introduce separate type for msg ids

and add some auxiliary types for fun params to a) make their purpose
clearer, and b) work around emacs indentation bugs

6 files changed, 37 insertions, 35 deletions

diff --git a/include/rabbit_msg_store_index.hrl b/include/rabbit_msg_store_index.hrl
index 289f8f60..2ae5b000 100644
--- a/include/rabbit_msg_store_index.hrl
+++ b/include/rabbit_msg_store_index.hrl
@@ -29,13 +29,13 @@
 -spec(new/1 :: (dir()) -> index_state()).
 -spec(recover/1 :: (dir()) -> rabbit_types:ok_or_error2(index_state(), any())).
 -spec(lookup/2 ::
-        (rabbit_guid:guid(), index_state()) -> ('not_found' | keyvalue())).
+        (rabbit_types:msg_id(), index_state()) -> ('not_found' | keyvalue())).
 -spec(insert/2 :: (keyvalue(), index_state()) -> 'ok').
 -spec(update/2 :: (keyvalue(), index_state()) -> 'ok').
--spec(update_fields/3 :: (rabbit_guid:guid(), ({fieldpos(), fieldvalue()} |
-                                               [{fieldpos(), fieldvalue()}]),
+-spec(update_fields/3 :: (rabbit_types:msg_id(), ({fieldpos(), fieldvalue()} |
+                                                  [{fieldpos(), fieldvalue()}]),
                           index_state()) -> 'ok').
--spec(delete/2 :: (rabbit_guid:guid(), index_state()) -> 'ok').
+-spec(delete/2 :: (rabbit_types:msg_id(), index_state()) -> 'ok').
 -spec(delete_object/2 :: (keyvalue(), index_state()) -> 'ok').
 -spec(delete_by_file/2 :: (fieldvalue(), index_state()) -> 'ok').
 -spec(terminate/1 :: (index_state()) -> any()).
diff --git a/src/rabbit_amqqueue.erl b/src/rabbit_amqqueue.erl
index 46b78c39..bbeff1f7 100644
--- a/src/rabbit_amqqueue.erl
+++ b/src/rabbit_amqqueue.erl
@@ -141,9 +141,9 @@
                     fun ((boolean()) -> rabbit_types:ok_or_error('not_found') |
                                         rabbit_types:connection_exit())).
 -spec(maybe_run_queue_via_backing_queue/2 ::
-        (pid(), (fun ((A) -> {[rabbit_guid:guid()], A}))) -> 'ok').
+        (pid(), (fun ((A) -> {[rabbit_types:msg_id()], A}))) -> 'ok').
 -spec(maybe_run_queue_via_backing_queue_async/2 ::
-        (pid(), (fun ((A) -> {[rabbit_guid:guid()], A}))) -> 'ok').
+        (pid(), (fun ((A) -> {[rabbit_types:msg_id()], A}))) -> 'ok').
 -spec(sync_timeout/1 :: (pid()) -> 'ok').
 -spec(update_ram_duration/1 :: (pid()) -> 'ok').
 -spec(set_ram_duration_target/2 :: (pid(), number() | 'infinity') -> 'ok').
diff --git a/src/rabbit_msg_file.erl b/src/rabbit_msg_file.erl
index 55e6ac47..71b4aa6f 100644
--- a/src/rabbit_msg_file.erl
+++ b/src/rabbit_msg_file.erl
@@ -39,15 +39,17 @@
 -type(position() :: non_neg_integer()).
 -type(msg_size() :: non_neg_integer()).
 -type(file_size() :: non_neg_integer()).
+-type(message_accumulator(A) ::
+        fun (({rabbit_types:msg_id(), msg_size(), position(), binary()}, A) ->
+                    A)).
 
--spec(append/3 :: (io_device(), rabbit_guid:guid(), msg()) ->
+-spec(append/3 :: (io_device(), rabbit_types:msg_id(), msg()) ->
                        rabbit_types:ok_or_error2(msg_size(), any())).
 -spec(read/2 :: (io_device(), msg_size()) ->
-                     rabbit_types:ok_or_error2({rabbit_guid:guid(), msg()},
+                     rabbit_types:ok_or_error2({rabbit_types:msg_id(), msg()},
                                                any())).
--spec(scan/4 :: (io_device(), file_size(),
-       fun (({rabbit_guid:guid(), msg_size(), position(), binary()}, A) -> A),
-       A) -> {'ok', A, position()}).
+-spec(scan/4 :: (io_device(), file_size(), message_accumulator(A), A) ->
+                     {'ok', A, position()}).
 
 -endif.
 
diff --git a/src/rabbit_msg_store.erl b/src/rabbit_msg_store.erl
index 9e65e442..02811da7 100644
--- a/src/rabbit_msg_store.erl
+++ b/src/rabbit_msg_store.erl
@@ -132,30 +132,30 @@
                       file_summary_ets   :: ets:tid(),
                       dedup_cache_ets    :: ets:tid(),
                       cur_file_cache_ets :: ets:tid()}).
--type(startup_fun_state() ::
-        {(fun ((A) -> 'finished' | {rabbit_guid:guid(), non_neg_integer(), A})),
-         A}).
+-type(msg_ref_delta_gen(A) ::
+        fun ((A) -> 'finished' |
+                    {rabbit_types:msg_id(), non_neg_integer(), A})).
 -type(maybe_guid_fun() :: 'undefined' | fun ((gb_set()) -> any())).
 -type(maybe_close_fds_fun() :: 'undefined' | fun (() -> 'ok')).
 -type(deletion_thunk() :: fun (() -> boolean())).
 
