2048 open file descriptors—see |
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<a |
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href="http://msdn.microsoft.com/en-us/library/6e3b887c.aspx"><code>_setmaxstdio()</code></a>.) |
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|
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|
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<dl> |
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|
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<dt><code>send(2)</code>, <code>write(2)</code></dt> |
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<dd>Windows: |
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<a href="http://msdn.microsoft.com/en-us/library/ms742203(v=vs.85).aspx"><code>WSASend()</code></a>, |
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<a href="http://msdn.microsoft.com/en-us/library/aa365748(v=VS.85).aspx"><code>WriteFileEx()</code></a> |
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</dd> |
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|
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|
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<dt><code>recv(2)</code>, <code>read(2)</code></dt> |
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<dd> |
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Windows: |
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<a href="http://msdn.microsoft.com/en-us/library/ms741688(v=VS.85).aspx"><code>WSARecv()</code></a>, |
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<a href="http://msdn.microsoft.com/en-us/library/aa365468(v=VS.85).aspx"><code>ReadFileEx()</code></a> |
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</dd> |
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|
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|
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<dt><code>connect(2)</code></dt> |
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<dd> |
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Windows: <a href="http://msdn.microsoft.com/en-us/library/ms737606(VS.85).aspx"><code>ConnectEx()</code></a> |
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|
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<p> |
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Non-blocking <code>connect()</code> is has difficult semantics in |
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Unix. The proper way to connect to a remote host is this: call |
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<code>connect(2)</code> while it returns |
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<code>EINPROGRESS</code> poll on the file descriptor for writablity. |
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Then use |
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<pre>int error; |
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socklen_t len = sizeof(int); |
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getsockopt(fd, SOL_SOCKET, SO_ERROR, &error, &len);</pre> |
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A zero <code>error</code> indicates that the connection succeeded. |
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(Documented in <code>connect(2)</code> under <code>EINPROGRESS</code> |
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on the Linux man page.) |
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</dd> |
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|
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|
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<dt><code>accept(2)</code></dt> |
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<dd> |
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Windows: <a href="http://msdn.microsoft.com/en-us/library/ms737524(v=VS.85).aspx"><code>AcceptEx()</code></a> |
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</dd> |
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|
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|
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<dt><code>sendfile(2)</code></dt> |
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<dd> |
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Windows: <a href="http://msdn.microsoft.com/en-us/library/ms740565(v=VS.85).aspx"><code>TransmitFile()</code></a> |
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|
