Logger Rate Limiter
Created: March 21, 2020 by [lek-tin]
Last updated: March 21, 2020
Design a logger system that receive stream of messages along with its timestamps, each message should be printed if and only if it is not printed in the last 10 seconds.
Given a message and a timestamp (in seconds granularity), return true if the message should be printed in the given timestamp, otherwise returns false.
It is possible that several messages arrive roughly at the same time.
Example
Logger logger = new Logger();
// logging string "foo" at timestamp 1
logger.shouldPrintMessage(1, "foo"); returns true;
// logging string "bar" at timestamp 2
logger.shouldPrintMessage(2,"bar"); returns true;
// logging string "foo" at timestamp 3
logger.shouldPrintMessage(3,"foo"); returns false;
// logging string "bar" at timestamp 8
logger.shouldPrintMessage(8,"bar"); returns false;
// logging string "foo" at timestamp 10
logger.shouldPrintMessage(10,"foo"); returns false;
// logging string "foo" at timestamp 11
logger.shouldPrintMessage(11,"foo"); returns true;
Solution (hashtable)
class Logger:
def __init__(self):
"""
Initialize your data structure here.
"""
self.counter = {}
def shouldPrintMessage(self, timestamp: int, message: str) -> bool:
"""
Returns true if the message should be printed in the given timestamp, otherwise returns false.
If this method returns false, the message will not be printed.
The timestamp is in seconds granularity.
"""
if message not in self.counter or self.counter[message] <= timestamp - 10:
self.counter[message] = timestamp
return True
return False
# Your Logger object will be instantiated and called as such:
# obj = Logger()
# param_1 = obj.shouldPrintMessage(timestamp,message)
Solution (deque)
from collections import deque
class Logger:
def __init__(self):
"""
Initialize your data structure here.
"""
self.dq = deque()
self.messages = set()
def shouldPrintMessage(self, timestamp: int, message: str) -> bool:
"""
Returns true if the message should be printed in the given timestamp, otherwise returns false.
If this method returns false, the message will not be printed.
The timestamp is in seconds granularity.
"""
while self.dq and self.dq[0][0] <= timestamp - 10:
self.messages.remove( self.dq.popleft()[1] )
if message in self.messages:
return False
self.messages.add(message)
self.dq.append( [timestamp, message] )
return True
# Your Logger object will be instantiated and called as such:
# obj = Logger()
# param_1 = obj.shouldPrintMessage(timestamp,message)