From fc00138b9064be7bd43deafba72a622d560e156d Mon Sep 17 00:00:00 2001
From: soffokl <soffokulus@gmail.com>
Date: Fri, 5 Apr 2024 10:19:30 +0600
Subject: [PATCH] Do not lock hermes caller while doing slow http requests

It's required to lock only for small period of time to update cache.
Sometimes http requests might be very slow and we don't need to block for many seconds preventing other goroutines to work.
---
 session/pingpong/hermes_caller.go | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/session/pingpong/hermes_caller.go b/session/pingpong/hermes_caller.go
index aa879b891e..d188204621 100644
--- a/session/pingpong/hermes_caller.go
+++ b/session/pingpong/hermes_caller.go
@@ -32,6 +32,7 @@ import (
 
 	"github.com/cenkalti/backoff/v4"
 	"github.com/ethereum/go-ethereum/common"
+
 	"github.com/mysteriumnetwork/node/identity"
 	"github.com/mysteriumnetwork/node/requests"
 	"github.com/mysteriumnetwork/payments/crypto"
@@ -106,7 +107,7 @@ type HermesCaller struct {
 // hermesCallerCache represents the cache for call responses
 type hermesCallerCache struct {
 	data map[string]hermesCallerCacheData
-	lock sync.Mutex
+	lock sync.RWMutex
 }
 
 // hermesCallerCacheData represents the cache data
@@ -311,8 +312,6 @@ func (ac *HermesCaller) RefreshLatestProviderPromise(chainID int64, id string, h
 
 // GetConsumerData gets consumer data from hermes, use a negative cacheTime to force update
 func (ac *HermesCaller) GetConsumerData(chainID int64, id string, cacheTime time.Duration) (HermesUserInfo, error) {
-	ac.cache.lock.Lock()
-	defer ac.cache.lock.Unlock()
 	if cacheTime > 0 {
 		cachedResponse, cachedError, ok := ac.getResponseFromCache(chainID, id, cacheTime)
 		if ok {
@@ -327,12 +326,8 @@ func (ac *HermesCaller) GetConsumerData(chainID int64, id string, cacheTime time
 	err = ac.doRequest(req, &resp)
 	if err != nil {
 		if errors.Is(err, ErrHermesNotFound) {
-			//also save not found status
-			ac.cache.data[getCacheKey(chainID, id)] = hermesCallerCacheData{
-				updatedAt: time.Now(),
-				info:      nil,
-				err:       err,
-			}
+			// also save not found status
+			ac.setCacheData(chainID, id, nil, err)
 		}
 		return HermesUserInfo{}, fmt.Errorf("could not request consumer data from hermes: %w", err)
 	}
@@ -347,13 +342,20 @@ func (ac *HermesCaller) GetConsumerData(chainID int64, id string, cacheTime time
 		return HermesUserInfo{}, fmt.Errorf("could not check promise validity: %w", err)
 	}
 
+	ac.setCacheData(chainID, id, &data, nil)
+
+	return data, nil
+}
+
+func (ac *HermesCaller) setCacheData(chainID int64, id string, data *HermesUserInfo, err error) {
+	ac.cache.lock.Lock()
+	defer ac.cache.lock.Unlock()
+
 	ac.cache.data[getCacheKey(chainID, id)] = hermesCallerCacheData{
 		updatedAt: time.Now(),
-		info:      &data,
-		err:       nil,
+		info:      data,
+		err:       err,
 	}
-
-	return data, nil
 }
 
 // GetProviderData gets provider data from hermes
@@ -431,6 +433,9 @@ func (ac *HermesCaller) doRequest(req *http.Request, to any) error {
 }
 
 func (ac *HermesCaller) getResponseFromCache(chainID int64, identity string, cacheDuration time.Duration) (HermesUserInfo, error, bool) {
+	ac.cache.lock.RLock()
+	defer ac.cache.lock.RUnlock()
+
 	cacheKey := getCacheKey(chainID, identity)
 	cachedResponse, ok := ac.cache.data[cacheKey]
 	if ok && cachedResponse.updatedAt.Add(cacheDuration).After(time.Now()) {