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Major overhaul of timeout sockets:

Browse source 
- setblocking(0) and settimeout(0) are now equivalent, and ditto for
  setblocking(1) and settimeout(None).

- Don't raise an exception from internal_select(); let the final call
  report the error (this means you will get an EAGAIN error instead of
  an ETIMEDOUT error -- I don't care).

- Move the select to inside the Py_{BEGIN,END}_ALLOW_THREADS brackets,
  so other theads can run (this was a bug in the original code).

- Redid the retry logic in connect() and connect_ex() to avoid masking
  errors.  This probably doesn't work for Windows yet; I'll fix that
  next.  It may also fail on other platforms, depending on what
  retrying a connect does; I need help with this.

- Get rid of the retry logic in accept().  I don't think it was needed
  at all.  But I may be wrong.
This commit is contained in:
Guido van Rossum 2002-06-13 15:07:44 +00:00
parent dfad1a9039
commit 11ba094957
5 changed files with 89 additions and 247 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

43
Doc/lib/libsocket.tex
View file

@ -72,8 +72,9 @@ argument types and out-of-memory conditions can be raised; errors
related to socket or address semantics raise the error
\exception{socket.error}.
Non-blocking mode is supported through the
\method{setblocking()} method.
Non-blocking mode is supported through
\method{setblocking()}. A generalization of this based on timeouts
is supported through \method{settimeout()}.
The module \module{socket} exports the following constants and functions:
@ -284,8 +285,7 @@ checked --- subsequent operations on the object may fail if the file
descriptor is invalid. This function is rarely needed, but can be
used to get or set socket options on a socket passed to a program as
standard input or output (such as a server started by the \UNIX{} inet
daemon). The socket is assumed to be in blocking mode without
a timeout.
daemon). The socket is assumed to be in blocking mode.
Availability: \UNIX.
\end{funcdesc}
@ -514,38 +514,39 @@ all sockets are in blocking mode. In non-blocking mode, if a
\method{send()} call can't immediately dispose of the data, a
\exception{error} exception is raised; in blocking mode, the calls
block until they can proceed.
\code{s.setblocking(0)} is equivalent to \code{s.settimeout(0)};
\code{s.setblocking(1)} is equivalent to \code{s.settimeout(None)}.
\end{methoddesc}
\begin{methoddesc}[socket]{settimeout}{value}
Set a timeout on blocking socket operations. Value can be a
nonnegative float expressing seconds, or \code{None}. If a float is
Set a timeout on blocking socket operations. The \var{value} argument
can be a nonnegative float expressing seconds, or \code{None}.
If a float is
given, subsequent socket operations will raise an \exception{error}
exception if the timeout period \var{value} has elapsed before the
operation has completed. Setting a timeout of \code{None} disables
timeouts on socket operations.
\code{s.settimeout(0.0)} is equivalent to \code{s.blocking(0)};
\code{s.settimeout(None)} is equivalent to \code{s.setblocking(1)}.
\versionadded{2.3}
\end{methoddesc}
\begin{methoddesc}[socket]{gettimeout}{}
Returns the timeout in floating seconds associated with socket
operations, or \code{None} if no timeout is set.
operations, or \code{None} if no timeout is set. This reflects
the last call to \method{setblocking()} or \method{settimeout()}.
\versionadded{2.3}
\end{methoddesc}
Some notes on the interaction between socket blocking and timeouts: A
socket object can be in one of three modes: blocking, non-blocking, or
timout. Sockets are always created in blocking mode. In blocking
mode, operations block until complete. In non-blocking mode,
operations fail (with an error that is unfortunately system-dependent)
if they cannot be completed immediately. In timeout mode, operations
fail if they cannot be completed within the timeout specified for the
socket.
Calling \method{settimeout()} cancels non-blocking mode as set by
\method{setblocking()}; calling \method{setblocking()} cancels a
previously set timeout. Setting the timeout to zero acts similarly
but is implemented different than setting the socket in non-blocking
mode (this could be considered a bug and may even be fixed).
Some notes on socket blocking and timeouts: A socket object can be in
one of three modes: blocking, non-blocking, or timout. Sockets are
always created in blocking mode. In blocking mode, operations block
until complete. In non-blocking mode, operations fail (with an error
that is unfortunately system-dependent) if they cannot be completed
immediately. In timeout mode, operations fail if they cannot be
completed within the timeout specified for the socket. The
\method{setblocking()} method is simply a shorthand for certain
\method{settimeout()} calls.
Timeout mode internally sets the socket in non-blocking mode. The
blocking and timeout modes are shared between file descriptors and

