Open only recently changed files to conserve file descriptors

kitsune

@@ -12,6 +12,11 @@ class WatchedFile:
     def __init__(self, path, seek_to_end):
         self.path = path
         self.seek_to_end = seek_to_end
+        stf = os.stat(self.path)
+        self.st_ctime_ns = stf.st_ctime_ns
+        self.st_size = stf.st_size
+        self.fileno = None
+        if stf.st_ctime_ns >= time.time_ns() - 1E9:
             self.reopen()
 
     def reopen(self):
@@ -19,7 +24,7 @@ class WatchedFile:
         self.fileno = self.fd.fileno()
         self.last_ts = 0
         if self.seek_to_end:
-            self.fd.seek(0, 2)
+            self.fd.seek(self.st_size, 0)
             self.seek_to_end = False
 
 def format_ts(ts_ns):
@@ -59,6 +64,7 @@ def watch(args):
         # has any of the files changed
         for f in watched_files.values():
             # XXX - we should also detect replaced files. 
+            if f.fileno:
                 st = os.stat(f.fileno)
                 try:
                     stf = os.stat(f.path)
@@ -83,6 +89,10 @@ def watch(args):
                         lines.pop()
                     for ln in lines:
                         print(f"{f.path:{filename_length}}", format_ts(f.last_ts), dead, ln)
+            else:
+                stf = os.stat(f.path)
+                if stf.st_ctime_ns != f.st_ctime_ns:
+                    f.reopen()
         time.sleep(0.1)
         seek_to_end = False