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91 lines
2.0 KiB
91 lines
2.0 KiB
# vim: set fileencoding=utf-8 :
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"""provide a trivial way to send messages between processes
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messages are being sent as files to an inbox, which is a directory, using a
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filename as a marker
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recv_all() is delivering all messages, which are newer than the marker file
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after completion reading is touching the marker file
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to re-read messages touch the marker file with an older timestamp or just
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delete the marker file to re-read all messages
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"""
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# Minimail
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# Copyleft 2019, p≡p foundation
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# this file is under GNU General Public License 3.0
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from secrets import token_urlsafe
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from time import sleep
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def unlock(inbox):
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"clear the inbox from lockfile"
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lockfile = inbox / "lock"
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try:
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lockfile.unlink()
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except:
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pass
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class Lock:
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"lock inbox context to be used by with statement"
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def __init__(self, inbox):
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self.inbox = inbox
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def __exit__(self, *exc):
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unlock(self.inbox)
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def __enter__(self):
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lockfile = self.inbox / "lock"
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while lockfile.is_file():
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sleep(1)
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lockfile.touch()
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def send(inbox, msg):
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"send msg to inbox in MIME format"
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with Lock(inbox):
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name = token_urlsafe(16) + ".eml"
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with open(inbox / name, "wb") as f:
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f.write(str(msg).encode())
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def newer(file1, file2=None):
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"return True if file1 is newer than file2"
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if not file1.is_file():
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return False
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elif not file2.is_file():
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return True
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stat1 = file1.stat()
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stat2 = file2.stat()
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return stat1.st_mtime > stat2.st_mtime
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def recv_all(inbox, marker):
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"""receive a list of new MIME messages from inbox, which are newer than the
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marker file"""
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r = []
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while not r:
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for p in inbox.glob("*.eml"):
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if newer(p, inbox / marker):
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with Lock(inbox):
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with open(p, "rb") as f:
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t = f.read(-1)
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r.append(t)
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if not r:
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sleep(1)
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(inbox / marker).touch(exist_ok=True)
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return r
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