5
Lib/test/test_socket.py
View file

@ -51,7 +51,10 @@ def _setUp(self):
self.queue = Queue.Queue(1)
# Do some munging to start the client test.
test_method = getattr(self, '_' + self._TestCase__testMethodName)
methodname = self.id()
i = methodname.rfind('.')
methodname = methodname[i+1:]
test_method = getattr(self, '_' + methodname)
self.client_thread = thread.start_new_thread(
self.clientRun, (test_method,))

6
Lib/test/test_timeout.py
View file

@ -59,17 +59,17 @@ def testRangeCheck(self):
self.assertRaises(ValueError, self.sock.settimeout, -1L)
self.assertRaises(ValueError, self.sock.settimeout, -1.0)
def testTimeoutThenoBlocking(self):
def testTimeoutThenBlocking(self):
"Test settimeout() followed by setblocking()"
self.sock.settimeout(10)
self.sock.setblocking(1)
self.assertEqual(self.sock.gettimeout(), None)
self.sock.setblocking(0)
self.assertEqual(self.sock.gettimeout(), None)
self.assertEqual(self.sock.gettimeout(), 0.0)
self.sock.settimeout(10)
self.sock.setblocking(0)
self.assertEqual(self.sock.gettimeout(), None)
self.assertEqual(self.sock.gettimeout(), 0.0)
self.sock.setblocking(1)
self.assertEqual(self.sock.gettimeout(), None)

