From 0d4e4bb8c74baac814f7b32a87ac80a0aa7a4088 Mon Sep 17 00:00:00 2001
From: Vlad <13818348+walldiss@users.noreply.github.com>
Date: Fri, 21 Apr 2023 16:49:47 +0800
Subject: [PATCH] refactor(api/gateway) return error from gateway if header is
 not synced yet (#2108)

## Overview

If header was not in header store, gateway would hang until client
context was canceled. PR allows gateway to return an error immediately
in this case.

---------

Co-authored-by: rene <41963722+renaynay@users.noreply.github.com>
---
 api/gateway/availability.go | 15 +++++++++++++++
 api/gateway/header.go       | 14 ++++++++++++++
 api/gateway/share.go        | 18 ++++++++++++++----
 3 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/api/gateway/availability.go b/api/gateway/availability.go
index e5e53e0dba..b35593e24f 100644
--- a/api/gateway/availability.go
+++ b/api/gateway/availability.go
@@ -2,6 +2,7 @@ package gateway
 
 import (
 	"encoding/json"
+	"fmt"
 	"net/http"
 	"strconv"
 
@@ -27,6 +28,20 @@ func (h *Handler) handleHeightAvailabilityRequest(w http.ResponseWriter, r *http
 		return
 	}
 
+	//TODO: change this to NetworkHead once the adjacency in the store is fixed.
+	head, err := h.header.LocalHead(r.Context())
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, heightAvailabilityEndpoint, err)
+		return
+	}
+	if headHeight := int(head.Height()); headHeight < height {
+		err = fmt.Errorf(
+			"current head local chain head: %d is lower than requested height: %d"+
+				" give header sync some time and retry later", headHeight, height)
+		writeError(w, http.StatusServiceUnavailable, heightAvailabilityEndpoint, err)
+		return
+	}
+
 	header, err := h.header.GetByHeight(r.Context(), uint64(height))
 	if err != nil {
 		writeError(w, http.StatusInternalServerError, heightAvailabilityEndpoint, err)
diff --git a/api/gateway/header.go b/api/gateway/header.go
index 50fb058213..88ac3b0923 100644
--- a/api/gateway/header.go
+++ b/api/gateway/header.go
@@ -2,6 +2,7 @@ package gateway
 
 import (
 	"encoding/json"
+	"fmt"
 	"net/http"
 	"strconv"
 
@@ -69,6 +70,19 @@ func (h *Handler) performGetHeaderRequest(
 		writeError(w, http.StatusBadRequest, endpoint, err)
 		return nil, err
 	}
+	//TODO: change this to NetworkHead once the adjacency in the store is fixed.
+	head, err := h.header.LocalHead(r.Context())
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, heightAvailabilityEndpoint, err)
+		return nil, err
+	}
+	if headHeight := int(head.Height()); headHeight < height {
+		err = fmt.Errorf(
+			"current head local chain head: %d is lower than requested height: %d"+
+				" give header sync some time and retry later", headHeight, height)
+		writeError(w, http.StatusServiceUnavailable, endpoint, err)
+		return nil, err
+	}
 	// perform request
 	header, err := h.header.GetByHeight(r.Context(), uint64(height))
 	if err != nil {
diff --git a/api/gateway/share.go b/api/gateway/share.go
index caa1714eef..13903fd14b 100644
--- a/api/gateway/share.go
+++ b/api/gateway/share.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/hex"
 	"encoding/json"
+	"fmt"
 	"net/http"
 	"strconv"
 
@@ -98,10 +99,19 @@ func (h *Handler) getShares(ctx context.Context, height uint64, nID namespace.ID
 		err    error
 		header *header.ExtendedHeader
 	)
-	switch height {
-	case 0:
-		header, err = h.header.LocalHead(ctx)
-	default:
+
+	//TODO: change this to NetworkHead once the adjacency in the store is fixed.
+	header, err = h.header.LocalHead(ctx)
+	if err != nil {
+		return nil, 0, err
+	}
+
+	if height > 0 {
+		if storeHeight := uint64(header.Height()); storeHeight < height {
+			return nil, 0, fmt.Errorf(
+				"current head local chain head: %d is lower than requested height: %d"+
+					" give header sync some time and retry later", storeHeight, height)
+		}
 		header, err = h.header.GetByHeight(ctx, height)
 	}
 	if err != nil {