Race condition on generated filenames using timestamps

[faustinoaq]

Hi @amberframework/contributors This issue is causing Travis Failures

Please, see amberframework/amber#775 (comment)

I suggest to fix it by using incremental names or wait at least 1.millisecond before generate migration file.

[faustinoaq]

The incremental names approach was suggested by @vladfaust on #20

[faustinoaq]

Another approach to solve this, is waiting at least 1.millisecond here before generating a migration file, like:

 sleep 1.millisecond
 migration_file = Micrate.create(ARGV.shift, Time.now, migrations_path) 
 puts "Created #{migration_file}"

on:

micrate/src/micrate/cli.cr

Lines 46 to 47 in 4168d23

	migration_file = Micrate.create(ARGV.shift, Time.now, migrations_path)
	puts "Created #{migration_file}"

WDYT?

[robacarp]

Sleeping before creating the file isn't going to prevent a race condition, it's just going to move it down the road a little bit. Generating a file with a timestamp, no matter how specific that timestamp, is always going to be subject to a race condition. Adding more digits to the migration timestamp isn't the answer either.

What about adding a "does this file exist?" check in the Micrate.create method? That will still be subject to a race condition when multiple migrations are generated concurrently, but running two commands consecutively will be safe.

[faustinoaq]

Interesting idea, Thank you for sharing it, I going to try that as well 😅

[faustinoaq]

Already fixed this on micrate v0.3.1. Still requires to be published on master. I didn't use master because has some breaking changes, so we would need to release micrate v0.4.0

Please see: https://github.com/amberframework/micrate/releases/tag/v0.3.1

[faustinoaq]

Fixed by #33

[eliasjpr]

Is this done? Would like to close this ticket and draft a new release