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<p> The exact API of <code>sendfile(2)</code> on Unix has not been agreed |
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on yet. Each operating system does it slightly different. All |
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<code>sendfile(2)</code> implementations (except possibly FreeBSD?) are blocking |
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even on non-blocking sockets. |
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<ul> |
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<li><a href="http://www.kernel.org/doc/man-pages/online/pages/man2/sendfile.2.html">Linux <code>sendfile(2)</code></a> |
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<li><a href="http://www.freebsd.org/cgi/man.cgi?query=sendfile&sektion=2">FreeBSD <code>sendfile(2)</code></a> |
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<li><a href="http://www.manpagez.com/man/2/sendfile/">Darwin <code>sendfile(2)</code></a> |
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</ul> |
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Marc Lehmann has written <a |
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href="https://github.com/joyent/node/blob/2c185a9dfd3be8e718858b946333c433c375c295/deps/libeio/eio.c#L954-1080">a |
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portable version in libeio</a>. |
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</dd> |
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|
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<dt><code>shutdown(2)</code>, graceful close, half-duplex connections</dt> |
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<dd> |
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<a |
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href="http://msdn.microsoft.com/en-us/library/ms738547(v=VS.85).aspx">Graceful |
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Shutdown, Linger Options, and Socket Closure</a> |
|||
<br/> |
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<a |
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href="http://msdn.microsoft.com/en-us/library/ms737757(VS.85).aspx"><code>DisconnectEx()</code></a> |
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|
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</dd> |
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|
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<dt><code>close(2)</code></dt> |
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<dd> |
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<a href="http://msdn.microsoft.com/en-us/library/ms737582(v=VS.85).aspx"><code>closesocket()</code></a> |
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</dd> |
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|
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|
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The following are nearly same in Windows overlapped and Unix |
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non-blocking sockets. The only difference is that the Unix variants |
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take integer file descriptors while Windows uses <code>SOCKET</code>. |
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<ul> |
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<li><a href="http://msdn.microsoft.com/en-us/library/ms740496(v=VS.85).aspx"><code>sockaddr</code></a> |
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<li><a href="http://msdn.microsoft.com/en-us/library/ms737550(v=VS.85).aspx"><code>bind()</code></a> |
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<li><a href="http://msdn.microsoft.com/en-us/library/ms738543(v=VS.85).aspx"><code>getsockname()</code></a> |
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</ul> |
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|
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<h3>Named Pipes</h3> |
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|
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Windows has "named pipes" which are more or less the same as <a |
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href="http://www.kernel.org/doc/man-pages/online/pages/man7/unix.7.html"><code>AF_Unix</code> |
|||
domain sockets</a>. <code>AF_Unix</code> sockets exist in the file system |
|||
often looking like |
|||
<pre>/tmp/<i>pipename</i></pre> |
|||
|
|||
Windows named pipes have a path, but they are not directly part of the file |
|||
