Add on-by-default option to use TCP keepalive in the REST client.

test/src/unit-capi-config.cc

@@ -229,6 +229,7 @@ void check_save_to_file() {
   ss << "rest.capnp_traversal_limit 2147483648\n";
   ss << "rest.curl.buffer_size 524288\n";
   ss << "rest.curl.retry_errors true\n";
+  ss << "rest.curl.tcp_keepalive true\n";
   ss << "rest.curl.verbose false\n";
   ss << "rest.http_compressor any\n";
   ss << "rest.load_enumerations_on_array_open false\n";
@@ -612,6 +613,7 @@ TEST_CASE("C API: Test config iter", "[capi][config]") {
   all_param_values["rest.capnp_traversal_limit"] = "2147483648";
   all_param_values["rest.curl.buffer_size"] = "524288";
   all_param_values["rest.curl.retry_errors"] = "true";
+  all_param_values["rest.curl.tcp_keepalive"] = "true";
   all_param_values["rest.curl.verbose"] = "false";
   all_param_values["rest.load_metadata_on_array_open"] = "false";
   all_param_values["rest.load_non_empty_domain_on_array_open"] = "false";

tiledb/api/c_api/config/config_api_external.h

@@ -739,6 +739,9 @@ TILEDB_EXPORT void tiledb_config_free(tiledb_config_t** config) TILEDB_NOEXCEPT;
  *    Set curl to run in verbose mode for REST requests <br>
  *    curl will print to stdout with this option
  *    **Default**: false
+ * -  `rest.curl.tcp_keepalive` <br>
+ *    Set curl to use TCP keepalive for REST requests <br>
+ *    **Default**: true
  * - `rest.load_metadata_on_array_open` <br>
  *    If true, array metadata will be loaded and sent to server together with
  *    the open array <br>

tiledb/sm/config/config.cc

@@ -91,6 +91,7 @@ const std::string Config::REST_RETRY_DELAY_FACTOR = "1.25";
 const std::string Config::REST_CURL_BUFFER_SIZE = "524288";
 const std::string Config::REST_CAPNP_TRAVERSAL_LIMIT = "2147483648";
 const std::string Config::REST_CURL_VERBOSE = "false";
+const std::string REST_CURL_TCP_KEEPALIVE = "true";
 const std::string Config::REST_CURL_RETRY_ERRORS = "true";
 const std::string Config::REST_LOAD_ENUMERATIONS_ON_ARRAY_OPEN = "false";
 const std::string Config::REST_LOAD_METADATA_ON_ARRAY_OPEN = "true";
@@ -257,6 +258,7 @@ const std::map<std::string, std::string> default_config_values = {
     std::make_pair("rest.curl.buffer_size", Config::REST_CURL_BUFFER_SIZE),
     std::make_pair(
         "rest.capnp_traversal_limit", Config::REST_CAPNP_TRAVERSAL_LIMIT),
+    std::make_pair("rest.curl.tcp_keepalive", REST_CURL_TCP_KEEPALIVE),
     std::make_pair("rest.curl.verbose", Config::REST_CURL_VERBOSE),
     std::make_pair("rest.curl.retry_errors", Config::REST_CURL_RETRY_ERRORS),
     std::make_pair(
@@ -803,6 +805,8 @@ Status Config::sanity_check(
     RETURN_NOT_OK(utils::parse::convert(value, &v));
   } else if (param == "ssl.verify") {
     RETURN_NOT_OK(utils::parse::convert(value, &v));
+  } else if (param == "rest.curl.tcp_keepalive") {
+    RETURN_NOT_OK(utils::parse::convert(value, &v));
   } else if (param == "vfs.min_parallel_size") {
     RETURN_NOT_OK(utils::parse::convert(value, &vuint64));
   } else if (param == "vfs.max_batch_size") {

tiledb/sm/cpp_api/config.h

@@ -913,6 +913,9 @@ class Config {
    *    Set curl to run in verbose mode for REST requests <br>
    *    curl will print to stdout with this option
    *    **Default**: false
+   * -  `rest.curl.tcp_keepalive` <br>
+   *    Set curl to use TCP keepalive for REST requests <br>
+   *    **Default**: true
    * - `rest.load_metadata_on_array_open` <br>
    *    If true, array metadata will be loaded and sent to server together with
    *    the open array <br>

tiledb/sm/rest/curl.cc

@@ -292,6 +292,11 @@ Status Curl::init(
     curl_easy_setopt(curl_.get(), CURLOPT_CAPATH, ssl_cfg.ca_path().c_str());
   }
 
+  bool tcp_keepalive =
+      config_->get<bool>("rest.curl.tcp_keepalive", Config::must_find);
+
+  curl_easy_setopt(curl_.get(), CURLOPT_TCP_KEEPALIVE, tcp_keepalive ? 1L : 0L);
+
   bool found;
   RETURN_NOT_OK(
       config_->get<uint64_t>("rest.retry_count", &retry_count_, &found));