diff options
Diffstat (limited to 'src/rabbit_queue_index.erl')
| -rw-r--r-- | src/rabbit_queue_index.erl | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/src/rabbit_queue_index.erl b/src/rabbit_queue_index.erl index 08c20ce2..9a9c4d18 100644 --- a/src/rabbit_queue_index.erl +++ b/src/rabbit_queue_index.erl @@ -28,7 +28,13 @@ %%---------------------------------------------------------------------------- %% The queue index is responsible for recording the order of messages -%% within a queue on disk. +%% within a queue on disk. As such it contains records of messages +%% being published, delivered and acknowledged. The publish record +%% includes the sequence ID, message ID and a small quantity of +%% metadata about the message; the delivery and acknowledgement +%% records just contain the sequence ID. A publish record may also +%% contain the complete message if provided to publish/5; this allows +%% the message store to be avoided altogether for small messages. %% %% Because of the fact that the queue can decide at any point to send %% a queue entry to disk, you can not rely on publishes appearing in @@ -36,7 +42,7 @@ %% then delivered, then ack'd. %% %% In order to be able to clean up ack'd messages, we write to segment -%% files. These files have a fixed maximum size: ?SEGMENT_ENTRY_COUNT +%% files. These files have a fixed number of entries: ?SEGMENT_ENTRY_COUNT %% publishes, delivers and acknowledgements. They are numbered, and so %% it is known that the 0th segment contains messages 0 -> %% ?SEGMENT_ENTRY_COUNT - 1, the 1st segment contains messages @@ -157,10 +163,6 @@ -define(PUB_RECORD_BYTES, (?PUB_RECORD_BODY_BYTES + ?PUB_RECORD_PREFIX_BYTES)). -%% %% 1 publish, 1 deliver, 1 ack per msg -%% -define(SEGMENT_TOTAL_SIZE, ?SEGMENT_ENTRY_COUNT * -%% (?PUB_RECORD_BYTES + (2 * ?REL_SEQ_ONLY_RECORD_BYTES))). - %% ---- misc ---- -define(PUB, {_, _, _}). %% {MsgId, MsgProps, IsPersistent} |