import socket
import thread

class BufferOverload(Exception):
    """ raised when the buffer's size exceeds config.max_events_in_buffer
    """

class OutChannel(object):
    def __init__(self, config, httpchannel):
        self.config = config
        self.httpchannel = httpchannel
        self.buffer = []
        self.lock = thread.allocate_lock()
        self.commands_pushed = 0

    def push_command(self, command):
        self.lock.acquire()
        try:
            self._push_command(command)
        finally:
            self.lock.release()
        self.commands_pushed += 1
        if self.commands_pushed >= self.config.max_events_per_request:
            self.httpchannel.close_when_done()

    def refresh_channel(self, httpchannel):
        self.httpchannel = httpchannel
        self.commands_pushed = 0

    def _push_command(self, command):
        self.buffer.append(command)
        if len(self.buffer) > self.config.max_events_in_buffer:
            raise BufferOverload()
        while self.buffer:
            try:
                self.httpchannel.push_with_producer(self.buffer[0])
            except socket.error:
                break
            else:
                self.buffer.pop(0)