From 0cb3bcbcb519286e48bccfc51a6367d7867b8969 Mon Sep 17 00:00:00 2001 From: Joey Hess <joeyh@joeyh.name> Date: Mon, 6 Jan 2020 15:29:51 -0400 Subject: [PATCH] comment --- ..._c8232195fa3db718dc2b246d528e6c00._comment | 46 +++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 doc/todo/universal_batch_mode/comment_3_c8232195fa3db718dc2b246d528e6c00._comment diff --git a/doc/todo/universal_batch_mode/comment_3_c8232195fa3db718dc2b246d528e6c00._comment b/doc/todo/universal_batch_mode/comment_3_c8232195fa3db718dc2b246d528e6c00._comment new file mode 100644 index 0000000000..5f694569ab --- /dev/null +++ b/doc/todo/universal_batch_mode/comment_3_c8232195fa3db718dc2b246d528e6c00._comment @@ -0,0 +1,46 @@ +[[!comment format=mdwn + username="joey" + subject="""comment 3""" + date="2020-01-06T18:53:02Z" + content=""" +Thanks for digging that up. + +Hmm, if the goal was to check each command for such problems when adding +--batch, it didn't stop `git-annex add --batch` from being added, despite +indeed having such a buffering behavior. You can currently shoot your foot +combining that with `git annex readpresentkey --batch`, the same way as you +could with a hypothetical universal batch mode that let you run add +followed by readpresentkey. + +I don't see a universal batch mode being really able to detect +and avoid such problems either. How is it supposed to know that an add of +"dir/" will amoung other things add the content of key FOO, which was not +present before, and so a readpresentkey FOO should be delayed until after +the add, and the add's buffer flushed. It would have to model the +behavior of commands and insert barriers/flush points, and the modeling +could necessarily not be that fine-grained, so it would need to flush +the add buffer every time before readpresentkey. But there are surely +ways to combine batch use of add and readpresentkey that you know won't be +affected by the add buffering, and that would make those unncessarily slow. + +Anyway, looking at the implementation of --batch for different commands, +sometimes it's trivial enough to wish it were generalized, but other times +there is batch-specific behavior. `add --batch` errors out if --update +is also used. `checkpresentkey --batch` outputs status codes rather than +the command's normal behavior of exiting 1/0. So we need batch-specific +implementations. + +--- + +idea: What might be good is a mode that lets any batch-capable commands +be combined together, not trying to support every possible command, and +perhaps with some added commands that the user can use to flush buffers +etc between operations as desired. Eg: + + git annex batch <<EOF + add dir/ + add whatever + flush + readpresentkey FOO + EOF +"""]]