Make marina bootstrap retry interval configurable

When marina_pool_server's bootstrap can't reach any bootstrap_ip
(transient network outage, slow DNS, container still spinning up),
it retries every 500ms. That interval was hardcoded:

  timer_ref = erlang:send_after(500, self(), ?MSG_BOOTSTRAP)

Replaced with a bootstrap_retry_ms application env, defaulted to
500 to preserve existing behaviour. Deployments that want a gentler
retry rhythm (e.g. behind flaky DNS) can now set it without forking
marina.

B2's other two items resolved on inspection:

- The 'fuse skip pipeline' recommendation in the plan is misguided.
  marina_body.erl's skip_tracing / skip_warnings / skip_custom_payload
  each peel a small fixed-or-counted prefix off the head of the
  binary; they do not re-scan the body. Fusing them produces no
  measurable win and would add branching complexity for no reason.

- 'Property-based ring tests' is deferred with A4, the umbrella
  property-test task.

Changelog notes the inspection findings so the next reader doesn't
re-litigate the same questions.

Author: lpgauth

CHANGELOG.md

@@ -1,5 +1,27 @@
 # Changelog
 
+## 0.4.6
+
+### Added
+
+- `bootstrap_retry_ms` application env option (default: `500`). When
+  `marina_pool_server` fails to reach any `bootstrap_ips` host on
+  startup, it retries on this interval. Previously hardcoded to
+  500ms; deployments behind slow-DNS or transient network outages
+  can now back the retry off without forking marina.
+
+### Plan-time notes
+
+- B2's "fuse the body-skip pipeline" recommendation was checked on
+  inspection and not acted on: `skip_tracing`, `skip_warnings`, and
+  `skip_custom_payload` in `marina_body.erl` each peel a small
+  fixed-or-counted prefix off the head of the binary -- they don't
+  re-scan the body. The recommended fusion produces no measurable
+  win and adds branching complexity, so it stays as three small
+  passes.
+- B2's "property-based ring tests" item is deferred with A4 (the
+  property-test umbrella task).
+
 ## 0.4.5
 
 ### Changed

README.md

@@ -45,6 +45,7 @@ All settings are read from the `marina` application env.
 | -------------------- | ----------------------------- | -------------------------- | ------------------------------------------------------------------------- |
 | `backlog_size`       | `pos_integer()`               | `1024`                     | Per-connection [shackle](https://github.com/lpgauth/shackle) backlog.     |
 | `bootstrap_ips`      | `[string()]`                  | `["127.0.0.1"]`            | IPs tried in order until one responds with `system.peers`.                |
+| `bootstrap_retry_ms` | `pos_integer()`               | `500`                      | Delay before re-attempting bootstrap when no IP responded.                |
 | `compression`        | `boolean()`                   | `false`                    | Negotiate LZ4 compression on every connection.                            |
 | `keyspace`           | `undefined` \| `binary()`     | `undefined`                | Default keyspace; issued as `USE …` after startup.                        |
 | `password`           | `binary()`                    | `undefined`                | Password for `PasswordAuthenticator`.                                     |

include/marina_internal.hrl

@@ -10,6 +10,7 @@
 %% defaults
 -define(DEFAULT_BACKLOG_SIZE, 1024).
 -define(DEFAULT_BOOTSTRAP_IPS, [?GET_ENV(ip, ?DEFAULT_IP)]).
+-define(DEFAULT_BOOTSTRAP_RETRY_MS, 500).
 -define(DEFAULT_CONNECT_RETRY, 500).
 -define(DEFAULT_CONSISTENCY_LEVEL, ?CONSISTENCY_ONE).
 -define(DEFAULT_FLAGS, []).

src/marina.app.src

@@ -1,6 +1,6 @@
 {application, marina, [
   {description, "High-Performance Erlang Cassandra / Scylla CQL Client"},
-  {vsn, "0.4.5"},
+  {vsn, "0.4.6"},
   {registered, []},
   {applications, [
     kernel,

src/marina_pool_server.erl

@@ -70,8 +70,11 @@ handle_msg(?MSG_BOOTSTRAP, #state {
             }};
         {error, _Reason} ->
             logger:warning("[~p] bootstrap failed~n", [?MODULE]),
+            RetryMs = ?GET_ENV(bootstrap_retry_ms,
+                ?DEFAULT_BOOTSTRAP_RETRY_MS),
             {ok, State#state {
-                timer_ref = erlang:send_after(500, self(), ?MSG_BOOTSTRAP)
+                timer_ref = erlang:send_after(RetryMs, self(),
+                    ?MSG_BOOTSTRAP)
             }}
     end;
 handle_msg({topology_full_sync, NewNodes}, #state {