rebase.useBuiltin doc & test mode
A message that is not in the archive (sent off-list or not yet received): [email protected]
v2 cover rebase.useBuiltin doc & test mode
I was missing a "=" in the t/README docs in 2/2 in v1. Also move the docs around slightly so this & my gettext series don't have conflicts.
*** BLURB HERE ***
Ævar Arnfjörð Bjarmason (2):
rebase doc: document rebase.useBuiltin
tests: add a special setup where rebase.useBuiltin is off
Documentation/config/rebase.txt | 14 ++++++++++++++ builtin/rebase.c | 5 ++++- t/README | 4 ++++ 3 files changed, 22 insertions(+), 1 deletion(-)
Range-diff:
1: a5508195c6 ! 1: ca87aacbfa tests: add a special setup where rebase.useBuiltin is off
@@ -29,12 +29,13 @@
--- a/t/README
+++ b/t/README
@@
- index to be written after every 'git repack' command, and overrides the
- 'core.multiPackIndex' setting to true.
+ GIT_TEST_PRELOAD_INDEX=<boolean> exercises the preload-index code path
+ by overriding the minimum number of cache entries required per thread.
-+GIT_TEST_REBASE_USE_BUILTIN<boolean>, when false, disables the builtin -+version of git-rebase. See 'rebase.useBuiltin' in git-config(1). ++GIT_TEST_REBASE_USE_BUILTIN=<boolean>, when false, disables the ++builtin version of git-rebase. See 'rebase.useBuiltin' in ++git-config(1).
+
- Naming Tests
- ------------
-
+ GIT_TEST_INDEX_THREADS=<n> enables exercising the multi-threaded loading
+ of the index for the whole test suite by bypassing the default number of
+ cache entries and thread minimums. Setting this to 1 will make the
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2.19.1.1182.g4ecb1133ce
PATCH v2 1/2 rebase doc: document rebase.useBuiltin
In reply to a message not in the archiveThe rebase.useBuiltin variable introduced in 55071ea248 ("rebase:
start implementing it as a builtin", 2018-08-07) was turned on by default in 5541bd5b8f ("rebase: default to using the builtin rebase", 2018-08-08), but had no documentation.
Let's document it so that users who run into any stability issues with the C rewrite know there's an escape hatch[1], and make it clear that needing to turn off builtin rebase means you've found a bug in git.
1. https://public-inbox.org/git/[email protected]/
--- Documentation/config/rebase.txt | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
Documentation/config/rebase.txt +14 -0
@@ -1,3 +1,17 @@ +rebase.useBuiltin:: + Set to `false` to use the legacy shellscript implementation of + linkgit:git-rebase[1]. Is `true` by default, which means use + the built-in rewrite of it in C. ++ +The C rewrite is first included with Git version 2.20. This option +serves an an escape hatch to re-enable the legacy version in case any +bugs are found in the rewrite. This option and the shellscript version +of linkgit:git-rebase[1] will be removed in some future release. ++ +If you find some reason to set this option to `false` other than +one-off testing you should report the behavior difference as a bug in +git. + rebase.stat:: Whether to show a diffstat of what changed upstream since the last rebase. False by default.
Signature · 1 line
2.19.1.1182.g4ecb1133ce
Re: [PATCH v2 1/2] rebase doc: document rebase.useBuiltin
Hi Ævar,
Quoted 5 lines · Ævar Arnfjörð Bjarmason
The rebase.useBuiltin variable introduced in
55071ea248("rebase:
start implementing it as a builtin", 2018-08-07) was turned on by default in5541bd5b8f("rebase: default to using the builtin rebase", 2018-08-08), but had no documentation.
Quoted 7 lines
Let's document it so that users who run into any stability issues with the C rewrite know there's an escape hatch[1], and make it clear that needing to turn off builtin rebase means you've found a bug in git.
1. https://public-inbox.org/git/[email protected]/
Signed-off-by Ævar Arnfjörð Bjarmason <[email protected]>
Makes sense.
Thanks,
Dscho
Quoted 30 lines
--- Documentation/config/rebase.txt | 14 ++++++++++++++ 1 file changed, 14 insertions(+)Documentation/config/rebase.txt +14
-0@@ -1,3 +1,17 @@ +rebase.useBuiltin:: + Set to `false` to use the legacy shellscript implementation of + linkgit:git-rebase[1]. Is `true` by default, which means use + the built-in rewrite of it in C. ++ +The C rewrite is first included with Git version 2.20. This option +serves an an escape hatch to re-enable the legacy version in case any +bugs are found in the rewrite. This option and the shellscript version +of linkgit:git-rebase[1] will be removed in some future release. ++ +If you find some reason to set this option to `false` other than +one-off testing you should report the behavior difference as a bug in +git. + rebase.stat:: Whether to show a diffstat of what changed upstream since the last rebase. False by default.Signature · 1 line
2.19.1.1182.g4ecb1133ce
Re: [PATCH v2 1/2] rebase doc: document rebase.useBuiltin
In reply to Ævar Arnfjörð BjarmasonQuoted 4 lines · Ævar Arnfjörð Bjarmason
The rebase.useBuiltin variable introduced in
55071ea248("rebase:
start implementing it as a builtin", 2018-08-07) was turned on by default in5541bd5b8f("rebase: default to using the builtin rebase", 2018-08-08), but had no documentation.