system; instead they look like |
|||
|
|||
<pre>\\.\pipe\<i>pipename</i></pre> |
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|
|||
|
|||
<dl> |
|||
<dt><code>socket(AF_Unix, SOCK_STREAM, 0), bind(2), listen(2)</code></dt> |
|||
<dd> |
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<a href="http://msdn.microsoft.com/en-us/library/aa365150(VS.85).aspx"><code>CreateNamedPipe()</code></a> |
|||
|
|||
<p>Use <code>FILE_FLAG_OVERLAPPED</code>, <code>PIPE_TYPE_BYTE</code>, |
|||
<code>PIPE_NOWAIT</code>. |
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</dd> |
|||
|
|||
|
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<dt><code>send(2)</code>, <code>write(2)</code></dt> |
|||
<dd> |
|||
<a href="http://msdn.microsoft.com/en-us/library/aa365748(v=VS.85).aspx"><code>WriteFileEx()</code></a> |
|||
</dd> |
|||
|
|||
|
|||
<dt><code>recv(2)</code>, <code>read(2)</code></dt> |
|||
<dd> |
|||
<a href="http://msdn.microsoft.com/en-us/library/aa365468(v=VS.85).aspx"><code>ReadFileEx()</code></a> |
|||
</dd> |
|||
|
|||
<dt><code>connect(2)</code></dt> |
|||
<dd> |
|||
<a href="http://msdn.microsoft.com/en-us/library/aa365150(VS.85).aspx"><code>CreateNamedPipe()</code></a> |
|||
</dd> |
|||
|
|||
|
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<dt><code>accept(2)</code></dt> |
|||
<dd> |
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<a href="http://msdn.microsoft.com/en-us/library/aa365146(v=VS.85).aspx"><code>ConnectNamedPipe()</code></a> |
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</dd> |
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|
|||
|
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</dl> |
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|
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Examples: |
|||
<ul> |
|||
<li><a |
|||
href="http://msdn.microsoft.com/en-us/library/aa365601(v=VS.85).aspx">Named |
|||
Pipe Server Using Completion Routines</a> |
|||
<li><a |
|||
href="http://msdn.microsoft.com/en-us/library/aa365603(v=VS.85).aspx">Named |
|||
Pipe Server Using Overlapped I/O</a> |
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</ul> |
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|
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|
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<h3>Regular Files</h3> |
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|
|||
<p> |
|||
In Unix file system files are not able to use non-blocking I/O. There are |
|||
some operating systems that have asynchronous I/O but it is not standard and |
|||
at least on Linux is done with pthreads in GNU libc. For this reason |
|||
applications designed to be portable across different Unixes must manage a |
|||
thread pool for issuing file I/O syscalls. |
|||
|
|||
<p> |
|||
The situation is better in Windows: true overlapped I/O is available when |
|||
reading or writing a stream of data to a file. |
|||
|
|||
<dl> |
|||
|
|||
<dt><code>write(2)</code></dt> |
|||
<dd> Windows: |
|||
<a href="http://msdn.microsoft.com/en-us/library/aa365748(v=VS.85).aspx"><code>WriteFileEx()</code></a> |
|||
|
|||
<p>Solaris's event completion ports has true in-kernel async writes with <a |
|||
href="http://download.oracle.com/docs/cd/E19253-01/816-5171/aio-write-3rt/index.html">aio_write(3RT)</a> |
|||
</dd> |
|||
|
|||
<dt><code>read(2)</code></dt> |
|||
<dd> Windows: |
|||
<a href="http://msdn.microsoft.com/en-us/library/aa365468(v=VS.85).aspx"><code>ReadFileEx()</code></a> |
|||
|
|||
<p>Solaris's event completion ports has true in-kernel async reads with <a |
|||
href="http://download.oracle.com/docs/cd/E19253-01/816-5171/aio-read-3rt/index.html">aio_read(3RT)</a> |
|||
</dd> |
|||
|
|||
</dl> |
|||
|
|||
<h3>Console/TTY</h3> |
|||
|
|||
<p>It is (usually?) possible to poll a Unix TTY file descriptor for |
|||
readability or writablity just like a TCP socket—this is very helpful |
|||
and nice. In Windows the situation is worse, not only is it a completely |
|||
different API but there are not overlapped versions to read and write to the |
|||
TTY. Polling for readability can be accomplished by waiting in another |
|||
thread with <a |
|||
href="http://msdn.microsoft.com/en-us/library/ms685061(VS.85).aspx"><code>RegisterWaitForSingleObject()</code></a>. |
|||
|
|||
<dl> |
|||
|
|||
<dt><code>read(2)</code></dt> |
|||
<dd> |
|||
<a |
|||
href="http://msdn.microsoft.com/en-us/library/ms684958(v=VS.85).aspx"><code>ReadConsole()</code></a> |
|||
and |
