使用异步服务器发送多个文件

Question

这里是 server.py

import asyncio
import aiofile

async def handler(reader, writer):
    data = await reader.read(n=-1)
    addr = writer.get_extra_info('peername')
    print('Addr', addr)
    # photo_120721_215652.jpg
    name = data[:23].decode()
    async with aiofile.async_open(name, 'wb') as afp:
        await afp.write(data[23:])
    print("handler end")


async def main():
    server = await asyncio.start_server(handler, '0.0.0.0', 8888)
    addr = server.sockets[0].getsockname()
    print(f'Serving on {addr}')
    async with server:
        await server.serve_forever()

asyncio.run(main())

这里是client.py

async def send_photos_to_server(filelist):
    retry = 0
    for file in filelist:
        while True:
            try:
                reader, writer = await asyncio.open_connection('192.168.1.100', 8888)
            except OSError:
                while retry != 5:
                    await asyncio.sleep(3)
                    retry += 1
            else:
                break # exit the loop 
        if retry == 5:
            print("No connection after {} retries")
            break

        name = file.split('/')[-1].encode()
        writer.write(name)
        await writer.drain()

        async with aiofile.async_open(file, 'rb') as afp:
            afp_reader = await afp.read(length=-1)
        writer.write(afp_reader)
        await writer.drain()
        writer.close()
        await writer.wait_closed()

filelist = ['./photos/photo_120721_215652.jpg',
            './photos/photo_120721_215654.jpg',
            './photos/photo_120721_215656.jpg']

asyncio.run(send_photos_to_server(filelist))

所以这段代码是有效的。但我不确定这是否是正确的方法。每次发送一个新文件，我们都会创建一个新的连接。当然，我可以将所有三个文件打包成一个存档，但我不确定它是否方便。此外，将文件名放入发送消息很不方便，因为在服务器端，我必须以某种方式找到它。那么有人可以解释如何修改此代码以获得更好的实践吗？我刚开始学习异步io，并不擅长。

Answer 1

服务器使用protocols - 它测量的规则描述了一方必须发送什么以及如何在另一个大小上读取它。

例如HTTP 首先发送标题、下一个空行和下一个数据（正文）。其中一个标头包含正文多长时间的信息。

对方首先要读取数据byte after byte，直到找到空行（'n\n'），然后它有标题，它可以找到正文的长度，并读取正确的字节数。

---

您可以创建自己的协议。

我假设您想在一个连接中发送所有文件。

你可以发送文件数量+\n，接下来使用for-loop发送文件名+\n，文件大小+\n，文件数据。

另一方也应该做类似的-首先读取所有\n以获取文件数，然后使用for-loop再次读取所有\n以获取文件名，全部读取\n以获取大小，使用size读取文件数据。

---

它表明使用 zip 压缩数据并发送它可能更简单 - 另一方将在这个 zip 文件中包含所有信息 - 文件名、大小、数据。

当然你可以减少它并且仍然以单独的连接发送每个文件。

---

示例代码

server.py

import asyncio
import aiofile

async def handler(reader, writer):

    # --- before for-loop ---
    
    data = await reader.read(n=-1)
    addr = writer.get_extra_info('peername')
    print('Addr', addr)

    # get number of images + `\n`
    start = 0
    end = data.find(b'\n', start)
    item = data[start:end]
    print('[DEBUG] start,end:', start, end, item)
    number = int(item.decode())
    print('number:', number)
    
    print('--------')

    # --- for-loop ---

    for _ in range(number):
        # get filename + '\n' 
        start = end+1
        end = data.find(b'\n', start)
        item = data[start:end]
        print('[DEBUG] start,end:', start, end, item)
        name = item.decode()
        print('name:', name)

        # get size + '\n'
        start = end+1
        end = data.find(b'\n', start)
        item = data[start:end]
        print('[DEBUG] start,end:', start, end, item)
        size = int(item.decode())
        print('size:', size)
        
        # get data
        start = end+1
        end = start+size-1
        item = data[start:end]
        print('[DEBUG] start,end:', start, end, item[:10])
        async with aiofile.async_open(name, 'wb') as afp:
            await afp.write(item)
            
        print('--------')

    # --- after for-loop ---
        
    print("handler end")


async def main():
    server = await asyncio.start_server(handler, '0.0.0.0', 8888)
    addr = server.sockets[0].getsockname()
    print(f'Serving on {addr}')
    async with server:
        await server.serve_forever()

asyncio.run(main())

client.py

import asyncio
import aiofile

async def send_photos_to_server(filelist):

    # --- before for-loop ---
    
    retry = 0

    while True:
        try:
            reader, writer = await asyncio.open_connection('0.0.0.0', 8888)
        except OSError:
            while retry != 5:
                await asyncio.sleep(3)
                retry += 1
        else:
            break # exit the loop 
    if retry == 5:
        print("No connection after {} retries")
        return
    
    # send number of images + '\n'
    text = str(len(filelist)) + '\n'
    writer.write(text.encode())
    await writer.drain()
    
    # --- for-loop ---
    
    for filename in filelist:

        # send filename + '\n'
        name = filename.split('/')[-1]
        text = name + '\n'
        writer.write(text.encode())
        await writer.drain()

        async with aiofile.async_open(filename, 'rb') as afp:
            afp_reader = await afp.read(length=-1)

        # send size + '\n'
        size = str(len(afp_reader)) 
        text = size + '\n'
        writer.write(text.encode())
        await writer.drain()

        # send data
        writer.write(afp_reader)
        await writer.drain()
        
        
    # --- after for-loop ---
    
    writer.close()
    await writer.wait_closed()

filelist = [
    '/home/furas/test/image1.png',
    '/home/furas/test/image2.png',
    '/home/furas/test/image3.png',
]

asyncio.run(send_photos_to_server(filelist))