I actually thought that everybody understood that this was merely an aid to be used during the development of the feature and never meant to be given to the end users.
With my devil's advocate hat on, how much do we trust it as an escape hatch? After all, the codepath to hide the "rebase in C" implementation and use the scripted version were never in 'master' (or 'next' for that matter) with this variable turned off, so I am reasonably sure it had no serious exposure to real world usage.
Having said that, assuming that the switching back to scripted version works correctly and assuming that we want to expose this to end users, I think the patch text makes sense.
Thanks.
Quoted 33 lines
Let's document it so that users who run into any stability issues with the C rewrite know there's an escape hatch[1], and make it clear that needing to turn off builtin rebase means you've found a bug in git.
1. https://public-inbox.org/git/[email protected]/
Signed-off-by Ævar Arnfjörð Bjarmason <[email protected]>--- Documentation/config/rebase.txt | 14 ++++++++++++++ 1 file changed, 14 insertions(+)Documentation/config/rebase.txt +14
-0@@ -1,3 +1,17 @@ +rebase.useBuiltin:: + Set to `false` to use the legacy shellscript implementation of + linkgit:git-rebase[1]. Is `true` by default, which means use + the built-in rewrite of it in C. ++ +The C rewrite is first included with Git version 2.20. This option +serves an an escape hatch to re-enable the legacy version in case any +bugs are found in the rewrite. This option and the shellscript version +of linkgit:git-rebase[1] will be removed in some future release. ++ +If you find some reason to set this option to `false` other than +one-off testing you should report the behavior difference as a bug in +git. + rebase.stat:: Whether to show a diffstat of what changed upstream since the last rebase. False by default.
Re: [PATCH v2 1/2] rebase doc: document rebase.useBuiltin
Hi Junio,
Quoted 10 lines · Junio C Hamano
Quoted 4 lines · Ævar Arnfjörð Bjarmason
The rebase.useBuiltin variable introduced in
55071ea248("rebase:
start implementing it as a builtin", 2018-08-07) was turned on by default in5541bd5b8f("rebase: default to using the builtin rebase", 2018-08-08), but had no documentation.I actually thought that everybody understood that this was merely an aid to be used during the development of the feature and never meant to be given to the end users.
It may have been from git.git's point of view, but from Git for Windows' point of view it was always meant to be a real feature flag.
Quoted 2 lines
With my devil's advocate hat on, how much do we trust it as an escape hatch?
As you know, only a fraction of the bug reports about the built-in rebase came in from Git for Windows: the autostash-with-submodules bug and the perf-regression one. By my counting that is 2 out of 5 bugs coming in via that route.
One of the reasons for that was that the built-in rebase that was shipped in Git for Windows v2.19.1 was marked as experimental.
And the way I could mark it experimental was by flipping the default to executing the scripted version:
https://github.com/git-for-windows/git/commit/cff1a96cfe (you will note that I added the same escape hatch for git stash by adding back git-stash.sh as git-legacy-stash.sh and imitating the same dance as for built-in rebase, and I also added back the scripted git-rebase--interactive.sh for use by git-legacy-rebase.sh).
Meaning: essentially, rebase.useBuiltin was defaulting to false, and if a user installed Git for Windows with the experimental built-in rebase, it was set to true in the system config.
There was not a single complaint about the scripted git rebase being broken in any way.
So we *do* have some real-world testing of that feature. (Obviously I have no numbers about Git for Windows' usage, apart from download numbers, and they do not say how many users opted in and how many did not, but Git for Windows v2.19.1 was downloaded more than 2.7 million times so far and I think it is safe to assume that some percentage tested that feature.)
Quoted 4 lines
After all, the codepath to hide the "rebase in C" implementation and use the scripted version were never in 'master' (or 'next' for that matter) with this variable turned off, so I am reasonably sure it had no serious exposure to real world usage.
See above for a counter-argument.
Quoted 3 lines
Having said that, assuming that the switching back to scripted version works correctly and assuming that we want to expose this to end users, I think the patch text makes sense.
Indeed.
I would still love to see the built-in rebase to be used by default in v2.20.0, and I am reasonably sure that the escape hatch works (because, as I told you above, it worked in the reverse, making the built-in rebase an opt-in in Git for Windows v2.19.1).
Ciao,
Dscho
Re: [PATCH v2 1/2] rebase doc: document rebase.useBuiltin
Quoted 3 lines · Johannes Schindelin
Meaning: essentially,
rebase.useBuiltinwas defaulting tofalse, and if a user installed Git for Windows with the experimental built-in rebase, it was set totruein the system config.
Oh, that changes the picture entirely. If that was what was shipped to Windows users for 2.19.X, then I'd say we should be able to trust the switch well enough. I just somehow thought that everybody in the Windows land has been using the -in-C version.
