From dd210df6abaf97025201ca78fe6b257861a1d685 Mon Sep 17 00:00:00 2001
From: Nurzhan Saktaganov <nurzhan.saktaganov@gmail.com>
Date: Tue, 8 Oct 2024 12:38:37 +0300
Subject: [PATCH] resolve issue #93

* Add a pause between bucketsDiscovery requests (default is 10 ms)
---
 discovery.go |  4 ++++
 vshard.go    | 10 ++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/discovery.go b/discovery.go
index 39c086f..f8b0792 100644
--- a/discovery.go
+++ b/discovery.go
@@ -261,6 +261,10 @@ func (r *Router) DiscoveryAllBuckets(ctx context.Context) error {
 				}
 
 				bucketsDiscoveryPaginationFrom = resp.NextFrom
+
+				// Don't spam many requests at once. Give storages time to handle them and other requests.
+				// https://github.com/tarantool/vshard/blob/b6fdbe950a2e4557f05b83bd8b846b126ec3724e/vshard/router/init.lua#L308
+				time.Sleep(r.cfg.DiscoveryWorkStep)
 			}
 		})
 	}
diff --git a/vshard.go b/vshard.go
index ba3dfbb..214d33f 100644
--- a/vshard.go
+++ b/vshard.go
@@ -93,8 +93,9 @@ type Config struct {
 
 	// Discovery
 	// DiscoveryTimeout is timeout between cron discovery job; by default there is no timeout.
-	DiscoveryTimeout time.Duration
-	DiscoveryMode    DiscoveryMode
+	DiscoveryTimeout  time.Duration
+	DiscoveryWorkStep time.Duration
+	DiscoveryMode     DiscoveryMode
 
 	// BucketsSearchMode defines policy for BucketDiscovery method.
 	// Default value is BucketsSearchLegacy.
@@ -234,6 +235,7 @@ func (r *Router) RouteMapClean() {
 
 func prepareCfg(cfg Config) (Config, error) {
 	const discoveryTimeoutDefault = 1 * time.Minute
+	const discoveryWorkStepDefault = 10 * time.Millisecond
 
 	err := validateCfg(cfg)
 	if err != nil {
@@ -244,6 +246,10 @@ func prepareCfg(cfg Config) (Config, error) {
 		cfg.DiscoveryTimeout = discoveryTimeoutDefault
 	}
 
+	if cfg.DiscoveryWorkStep == 0 {
+		cfg.DiscoveryWorkStep = discoveryWorkStepDefault
+	}
+
 	if cfg.Loggerf == nil {
 		cfg.Loggerf = emptyLogfProvider
 	}