Simplify the setup code in repo-settings.c in various ways, making the
code shorter, easier to read, and requiring fewer hacks to do the same
thing as it did before:
Since 7211b9e753 (repo-settings: consolidate some config settings,
2019-08-13) we have memset() the whole "settings" structure to -1 in
prepare_repo_settings(), and subsequently relied on the -1 value.
Most of the fields did not need to be initialized to -1, and because
we were doing that we had the enum labels "UNTRACKED_CACHE_UNSET" and
"FETCH_NEGOTIATION_UNSET" purely to reflect the resulting state
created this memset() in prepare_repo_settings(). No other code used
or relied on them, more on that below.
For the rest most of the subsequent "are we -1, then read xyz" can
simply be removed by re-arranging what we read first. E.g. when
setting the "index.version" setting we should have first read
"feature.experimental", so that it (and "feature.manyfiles") can
provide a default for our "index.version".
Instead the code setting it, added when "feature.manyFiles"[1] was
created, was using the UPDATE_DEFAULT_BOOL() macro added in an earlier
commit[2]. That macro is now gone, since it was only needed for this
pattern of reading things in the wrong order.
This also fixes an (admittedly obscure) logic error where we'd
conflate an explicit "-1" value in the config with our own earlier
memset() -1.
We can also remove the UPDATE_DEFAULT_BOOL() wrapper added in
[3]. Using it is redundant to simply using the return value from
repo_config_get_bool(), which is non-zero if the provided key exists
in the config.
Details on edge cases relating to the memset() to -1, continued from
"more on that below" above:
* UNTRACKED_CACHE_KEEP:
In [4] the "unset" and "keep" handling for core.untrackedCache was
consolidated. But it while we understand the "keep" value, we don't
handle it differently than the case of any other unknown value.
So let's retain UNTRACKED_CACHE_KEEP and remove the
UNTRACKED_CACHE_UNSET setting (which was always implicitly
UNTRACKED_CACHE_KEEP before). We don't need to inform any code
after prepare_repo_settings() that the setting was "unset", as far
as anyone else is concerned it's core.untrackedCache=keep. if
"core.untrackedcache" isn't present in the config.
* FETCH_NEGOTIATION_UNSET & FETCH_NEGOTIATION_NONE:
Since these two two enum fields added in [5] don't rely on the
memzero() setting them to "-1" anymore we don't have to provide
them with explicit values.
1. c6cc4c5afd (repo-settings: create feature.manyFiles setting,
2019-08-13)
2. 31b1de6a09 (commit-graph: turn on commit-graph by default,
2019-08-13)
3. 31b1de6a09 (commit-graph: turn on commit-graph by default,
2019-08-13)
4. ad0fb65999 (repo-settings: parse core.untrackedCache,
2019-08-13)
5. aaf633c2ad (repo-settings: create feature.experimental setting,
2019-08-13)
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change tweak_untracked_cache() in "read-cache.c" to use a switch() to
have the compiler assert that we checked all possible values in the
"enum untracked_cache_setting" type, and likewise remove the "default"
case in fetch_negotiator_init() in favor of checking for
"FETCH_NEGOTIATION_UNSET" and "FETCH_NEGOTIATION_NONE".
As will be discussed in a subsequent we'll only ever have either of
these set to FETCH_NEGOTIATION_NONE, FETCH_NEGOTIATION_UNSET and
UNTRACKED_CACHE_UNSET within the prepare_repo_settings() function
itself. In preparation for fixing that code let's add a BUG() here to
mark this as unreachable code.
See ad0fb65999 (repo-settings: parse core.untrackedCache, 2019-08-13)
for when the "unset" and "keep" handling for core.untrackedCache was
consolidated, and aaf633c2ad (repo-settings: create
feature.experimental setting, 2019-08-13) for the addition of the
"default" pattern in "fetch-negotiator.c".
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a noop fetch negotiator. This is introduced to allow partial clones
to skip the unneeded negotiation step when fetching missing objects
using a "git fetch" subprocess. (The implementation of spawning a "git
fetch" subprocess will be done in a subsequent patch.) But this can also
be useful for end users, e.g. as a blunt fix for object corruption.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'feature.experimental' setting includes config options that are
not committed to become defaults, but could use additional testing.
Update the following config settings to take new defaults, and to
use the repo_settings struct if not already using them:
* 'pack.useSparse=true'
* 'fetch.negotiationAlgorithm=skipping'
In the case of fetch.negotiationAlgorithm, the existing logic
would load the config option only when about to use the setting,
so had a die() statement on an unknown string value. This is
removed as now the config is parsed under prepare_repo_settings().
In general, this die() is probably misplaced and not valuable.
A test was removed that checked this die() statement executed.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change the handling of fetch.negotiationAlgorithm=<str> to error out
on unknown strings, i.e. everything except "default" or "skipping".
This changes the behavior added in 42cc7485a2 ("negotiator/skipping:
skip commits during fetch", 2018-07-16) which would ignore all unknown
values and silently fall back to the "default" value.
For a feature like this it's much better to produce an error than
proceed. We don't want users to debug some amazingly slow fetch that
should benefit from "skipping", only to find that they'd forgotten to
deploy the new git version on that particular machine.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Introduce a new negotiation algorithm used during fetch that skips
commits in an effort to find common ancestors faster. The skips grow
similarly to the Fibonacci sequence as the commit walk proceeds further
away from the tips. The skips may cause unnecessary commits to be
included in the packfile, but the negotiation step typically ends more
quickly.
Usage of this algorithm is guarded behind the configuration flag
fetch.negotiationAlgorithm.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Introduce the new files fetch-negotiator.{h,c}, which contains an API
behind which the details of negotiation are abstracted. Currently, only
one algorithm is available: the existing one.
This patch is written to be easily reviewed: static functions are
moved verbatim from fetch-pack.c to negotiator/default.c, and it can be
seen that the lines replaced by negotiator->X() calls are present in the
X() functions respectively.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Ævar Arnfjörð Bjarmason
Jonathan Tan
Derrick Stolee