Merge branch 'master' into rabbitmq-server-255

10 files changed, 94 insertions, 4 deletions

diff --git a/src/rabbit.erl b/src/rabbit.erl
index 2b9237a15b..8d5dbb0260 100644
--- a/src/rabbit.erl
+++ b/src/rabbit.erl
@@ -285,12 +285,21 @@ hipe_compile() ->
                    %% happens when RabbitMQ is stopped (just the
                    %% application, not the entire node) and started
                    %% again.
-                   HM:module_info(native) =:= false],
+                   already_hipe_compiled(HM)],
     case HipeModules of
         [] -> {ok, already_compiled};
         _  -> do_hipe_compile(HipeModules)
     end.
 
+already_hipe_compiled(Mod) ->
+    try
+    %% OTP 18.x or later
+	Mod:module_info(native) =:= false
+    %% OTP prior to 18.x
+    catch error:badarg ->
+	code:is_module_native(Mod) =:= false
+    end.
+
 do_hipe_compile(HipeModules) ->
     Count = length(HipeModules),
     io:format("~nHiPE compiling:  |~s|~n                 |",
diff --git a/src/rabbit_channel_sup.erl b/src/rabbit_channel_sup.erl
index e8f45f7305..66f6a81697 100644
--- a/src/rabbit_channel_sup.erl
+++ b/src/rabbit_channel_sup.erl
@@ -16,6 +16,16 @@
 
 -module(rabbit_channel_sup).
 
+%% Supervises processes that implement AMQP 0-9-1 channels:
+%%
+%%  * Channel process itself
+%%  * Network writer (for network connections)
+%%  * Limiter (handles channel QoS and flow control)
+%%
+%% Every rabbit_channel_sup is supervised by rabbit_channel_sup_sup.
+%%
+%% See also rabbit_channel, rabbit_writer, rabbit_limiter.
+
 -behaviour(supervisor2).
 
 -export([start_link/1]).
diff --git a/src/rabbit_channel_sup_sup.erl b/src/rabbit_channel_sup_sup.erl
index 2be2af91a7..9cfbb78a2b 100644
--- a/src/rabbit_channel_sup_sup.erl
+++ b/src/rabbit_channel_sup_sup.erl
@@ -16,6 +16,11 @@
 
 -module(rabbit_channel_sup_sup).
 
+%% Supervisor for AMQP 0-9-1 channels. Every AMQP 0-9-1 connection has
+%% one of these.
+%%
+%% See also rabbit_channel_sup, rabbit_connection_helper_sup, rabbit_reader.
+
 -behaviour(supervisor2).
 
 -export([start_link/0, start_channel/2]).
diff --git a/src/rabbit_connection_helper_sup.erl b/src/rabbit_connection_helper_sup.erl
index d3c05ee416..d6492331ef 100644
--- a/src/rabbit_connection_helper_sup.erl
+++ b/src/rabbit_connection_helper_sup.erl
@@ -16,6 +16,15 @@
 
 -module(rabbit_connection_helper_sup).
 
+%% Supervises auxiliary processes of AMQP 0-9-1 connections:
+%%
+%%  * Channel supervisor
+%%  * Heartbeat receiver
+%%  * Heartbeat sender
+%%  * Exclusive queue collector
+%%
+%% See also rabbit_heartbeat, rabbit_channel_sup_sup, rabbit_queue_collector.
+
 -behaviour(supervisor2).
 
 -export([start_link/0]).
diff --git a/src/rabbit_connection_sup.erl b/src/rabbit_connection_sup.erl
index a64a2217da..09cddb0247 100644
--- a/src/rabbit_connection_sup.erl
+++ b/src/rabbit_connection_sup.erl
@@ -16,6 +16,15 @@
 
 -module(rabbit_connection_sup).
 
+%% Supervisor for a (network) AMQP 0-9-1 client connection.
+%%
+%% Supervises
+%%
+%%  * rabbit_reader
+%%  * Auxiliary process supervisor
+%%
+%% See also rabbit_reader, rabbit_connection_helper_sup.
+
 -behaviour(supervisor2).
 -behaviour(ranch_protocol).
 
