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# to you under the Apache License, Version 2.0 (the

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#   http://www.apache.org/licenses/LICENSE-2.0

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import logging

import sys

import os

import traceback

import threading

import Queue

from thrift.Thrift import TProcessor

from thrift.transport import TTransport

from thrift.protocol import TBinaryProtocol

class TServer:

  """Base interface for a server, which must have a serve method."""

  """ 3 constructors for all servers:

  1) (processor, serverTransport)

  2) (processor, serverTransport, transportFactory, protocolFactory)

  3) (processor, serverTransport,

      inputTransportFactory, outputTransportFactory,

      inputProtocolFactory, outputProtocolFactory)"""

  def __init__(self, *args):

    if (len(args) == 2):

      self.__initArgs__(args[0], args[1],

                        TTransport.TTransportFactoryBase(),

                        TTransport.TTransportFactoryBase(),

                        TBinaryProtocol.TBinaryProtocolFactory(),

                        TBinaryProtocol.TBinaryProtocolFactory())

    elif (len(args) == 4):

      self.__initArgs__(args[0], args[1], args[2], args[2], args[3], args[3])

    elif (len(args) == 6):

      self.__initArgs__(args[0], args[1], args[2], args[3], args[4], args[5])

  def __initArgs__(self, processor, serverTransport,

                   inputTransportFactory, outputTransportFactory,

                   inputProtocolFactory, outputProtocolFactory):

    self.processor = processor

    self.serverTransport = serverTransport

    self.inputTransportFactory = inputTransportFactory

    self.outputTransportFactory = outputTransportFactory

    self.inputProtocolFactory = inputProtocolFactory

    self.outputProtocolFactory = outputProtocolFactory

  def serve(self):

    pass

class TSimpleServer(TServer):

  """Simple single-threaded server that just pumps around one transport."""

  def __init__(self, *args):

    TServer.__init__(self, *args)

  def serve(self):

    self.serverTransport.listen()

    while True:

      client = self.serverTransport.accept()

      itrans = self.inputTransportFactory.getTransport(client)

      otrans = self.outputTransportFactory.getTransport(client)

      iprot = self.inputProtocolFactory.getProtocol(itrans)

      oprot = self.outputProtocolFactory.getProtocol(otrans)

      try:

        while True:

          self.processor.process(iprot, oprot)

      except TTransport.TTransportException, tx:

        pass

      except Exception, x:

        logging.exception(x)

      itrans.close()

      otrans.close()

class TThreadedServer(TServer):

  """Threaded server that spawns a new thread per each connection."""

  def __init__(self, *args):

    TServer.__init__(self, *args)

  def serve(self):

    self.serverTransport.listen()

    while True:

      try:

        client = self.serverTransport.accept()

        t = threading.Thread(target = self.handle, args=(client,))

        t.start()

      except KeyboardInterrupt:

        raise

      except Exception, x:

        logging.exception(x)

  def handle(self, client):

    itrans = self.inputTransportFactory.getTransport(client)

    otrans = self.outputTransportFactory.getTransport(client)

    iprot = self.inputProtocolFactory.getProtocol(itrans)

    oprot = self.outputProtocolFactory.getProtocol(otrans)

    try:

      while True:

        self.processor.process(iprot, oprot)

    except TTransport.TTransportException, tx:

      pass

    except Exception, x:

      logging.exception(x)

    itrans.close()

    otrans.close()

class TThreadPoolServer(TServer):

  """Server with a fixed size pool of threads which service requests."""

  def __init__(self, *args):

    TServer.__init__(self, *args)

    self.clients = Queue.Queue()

    self.threads = 10

  def setNumThreads(self, num):

    """Set the number of worker threads that should be created"""

    self.threads = num

  def serveThread(self):

    """Loop around getting clients from the shared queue and process them."""

    while True:

      try:

        client = self.clients.get()

        self.serveClient(client)

      except Exception, x:

        logging.exception(x)

  def serveClient(self, client):

    """Process input/output from a client for as long as possible"""

    itrans = self.inputTransportFactory.getTransport(client)

    otrans = self.outputTransportFactory.getTransport(client)

    iprot = self.inputProtocolFactory.getProtocol(itrans)

    oprot = self.outputProtocolFactory.getProtocol(otrans)

    try:

      while True:

        self.processor.process(iprot, oprot)

    except TTransport.TTransportException, tx:

      pass

    except Exception, x:

      logging.exception(x)

    itrans.close()

    otrans.close()

  def serve(self):

    """Start a fixed number of worker threads and put client into a queue"""

    for i in range(self.threads):

      try:

        t = threading.Thread(target = self.serveThread)

        t.start()

      except Exception, x:

        logging.exception(x)

    # Pump the socket for clients

    self.serverTransport.listen()

    while True:

      try:

        client = self.serverTransport.accept()

        self.clients.put(client)

      except Exception, x:

        logging.exception(x)

class TForkingServer(TServer):

  """A Thrift server that forks a new process for each request"""

  """

  This is more scalable than the threaded server as it does not cause

  GIL contention.

  Note that this has different semantics from the threading server.

  Specifically, updates to shared variables will no longer be shared.

  It will also not work on windows.

  This code is heavily inspired by SocketServer.ForkingMixIn in the

  Python stdlib.

  """

  def __init__(self, *args):

    TServer.__init__(self, *args)

    self.children = []

  def serve(self):

    def try_close(file):

      try:

        file.close()

      except IOError, e:

        logging.warning(e, exc_info=True)

    self.serverTransport.listen()

    while True:

      client = self.serverTransport.accept()

      try:

        pid = os.fork()

        if pid: # parent

          # add before collect, otherwise you race w/ waitpid

          self.children.append(pid)

          self.collect_children()

          # Parent must close socket or the connection may not get

          # closed promptly

          itrans = self.inputTransportFactory.getTransport(client)

          otrans = self.outputTransportFactory.getTransport(client)

          try_close(itrans)

          try_close(otrans)

        else:

          itrans = self.inputTransportFactory.getTransport(client)

          otrans = self.outputTransportFactory.getTransport(client)

          iprot = self.inputProtocolFactory.getProtocol(itrans)

          oprot = self.outputProtocolFactory.getProtocol(otrans)

          ecode = 0

          try:

            try:

              while True:

                self.processor.process(iprot, oprot)

            except TTransport.TTransportException, tx:

              pass

            except Exception, e:

              logging.exception(e)

              ecode = 1

          finally:

            try_close(itrans)

            try_close(otrans)

          os._exit(ecode)

      except TTransport.TTransportException, tx:

        pass

      except Exception, x:

        logging.exception(x)

  def collect_children(self):

    while self.children:

      try:

        pid, status = os.waitpid(0, os.WNOHANG)

      except os.error:

        pid = None

      if pid:

        self.children.remove(pid)

      else:

        break