api: cache responses (#74)

Co-authored-by: luke miles <[email protected]>

api/proof.go

@@ -55,15 +55,19 @@ func (s *Server) GetProof(w http.ResponseWriter, r *http.Request) {
 	)
 	if errors.Is(err, pgx.ErrNoRows) {
 		s.sendJSONError(r, w, nil, http.StatusNotFound, "tree not found")
+		w.Header().Set("Cache-Control", "public, max-age=60")
 		return
 	} else if err != nil {
 		s.sendJSONError(r, w, err, http.StatusInternalServerError, "selecting proof")
 		return
 	}
 
 	// cache for 1 year if we're returning an unhashed leaf proof
+	// or 60 seconds for an address proof
 	if leaf != "" {
 		w.Header().Set("Cache-Control", "public, max-age=31536000")
+	} else {
+		w.Header().Set("Cache-Control", "public, max-age=60")
 	}
 	s.sendJSON(r, w, resp)
 }

api/root.go

@@ -6,7 +6,6 @@ import (
 	"strings"
 
 	"github.com/ethereum/go-ethereum/common/hexutil"
-	"github.com/jackc/pgx/v4"
 )
 
 func proofURLToDBQuery(param string) string {
@@ -54,15 +53,11 @@ func (s *Server) GetRoot(w http.ResponseWriter, r *http.Request) {
 	roots := make([]hexutil.Bytes, 0)
 	rb := make(hexutil.Bytes, 0)
 
-	_, err := s.db.QueryFunc(ctx, q, []interface{}{dbQuery}, []interface{}{&rb}, func(qfr pgx.QueryFuncRow) error {
-		roots = append(roots, rb)
-		return nil
-	})
-
 	if err != nil {
 		s.sendJSONError(r, w, err, http.StatusInternalServerError, "selecting root")
 		return
 	} else if len(roots) == 0 { // db.QueryFunc doesn't return pgx.ErrNoRows
+		w.Header().Set("Cache-Control", "public, max-age=60")
 		s.sendJSONError(r, w, nil, http.StatusNotFound, "root not found for proofs")
 		return
 	}

api/tree.go

@@ -190,6 +190,7 @@ func (s *Server) GetTree(w http.ResponseWriter, r *http.Request) {
 	)
 	if errors.Is(err, pgx.ErrNoRows) {
 		s.sendJSONError(r, w, nil, http.StatusNotFound, "tree not found for root")
+		w.Header().Set("Cache-Control", "public, max-age=60")
 		return
 	} else if err != nil {
 		s.sendJSONError(r, w, err, http.StatusInternalServerError, "selecting tree")