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Fix deadlock in id_generators. No idea why this was an actual deadlock.

This commit is contained in:
Erik Johnston 2015-04-29 19:15:23 +01:00
parent 3e71d13acf
commit d2d61a8288
1 changed files with 16 additions and 14 deletions
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30
synapse/storage/util/id_generators.py
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@ -86,10 +86,10 @@ class StreamIdGenerator(object):
with stream_id_gen.get_next_txn(txn) as stream_id:
# ... persist event ...
"""
with self._lock:
if not self._current_max:
self._compute_current_max(txn)
if not self._current_max:
self._compute_current_max(txn)
with self._lock:
self._current_max += 1
next_id = self._current_max
@ -110,22 +110,24 @@ class StreamIdGenerator(object):
"""Returns the maximum stream id such that all stream ids less than or
equal to it have been successfully persisted.
"""
if not self._current_max:
yield store.runInteraction(
"_compute_current_max",
self._get_or_compute_current_max,
)
with self._lock:
if self._unfinished_ids:
defer.returnValue(self._unfinished_ids[0] - 1)
if not self._current_max:
yield store.runInteraction(
"_compute_current_max",
self._compute_current_max,
)
defer.returnValue(self._current_max)
def _compute_current_max(self, txn):
txn.execute("SELECT MAX(stream_ordering) FROM events")
val, = txn.fetchone()
def _get_or_compute_current_max(self, txn):
with self._lock:
txn.execute("SELECT MAX(stream_ordering) FROM events")
rows = txn.fetchall()
val, = rows[0]
self._current_max = int(val) if val else 1
self._current_max = int(val) if val else 1
return self._current_max
return self._current_max