diff --git a/src/rabbit_mnesia.erl b/src/rabbit_mnesia.erl
index 974a910d49..9ef37d3c48 100644
--- a/src/rabbit_mnesia.erl
+++ b/src/rabbit_mnesia.erl
@@ -102,7 +102,7 @@ init() ->
     ensure_mnesia_dir(),
     case is_virgin_node() of
         true  ->
-            rabbit_log:info("Database directory at ~s is empty. Initialising from scratch... ~n",
+            rabbit_log:info("Database directory at ~s is empty. Initialising from scratch...~n",
                             [dir()]),
             init_from_config();
         false ->
diff --git a/src/rabbit_priority_queue.erl b/src/rabbit_priority_queue.erl
index 7439b5bc32..b58a8c535e 100644
--- a/src/rabbit_priority_queue.erl
+++ b/src/rabbit_priority_queue.erl
@@ -647,6 +647,12 @@ combine_status(P, New, Old) ->
 
 cse(infinity, _)            -> infinity;
 cse(_, infinity)            -> infinity;
+%% queue modes
+cse(_, default)             -> default;
+cse(default, _)             -> default;
+cse(_, lazy)                -> lazy;
+cse(lazy, _)                -> lazy;
+%% numerical stats
 cse(A, B) when is_number(A) -> A + B;
 cse({delta, _, _, _}, _)    -> {delta, todo, todo, todo};
 cse(A, B)                   -> exit({A, B}).
diff --git a/src/rabbit_upgrade.erl b/src/rabbit_upgrade.erl
index daf39b8acc..0a85ef3e7d 100644
--- a/src/rabbit_upgrade.erl
+++ b/src/rabbit_upgrade.erl
@@ -100,7 +100,12 @@ ensure_backup_taken() ->
                      false -> ok = take_backup();
                      _     -> ok
                  end;
-        true  -> throw({error, previous_upgrade_failed})
+        true  ->
+          error("Found lock file at ~s.
+            Either previous upgrade is in progress or has failed.
+            Database backup path: ~s",
+            [lock_filename(), backup_dir()]),
+          throw({error, previous_upgrade_failed})
     end.
 
 take_backup() ->
@@ -108,7 +113,7 @@ take_backup() ->
     case rabbit_mnesia:copy_db(BackupDir) of
         ok         -> info("upgrades: Mnesia dir backed up to ~p~n",
                            [BackupDir]);
-        {error, E} -> throw({could_not_back_up_mnesia_dir, E})
+        {error, E} -> throw({could_not_back_up_mnesia_dir, E, BackupDir})
     end.
 
 ensure_backup_removed() ->
diff --git a/src/tcp_listener.erl b/src/tcp_listener.erl
index 571622c80d..dcb607ccdd 100644
--- a/src/tcp_listener.erl
+++ b/src/tcp_listener.erl
@@ -16,6 +16,36 @@
 
 -module(tcp_listener).
 
+%% Represents a running TCP listener (a process that listens for inbound
+%% TCP or TLS connections). Every protocol supported typically has one
+%% or two listeners, plain TCP and (optionally) TLS, but there can
+%% be more, e.g. when multiple network interfaces are involved.
+%%
+%% A listener has 6 properties (is a tuple of 6):
+%%
+%%  * IP address
+%%  * Port
+%%  * Node
+%%  * Label (human-friendly name, e.g. AMQP 0-9-1)
+%%  * Startup callback
+%%  * Shutdown callback
+%%
+%% Listeners use Ranch in embedded mode to accept and "bridge" client
+%% connections with protocol entry points such as rabbit_reader.
+%%
+%% Listeners are tracked in a Mnesia table so that they can be
+%%
+%%  * Shut down
+%%  * Listed (e.g. in the management UI)
+%%
+%% Every tcp_listener process has callbacks that are executed on start
+%% and termination. Those must take care of listener registration
+%% among other things.
+%%
+%% Listeners are supervised by tcp_listener_sup (one supervisor per protocol).
+%%
+%% See also rabbit_networking and tcp_listener_sup.
+
 -behaviour(gen_server).
 
 -export([start_link/5]).
diff --git a/src/tcp_listener_sup.erl b/src/tcp_listener_sup.erl
index 54da154d8d..4df8a45ac1 100644
--- a/src/tcp_listener_sup.erl
+++ b/src/tcp_listener_sup.erl
@@ -16,6 +16,13 @@
 
 -module(tcp_listener_sup).
 
+%% Supervises TCP listeners. There is a separate supervisor for every
+%% protocol. In case of AMQP 0-9-1, it resides under rabbit_sup. Plugins
+%% that provide protocol support (e.g. STOMP) have an instance of this supervisor in their
+%% app supervision tree.
+%%
+%% See also rabbit_networking and tcp_listener.
+
 -behaviour(supervisor).
 
 -export([start_link/9, start_link/10]).