perf(git/repo): cache ref/file lookups, invalidate on status refresh

lua/git/repo.lua

@@ -35,6 +35,7 @@ local global = util.Emitter.new()
 ---@field private _watcher? uv.uv_fs_event_t
 ---@field private _schedule_refresh fun(self: ow.Git.Repo)
 ---@field private _refresh_handle ow.Git.Util.DebounceHandle
+---@field private _cache table<string, any>
 local Repo = {}
 Repo.__index = Repo
 
@@ -56,6 +57,7 @@ function Repo:_fetch_status()
         STATUS_CMD,
         { cwd = self.worktree, text = true },
         vim.schedule_wrap(function(obj)
+            self._cache = {}
             if obj.code ~= 0 then
                 util.error("git status failed: %s", vim.trim(obj.stderr or ""))
                 return
@@ -82,6 +84,7 @@ function Repo.new(gitdir, worktree)
         tabs = {},
         status = status.parse(""),
         _events = util.Emitter.new(),
+        _cache = {},
     }, Repo)
     self._schedule_refresh, self._refresh_handle =
         util.debounce(Repo._fetch_status, 50)
@@ -90,6 +93,20 @@ function Repo.new(gitdir, worktree)
     return self
 end
 
+---@generic T
+---@param key string
+---@param compute fun(self: ow.Git.Repo): T
+---@return T
+function Repo:get_cached(key, compute)
+    local hit = self._cache[key]
+    if hit ~= nil then
+        return hit
+    end
+    local value = compute(self)
+    self._cache[key] = value
+    return value
+end
+
 function Repo:start_watcher()
     local watcher, err = vim.uv.new_fs_event()
     if not watcher then
@@ -168,18 +185,20 @@ end
 
 ---@return string[]
 function Repo:list_refs()
-    local out = util.exec({
-        "git",
-        "for-each-ref",
-        "--format=%(refname:short)",
-        "refs/heads",
-        "refs/tags",
-        "refs/remotes",
-    }, { cwd = self.worktree, silent = true })
-    if not out then
-        return {}
-    end
-    return util.split_lines(out)
+    return self:get_cached("refs", function(self)
+        local out = util.exec({
+            "git",
+            "for-each-ref",
+            "--format=%(refname:short)",
+            "refs/heads",
+            "refs/tags",
+            "refs/remotes",
+        }, { cwd = self.worktree, silent = true })
+        if not out then
+            return {}
+        end
+        return util.split_lines(out)
+    end)
 end
 
 local PSEUDO_REFS = {
@@ -194,31 +213,35 @@ local PSEUDO_REFS = {
 
 ---@return string[]
 function Repo:list_pseudo_refs()
-    local refs = {}
-    for _, name in ipairs(PSEUDO_REFS) do
-        if name == "HEAD" or vim.uv.fs_stat(self.gitdir .. "/" .. name) then
-            table.insert(refs, name)
+    return self:get_cached("pseudo_refs", function(self)
+        local refs = {}
+        for _, name in ipairs(PSEUDO_REFS) do
+            if name == "HEAD" or vim.uv.fs_stat(self.gitdir .. "/" .. name) then
+                table.insert(refs, name)
+            end
         end
-    end
-    return refs
+        return refs
+    end)
 end
 
 ---@return string[]
 function Repo:list_stash_refs()
-    if not vim.uv.fs_stat(self.gitdir .. "/refs/stash") then
-        return {}
-    end
-    local refs = { "stash" }
-    local out = util.exec(
-        { "git", "stash", "list", "--pretty=format:%gd" },
-        { cwd = self.worktree, silent = true }
-    )
-    if out then
-        for _, entry in ipairs(util.split_lines(out)) do
-            table.insert(refs, entry)
+    return self:get_cached("stash_refs", function(self)
+        if not vim.uv.fs_stat(self.gitdir .. "/refs/stash") then
+            return {}
         end
-    end
-    return refs
+        local refs = { "stash" }
+        local out = util.exec(
+            { "git", "stash", "list", "--pretty=format:%gd" },
+            { cwd = self.worktree, silent = true }
+        )
+        if out then
+            for _, entry in ipairs(util.split_lines(out)) do
+                table.insert(refs, entry)
+            end
+        end
+        return refs
+    end)
 end
 
 ---@param rev string