Time warp and the question of flipping the graph

Colin Clark colinbdclark at gmail.com
Thu May 19 21:10:51 UTC 2011

Hi everyone,

This afternoon, I forgot to include the --no-ff flag when merging Mike's FLUID-4243 branch into the project repo. This caused the graph to "flip." Justin kindly walked me through the steps to fix it, which involved deleting the master branch in the project repo and replacing it with a version that had been reset to the point immediately prior to my merge.

The result, however, was an unbelievably massive commit message to fluid-commits documenting every change to Infusion since its inception in 2007. If you're feeling nostalgic, have a look. If not, avoid it. It caused my email client to thrash for a good 30 seconds.

The more I think about this, the more the fix seems wrong. It's an easy mistake to make--virtually any time you forget the "no fast forwards" flag, you'll cause the graph to flip. The fix is really brute force--we're basically invalidating our shared definition of the master branch is and replacing it with an individual one, forcing everyone to update all their branches to match. It takes time, and it's a really high cost thing.

Are we sure we want to keep doing a fix like this when people flip the graph, or the graph flip something we can live with from time to time?


Colin Clark
Technical Lead, Fluid Project

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