Execution time = mismatch

[Jonob]

I am running a php script that:

-queries a local database to retrieve an amount

-executes a curl statement to update an external database with the amount + x

-queries the local database again to insert a new row

 

One of the problems that I am having is that if I have two different users from the same company running the same script at the same time, the execution time of the curl command (2-4 seconds), can cause a mismatch in what should be updated in the external database. This is the because the curl statement has not yet returned from the first user...so the second user is working off incorrect figures.

 

I am not sure of the best options here.

 

I thought of creating a field in the company table that records when a curl statement is being executed for that company - this flag is to prevent any simultaneous curl statements being executed until a response is received. The flag is automatically reset when a response from curl is received.

 

If another user tries to execute the script then I could check to see if the flag is locked or not. If it is locked, then I could either:

-Loop the the code and sleep for (5) seconds, and then check again if the flag has been reset. If after (3) loops, then reset the flag automatically (i've never seen the curl take longer than 5 seconds) and continue processing; OR

-Just notify the second user that they should wait for (5) seconds before trying again.

 

Are there any other (more elegant) ways of approaching this?

[shadiadiph]

could do function to select row count from the database and before inserting recheck the row count matches. if not return a message has been updated would you like to proceed?