Quoted 10 lines
Quoted 3 lines
Having said that, assuming that the switching back to scripted version works correctly and assuming that we want to expose this to end users, I think the patch text makes sense.
Indeed.
I would still love to see the built-in rebase to be used by default in v2.20.0, and I am reasonably sure that the escape hatch works (because, as I told you above, it worked in the reverse, making the built-in rebase an opt-in in Git for Windows v2.19.1).
Good. That makes things a lot simpler.
Thanks.
PATCH v2 2/2 tests: add a special setup where rebase.useBuiltin is off
In reply to a message not in the archiveAdd a GIT_TEST_REBASE_USE_BUILTIN=false test mode which is equivalent to running with rebase.useBuiltin=false. This is needed to spot that we're not introducing any regressions in the legacy rebase version while we're carrying both it and the new builtin version.
--- builtin/rebase.c | 5 ++++- t/README | 4 ++++ 2 files changed, 8 insertions(+), 1 deletion(-)
builtin/rebase.c +4 -1
@@ -48,7 +48,10 @@ static int use_builtin_rebase(void) {struct child_process cp =CHILD_PROCESS_INIT ;struct strbuf out =STRBUF_INIT ; -int ret; +int ret, env =git_env_bool ("GIT_TEST_REBASE_USE_BUILTIN" ,-1 ); + +if (env !=-1 ) +return env;argv_array_pushl (&cp.args,"config" ,"--bool" ,"rebase.usebuiltin" ,NULL );
t/README +4 -0
@@ -339,6 +339,10 @@ for the index version specified. Can be set to any valid version GIT_TEST_PRELOAD_INDEX=<boolean> exercises the preload-index code path by overriding the minimum number of cache entries required per thread. +GIT_TEST_REBASE_USE_BUILTIN=<boolean>, when false, disables the +builtin version of git-rebase. See 'rebase.useBuiltin' in +git-config(1). + GIT_TEST_INDEX_THREADS=<n> enables exercising the multi-threaded loading of the index for the whole test suite by bypassing the default number of cache entries and thread minimums. Setting this to 1 will make the
Signature · 1 line
2.19.1.1182.g4ecb1133ce
Re: [PATCH v2 2/2] tests: add a special setup where rebase.useBuiltin is off
Hi Ævar,
Quoted 10 lines · Ævar Arnfjörð Bjarmason
Add a GIT_TEST_REBASE_USE_BUILTIN=false test mode which is equivalent to running with rebase.useBuiltin=false. This is needed to spot that we're not introducing any regressions in the legacy rebase version while we're carrying both it and the new builtin version.
Signed-off-by Ævar Arnfjörð Bjarmason <[email protected]>--- builtin/rebase.c | 5 ++++- t/README | 4 ++++ 2 files changed, 8 insertions(+), 1 deletion(-)
I am slightly surprised not to see any ci/ change in this diffstat. Did you mean to add a test axis for Travis, or not?
Ciao,
Dscho
Quoted 36 lines
builtin/rebase.c +4
-1@@ -48,7 +48,10 @@ static int use_builtin_rebase(void) {struct child_process cp =CHILD_PROCESS_INIT ;struct strbuf out =STRBUF_INIT ; -int ret; +int ret, env =git_env_bool ("GIT_TEST_REBASE_USE_BUILTIN" ,-1 ); + +if (env !=-1 ) +return env;argv_array_pushl (&cp.args,"config" ,"--bool" ,"rebase.usebuiltin" ,NULL );t/README +4
-0@@ -339,6 +339,10 @@ for the index version specified. Can be set to any valid version GIT_TEST_PRELOAD_INDEX=<boolean> exercises the preload-index code path by overriding the minimum number of cache entries required per thread. +GIT_TEST_REBASE_USE_BUILTIN=<boolean>, when false, disables the +builtin version of git-rebase. See 'rebase.useBuiltin' in +git-config(1). + GIT_TEST_INDEX_THREADS=<n> enables exercising the multi-threaded loading of the index for the whole test suite by bypassing the default number of cache entries and thread minimums. Setting this to 1 will make theSignature · 1 line
2.19.1.1182.g4ecb1133ce
Re: [PATCH v2 2/2] tests: add a special setup where rebase.useBuiltin is off
Quoted 9 lines · Johannes Schindelin
Hi Ævar,
Quoted 5 lines · Ævar Arnfjörð Bjarmason
Add a GIT_TEST_REBASE_USE_BUILTIN=false test mode which is equivalent to running with rebase.useBuiltin=false. This is needed to spot that we're not introducing any regressions in the legacy rebase version while we're carrying both it and the new builtin version.
Quoted 8 lines
Quoted 5 lines
Signed-off-by Ævar Arnfjörð Bjarmason <[email protected]>--- builtin/rebase.c | 5 ++++- t/README | 4 ++++ 2 files changed, 8 insertions(+), 1 deletion(-)I am slightly surprised not to see any ci/ change in this diffstat. Did you mean to add a test axis for Travis, or not?
No, but that's a logical follow-up by someone more familiar with the CI setup. I'm using this so I can test versions of "next" when building my own package.