diff options
Diffstat (limited to 'redis/selector.py')
| -rw-r--r-- | redis/selector.py | 196 |
1 files changed, 0 insertions, 196 deletions
diff --git a/redis/selector.py b/redis/selector.py deleted file mode 100644 index bce84a5..0000000 --- a/redis/selector.py +++ /dev/null @@ -1,196 +0,0 @@ -import errno -import select -from redis.exceptions import RedisError - - -_DEFAULT_SELECTOR = None - - -class BaseSelector(object): - """ - Base class for all Selectors - """ - def __init__(self, sock): - self.sock = sock - - def can_read(self, timeout=0): - """ - Return True if data is ready to be read from the socket, - otherwise False. - - This doesn't guarentee that the socket is still connected, just that - there is data to read. - - Automatically retries EINTR errors based on PEP 475. - """ - while True: - try: - return self.check_can_read(timeout) - except (select.error, IOError) as ex: - if self.errno_from_exception(ex) == errno.EINTR: - continue - return False - - def is_ready_for_command(self, timeout=0): - """ - Return True if the socket is ready to send a command, - otherwise False. - - Automatically retries EINTR errors based on PEP 475. - """ - while True: - try: - return self.check_is_ready_for_command(timeout) - except (select.error, IOError) as ex: - if self.errno_from_exception(ex) == errno.EINTR: - continue - return False - - def check_can_read(self, timeout): - """ - Perform the can_read check. Subclasses should implement this. - """ - raise NotImplementedError - - def check_is_ready_for_command(self, timeout): - """ - Perform the is_ready_for_command check. Subclasses should - implement this. - """ - raise NotImplementedError - - def close(self): - """ - Close the selector. - """ - self.sock = None - - def errno_from_exception(self, ex): - """ - Get the error number from an exception - """ - if hasattr(ex, 'errno'): - return ex.errno - elif ex.args: - return ex.args[0] - else: - return None - - -if hasattr(select, 'select'): - class SelectSelector(BaseSelector): - """ - A select-based selector that should work on most platforms. - - This is the worst poll strategy and should only be used if no other - option is available. - """ - def check_can_read(self, timeout): - """ - Return True if data is ready to be read from the socket, - otherwise False. - - This doesn't guarentee that the socket is still connected, just - that there is data to read. - """ - return bool(select.select([self.sock], [], [], timeout)[0]) - - def check_is_ready_for_command(self, timeout): - """ - Return True if the socket is ready to send a command, - otherwise False. - """ - r, w, e = select.select([self.sock], [self.sock], [self.sock], - timeout) - return bool(w and not r and not e) - - -if hasattr(select, 'poll'): - class PollSelector(BaseSelector): - """ - A poll-based selector that should work on (almost?) all versions - of Unix - """ - READ_MASK = select.POLLIN | select.POLLPRI - ERROR_MASK = select.POLLERR | select.POLLHUP - WRITE_MASK = select.POLLOUT - - _READ_POLLER_MASK = READ_MASK | ERROR_MASK - _READY_POLLER_MASK = READ_MASK | ERROR_MASK | WRITE_MASK - - def __init__(self, sock): - super(PollSelector, self).__init__(sock) - self.read_poller = select.poll() - self.read_poller.register(sock, self._READ_POLLER_MASK) - self.ready_poller = select.poll() - self.ready_poller.register(sock, self._READY_POLLER_MASK) - - def close(self): - """ - Close the selector. - """ - for poller in (self.read_poller, self.ready_poller): - try: - poller.unregister(self.sock) - except (KeyError, ValueError): - # KeyError is raised if somehow the socket was not - # registered - # ValueError is raised if the socket's file descriptor is - # negative. - # In either case, we can't do anything better than to - # remove the reference to the poller. - pass - self.read_poller = None - self.ready_poller = None - self.sock = None - - def check_can_read(self, timeout=0): - """ - Return True if data is ready to be read from the socket, - otherwise False. - - This doesn't guarentee that the socket is still connected, just - that there is data to read. - """ - timeout = int(timeout * 1000) - events = self.read_poller.poll(timeout) - return bool(events and events[0][1] & self.READ_MASK) - - def check_is_ready_for_command(self, timeout=0): - """ - Return True if the socket is ready to send a command, - otherwise False - """ - timeout = timeout * 1000 - events = self.ready_poller.poll(timeout) - return bool(events and events[0][1] == self.WRITE_MASK) - - -def has_selector(selector): - "Determine if the current platform has the selector available" - try: - if selector == 'poll': - # the select module offers the poll selector even if the platform - # doesn't support it. Attempt to poll for nothing to make sure - # poll is available - p = select.poll() - p.poll(0) - else: - # the other selectors will fail when instantiated - getattr(select, selector)().close() - return True - except (OSError, AttributeError): - return False - - -def DefaultSelector(sock): - "Return the best selector for the platform" - global _DEFAULT_SELECTOR - if _DEFAULT_SELECTOR is None: - if has_selector('poll'): - _DEFAULT_SELECTOR = PollSelector - elif hasattr(select, 'select'): - _DEFAULT_SELECTOR = SelectSelector - else: - raise RedisError('Platform does not support any selectors') - return _DEFAULT_SELECTOR(sock) |