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Changed the sockets example so that it uses scoped_ptr to

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contain the connection object.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402469
This commit is contained in:
Davis King 2008-08-13 01:39:13 +00:00
parent 3c8e14c221
commit 7218589f0a
1 changed files with 31 additions and 15 deletions
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46
examples/sockets_ex_2.cpp
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@ -24,22 +24,24 @@ int main()
try
{
// Connect to Google's web server which listens on port 80. If this
// fails it will throw a dlib::socket_error exception.
connection* con = connect("www.google.com",80);
// fails it will throw a dlib::socket_error exception. Note that we
// are using a smart pointer here to contain the connection pointer
// returned from connect. Doing this ensures that the connection
// is deleted even if someone throws an exception somewhere in your code.
scoped_ptr<connection> con(connect("www.google.com",80));
{
// create a stream buffer for our connection
// Create a stream buffer for our connection
sockstreambuf::kernel_2a buf(con);
// now stick that stream buffer into an iostream object
// Now stick that stream buffer into an iostream object
iostream stream(&buf);
// this command causes the iostream to flush its output buffers
// This command causes the iostream to flush its output buffers
// whenever someone makes a read request.
stream.tie(&stream);
// now we make the HTTP GET request for the main Google page.
stream << "GET / HTTP/1.0\r\n"
<< "\r\n";
// Now we make the HTTP GET request for the main Google page.
stream << "GET / HTTP/1.0\r\n\r\n";
// Here we print each character we get back one at a time.
int ch = stream.get();
@ -49,17 +51,31 @@ int main()
ch = stream.get();
}
// at the end of this scope buf will be destructed and flush
// At the end of this scope buf will be destructed and flush
// anything it still contains to the connection. Thus putting
// this scope here makes it safe to call close_gracefully() next.
// If we just called close_gracefully() before buf was destructed
// then buf would try to flush its data to a closed connection
// this } here makes it safe to destroy the connection later on.
// If we just destroyed the connection before buf was destructed
// then buf might try to flush its data to a closed connection
// which would be an error.
}
// Don't forget to close the connection. Not doing so will
// cause a resource leak. And once it is closed the con pointer
// is invalid so don't touch it.
// Here we call close_gracefully(). It takes a connection and performs
// a proper TCP shutdown by sending a FIN packet to the other end of the
// connection and waiting half a second for the other end to close the
// connection as well. If half a second goes by without the other end
// responding then the connection is forcefully shutdown and deleted.
//
// You usually want to perform a graceful shutdown of your TCP connections
// because there might be some data you tried to send that is still buffered
// in the operating system's output buffers. If you just killed the
// connection it might not be sent to the other side (although maybe
// you don't care, and in the case of this example it doesn't really matter.
// But I'm only putting this here for the purpose of illustration :-).
// In any case, this function is provided to allow you to perform a graceful
// close if you so choose.
//
// Also note that the timeout can be changed by suppling an optional second
// argument to this function.
close_gracefully(con);
}
catch (exception& e)