Question

I have a python script that gets data from a USB weather station, now it puts the data into MySQL whenever the data is received from the station.

I have a MySQL class with an insert function, what i want i that the function checks if it has been run the last 5 minutes if it has, quit.

Could not find any code on the internet that does this.

Maybe I need to have a sub-process, but I am not familiar with that at all.

Does anyone have an example that I can use?

Answer 1

Probably the most straight-forward approach (you can put this into a decorator if you like, but that’s just cosmetics I think):

import time
import datetime

class MySQLWrapper:
  def __init__(self, min_period_seconds):
    self.min_period = datetime.timedelta(seconds=min_period_seconds)
    self.last_calltime = datetime.datetime.now() - self.min_period
  def insert(self, item):
    now = datetime.datetime.now()
    if now-self.last_calltime < self.min_period:
      print "not insert"
    else:
     self.last_calltime = now
     print "insert", item

m = MySQLWrapper(5)
m.insert(1) # insert 1
m.insert(2) # not insert
time.sleep(5)
m.insert(3) # insert 3

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As a side-note: Have you noticed RRDTool during your web-search for related stuff? It does apparantly what you want to achieve, i.e.

• a database to store the most recent values of arbitrary resolution/update frequency.
• extrapolation/interpolation of values if updates are too frequent or missing.
• generates graphs from the data.

An approach could be to store all data you can get into your MySQL database and forward a subset to such RRDTool database to generate a nice time series visualization of it. Depending on what you might need.