readable, writable, exceptional = select.select(inputs, outputs, inputs)

# coding: utf-8
import select
import socket
import Queue
from time import sleep


# Create a TCP/IP
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.setblocking(False)

# Bind the socket to the port
server_address = ('localhost', 8090)
print ('starting up on %s port %s' % server_address)
server.bind(server_address)

# Listen for incoming connections
server.listen(5)

# Sockets from which we expect to read
inputs = [server]

# Sockets to which we expect to write
# 處理要發(fā)送的消息
outputs = []

# Outgoing message queues (socket: Queue)
message_queues = {}

while inputs:
  # Wait for at least one of the sockets to be ready for processing
  print ('waiting for the next event')
  # 開始select 監(jiān)聽, 對input_list 中的服務器端server 進行監(jiān)聽
  # 一旦調用socket的send, recv函數，將會再次調用此模塊
  readable, writable, exceptional = select.select(inputs, outputs, inputs)

  # Handle inputs
  # 循環(huán)判斷是否有客戶端連接進來, 當有客戶端連接進來時select 將觸發(fā)
  for s in readable:
    # 判斷當前觸發(fā)的是不是服務端對象, 當觸發(fā)的對象是服務端對象時,說明有新客戶端連接進來了
    # 表示有新用戶來連接
    if s is server:
      # A "readable" socket is ready to accept a connection
      connection, client_address = s.accept()
      print ('connection from', client_address)
      # this is connection not server
      connection.setblocking(0)
      # 將客戶端對象也加入到監(jiān)聽的列表中, 當客戶端發(fā)送消息時 select 將觸發(fā)
      inputs.append(connection)

      # Give the connection a queue for data we want to send
      # 為連接的客戶端單獨創(chuàng)建一個消息隊列，用來保存客戶端發(fā)送的消息
      message_queues[connection] = Queue.Queue()
    else:
      # 有老用戶發(fā)消息, 處理接受
      # 由于客戶端連接進來時服務端接收客戶端連接請求，將客戶端加入到了監(jiān)聽列表中(input_list), 客戶端發(fā)送消息將觸發(fā)
      # 所以判斷是否是客戶端對象觸發(fā)
      data = s.recv(1024)
      # 客戶端未斷開
      if data != '':
        # A readable client socket has data
        print ('received "%s" from %s' % (data, s.getpeername()))
        # 將收到的消息放入到相對應的socket客戶端的消息隊列中
        message_queues[s].put(data)
        # Add output channel for response
        # 將需要進行回復操作socket放到output 列表中, 讓select監(jiān)聽
        if s not in outputs:
          outputs.append(s)
      else:
        # 客戶端斷開了連接, 將客戶端的監(jiān)聽從input列表中移除
        # Interpret empty result as closed connection
        print ('closing', client_address)
        # Stop listening for input on the connection
        if s in outputs:
          outputs.remove(s)
        inputs.remove(s)
        s.close()

        # Remove message queue
        # 移除對應socket客戶端對象的消息隊列
        del message_queues[s]

  # Handle outputs
  # 如果現(xiàn)在沒有客戶端請求, 也沒有客戶端發(fā)送消息時, 開始對發(fā)送消息列表進行處理, 是否需要發(fā)送消息
  # 存儲哪個客戶端發(fā)送過消息
  for s in writable:
    try:
      # 如果消息隊列中有消息,從消息隊列中獲取要發(fā)送的消息
      message_queue = message_queues.get(s)
      send_data = ''
      if message_queue is not None:
        send_data = message_queue.get_nowait()
      else:
        # 客戶端連接斷開了
        print "has closed "
    except Queue.Empty:
      # 客戶端連接斷開了
      print "%s" % (s.getpeername())
      outputs.remove(s)
    else:
      # print "sending %s to %s " % (send_data, s.getpeername)
      # print "send something"
      if message_queue is not None:
        s.send(send_data)
      else:
        print "has closed "
      # del message_queues[s]
      # writable.remove(s)
      # print "Client %s disconnected" % (client_address)

  # # Handle "exceptional conditions"
  # 處理異常的情況
  for s in exceptional:
    print ('exception condition on', s.getpeername())
    # Stop listening for input on the connection
    inputs.remove(s)
    if s in outputs:
      outputs.remove(s)
    s.close()

    # Remove message queue
    del message_queues[s]

  sleep(1)

# coding: utf-8
import socket


messages = ['This is the message ', 'It will be sent ', 'in parts ', ]

server_address = ('localhost', 8090)

# Create aTCP/IP socket

socks = [socket.socket(socket.AF_INET, socket.SOCK_STREAM), socket.socket(socket.AF_INET, socket.SOCK_STREAM), ]

# Connect thesocket to the port where the server is listening

print ('connecting to %s port %s' % server_address)
# 連接到服務器
for s in socks:
  s.connect(server_address)

for index, message in enumerate(messages):
  # Send messages on both sockets
  for s in socks:
    print ('%s: sending "%s"' % (s.getsockname(), message + str(index)))
    s.send(bytes(message + str(index)).decode('utf-8'))
  # Read responses on both sockets

for s in socks:
  data = s.recv(1024)
  print ('%s: received "%s"' % (s.getsockname(), data))
  if data != "":
    print ('closingsocket', s.getsockname())
    s.close()