[2.4. Database row caching](https://livebook.manning.com/book/redis-in-action/chapter-2/59)

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def schedule_row_cache(conn, row_id, delay): conn.zadd('delay:', row_id, delay) #A conn.zadd('schedule:', row_id, time.time()) #B

`def cache_rows(conn):
while not QUIT:
next = conn.zrange('schedule:', 0, 0, withscores=True) #A
now = time.time()
if not next or next[0][1] > now:
time.sleep(.05) #B
continue

    row_id = next[0][0]
    delay = conn.zscore('delay:', row_id)                   #C
    if delay <= 0:
        conn.zrem('delay:', row_id)                         #D
        conn.zrem('schedule:', row_id)                      #D
        conn.delete('inv:' + row_id)                        #D
        continue

    row = Inventory.get(row_id)                             #E
    conn.zadd('schedule:', row_id, now + delay)             #F
    conn.set('inv:' + row_id, json.dumps(row.to_dict()))    #F`

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commit error. sorry