277
Modules/socketmodule.c
View file

@ -446,26 +446,6 @@ set_gaierror(int error)
return NULL;
}
/* For timeout errors */
static PyObject *
timeout_err(void)
{
PyObject *v;
#ifdef MS_WINDOWS
v = Py_BuildValue("(is)", WSAETIMEDOUT, "Socket operation timed out");
#else
v = Py_BuildValue("(is)", ETIMEDOUT, "Socket operation timed out");
#endif
if (v != NULL) {
PyErr_SetObject(socket_error, v);
Py_DECREF(v);
}
return NULL;
}
/* Function to perform the setting of socket blocking mode
internally. block = (1 | 0). */
static int
@ -508,16 +488,18 @@ internal_setblocking(PySocketSockObject *s, int block)
return 1;
}
/* For access to the select module to poll the socket for timeout
functionality. writing is 1 for writing, 0 for reading.
Return value: -1 if error, 0 if not ready, >= 1 if ready.
An exception is set when the return value is <= 0 (!). */
static int
/* Do a select() on the socket, if necessary (sock_timeout > 0).
The argument writing indicates the direction.
This does not raise an exception or return a success indicator;
we'll let the actual socket call do that. */
static void
internal_select(PySocketSockObject *s, int writing)
{
fd_set fds;
struct timeval tv;
int count;
if (s->sock_timeout <= 0.0)
return;
/* Construct the arguments to select */
tv.tv_sec = (int)s->sock_timeout;
@ -527,22 +509,9 @@ internal_select(PySocketSockObject *s, int writing)
/* See if the socket is ready */
if (writing)
count = select(s->sock_fd+1, NULL, &fds, NULL, &tv);
select(s->sock_fd+1, NULL, &fds, NULL, &tv);
else
count = select(s->sock_fd+1, &fds, NULL, NULL, &tv);
/* Check for errors */
if (count < 0) {
s->errorhandler();
return -1;
}
/* Set the error if the timeout has elapsed, i.e, we were not
polled. */
if (count == 0)
timeout_err();
return count;
select(s->sock_fd+1, &fds, NULL, NULL, &tv);
}
/* Initialize a new socket object. */
@ -558,7 +527,6 @@ init_sockobject(PySocketSockObject *s,
s->sock_family = family;
s->sock_type = type;
s->sock_proto = proto;
s->sock_blocking = 1; /* Start in blocking mode */
s->sock_timeout = -1.0; /* Start without timeout */
s->errorhandler = &set_error;
@ -997,45 +965,11 @@ sock_accept(PySocketSockObject *s)
return NULL;
memset(addrbuf, 0, addrlen);
errno = 0; /* Reset indicator for use with timeout behavior */
Py_BEGIN_ALLOW_THREADS
internal_select(s, 0);
newfd = accept(s->sock_fd, (struct sockaddr *) addrbuf, &addrlen);
Py_END_ALLOW_THREADS
if (s->sock_timeout >= 0.0) {
#ifdef MS_WINDOWS
if (newfd == INVALID_SOCKET)
if (!s->sock_blocking)
return s->errorhandler();
/* Check if we have a true failure
for a blocking socket */
if (errno != WSAEWOULDBLOCK)
return s->errorhandler();
#else
if (newfd < 0) {
if (!s->sock_blocking)
return s->errorhandler();
/* Check if we have a true failure
for a blocking socket */
if (errno != EAGAIN && errno != EWOULDBLOCK)
return s->errorhandler();
}
#endif
/* try waiting the timeout period */
if (internal_select(s, 0) <= 0)
return NULL;
Py_BEGIN_ALLOW_THREADS
newfd = accept(s->sock_fd,
(struct sockaddr *)addrbuf,
&addrlen);
Py_END_ALLOW_THREADS
}
/* At this point, we really have an error, whether using timeout
behavior or regular socket behavior */
#ifdef MS_WINDOWS
if (newfd == INVALID_SOCKET)
#else
@ -1074,7 +1008,10 @@ Wait for an incoming connection. Return a new socket representing the\n\
connection, and the address of the client. For IP sockets, the address\n\
info is a pair (hostaddr, port).";
/* s.setblocking(1 | 0) method */
/* s.setblocking(flag) method. Argument:
False -- non-blocking mode; same as settimeout(0)
True -- blocking mode; same as settimeout(None)
*/
static PyObject *
sock_setblocking(PySocketSockObject *s, PyObject *arg)
@ -1085,8 +1022,7 @@ sock_setblocking(PySocketSockObject *s, PyObject *arg)
if (block == -1 && PyErr_Occurred())
return NULL;
s->sock_blocking = block;
