我有一个日志文件正在写的另一个进程,我想观察变化。每次发生更改时,我都希望将新数据读入并对其进行一些处理。

最好的方法是什么?我希望在PyWin32库中有某种钩子。我找到了win32文件。函数FindNextChangeNotification,但不知道如何要求它监视特定的文件。

如果有人做过类似的事情,我真的很感激能听到…

[编辑]我应该提到我追求的是一种不需要轮询的解决方案。

[编辑]诅咒!这似乎不能在映射的网络驱动器上工作。我猜windows不会像在本地磁盘上那样“听到”任何对文件的更新。


当前回答

这是一个检查文件更改的示例。这可能不是最好的方法,但肯定是一条捷径。

方便的工具,重新启动应用程序时,已作出更改的源。我在玩pygame的时候做了这个,这样我就可以看到文件保存后立即发生的效果。

当在pygame中使用时,确保'while'循环中的东西被放置在你的游戏循环中,也就是更新或其他什么。否则你的应用将陷入无限循环,你将看不到游戏的更新。

file_size_stored = os.stat('neuron.py').st_size

  while True:
    try:
      file_size_current = os.stat('neuron.py').st_size
      if file_size_stored != file_size_current:
        restart_program()
    except: 
      pass

如果你想要重启代码我在网上找到的。在这儿。(与问题无关,但可能会派上用场)

def restart_program(): #restart application
    python = sys.executable
    os.execl(python, python, * sys.argv)

让电子做你想让它们做的事情。

其他回答

如果轮询对您来说足够好,我只观察“修改的时间”文件统计是否发生变化。阅读方法:

os.stat(filename).st_mtime

(还要注意,Windows本机更改事件解决方案并不在所有情况下都有效,例如在网络驱动器上。)

import os

class Monkey(object):
    def __init__(self):
        self._cached_stamp = 0
        self.filename = '/path/to/file'

    def ook(self):
        stamp = os.stat(self.filename).st_mtime
        if stamp != self._cached_stamp:
            self._cached_stamp = stamp
            # File has changed, so do something...
import inotify.adapters
from datetime import datetime


LOG_FILE='/var/log/mysql/server_audit.log'


def main():
    start_time = datetime.now()
    while True:
        i = inotify.adapters.Inotify()
        i.add_watch(LOG_FILE)
        for event in i.event_gen(yield_nones=False):
            break
        del i

        with open(LOG_FILE, 'r') as f:
            for line in f:
                entry = line.split(',')
                entry_time = datetime.strptime(entry[0],
                                               '%Y%m%d %H:%M:%S')
                if entry_time > start_time:
                    start_time = entry_time
                    print(entry)


if __name__ == '__main__':
    main()
ACTIONS = {
  1 : "Created",
  2 : "Deleted",
  3 : "Updated",
  4 : "Renamed from something",
  5 : "Renamed to something"
}
FILE_LIST_DIRECTORY = 0x0001

class myThread (threading.Thread):
    def __init__(self, threadID, fileName, directory, origin):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.fileName = fileName
        self.daemon = True
        self.dir = directory
        self.originalFile = origin
    def run(self):
        startMonitor(self.fileName, self.dir, self.originalFile)

def startMonitor(fileMonitoring,dirPath,originalFile):
    hDir = win32file.CreateFile (
        dirPath,
        FILE_LIST_DIRECTORY,
        win32con.FILE_SHARE_READ | win32con.FILE_SHARE_WRITE,
        None,
        win32con.OPEN_EXISTING,
        win32con.FILE_FLAG_BACKUP_SEMANTICS,
        None
    )
    # Wait for new data and call ProcessNewData for each new chunk that's
    # written
    while 1:
        # Wait for a change to occur
        results = win32file.ReadDirectoryChangesW (
            hDir,
            1024,
            False,
            win32con.FILE_NOTIFY_CHANGE_LAST_WRITE,
            None,
            None
        )
        # For each change, check to see if it's updating the file we're
        # interested in
        for action, file_M in results:
            full_filename = os.path.join (dirPath, file_M)
            #print file, ACTIONS.get (action, "Unknown")
            if len(full_filename) == len(fileMonitoring) and action == 3:
                #copy to main file
                ...

为了用轮询和最小依赖来观察单个文件,下面是一个完整的例子,基于Deestan的回答(上面):

import os
import sys 
import time

class Watcher(object):
    running = True
    refresh_delay_secs = 1

    # Constructor
    def __init__(self, watch_file, call_func_on_change=None, *args, **kwargs):
        self._cached_stamp = 0
        self.filename = watch_file
        self.call_func_on_change = call_func_on_change
        self.args = args
        self.kwargs = kwargs

    # Look for changes
    def look(self):
        stamp = os.stat(self.filename).st_mtime
        if stamp != self._cached_stamp:
            self._cached_stamp = stamp
            # File has changed, so do something...
            print('File changed')
            if self.call_func_on_change is not None:
                self.call_func_on_change(*self.args, **self.kwargs)

    # Keep watching in a loop        
    def watch(self):
        while self.running: 
            try: 
                # Look for changes
                time.sleep(self.refresh_delay_secs) 
                self.look() 
            except KeyboardInterrupt: 
                print('\nDone') 
                break 
            except FileNotFoundError:
                # Action on file not found
                pass
            except: 
                print('Unhandled error: %s' % sys.exc_info()[0])

# Call this function each time a change happens
def custom_action(text):
    print(text)

watch_file = 'my_file.txt'

# watcher = Watcher(watch_file)  # simple
watcher = Watcher(watch_file, custom_action, text='yes, changed')  # also call custom action function
watcher.watch()  # start the watch going

最简单的解决方案是在间隔之后获取同一个文件的两个实例并进行比较。你可以试试这样的东西

    while True:
        # Capturing the two instances models.py after certain interval of time
        print("Looking for changes in " + app_name.capitalize() + " models.py\nPress 'CTRL + C' to stop the program")
        with open(app_name.capitalize() + '/filename', 'r+') as app_models_file:
            filename_content = app_models_file.read()
        time.sleep(5)
        with open(app_name.capitalize() + '/filename', 'r+') as app_models_file_1:
            filename_content_1 = app_models_file_1.read()
        # Comparing models.py after certain interval of time
        if filename_content == filename_content_1:
            pass
        else:
            print("You made a change in " + app_name.capitalize() + " filename.\n")
            cmd = str(input("Do something with the file?(y/n):"))
            if cmd == 'y':
                # Do Something
            elif cmd == 'n':
                # pass or do something
            else:
                print("Invalid input")