|||
<a |
|||
href="http://msdn.microsoft.com/en-us/library/ms684961(v=VS.85).aspx"><code>ReadConsoleInput()</code></a> |
|||
do not support overlapped I/O and there are no overlapped |
|||
counter-parts. One strategy to get around this is |
|||
<pre><a href="http://msdn.microsoft.com/en-us/library/ms685061(VS.85).aspx">RegisterWaitForSingleObject</a>(&tty_wait_handle, tty_handle, |
|||
tty_want_poll, NULL, INFINITE, WT_EXECUTEINWAITTHREAD | |
|||
WT_EXECUTEONLYONCE)</pre> |
|||
which will execute <code>tty_want_poll()</code> in a different thread. |
|||
You can use this to notify the calling thread that |
|||
<code>ReadConsoleInput()</code> will not block. |
|||
</dd> |
|||
|
|||
|
|||
<dt><code>write(2)</code></dt> |
|||
<dd> |
|||
<a href="http://msdn.microsoft.com/en-us/library/ms687401(v=VS.85).aspx"><code>WriteConsole()</code></a> |
|||
is also blocking but this is probably acceptable. |
|||
</dd> |
|||
|
|||
|
|||
<dt><a |
|||
href="http://www.kernel.org/doc/man-pages/online/pages/man3/tcsetattr.3.html"><code>tcsetattr(3)</code></a></dt> |
|||
<dd> |
|||
<a href="http://msdn.microsoft.com/en-us/library/ms686033(VS.85).aspx"><code>SetConsoleMode()</code></a> |
|||
</dd> |
|||
|
|||
|
|||
</dl> |
|||
|
|||
|
|||
|
|||
<h2>Assorted Links</h2> |
|||
<p> |
|||
tips |
|||
<ul> |
|||
<li> overlapped = non-blocking. |
|||
<li> There is no overlapped <a href="http://msdn.microsoft.com/en-us/library/ms738518(VS.85).aspx"><code>GetAddrInfoEx()</code></a> function. It seems Asynchronous Procedure Calls must be used instead. |
|||
<li> <a href=http://msdn.microsoft.com/en-us/library/ms740673(VS.85).aspx"><code>Windows Sockets 2</code></a> |
|||
</ul> |
|||
|
|||
<p> |
|||
IOCP: |
|||
<ul> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms686358(v=vs.85).aspx">Synchronization and Overlapped Input and Output</a> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms741665(v=VS.85).aspx"><code>OVERLAPPED</code> Structure</a> |
|||
<ul> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms683209(v=VS.85).aspx"><code>GetOverlappedResult()</code></a> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms683244(v=VS.85).aspx"><code>HasOverlappedIoCompleted()</code></a> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/aa363792(v=vs.85).aspx"><code>CancelIoEx()</code></a> |
|||
— cancels an overlapped operation. |
|||
</ul> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms742203(v=vs.85).aspx"><code>WSASend()</code></a> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms741688(v=VS.85).aspx"><code>WSARecv()</code></a> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms737606(VS.85).aspx"><code>ConnectEx()</code></a> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms740565(v=VS.85).aspx"><code>TransmitFile()</code></a> |
|||
— an async <code>sendfile()</code> for windows. |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms741565(v=VS.85).aspx"><code>WSADuplicateSocket()</code></a> |
|||
— describes how to share a socket between two processes. |
|||
<li id="setmaxstdio"><a href="http://msdn.microsoft.com/en-us/library/6e3b887c.aspx"><code>_setmaxstdio()</code></a> |
|||
— something like setting the maximum number of file decriptors |
|||
and <a |
|||
href="http://www.kernel.org/doc/man-pages/online/pages/man2/setrlimit.2.html"><code>setrlimit(3)</code></a> |
|||
AKA <code>ulimit -n</code>. Note the file descriptor limit on windows is |
|||
2048. |
|||
</ul> |
|||
|
|||
<p> |
|||
APC: |
|||
<ul> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms681951(v=vs.85).aspx">Asynchronous Procedure Calls</a> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/ms682016"><code>DNSQuery()</code></a> |
|||
— General purpose DNS query function like <code>res_query()</code> on Unix. |
|||
</ul> |
|||
|
|||
|
|||
Pipes: |
|||
<ul> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/aa365781(v=VS.85).aspx"><code>Pipe functions</code></a> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/aa365150(VS.85).aspx"><code>CreateNamedPipe</code></a> |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/aa365144(v=VS.85).aspx"><code>CallNamedPipe</code></a> |
|||
— like <code>accept</code> is for Unix pipes. |
|||
<li><a href="http://msdn.microsoft.com/en-us/library/aa365146(v=VS.85).aspx"><code>ConnectNamedPipe</code></a> |
|||
</ul> |
|||
|
|||
<code>WaitForMultipleObjectsEx</code> is pronounced "wait for multiple object sex". |
|||
|
|||
Also useful: |
|||
<a |
|||
