The revision walker machinery learned to take advantage of the
commit generation numbers stored in the commit-graph file.
* ds/reachable-topo-order:
t6012: make rev-list tests more interesting
revision.c: generation-based topo-order algorithm
commit/revisions: bookkeeping before refactoring
revision.c: begin refactoring --topo-order logic
test-reach: add rev-list tests
test-reach: add run_three_modes method
prio-queue: add 'peek' operation
The get_reachable_subset() method returns the list of commits in
the 'to' array that are reachable from at least one commit in the
'from' array. Add tests that check this method works in a few
cases:
1. All commits in the 'to' list are reachable. This exercises the
early-termination condition.
2. Some commits in the 'to' list are reachable. This exercises the
loop-termination condition.
3. No commits in the 'to' list are reachable. This exercises the
NULL return condition.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The rev-list command is critical to Git's functionality. Ensure it
works in the three commit-graph environments constructed in
t6600-test-reach.sh. Here are a few important types of rev-list
operations:
* Basic: git rev-list --topo-order HEAD
* Range: git rev-list --topo-order compare..HEAD
* Ancestry: git rev-list --topo-order --ancestry-path compare..HEAD
* Symmetric Difference: git rev-list --topo-order compare...HEAD
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'test_three_modes' method assumes we are using the 'test-tool
reach' command for our test. However, we may want to use the data
shape of our commit graph and the three modes (no commit-graph,
full commit-graph, partial commit-graph) for other git commands.
Split test_three_modes to be a simple translation on a more general
run_three_modes method that executes the given command and tests
the actual output to the expected output.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The can_all_from_reach_with_flag() algorithm was refactored in 4fbcca4e
"commit-reach: make can_all_from_reach... linear" but incorrectly
assumed that all objects provided were commits. During a fetch
negotiation, ok_to_give_up() in upload-pack.c may provide unpeeled tags
to the 'from' array. The current code creates a segfault.
Add a direct call to can_all_from_reach_with_flag() in 'test-tool reach'
and add a test in t6600-test-reach.sh that demonstrates this segfault.
Correct the issue by peeling tags when investigating the initial list
of objects in the 'from' array.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The commit_contains method has two modes which depend on the given
ref_filter struct. We have the "normal" algorithm (which is also the
typically-slow operation) and the "tag" algorithm. This difference is
essentially what changes performance for 'git branch --contains' versus
'git tag --contains'. There are thoughts that the data shapes used by
these two applications justify the different implementations.
Create tests using 'test-tool reach commit_contains [--tag]' to cover
both methods.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The can_all_from_reach_with_flags method is used by ok_to_give_up in
upload-pack.c to see if we have done enough negotiation during a fetch.
This method is intentionally created to preserve state between calls to
assist with stateful negotiation, such as over SSH.
To make this method testable, add a new can_all_from_reach method that
does the initial setup and final tear-down. We will later use this
method in production code. Call the method from 'test-tool reach' for
now.
Since this is a many-to-many reachability query, add a new type of input
to the 'test-tool reach' input format. Lines "Y:<committish>" create a
list of commits to be the reachability targets from the commits in the
'X' list. In the context of fetch negotiation, the 'X' commits are the
'want' commits and the 'Y' commits are the 'have' commits.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The get_merge_bases_many method returns a list of merge bases for a
single commit (A) against a list of commits (X). Some care is needed in
constructing the expected behavior because the result is not the
expected merge-base for an octopus merge with those parents but instead
the set of maximal commits that are reachable from A and at least one of
the commits in X.
Add get_merge_bases_many to 'test-tool reach' and create a test that
demonstrates that this output returns multiple results. Specifically, we
select a list of three commits such that we output two commits that are
reachable from one of the first two, respectively, and none are
reachable from the third.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The is_descendant_of method takes a single commit as its first parameter
and a list of commits as its second parameter. Extend the input of the
'test-tool reach' command to take multiple lines of the form
"X:<committish>" to construct a list of commits. Pass these to
is_descendant_of and create tests that check each result.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As we prepare to change the behavior of the algorithms in
commit-reach.c, create a new test-tool subcommand 'reach' to test these
methods on interesting commit-graph shapes.
To use the new test-tool, use 'test-tool reach <method>' and provide
input to stdin that describes the inputs to the method. Currently, we
only implement the ref_newer method, which requires two commits. Use
lines "A:<committish>" and "B:<committish>" for the two inputs. We will
expand this input later to accommodate methods that take lists of
commits.
The test t6600-test-reach.sh creates a repo whose commits form a
two-dimensional grid. This grid makes it easy for us to determine
reachability because commit-A-B can reach commit-X-Y if and only if A is
at least X and B is at least Y. This helps create interesting test cases
for each result of the methods in commit-reach.c.
We test all methods in three different states of the commit-graph file:
Non-existent (no generation numbers), fully computed, and mixed (some
commits have generation numbers and others do not).
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
