Use db.ListOptions directly instead of Paginator interface to make it easier to use and fix performance of /pulls and /issues (#29990)

This PR uses `db.ListOptions` instead of `Paginor` to make the code
simpler.
And it also fixed the performance problem when viewing /pulls or
/issues. Before the counting in fact will also do the search.

---------

Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: silverwind <me@silverwind.io>

models/issues/issue_search.go

@@ -21,7 +21,7 @@ import (
 
 // IssuesOptions represents options of an issue.
 type IssuesOptions struct { //nolint
-	db.Paginator
+	Paginator          *db.ListOptions
 	RepoIDs            []int64 // overwrites RepoCond if the length is not 0
 	AllPublic          bool    // include also all public repositories
 	RepoCond           builder.Cond
@@ -104,23 +104,11 @@ func applyLimit(sess *xorm.Session, opts *IssuesOptions) *xorm.Session {
 		return sess
 	}
 
-	// Warning: Do not use GetSkipTake() for *db.ListOptions
-	// Its implementation could reset the page size with setting.API.MaxResponseItems
-	if listOptions, ok := opts.Paginator.(*db.ListOptions); ok {
-		if listOptions.Page >= 0 && listOptions.PageSize > 0 {
-			var start int
-			if listOptions.Page == 0 {
-				start = 0
-			} else {
-				start = (listOptions.Page - 1) * listOptions.PageSize
-			}
-			sess.Limit(listOptions.PageSize, start)
-		}
-		return sess
+	start := 0
+	if opts.Paginator.Page > 1 {
+		start = (opts.Paginator.Page - 1) * opts.Paginator.PageSize
 	}
-
-	start, limit := opts.Paginator.GetSkipTake()
-	sess.Limit(limit, start)
+	sess.Limit(opts.Paginator.PageSize, start)
 
 	return sess
 }

models/issues/issue_stats.go

@@ -68,13 +68,17 @@ func CountIssuesByRepo(ctx context.Context, opts *IssuesOptions) (map[int64]int6
 }
 
 // CountIssues number return of issues by given conditions.
-func CountIssues(ctx context.Context, opts *IssuesOptions) (int64, error) {
+func CountIssues(ctx context.Context, opts *IssuesOptions, otherConds ...builder.Cond) (int64, error) {
 	sess := db.GetEngine(ctx).
 		Select("COUNT(issue.id) AS count").
 		Table("issue").
 		Join("INNER", "repository", "`issue`.repo_id = `repository`.id")
 	applyConditions(sess, opts)
 
+	for _, cond := range otherConds {
+		sess.And(cond)
+	}
+
 	return sess.Count()
 }