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async_query_example.py
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72 lines (56 loc) · 1.69 KB
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import time
from ctypes import *
from taos import *
def fetch_callback(p_param, p_result, num_of_rows):
print("fetched ", num_of_rows, "rows")
p = cast(p_param, POINTER(Counter))
result = TaosResult(p_result)
if num_of_rows == 0:
print("fetching completed")
p.contents.done = True
result.close()
return
if num_of_rows < 0:
p.contents.done = True
result.check_error(num_of_rows)
result.close()
return None
for row in result.rows_iter(num_of_rows):
print(row)
p.contents.count += result.row_count
result.fetch_rows_a(fetch_callback, p_param)
def query_callback(p_param, p_result, code):
if p_result is None:
return
result = TaosResult(p_result)
if code == 0:
result.fetch_rows_a(fetch_callback, p_param)
result.check_error(code)
class Counter(Structure):
_fields_ = [("count", c_int), ("done", c_bool)]
def __str__(self):
return "{ count: %d, done: %s }" % (self.count, self.done)
def test_query(conn):
counter = Counter(count=0)
conn.query_a("select ts, current, voltage from power.meters", query_callback, byref(counter))
while not counter.done:
print(counter)
time.sleep(1)
print(counter)
conn.close()
if __name__ == "__main__":
test_query(connect())
# possible output:
# { count: 0, done: False }
# fetched 8 rows
# 1538548685000 10.300000 219
# 1538548695000 12.600000 218
# 1538548696800 12.300000 221
# 1538548696650 10.300000 218
# 1538548685500 11.800000 221
# 1538548696600 13.400000 223
# 1538548685500 10.800000 223
# 1538548686500 11.500000 221
# fetched 0 rows
# fetching completed
# { count: 8, done: True }