href="http://msdn.microsoft.com/en-us/library/xw1ew2f8(v=vs.80).aspx">Introduction |
|||
to Visual C++ for Unix Users</a> |
|||
|
|||
<br><br> |
|||
<a |
|||
href="http://ebookbrowse.com/network-programming-for-microsoft-windows-2nd-edition-2002-pdf-d73663829">Network |
|||
Programming For Microsoft Windows 2nd Edition 2002</a>. Juicy details on |
|||
page 119. |
|||
|
|||
</body></html> |
@ -1,141 +0,0 @@ |
|||
/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
|
|||
* |
|||
* Permission is hereby granted, free of charge, to any person obtaining a copy |
|||
* of this software and associated documentation files (the "Software"), to |
|||
* deal in the Software without restriction, including without limitation the |
|||
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or |
|||
* sell copies of the Software, and to permit persons to whom the Software is |
|||
* furnished to do so, subject to the following conditions: |
|||
* |
|||
* The above copyright notice and this permission notice shall be included in |
|||
* all copies or substantial portions of the Software. |
|||
* |
|||
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
|||
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
|||
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
|||
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
|||
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
|||
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
|||
* IN THE SOFTWARE. |
|||
*/ |
|||
|
|||
#include "uv.h" |
|||
#include "task.h" |
|||
|
|||
#include <stdio.h> |
|||
#include <stdlib.h> |
|||
#include <string.h> |
|||
|
|||
#define CHECK_HANDLE(handle) \ |
|||
ASSERT((uv_udp_t*)(handle) == &server1 \ |
|||
|| (uv_udp_t*)(handle) == &server2 \ |
|||
|| (uv_udp_t*)(handle) == &client) |
|||
|
|||
#define CHECK_REQ(req) \ |
|||
ASSERT((req) == &req_); |
|||
|
|||
static uv_udp_t client; |
|||
static uv_udp_t server1; |
|||
static uv_udp_t server2; |
|||
static uv_udp_send_t req_; |
|||
|
|||
static int send_cb_called; |
|||
static int recv_cb_called; |
|||
static int close_cb_called; |
|||
|
|||
|
|||
static uv_buf_t alloc_cb(uv_handle_t* handle, size_t suggested_size) { |
|||
static char slab[65536]; |
|||
CHECK_HANDLE(handle); |
|||
return uv_buf_init(slab, sizeof slab); |
|||
} |
|||
|
|||
|
|||
static void close_cb(uv_handle_t* handle) { |
|||
CHECK_HANDLE(handle); |
|||
close_cb_called++; |
|||
} |
|||
|
|||
|
|||
static void send_cb(uv_udp_send_t* req, int status) { |
|||
CHECK_REQ(req); |
|||
CHECK_HANDLE(req->handle); |
|||
ASSERT(status == 0); |
|||
send_cb_called++; |
|||
} |
|||
|
|||
static void ipv4_recv_cb(uv_udp_t* handle, |
|||
ssize_t nread, |
|||
uv_buf_t buf, |
|||
struct sockaddr* addr, |
|||
unsigned flags) { |
|||
CHECK_HANDLE(handle); |
|||
ASSERT(nread >= 0); |
|||
|
|||
uv_close((uv_handle_t*)&server1, close_cb); |
|||
uv_close((uv_handle_t*)&server2, close_cb); |
|||
uv_close((uv_handle_t*)&client, close_cb); |
|||
|
|||
recv_cb_called++; |
|||
} |
|||
|
|||
|
|||
static void ipv6_recv_cb(uv_udp_t* handle, |
|||
ssize_t nread, |
|||
uv_buf_t buf, |
|||
struct sockaddr* addr, |
|||
unsigned flags) { |
|||
ASSERT(0 && "this function should not have been called"); |
|||
} |
|||
|
|||
|
|||
TEST_IMPL(udp_ipv6_only) { |
|||
struct sockaddr_in6 addr6; |
|||
struct sockaddr_in addr; |
|||
uv_buf_t buf; |
|||
int r; |
|||
|
|||
uv_init(); |
|||
|
|||
addr = uv_ip4_addr("127.0.0.1", TEST_PORT); |
|||
addr6 = uv_ip6_addr(":::0", TEST_PORT); |
|||
|
|||
r = uv_udp_init(&server1); |
|||
ASSERT(r == 0); |
|||
|
|||
r = uv_udp_bind(&server1, addr, 0); |
|||
ASSERT(r == 0); |
|||
|
|||
r = uv_udp_recv_start(&server1, alloc_cb, ipv4_recv_cb); |
|||
ASSERT(r == 0); |
|||
|
|||
r = uv_udp_init(&server2); |
|||
ASSERT(r == 0); |
|||
|
|||
r = uv_udp_bind6(&server2, addr6, UV_UDP_IPV6ONLY); |
|||
ASSERT(r == 0); |
|||
|
|||
r = uv_udp_recv_start(&server2, alloc_cb, ipv6_recv_cb); |
|||
ASSERT(r == 0); |
|||
|
|||
r = uv_udp_init(&client); |
|||
ASSERT(r == 0); |
|||
|
|||
buf = uv_buf_init("PING", 4); |
|||
|
|||
/* This should fail but still call send_cb(). */ |
|||
r = uv_udp_send(&req_, &client, &buf, 1, addr, send_cb); |
|||
ASSERT(r == 0); |
|||
|
|||
ASSERT(close_cb_called == 0); |
|||
ASSERT(send_cb_called == 0); |
|||
ASSERT(recv_cb_called == 0); |
|||
|
|||
uv_run(); |
|||
|
|||
ASSERT(recv_cb_called == 1); |
|||
ASSERT(send_cb_called == 1); |
|||
ASSERT(close_cb_called == 3); |
|||
|
|||
return 0; |
|||
} |
Loading…
Reference in new issue