nghttpx: Add --backend-response-buffer option

src/shrpx.cc

@@ -747,6 +747,7 @@ void fill_default_config() {
   mod_config()->listener_disable_timeout = 0.;
   mod_config()->auto_tls_ticket_key = true;
   mod_config()->tls_ctx_per_worker = false;
+  mod_config()->downstream_response_buffer_size = 64 * 1024;
 }
 } // namespace
 
@@ -877,6 +878,11 @@ Performance:
               Set maximum number of open files (RLIMIT_NOFILE) to <N>.
               If 0 is given, nghttpx does not set the limit.
               Default: )" << get_config()->rlimit_nofile << R"(
+  --backend-response-buffer=<SIZE>
+              Set buffer size used to store backend response.
+              Default: )"
+      << util::utos_with_unit(get_config()->downstream_response_buffer_size)
+      << R"(
 
 Timeout:
   --frontend-http2-read-timeout=<SEC>
@@ -1273,6 +1279,7 @@ int main(int argc, char **argv) {
         {"tls-ticket-key-file", required_argument, &flag, 68},
         {"rlimit-nofile", required_argument, &flag, 69},
         {"tls-ctx-per-worker", no_argument, &flag, 70},
+        {"backend-response-buffer", required_argument, &flag, 71},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -1594,6 +1601,10 @@ int main(int argc, char **argv) {
         // --tls-ctx-per-worker
         cmdcfgs.emplace_back(SHRPX_OPT_TLS_CTX_PER_WORKER, "yes");
         break;
+      case 71:
+        // --backend-response-buffer
+        cmdcfgs.emplace_back(SHRPX_OPT_BACKEND_RESPONSE_BUFFER, optarg);
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -141,6 +141,7 @@ const char SHRPX_OPT_LISTENER_DISABLE_TIMEOUT[] = "listener-disable-timeout";
 const char SHRPX_OPT_TLS_TICKET_KEY_FILE[] = "tls-ticket-key-file";
 const char SHRPX_OPT_RLIMIT_NOFILE[] = "rlimit-nofile";
 const char SHRPX_OPT_TLS_CTX_PER_WORKER[] = "tls-ctx-per-worker";
+const char SHRPX_OPT_BACKEND_RESPONSE_BUFFER[] = "backend-response-buffer";
 
 namespace {
 Config *config = nullptr;
@@ -1130,6 +1131,22 @@ int parse_config(const char *opt, const char *optarg) {
     return 0;
   }
 
+  if (util::strieq(opt, SHRPX_OPT_BACKEND_RESPONSE_BUFFER)) {
+    size_t n;
+    if (parse_uint_with_unit(&n, opt, optarg) != 0) {
+      return -1;
+    }
+
+    if (n == 0) {
+      LOG(ERROR) << opt << ": specify an integer strictly more than 0";
+      return -1;
+    }
+
+    mod_config()->downstream_response_buffer_size = n;
+
+    return 0;
+  }
+
   if (util::strieq(opt, SHRPX_OPT_TLS_CTX_PER_WORKER)) {
     mod_config()->tls_ctx_per_worker = util::strieq(optarg, "yes");
 

src/shrpx_config.h

@@ -129,6 +129,7 @@ extern const char SHRPX_OPT_LISTENER_DISABLE_TIMEOUT[];
 extern const char SHRPX_OPT_TLS_TICKET_KEY_FILE[];
 extern const char SHRPX_OPT_RLIMIT_NOFILE[];
 extern const char SHRPX_OPT_TLS_CTX_PER_WORKER[];
+extern const char SHRPX_OPT_BACKEND_RESPONSE_BUFFER[];
 
 union sockaddr_union {
   sockaddr sa;
@@ -256,6 +257,7 @@ struct Config {
   size_t padding;
   size_t worker_frontend_connections;
   size_t rlimit_nofile;
+  size_t downstream_response_buffer_size;
   // Bit mask to disable SSL/TLS protocol versions.  This will be
   // passed to SSL_CTX_set_options().
   long int tls_proto_mask;

src/shrpx_downstream.cc

@@ -642,7 +642,8 @@ Memchunks4K *Downstream::get_response_buf() { return &response_buf_; }
 
 bool Downstream::response_buf_full() {
   if (dconn_) {
-    return response_buf_.rleft() >= 64 * 1024;
+    return response_buf_.rleft() >=
+           get_config()->downstream_response_buffer_size;
   } else {
     return false;
   }