Gregory's Serverdoing something exactly once is basically impossible
better to do it at least once and make the thing support being run more than once (idempotency)
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Top-level
 2 comments
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Top-level
doing something exactly once is basically impossible 2 comments
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a basic strategy (write-ahead-logging) is
- write to disk that you're going to do thing A with parameters B -- ensure this itself is fault tolerant eg with sqlite
- once the log is committed, you can safely return to the caller. don't return before then
- do the thing A with B
- report results
- remove the log entry
finally, on program startup, go through the current log and do everything in it
a basic strategy (write-ahead-logging) is
- write to disk that you're going to do thing A with parameters B -- ensure this itself is fault tolerant eg with sqlite
- once the log is committed, you can safely return to the caller. don't return before then
- do the thing A with B
- report results
- remove the log entry