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。
它不应该在windows上工作(也许与cygwin ?),但对于unix用户,您应该使用“fcntl”系统调用。下面是Python中的一个例子。如果你需要用C语言写的话,基本上是相同的代码(相同的函数名)
import time
import fcntl
import os
import signal
FNAME = "/HOME/TOTO/FILETOWATCH"
def handler(signum, frame):
print "File %s modified" % (FNAME,)
signal.signal(signal.SIGIO, handler)
fd = os.open(FNAME, os.O_RDONLY)
fcntl.fcntl(fd, fcntl.F_SETSIG, 0)
fcntl.fcntl(fd, fcntl.F_NOTIFY,
fcntl.DN_MODIFY | fcntl.DN_CREATE | fcntl.DN_MULTISHOT)
while True:
time.sleep(10000)
在对蒂姆·戈尔登的剧本进行了一些修改后,我有了以下似乎工作得相当不错的内容:
import os
import win32file
import win32con
path_to_watch = "." # look at the current directory
file_to_watch = "test.txt" # look for changes to a file called test.txt
def ProcessNewData( newData ):
print "Text added: %s"%newData
# Set up the bits we'll need for output
ACTIONS = {
1 : "Created",
2 : "Deleted",
3 : "Updated",
4 : "Renamed from something",
5 : "Renamed to something"
}
FILE_LIST_DIRECTORY = 0x0001
hDir = win32file.CreateFile (
path_to_watch,
FILE_LIST_DIRECTORY,
win32con.FILE_SHARE_READ | win32con.FILE_SHARE_WRITE,
None,
win32con.OPEN_EXISTING,
win32con.FILE_FLAG_BACKUP_SEMANTICS,
None
)
# Open the file we're interested in
a = open(file_to_watch, "r")
# Throw away any exising log data
a.read()
# 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 in results:
full_filename = os.path.join (path_to_watch, file)
#print file, ACTIONS.get (action, "Unknown")
if file == file_to_watch:
newText = a.read()
if newText != "":
ProcessNewData( newText )
它可能需要进行更多的错误检查,但对于简单地观察日志文件并在将其输出到屏幕之前对其进行一些处理,这样做效果很好。
谢谢大家的投入-很棒的东西!
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
...
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...