[performance] remove throttling timers (#1466)

* remove throttling timers, support setting retry-after, use retry-after in transport

* remove unused variables

* add throttling-retry-after to cmd flags

* update envparsing to include new throttling-retry-after

* update example config to include retry-after documentation

* also support retry-after formatted as date-time, ensure max backoff time

---------

Signed-off-by: kim <grufwub@gmail.com>

3 files changed, 30 insertions, 3 deletions

diff --git a/internal/config/config.go b/internal/config/config.go
index 7025ab63a..516fb11d6 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -133,9 +133,10 @@ type Configuration struct {
 	SyslogProtocol string `name:"syslog-protocol" usage:"Protocol to use when directing logs to syslog. Leave empty to connect to local syslog."`
 	SyslogAddress  string `name:"syslog-address" usage:"Address:port to send syslog logs to. Leave empty to connect to local syslog."`
 
-	AdvancedCookiesSamesite      string `name:"advanced-cookies-samesite" usage:"'strict' or 'lax', see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie/SameSite"`
-	AdvancedRateLimitRequests    int    `name:"advanced-rate-limit-requests" usage:"Amount of HTTP requests to permit within a 5 minute window. 0 or less turns rate limiting off."`
-	AdvancedThrottlingMultiplier int    `name:"advanced-throttling-multiplier" usage:"Multiplier to use per cpu for http request throttling. 0 or less turns throttling off."`
+	AdvancedCookiesSamesite      string        `name:"advanced-cookies-samesite" usage:"'strict' or 'lax', see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie/SameSite"`
+	AdvancedRateLimitRequests    int           `name:"advanced-rate-limit-requests" usage:"Amount of HTTP requests to permit within a 5 minute window. 0 or less turns rate limiting off."`
+	AdvancedThrottlingMultiplier int           `name:"advanced-throttling-multiplier" usage:"Multiplier to use per cpu for http request throttling. 0 or less turns throttling off."`
+	AdvancedThrottlingRetryAfter time.Duration `name:"advanced-throttling-retry-after" usage:"Retry-After duration response to send for throttled requests."`
 
 	// Cache configuration vars.
 	Cache CacheConfiguration `name:"cache"`
diff --git a/internal/config/flags.go b/internal/config/flags.go
index e594615d1..d8c31368b 100644
--- a/internal/config/flags.go
+++ b/internal/config/flags.go
@@ -139,6 +139,7 @@ func (s *ConfigState) AddServerFlags(cmd *cobra.Command) {
 		cmd.Flags().String(AdvancedCookiesSamesiteFlag(), cfg.AdvancedCookiesSamesite, fieldtag("AdvancedCookiesSamesite", "usage"))
 		cmd.Flags().Int(AdvancedRateLimitRequestsFlag(), cfg.AdvancedRateLimitRequests, fieldtag("AdvancedRateLimitRequests", "usage"))
 		cmd.Flags().Int(AdvancedThrottlingMultiplierFlag(), cfg.AdvancedThrottlingMultiplier, fieldtag("AdvancedThrottlingMultiplier", "usage"))
+		cmd.Flags().Duration(AdvancedThrottlingRetryAfterFlag(), cfg.AdvancedThrottlingRetryAfter, fieldtag("AdvancedThrottlingRetryAfter", "usage"))
 	})
 }
 
diff --git a/internal/config/helpers.gen.go b/internal/config/helpers.gen.go
index 3bf62efc6..64e7d02f7 100644
--- a/internal/config/helpers.gen.go
+++ b/internal/config/helpers.gen.go
@@ -1999,6 +1999,31 @@ func GetAdvancedThrottlingMultiplier() int { return global.GetAdvancedThrottling
 // SetAdvancedThrottlingMultiplier safely sets the value for global configuration 'AdvancedThrottlingMultiplier' field
 func SetAdvancedThrottlingMultiplier(v int) { global.SetAdvancedThrottlingMultiplier(v) }
 
+// GetAdvancedThrottlingRetryAfter safely fetches the Configuration value for state's 'AdvancedThrottlingRetryAfter' field
+func (st *ConfigState) GetAdvancedThrottlingRetryAfter() (v time.Duration) {
+	st.mutex.Lock()
+	v = st.config.AdvancedThrottlingRetryAfter
+	st.mutex.Unlock()
+	return
+}
+
+// SetAdvancedThrottlingRetryAfter safely sets the Configuration value for state's 'AdvancedThrottlingRetryAfter' field
+func (st *ConfigState) SetAdvancedThrottlingRetryAfter(v time.Duration) {
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+	st.config.AdvancedThrottlingRetryAfter = v
+	st.reloadToViper()
+}
+
+// AdvancedThrottlingRetryAfterFlag returns the flag name for the 'AdvancedThrottlingRetryAfter' field
+func AdvancedThrottlingRetryAfterFlag() string { return "advanced-throttling-retry-after" }
+
+// GetAdvancedThrottlingRetryAfter safely fetches the value for global configuration 'AdvancedThrottlingRetryAfter' field
+func GetAdvancedThrottlingRetryAfter() time.Duration { return global.GetAdvancedThrottlingRetryAfter() }
+
+// SetAdvancedThrottlingRetryAfter safely sets the value for global configuration 'AdvancedThrottlingRetryAfter' field
+func SetAdvancedThrottlingRetryAfter(v time.Duration) { global.SetAdvancedThrottlingRetryAfter(v) }
+
 // GetCacheGTSAccountMaxSize safely fetches the Configuration value for state's 'Cache.GTS.AccountMaxSize' field
 func (st *ConfigState) GetCacheGTSAccountMaxSize() (v int) {
 	st.mutex.Lock()