Add tests for head message timestamp queue statistic. Distinguish the former statistics tests as channel (_ch) statistics. Expand name.

2 files changed, 37 insertions, 39 deletions

diff --git a/src/rabbit_backing_queue.erl b/src/rabbit_backing_queue.erl
index 71ad7f5b98..b567906378 100644
--- a/src/rabbit_backing_queue.erl
+++ b/src/rabbit_backing_queue.erl
@@ -22,7 +22,7 @@
                     messages_unacknowledged_ram, messages_persistent,
                     message_bytes, message_bytes_ready,
                     message_bytes_unacknowledged, message_bytes_ram,
-                    message_bytes_persistent, head_msg_timestamp,
+                    message_bytes_persistent, head_message_timestamp,
                     disk_reads, disk_writes, backing_queue_status]).
 
 -ifdef(use_specs).
diff --git a/src/rabbit_variable_queue.erl b/src/rabbit_variable_queue.erl
index f37b578aa5..bbca0bd410 100644
--- a/src/rabbit_variable_queue.erl
+++ b/src/rabbit_variable_queue.erl
@@ -877,13 +877,12 @@ info(message_bytes_ram, #vqstate{ram_bytes = RamBytes}) ->
     RamBytes;
 info(message_bytes_persistent, #vqstate{persistent_bytes = PersistentBytes}) ->
     PersistentBytes;
-info(head_msg_timestamp, #vqstate{
+info(head_message_timestamp, #vqstate{
           q3               = Q3, 
           q4               = Q4,
           ram_pending_ack  = RPA,
-          disk_pending_ack = DPA,
           qi_pending_ack   = QPA}) ->
-          head_msg_timestamp(Q3, Q4, RPA, DPA, QPA);
+          head_message_timestamp(Q3, Q4, RPA, QPA);
 info(disk_reads, #vqstate{disk_read_count = Count}) ->
     Count;
 info(disk_writes, #vqstate{disk_write_count = Count}) ->
@@ -918,42 +917,41 @@ invoke(      _,   _, State) -> State.
 
 is_duplicate(_Msg, State) -> {false, State}.
 
-%% Get the Timestamp property of the first message, if present.
-%% The first message is the one with the oldest timestamp among the heads of the 
-%% pending acks and unread message queues.
-%% Unacked messages are included as they are regarded as unprocessed until acked,
-%% also to avoid the timestamp oscillating during repeated rejects.
-head_msg_timestamp(Q3, Q4, RPA, DPA, QPA) -> 
-    HeadMsgs = [ HeadMsgStatus#msg_status.msg || HeadMsgStatus <- 
-        [ case ?QUEUE:is_empty(Q4) of
-			  false -> {value, MsgStatus} = ?QUEUE:peek(Q4), MsgStatus;
-			  true -> undefined
-		  end,
-		  case ?QUEUE:is_empty(Q3) of
-			  false -> {value, MsgStatus} = ?QUEUE:peek(Q3), MsgStatus;
-			  true -> undefined
-		  end,
-		  case gb_trees:is_empty(RPA) of
-			  false -> {_SeqId, MsgStatus} = gb_trees:smallest(RPA), MsgStatus;
-			  true  -> undefined
-		  end,
-		  case gb_trees:is_empty(DPA) of
-			  false -> {_SeqId, MsgStatus} = gb_trees:smallest(DPA), MsgStatus;
-			  true  -> undefined
-		  end,
-		  case gb_trees:is_empty(QPA) of
-			  false -> {_SeqId, MsgStatus} = gb_trees:smallest(QPA), MsgStatus;
-			  true  -> undefined
-		  end],
-        HeadMsgStatus /= undefined ],
+%% Get the Timestamp property of the first msg, if present. This is the one with the oldest timestamp 
+%% among the heads of the pending acks and unread queues.
+%% We can't check disk_pending_acks as these are paged out - we assume some will soon be paged in 
+%% rather than forcing it to happen.
+%% Pending ack msgs are included as they are regarded as unprocessed until acked, this also prevents
+%% the result apparently oscillating during repeated rejects.
+%% Q3 is only checked when Q4 is empty as any Q4 msg will be earlier.
+head_message_timestamp(Q3, Q4, RPA, QPA) -> 
+    HeadMsgs = [ HeadMsgStatus#msg_status.msg || 
+		   HeadMsgStatus <- 
+		       [ case ?QUEUE:is_empty(Q4) of
+			     false -> {value, MsgStatus} = ?QUEUE:peek(Q4), MsgStatus;
+			     true -> case ?QUEUE:is_empty(Q3) of  
+					 false -> {value, MsgStatus} = ?QUEUE:peek(Q3), MsgStatus;
+					 true -> undefined
+				     end
+			 end,
+			 case gb_trees:is_empty(RPA) of
+			     false -> {_SeqId, MsgStatus} = gb_trees:smallest(RPA), MsgStatus;
+			     true  -> undefined
+			 end,
+			 case gb_trees:is_empty(QPA) of
+			     false -> {_SeqId, MsgStatus} = gb_trees:smallest(QPA), MsgStatus;
+			     true  -> undefined
+			 end],
+		   HeadMsgStatus /= undefined ],
     Timestamps = 
-        [ Timestamp || Timestamp <-
-            [ rabbit_basic:extract_timestamp(HeadMsg#basic_message.content) || HeadMsg <- 
-              HeadMsgs ],
-            Timestamp /= undefined ],
-	case Timestamps == [] of 
-        true -> undefined;
-		false -> lists:min(Timestamps)
+        [ Timestamp || 
+	    Timestamp <-
+		[ rabbit_basic:extract_timestamp(HeadMsg#basic_message.content) || HeadMsg <- 
+										       HeadMsgs ],
+	    Timestamp /= undefined ],
+    case Timestamps == [] of 
+        true -> '';
+	false -> lists:min(Timestamps)
     end.