def _Acquire(self, lease_time):
now = int(time.time() * 1e6)
expires = int((time.time() + lease_time) * 1e6)
# Only latest value
latest_value = row_filters.CellsColumnLimitFilter(1)
# Match any lease time value > now which means someone else holds a lock
# We can't store these as ints, encode to str.
current_lease = row_filters.ValueRangeFilter(
start_value=utils.SmartStr(now), inclusive_start=False)
# aff4:lease
family, column = self.store.GetFamilyColumn(self.store.LEASE_ATTRIBUTE)
col_filter = row_filters.ColumnRangeFilter(
family, start_column=column, end_column=column)
# Note filter chains are evaluated in order so there are performance
# considerations with which filter to apply first
filter_chain = row_filters.RowFilterChain(
[col_filter, current_lease, latest_value])
mutate_row = self.store.table.row(self.subject, filter_=filter_chain)
# state=False means no lease or it's expired, in this case take the lock.
mutate_row.set_cell(family, column, utils.SmartStr(expires), state=False)
# Check in review: I think we want to retry the RPC here? Or should we just
# raise like we can't get the lock?
existing_lock = self.store.CallWithRetry(mutate_row.commit, "write")
if existing_lock:
raise ExistingLock("Row %s locked." % self.subject)
# We have the lock
self.expires = expires
self.locked = True
def filter_limit_value_range(project_id, instance_id, table_id):
client = bigtable.Client(project=project_id, admin=True)
instance = client.instance(instance_id)
table = instance.table(table_id)
rows = table.read_rows(
filter_=row_filters.ValueRangeFilter(b"PQ2A.190405", b"PQ2A.190406"))
for row in rows:
print_row(row)