s->sock_timeout = -1.0; /* Always clear the timeout */
s->sock_timeout = block ? -1.0 : 0.0;
internal_setblocking(s, block);
Py_INCREF(Py_None);
@ -1097,44 +1033,34 @@ static char setblocking_doc[] =
"setblocking(flag)\n\
\n\
Set the socket to blocking (flag is true) or non-blocking (false).\n\
This uses the FIONBIO ioctl with the O_NDELAY flag.";
setblocking(True) is equivalent to settimeout(None);\n\
setblocking(False) is equivalent to settimeout(0.0).";
/* s.settimeout(None | float) method.
Causes an exception to be raised when the given time has
elapsed when performing a blocking socket operation. */
/* s.settimeout(timeout) method. Argument:
None -- no timeout, blocking mode; same as setblocking(True)
0.0 -- non-blocking mode; same as setblocking(False)
> 0 -- timeout mode; operations time out after timeout seconds
< 0 -- illegal; raises an exception
*/
static PyObject *
sock_settimeout(PySocketSockObject *s, PyObject *arg)
{
double value;
double timeout;
if (arg == Py_None)
value = -1.0;
timeout = -1.0;
else {
value = PyFloat_AsDouble(arg);
if (value < 0.0) {
timeout = PyFloat_AsDouble(arg);
if (timeout < 0.0) {
if (!PyErr_Occurred())
PyErr_SetString(PyExc_ValueError,
"Invalid timeout value");
"Timeout value out of range");
return NULL;
}
}
s->sock_timeout = value;
/* The semantics of setting socket timeouts are:
If you settimeout(!=None):
The actual socket gets put in non-blocking mode and the select
is used to control timeouts.
Else if you settimeout(None) [then value is -1.0]:
The old behavior is used AND automatically, the socket is set
to blocking mode. That means that someone who was doing
non-blocking stuff before, sets a timeout, and then unsets
one, will have to call setblocking(0) again if he wants
non-blocking stuff. This makes sense because timeout stuff is
blocking by nature. */
internal_setblocking(s, value < 0.0);
s->sock_blocking = 1; /* Always negate setblocking() */
s->sock_timeout = timeout;
internal_setblocking(s, timeout < 0.0);
Py_INCREF(Py_None);
return Py_None;
@ -1143,8 +1069,10 @@ sock_settimeout(PySocketSockObject *s, PyObject *arg)
static char settimeout_doc[] =
"settimeout(timeout)\n\
\n\
Set a timeout on blocking socket operations. 'timeout' can be a float,\n\
giving seconds, or None. Setting a timeout of None disables timeout.";
Set a timeout on socket operations. 'timeout' can be a float,\n\
giving in seconds, or None. Setting a timeout of None disables\n\
the timeout feature and is equivalent to setblocking(1).\n\
Setting a timeout of zero is the same as setblocking(0).";
/* s.gettimeout() method.
Returns the timeout associated with a socket. */
@ -1355,50 +1283,20 @@ sock_connect(PySocketSockObject *s, PyObject *addro)
if (!getsockaddrarg(s, addro, &addr, &addrlen))
return NULL;
errno = 0; /* Reset the err indicator for use with timeouts */
Py_BEGIN_ALLOW_THREADS
res = connect(s->sock_fd, addr, addrlen);
Py_END_ALLOW_THREADS
if (s->sock_timeout >= 0.0) {
if (res < 0) {
/* Return if we're already connected */
#ifdef MS_WINDOWS
if (errno == WSAEINVAL || errno == WSAEISCONN)
#else
if (errno == EISCONN)
#endif
goto connected;
/* Check if we have an error */
if (!s->sock_blocking)
return s->errorhandler();
/* Check if we have a true failure
for a blocking socket */
#ifdef MS_WINDOWS
if (errno != WSAEWOULDBLOCK)
#else
if (errno != EINPROGRESS && errno != EALREADY &&
errno != EWOULDBLOCK)
#endif
return s->errorhandler();
}
/* Check if we're ready for the connect via select */
if (internal_select(s, 1) <= 0)
return NULL;
/* Complete the connection now */
Py_BEGIN_ALLOW_THREADS
if (s->sock_timeout > 0.0) {
res = connect(s->sock_fd, addr, addrlen);
Py_END_ALLOW_THREADS
if (res == EINPROGRESS) {
internal_select(s, 1);
res = connect(s->sock_fd, addr, addrlen);
}
}
else
res = connect(s->sock_fd, addr, addrlen);
Py_END_ALLOW_THREADS
if (res < 0)
return s->errorhandler();
