Wait for confirmations before you call a deposit final
Zero-confirmation deposits can be reversed. A confirmations table with a per-coin threshold makes the wait explicit and the crediting safe.
Tagged “cron”
3 entries
Stop two cron runs from overlapping
A non-blocking file lock in three lines, and why a database flag is the wrong tool for this particular job.
Run a cron job on hosting that has no cron
A key-gated HTTP entry point plus a lock file, so an external pinger can drive your scheduled work without letting anyone else drive it.