Rename reconnect_timer -> connect_timer

The former was misleading since the timer only applies to initial
connection attempts, reconnection attempts being governed by
watchdog_timer. The name is a historic remnant from a (dark, pre-OTP)
time in which RFC 3539 was followed less slavishly than it is now, and
the timer actually did apply to reconnection attempts.

Note that connect_timer corresponds to RFC 6733 Tc, while watchdog_timer
corresponds to RFC 3539 TwInit. The latter RFC makes clear that TwInit
should apply to reconnection attempts. It's less clear if only RFC 6733
is read.

Note also that reconnect_timer is still accepted for backwards
compatibility. It would be possible to add an option to make
reconnect_timer behave strictly as the name suggests (ie. ignore RFC 3539
and interpret RFC 6733 at face value; something that has some value for
testing at least) but no such option is implemented in this commit.

4 files changed, 17 insertions, 8 deletions

diff --git a/lib/diameter/src/base/diameter.erl b/lib/diameter/src/base/diameter.erl
index 77200cc7d0..d74e091e11 100644
--- a/lib/diameter/src/base/diameter.erl
+++ b/lib/diameter/src/base/diameter.erl
@@ -343,7 +343,7 @@ call(SvcName, App, Message) ->
     | {capx_timeout, 'Unsigned32'()}
     | {disconnect_cb, evaluable()}
     | {length_errors, exit | handle | discard}
-    | {reconnect_timer, 'Unsigned32'()}
+    | {connect_timer, 'Unsigned32'()}
     | {watchdog_timer, 'Unsigned32'() | {module(), atom(), list()}}
     | {watchdog_config, [{okay|suspect, non_neg_integer()}]}
     | {spawn_opt, list()}
diff --git a/lib/diameter/src/base/diameter_config.erl b/lib/diameter/src/base/diameter_config.erl
index 34b40c3a29..f5ea459fd0 100644
--- a/lib/diameter/src/base/diameter_config.erl
+++ b/lib/diameter/src/base/diameter_config.erl
@@ -537,7 +537,9 @@ opt({capx_timeout, Tmo}) ->
 opt({length_errors, T}) ->
     lists:member(T, [exit, handle, discard]);
 
-opt({reconnect_timer, Tmo}) ->
+opt({K, Tmo})
+  when K == reconnect_timer;  %% deprecated
+       K == connect_timer ->
     ?IS_UINT32(Tmo);
 
 opt({watchdog_timer, {M,F,A}})
diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl
index 47e03cd0a0..70e66537ed 100644
--- a/lib/diameter/src/base/diameter_service.erl
+++ b/lib/diameter/src/base/diameter_service.erl
@@ -1143,10 +1143,17 @@ q_restart(false, _) ->
 %%   communicate.
 
 default_tc(connect, Opts) ->
-    proplists:get_value(reconnect_timer, Opts, ?DEFAULT_TC);
+    connect_timer(Opts, ?DEFAULT_TC);
 default_tc(accept, _) ->
     0.
 
+%% Accept both connect_timer and the (older) reconnect_timer, the
+%% latter being a remnant from a time in which the timer did apply to
+%% reconnect attempts.
+connect_timer(Opts, Def0) ->
+    Def = proplists:get_value(reconnect_timer, Opts, Def0),
+    proplists:get_value(connect_timer, Opts, Def).
+
 %% Bound tc below if the watchdog was restarted recently to avoid
 %% continuous restarted in case of faulty config or other problems.
 tc(Time, Tc) ->
@@ -1181,7 +1188,7 @@ tc(false = No, _, _) ->  %% removed
 %% another watchdog to be able to detect that it should transition
 %% from initial into reopen rather than okay. That someone is either
 %% the accepting watchdog upon reception of a CER from the previously
-%% connected peer, or us after reconnect_timer timeout.
+%% connected peer, or us after connect_timer timeout.
 
 close(#watchdog{type = connect}, _) ->
     ok;
@@ -1194,16 +1201,16 @@ close(#watchdog{type = accept,
 
 %% Tell watchdog to (maybe) die later ...
 c(Pid, true, Opts) ->
-    Tc = proplists:get_value(reconnect_timer, Opts, 2*?DEFAULT_TC),
+    Tc = connect_timer(Opts, 2*?DEFAULT_TC),
     erlang:send_after(Tc, Pid, close);
 
 %% ... or now.
 c(Pid, false, _Opts) ->
     Pid ! close.
 
-%% The RFC's only document the behaviour of Tc, our reconnect_timer,
+%% The RFC's only document the behaviour of Tc, our connect_timer,
 %% for the establishment of connections but we also give
-%% reconnect_timer semantics for a listener, being the time within
+%% connect_timer semantics for a listener, being the time within
 %% which a new connection attempt is expected of a connecting peer.
 %% The value should be greater than the peer's Tc + jitter.
 
diff --git a/lib/diameter/src/base/diameter_watchdog.erl b/lib/diameter/src/base/diameter_watchdog.erl
index 7e75801718..55d46fadea 100644
--- a/lib/diameter/src/base/diameter_watchdog.erl
+++ b/lib/diameter/src/base/diameter_watchdog.erl
@@ -329,7 +329,7 @@ code_change(_, State, _) ->
 %% the commentary is ours.
 
 %% Service or watchdog is telling the watchdog of an accepting
-%% transport to die after reconnect_timer expiry or reestablished
+%% transport to die after connect_timer expiry or reestablished
 %% connection (in another transport process) respectively.
 transition(close, #watchdog{status = down}) ->
     {{accept, _}, _, _} = getr(restart), %% assert