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rwlock: include actionable in error message #3270

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merged 2 commits into from Feb 5, 2020
Merged

rwlock: include actionable in error message #3270

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1c17d02
rwlock: include actionable in error message
Jan 31, 2020
e6ed5cc
rwlock: check blockers on a single method
Feb 5, 2020
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49 changes: 18 additions & 31 deletions dvc/rwlock.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,6 @@
from contextlib import contextmanager

from voluptuous import Schema, Invalid
from funcy.py3 import lmap, lfilter, lmapcat

from .exceptions import DvcException
from .lock import LockError
Expand Down Expand Up @@ -61,38 +60,25 @@ def _infos_to_str(infos):
)


def _check_no_writers(lock, info, path_infos):
for path_info in path_infos:
blocking_urls = lfilter(path_info.overlaps, lock["write"])
if not blocking_urls:
continue
def _check_blockers(lock, info, *, mode, waiters):
for path_info in waiters:
blockers = [
info
for path, infos in lock[mode].items()
if path_info.overlaps(path)
if info not in (infos if type(infos) is list else [infos])
]
Comment on lines +65 to +70
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This logic is broken now. We create a list of info passed as param repeated 0 to several times, while in previous logic we were listing infos we've got from lock.

The right logic I guess is:

blockers = [
    blocker
    for path, infos in lock[mode].items()
    if path_info.overlaps(path)
    for blocker in (infos if isinstance(infos, list) else [infos])
    if blocker != info
]

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Fixed in #3285.


writers = lmap(lock["write"].get, blocking_urls)
writers = lfilter(lambda i: info != i, writers)
if not writers:
if not blockers:
continue

raise LockError(
"'{}' is busy, it is being written to by:\n{}".format(
str(path_info), _infos_to_str(writers)
)
)


def _check_no_readers(lock, info, path_infos):
for path_info in path_infos:
blocking_urls = lfilter(path_info.overlaps, lock["read"])
if not blocking_urls:
continue

readers = lmapcat(lock["read"].get, blocking_urls)
readers = lfilter(lambda i: info != i, readers)
if not readers:
continue

raise LockError(
"'{}' is busy, it is being read by:\n{}".format(
str(path_info), _infos_to_str(readers)
"'{path}' is busy, it is being blocked by:\n"
"{blockers}\n"
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"\n"
"If there are no processes with such PIDs, you can manually remove"
"'.dvc/tmp/rwlock' and try again.".format(
path=str(path_info), blockers=_infos_to_str(blockers)
)
)

Expand Down Expand Up @@ -171,8 +157,9 @@ def rwlock(tmp_dir, cmd, read, write):
info = {"pid": os.getpid(), "cmd": cmd}

with _edit_rwlock(tmp_dir) as lock:
_check_no_writers(lock, info, read + write)
_check_no_readers(lock, info, write)

_check_blockers(lock, info, mode="write", waiters=read + write)
_check_blockers(lock, info, mode="read", waiters=write)

rchanges = _acquire_read(lock, info, read)
wchanges = _acquire_write(lock, info, write)
Expand Down