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Diffstat (limited to 'python/urllib3/util/wait.py')
-rw-r--r-- | python/urllib3/util/wait.py | 150 |
1 files changed, 0 insertions, 150 deletions
diff --git a/python/urllib3/util/wait.py b/python/urllib3/util/wait.py deleted file mode 100644 index 4db71ba..0000000 --- a/python/urllib3/util/wait.py +++ /dev/null @@ -1,150 +0,0 @@ -import errno -from functools import partial -import select -import sys -try: - from time import monotonic -except ImportError: - from time import time as monotonic - -__all__ = ["NoWayToWaitForSocketError", "wait_for_read", "wait_for_write"] - - -class NoWayToWaitForSocketError(Exception): - pass - - -# How should we wait on sockets? -# -# There are two types of APIs you can use for waiting on sockets: the fancy -# modern stateful APIs like epoll/kqueue, and the older stateless APIs like -# select/poll. The stateful APIs are more efficient when you have a lots of -# sockets to keep track of, because you can set them up once and then use them -# lots of times. But we only ever want to wait on a single socket at a time -# and don't want to keep track of state, so the stateless APIs are actually -# more efficient. So we want to use select() or poll(). -# -# Now, how do we choose between select() and poll()? On traditional Unixes, -# select() has a strange calling convention that makes it slow, or fail -# altogether, for high-numbered file descriptors. The point of poll() is to fix -# that, so on Unixes, we prefer poll(). -# -# On Windows, there is no poll() (or at least Python doesn't provide a wrapper -# for it), but that's OK, because on Windows, select() doesn't have this -# strange calling convention; plain select() works fine. -# -# So: on Windows we use select(), and everywhere else we use poll(). We also -# fall back to select() in case poll() is somehow broken or missing. - -if sys.version_info >= (3, 5): - # Modern Python, that retries syscalls by default - def _retry_on_intr(fn, timeout): - return fn(timeout) -else: - # Old and broken Pythons. - def _retry_on_intr(fn, timeout): - if timeout is None: - deadline = float("inf") - else: - deadline = monotonic() + timeout - - while True: - try: - return fn(timeout) - # OSError for 3 <= pyver < 3.5, select.error for pyver <= 2.7 - except (OSError, select.error) as e: - # 'e.args[0]' incantation works for both OSError and select.error - if e.args[0] != errno.EINTR: - raise - else: - timeout = deadline - monotonic() - if timeout < 0: - timeout = 0 - if timeout == float("inf"): - timeout = None - continue - - -def select_wait_for_socket(sock, read=False, write=False, timeout=None): - if not read and not write: - raise RuntimeError("must specify at least one of read=True, write=True") - rcheck = [] - wcheck = [] - if read: - rcheck.append(sock) - if write: - wcheck.append(sock) - # When doing a non-blocking connect, most systems signal success by - # marking the socket writable. Windows, though, signals success by marked - # it as "exceptional". We paper over the difference by checking the write - # sockets for both conditions. (The stdlib selectors module does the same - # thing.) - fn = partial(select.select, rcheck, wcheck, wcheck) - rready, wready, xready = _retry_on_intr(fn, timeout) - return bool(rready or wready or xready) - - -def poll_wait_for_socket(sock, read=False, write=False, timeout=None): - if not read and not write: - raise RuntimeError("must specify at least one of read=True, write=True") - mask = 0 - if read: - mask |= select.POLLIN - if write: - mask |= select.POLLOUT - poll_obj = select.poll() - poll_obj.register(sock, mask) - - # For some reason, poll() takes timeout in milliseconds - def do_poll(t): - if t is not None: - t *= 1000 - return poll_obj.poll(t) - - return bool(_retry_on_intr(do_poll, timeout)) - - -def null_wait_for_socket(*args, **kwargs): - raise NoWayToWaitForSocketError("no select-equivalent available") - - -def _have_working_poll(): - # Apparently some systems have a select.poll that fails as soon as you try - # to use it, either due to strange configuration or broken monkeypatching - # from libraries like eventlet/greenlet. - try: - poll_obj = select.poll() - _retry_on_intr(poll_obj.poll, 0) - except (AttributeError, OSError): - return False - else: - return True - - -def wait_for_socket(*args, **kwargs): - # We delay choosing which implementation to use until the first time we're - # called. We could do it at import time, but then we might make the wrong - # decision if someone goes wild with monkeypatching select.poll after - # we're imported. - global wait_for_socket - if _have_working_poll(): - wait_for_socket = poll_wait_for_socket - elif hasattr(select, "select"): - wait_for_socket = select_wait_for_socket - else: # Platform-specific: Appengine. - wait_for_socket = null_wait_for_socket - return wait_for_socket(*args, **kwargs) - - -def wait_for_read(sock, timeout=None): - """ Waits for reading to be available on a given socket. - Returns True if the socket is readable, or False if the timeout expired. - """ - return wait_for_socket(sock, read=True, timeout=timeout) - - -def wait_for_write(sock, timeout=None): - """ Waits for writing to be available on a given socket. - Returns True if the socket is readable, or False if the timeout expired. - """ - return wait_for_socket(sock, write=True, timeout=timeout) |