Make min_backoff_ms timeout configurable

include/grpc/impl/codegen/grpc_types.h

@@ -237,6 +237,8 @@ typedef struct {
 /** Secondary user agent: goes at the end of the user-agent metadata
     sent on each request. A string. */
 #define GRPC_ARG_SECONDARY_USER_AGENT_STRING "grpc.secondary_user_agent"
+/** The minimum time between subsequent connection attempts, in ms */
+#define GRPC_ARG_MIN_RECONNECT_BACKOFF_MS "grpc.min_reconnect_backoff_ms"
 /** The maximum time between subsequent connection attempts, in ms */
 #define GRPC_ARG_MAX_RECONNECT_BACKOFF_MS "grpc.max_reconnect_backoff_ms"
 /** The time between the first and second connection attempts, in ms */

src/core/ext/filters/client_channel/subchannel.c

@@ -59,9 +59,9 @@
 #define INTERNAL_REF_BITS 16
 #define STRONG_REF_MASK (~(gpr_atm)((1 << INTERNAL_REF_BITS) - 1))
 
-#define GRPC_SUBCHANNEL_MIN_CONNECT_TIMEOUT_SECONDS 20
 #define GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS 1
 #define GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER 1.6
+#define GRPC_SUBCHANNEL_RECONNECT_MIN_BACKOFF_SECONDS 20
 #define GRPC_SUBCHANNEL_RECONNECT_MAX_BACKOFF_SECONDS 120
 #define GRPC_SUBCHANNEL_RECONNECT_JITTER 0.2
 
@@ -353,8 +353,8 @@ grpc_subchannel *grpc_subchannel_create(grpc_exec_ctx *exec_ctx,
                                "subchannel");
   int initial_backoff_ms =
       GRPC_SUBCHANNEL_INITIAL_CONNECT_BACKOFF_SECONDS * 1000;
+  int min_backoff_ms = GRPC_SUBCHANNEL_RECONNECT_MIN_BACKOFF_SECONDS * 1000;
   int max_backoff_ms = GRPC_SUBCHANNEL_RECONNECT_MAX_BACKOFF_SECONDS * 1000;
-  int min_backoff_ms = GRPC_SUBCHANNEL_MIN_CONNECT_TIMEOUT_SECONDS * 1000;
   bool fixed_reconnect_backoff = false;
   if (c->args) {
     for (size_t i = 0; i < c->args->num_args; i++) {
@@ -365,6 +365,12 @@ grpc_subchannel *grpc_subchannel_create(grpc_exec_ctx *exec_ctx,
             grpc_channel_arg_get_integer(
                 &c->args->args[i],
                 (grpc_integer_options){initial_backoff_ms, 100, INT_MAX});
+      } else if (0 == strcmp(c->args->args[i].key,
+                             GRPC_ARG_MIN_RECONNECT_BACKOFF_MS)) {
+        fixed_reconnect_backoff = false;
+        min_backoff_ms = grpc_channel_arg_get_integer(
+            &c->args->args[i],
+            (grpc_integer_options){min_backoff_ms, 100, INT_MAX});
       } else if (0 == strcmp(c->args->args[i].key,
                              GRPC_ARG_MAX_RECONNECT_BACKOFF_MS)) {
         fixed_reconnect_backoff = false;