connected:
Py_INCREF(Py_None);
return Py_None;
}
@ -1422,47 +1320,18 @@ sock_connect_ex(PySocketSockObject *s, PyObject *addro)
if (!getsockaddrarg(s, addro, &addr, &addrlen))
return NULL;
errno = 0; /* Reset the err indicator for use with timeouts */
Py_BEGIN_ALLOW_THREADS
res = connect(s->sock_fd, addr, addrlen);
if (s->sock_timeout > 0.0) {
res = connect(s->sock_fd, addr, addrlen);
if (res == EINPROGRESS) {
internal_select(s, 1);
res = connect(s->sock_fd, addr, addrlen);
}
}
else
res = connect(s->sock_fd, addr, addrlen);
Py_END_ALLOW_THREADS
if (s->sock_timeout >= 0.0) {
if (res < 0) {
/* Return if we're already connected */
#ifdef MS_WINDOWS
if (errno == WSAEINVAL || errno == WSAEISCONN)
#else
if (errno == EISCONN)
#endif
goto conex_finally;
/* Check if we have an error */
if (!s->sock_blocking)
goto conex_finally;
/* Check if we have a true failure
for a blocking socket */
#ifdef MS_WINDOWS
if (errno != WSAEWOULDBLOCK)
#else
if (errno != EINPROGRESS && errno != EALREADY &&
errno != EWOULDBLOCK)
#endif
goto conex_finally;
}
/* Check if we're ready for the connect via select */
if (internal_select(s, 1) <= 0)
return NULL;
/* Complete the connection now */
Py_BEGIN_ALLOW_THREADS
res = connect(s->sock_fd, addr, addrlen);
Py_END_ALLOW_THREADS
}
conex_finally:
if (res != 0) {
#ifdef MS_WINDOWS
res = WSAGetLastError();
@ -1683,7 +1552,7 @@ sock_recv(PySocketSockObject *s, PyObject *args)
if (len < 0) {
PyErr_SetString(PyExc_ValueError,
"negative buffersize in connect");
"negative buffersize in recv");
return NULL;
}
@ -1691,14 +1560,8 @@ sock_recv(PySocketSockObject *s, PyObject *args)
if (buf == NULL)
return NULL;
if (s->sock_timeout >= 0.0) {
if (s->sock_blocking) {
if (internal_select(s, 0) <= 0)
return NULL;
}
}
Py_BEGIN_ALLOW_THREADS
internal_select(s, 0);
n = recv(s->sock_fd, PyString_AS_STRING(buf), len, flags);
Py_END_ALLOW_THREADS
@ -1741,15 +1604,9 @@ sock_recvfrom(PySocketSockObject *s, PyObject *args)
if (buf == NULL)
return NULL;
if (s->sock_timeout >= 0.0) {
if (s->sock_blocking) {
if (internal_select(s, 0) <= 0)
return NULL;
}
}
Py_BEGIN_ALLOW_THREADS
memset(addrbuf, 0, addrlen);
internal_select(s, 0);
n = recvfrom(s->sock_fd, PyString_AS_STRING(buf), len, flags,
#ifndef MS_WINDOWS
#if defined(PYOS_OS2) && !defined(PYCC_GCC)
@ -1799,14 +1656,8 @@ sock_send(PySocketSockObject *s, PyObject *args)
if (!PyArg_ParseTuple(args, "s#|i:send", &buf, &len, &flags))
return NULL;
if (s->sock_timeout >= 0.0) {
if (s->sock_blocking) {
if (internal_select(s, 1) <= 0)
return NULL;
}
}
Py_BEGIN_ALLOW_THREADS
internal_select(s, 1);
n = send(s->sock_fd, buf, len, flags);
Py_END_ALLOW_THREADS
@ -1834,14 +1685,8 @@ sock_sendall(PySocketSockObject *s, PyObject *args)
if (!PyArg_ParseTuple(args, "s#|i:sendall", &buf, &len, &flags))
return NULL;
if (s->sock_timeout >= 0.0) {
if (s->sock_blocking) {
if (internal_select(s, 1) <= 0)
return NULL;
}
}
Py_BEGIN_ALLOW_THREADS
internal_select(s, 1);
do {
n = send(s->sock_fd, buf, len, flags);
if (n < 0)
@ -1888,14 +1733,8 @@ sock_sendto(PySocketSockObject *s, PyObject *args)
if (!getsockaddrarg(s, addro, &addr, &addrlen))
return NULL;
if (s->sock_timeout >= 0.0) {
if (s->sock_blocking) {
if (internal_select(s, 1) <= 0)
return NULL;
}
}
Py_BEGIN_ALLOW_THREADS
internal_select(s, 1);
n = sendto(s->sock_fd, buf, len, flags, addr, addrlen);
Py_END_ALLOW_THREADS

5
Modules/socketmodule.h
View file

@ -83,9 +83,8 @@ typedef struct {
PyObject *(*errorhandler)(void); /* Error handler; checks
errno, returns NULL and
sets a Python exception */
int sock_blocking; /* Flag indicated whether the
socket is in blocking mode */
double sock_timeout; /* Operation timeout value */
double sock_timeout; /* Operation timeout in seconds;
0.0 means non-blocking */
} PySocketSockObject;
/* --- C API ----------------------------------------------------*/