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iocp-links: Simplify function example

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This commit is contained in:
Ryan Dahl 2011-03-29 17:13:19 -07:00
parent 311fbe3f8f
commit 0dbaa019d1
1 changed files with 14 additions and 52 deletions
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iocp-links.html
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@ -24,12 +24,12 @@
table th {
text-align: left;
padding: 0.5em;
padding: 0.2em;
white-space: nowrap;
}
table td {
padding: 0.5em;
padding: 0.2em;
text-align: left;
white-space: nowrap;
}
@ -120,70 +120,28 @@ Common practice for accessing the disk asynchronously is still done using custom
userland thread pools—not POSIX AIO.
<p>Windows IOCPs does support both sockets and regular file I/O which
greatly simplifies the handling of disks. Although the function names are
not exactly the same in Windows for sockets and regular files, the
they act similar.
<table>
<tr>
<th></th>
<th>Regular File Read</th>
<th>Regular File Write</th>
<th>Socket Read</th>
<th>Socket Write</th>
</tr>
<tr>
<th>Windows</th>
<td><code>ReadFile()</code></td>
<td><code>WriteFile()</code></td>
<td><code>WSARecv()</code></td>
<td><code>WSASend()</code></td>
</tr>
<tr>
<th>POSIX</th>
<td><code>read()</code></td>
<td><code>write()</code></td>
<td><code>read()</code> or <code>recv()</code></td>
<td><code>write()</code> or <code>send()</code></td>
</tr>
</table>
<p><code>ReadFile()</code> and <code>WSARecv()</code> operate on regular
files and sockets, respectively. They both are for sending data. Both take a
<a href="http://msdn.microsoft.com/en-us/library/ms741665(v=VS.85).aspx"><code>OVERLAPPED</code></a>
argument.
greatly simplifies the handling of disks. For example,
<a href="http://msdn.microsoft.com/en-us/library/aa365468(v=VS.85).aspx"><code>ReadFileEx()</code></a>
operates on both.
As a first example let's look at how <code>ReadFile()</code> works.
<pre>
typedef void* HANDLE;
typedef HANDLE SOCKET;
BOOL ReadFile(HANDLE file,
void* buffer,
DWORD numberOfBytesToRead,
DWORD* numberOfBytesRead,
OVERLAPPED* overlapped);
int WSARecv(SOCKET s,
WSABUF* buffers,
DWORD bufferCount,
DWORD* numberOfBytesRecvd,
DWORD* flags,
OVERLAPPED* overlapped,
OVERLAPPED_COMPLETION_ROUTINE completionRoutine);
</pre>
For now ignore the <code>completionRoutine</code> parameter in
<code>WSARecv</code>.
<p>
Both functions have the possibility of executing the read synchronously
The function has the possibility of executing the read synchronously
or asynchronously. A synchronous operation is indicated by
returning 0 and <a
href="http://msdn.microsoft.com/en-us/library/ms741580(v=VS.85).aspx">WSAGetLastError()</code></a>
returning <code>WSA_IO_PENDING</code>.
<p>
When either function operates asynchronously the
When <code>ReadFile()</code> operates asynchronously the
the user-supplied <a
href="http://msdn.microsoft.com/en-us/library/ms741665(v=VS.85).aspx"><code>OVERLAPPED*</code></a>
is a handle to the incomplete operation.
@ -327,13 +285,17 @@ hard limit of 2048 open file descriptors&mdash;see
<dl>
<dt><code>send(2)</code>, <code>write(2)</code></dt>
<dd>Windows: <a href="http://msdn.microsoft.com/en-us/library/ms742203(v=vs.85).aspx"><code>WSASend()</code></a>
<dd>Windows:
<a href="http://msdn.microsoft.com/en-us/library/ms742203(v=vs.85).aspx"><code>WSASend()</code></a>,
<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>
Windows: <a href="http://msdn.microsoft.com/en-us/library/ms741688(v=VS.85).aspx"><code>WSARecv()</code></a>
Windows:
<a href="http://msdn.microsoft.com/en-us/library/ms741688(v=VS.85).aspx"><code>WSARecv()</code></a>,
<a href="http://msdn.microsoft.com/en-us/library/aa365468(v=VS.85).aspx"><code>ReadFileEx()</code></a>
</dd>