support for the --max-candidates flag (#298)

git-repository/src/commit.rs

@@ -116,6 +116,7 @@ pub mod describe {
         pub(crate) select: SelectRef,
         pub(crate) first_parent: bool,
         pub(crate) id_as_fallback: bool,
+        pub(crate) max_candidates: usize,
     }
 
     impl<'repo> Platform<'repo> {
@@ -131,6 +132,12 @@ pub mod describe {
             self
         }
 
+        /// Only consider the given amount of candidates, instead of the default of 10.
+        pub fn max_candidates(mut self, candidates: usize) -> Self {
+            self.max_candidates = candidates;
+            self
+        }
+
         /// If true, even if no candidate is available a format will always be produced.
         pub fn id_as_fallback(mut self, use_fallback: bool) -> Self {
             self.id_as_fallback = use_fallback;
@@ -158,6 +165,7 @@ pub mod describe {
                     name_by_oid: self.select.names(self.repo)?,
                     fallback_to_oid: self.id_as_fallback,
                     first_parent: self.first_parent,
+                    max_candidates: self.max_candidates,
                     ..Default::default()
                 },
             )?;

git-repository/src/object/commit.rs

@@ -134,6 +134,7 @@ impl<'repo> Commit<'repo> {
             select: Default::default(),
             first_parent: false,
             id_as_fallback: false,
+            max_candidates: 10,
         }
     }
 }

git-revision/src/describe.rs

@@ -104,7 +104,7 @@ pub struct Options<'name> {
     pub name_by_oid: hash_hasher::HashedMap<git_hash::ObjectId, Cow<'name, BStr>>,
     /// The amount of names we will keep track of. Defaults to the maximum of 32.
     ///
-    /// If the number is exceeded, it will be capped at 32.
+    /// If the number is exceeded, it will be capped at 32 and defaults to 10.
     pub max_candidates: usize,
     /// If no candidate for naming, always show the abbreviated hash. Default: false.
     pub fallback_to_oid: bool,
@@ -117,7 +117,7 @@ pub struct Options<'name> {
 impl<'name> Default for Options<'name> {
     fn default() -> Self {
         Options {
-            max_candidates: 28, // the same number as git uses, otherwise we perform worse by default on big repos
+            max_candidates: 10, // the same number as git uses, otherwise we perform worse by default on big repos
             name_by_oid: Default::default(),
             fallback_to_oid: false,
             first_parent: false,

gitoxide-core/src/repository/commit.rs

@@ -13,6 +13,7 @@ pub fn describe(
         first_parent,
         always,
         statistics,
+        max_candidates,
         long_format,
     }: describe::Options,
 ) -> Result<()> {
@@ -34,6 +35,7 @@ pub fn describe(
         .names(select_ref)
         .traverse_first_parent(first_parent)
         .id_as_fallback(always)
+        .max_candidates(max_candidates)
         .try_resolve()?
         .with_context(|| format!("Did not find a single candidate ref for naming id '{}'", commit.id))?;
 
@@ -57,5 +59,6 @@ pub mod describe {
         pub always: bool,
         pub long_format: bool,
         pub statistics: bool,
+        pub max_candidates: usize,
     }
 }

src/plumbing/main.rs

@@ -165,6 +165,7 @@ pub fn main() -> Result<()> {
                     always,
                     long,
                     statistics,
+                    max_candidates,
                     rev_spec,
                 } => prepare_and_run(
                     "repository-commit-describe",
@@ -184,6 +185,7 @@ pub fn main() -> Result<()> {
                                 long_format: long,
                                 first_parent,
                                 statistics,
+                                max_candidates,
                                 always,
                             },
                         )

src/plumbing/options.rs

@@ -411,6 +411,10 @@ pub mod repo {
                 #[clap(long, short = 'l')]
                 long: bool,
 
+                /// Consider only the given `n` candidates. This can take longer, but potentially produces more accurate results.
+                #[clap(long, short = 'c', default_value = "10")]
+                max_candidates: usize,
+
                 /// Print information on stderr to inform about performance statistics
                 #[clap(long, short = 's')]
                 statistics: bool,