 -spec(start_link/4 ::
         (atom(), file:filename(), [binary()] | 'undefined',
-         startup_fun_state()) -> rabbit_types:ok_pid_or_error()).
+         {msg_ref_delta_gen(A), A}) -> rabbit_types:ok_pid_or_error()).
 -spec(successfully_recovered_state/1 :: (server()) -> boolean()).
 -spec(client_init/4 :: (server(), client_ref(), maybe_guid_fun(),
                         maybe_close_fds_fun()) -> client_msstate()).
 -spec(client_terminate/1 :: (client_msstate()) -> 'ok').
 -spec(client_delete_and_terminate/1 :: (client_msstate()) -> 'ok').
 -spec(client_ref/1 :: (client_msstate()) -> client_ref()).
--spec(write/3 :: (rabbit_guid:guid(), msg(), client_msstate()) -> 'ok').
--spec(read/2 :: (rabbit_guid:guid(), client_msstate()) ->
+-spec(write/3 :: (rabbit_types:msg_id(), msg(), client_msstate()) -> 'ok').
+-spec(read/2 :: (rabbit_types:msg_id(), client_msstate()) ->
              {rabbit_types:ok(msg()) | 'not_found', client_msstate()}).
--spec(contains/2 :: (rabbit_guid:guid(), client_msstate()) -> boolean()).
--spec(remove/2 :: ([rabbit_guid:guid()], client_msstate()) -> 'ok').
--spec(release/2 :: ([rabbit_guid:guid()], client_msstate()) -> 'ok').
--spec(sync/3 :: ([rabbit_guid:guid()], fun (() -> any()), client_msstate()) ->
-             'ok').
+-spec(contains/2 :: (rabbit_types:msg_id(), client_msstate()) -> boolean()).
+-spec(remove/2 :: ([rabbit_types:msg_id()], client_msstate()) -> 'ok').
+-spec(release/2 :: ([rabbit_types:msg_id()], client_msstate()) -> 'ok').
+-spec(sync/3 ::
+        ([rabbit_types:msg_id()], fun (() -> any()), client_msstate()) -> 'ok').
 
 -spec(sync/1 :: (server()) -> 'ok').
 -spec(set_maximum_since_use/2 :: (server(), non_neg_integer()) -> 'ok').
diff --git a/src/rabbit_queue_index.erl b/src/rabbit_queue_index.erl
index 76b1136f..7b5aa120 100644
--- a/src/rabbit_queue_index.erl
+++ b/src/rabbit_queue_index.erl
@@ -187,21 +187,21 @@
                               dirty_count         :: integer(),
                               max_journal_entries :: non_neg_integer(),
                               on_sync             :: on_sync_fun(),
-                              unsynced_guids      :: [rabbit_guid:guid()]
-                             }).
--type(startup_fun_state() ::
-        {fun ((A) -> 'finished' | {rabbit_guid:guid(), non_neg_integer(), A}),
-         A}).
+                              unsynced_guids      :: [rabbit_types:msg_id()]
+                            }).
+-type(contains_predicate() :: fun ((rabbit_types:msg_id()) -> boolean())).
+-type(walker(A) :: fun ((A) -> 'finished' |
+                               {rabbit_types:msg_id(), non_neg_integer(), A})).
 -type(shutdown_terms() :: [any()]).
 
 -spec(init/2 :: (rabbit_amqqueue:name(), on_sync_fun()) -> qistate()).
 -spec(shutdown_terms/1 :: (rabbit_amqqueue:name()) -> shutdown_terms()).
 -spec(recover/5 :: (rabbit_amqqueue:name(), shutdown_terms(), boolean(),
-                    fun ((rabbit_guid:guid()) -> boolean()), on_sync_fun()) ->
-             {'undefined' | non_neg_integer(), qistate()}).
+                    contains_predicate(), on_sync_fun()) ->
+                        {'undefined' | non_neg_integer(), qistate()}).
 -spec(terminate/2 :: ([any()], qistate()) -> qistate()).
 -spec(delete_and_terminate/1 :: (qistate()) -> qistate()).
--spec(publish/5 :: (rabbit_guid:guid(), seq_id(),
+-spec(publish/5 :: (rabbit_types:msg_id(), seq_id(),
                     rabbit_types:message_properties(), boolean(), qistate())
                    -> qistate()).
 -spec(deliver/2 :: ([seq_id()], qistate()) -> qistate()).
@@ -209,14 +209,13 @@
 -spec(sync/2 :: ([seq_id()], qistate()) -> qistate()).
 -spec(flush/1 :: (qistate()) -> qistate()).
 -spec(read/3 :: (seq_id(), seq_id(), qistate()) ->
-                     {[{rabbit_guid:guid(), seq_id(),
+                     {[{rabbit_types:msg_id(), seq_id(),
                         rabbit_types:message_properties(),
                         boolean(), boolean()}], qistate()}).
 -spec(next_segment_boundary/1 :: (seq_id()) -> seq_id()).
 -spec(bounds/1 :: (qistate()) ->
              {non_neg_integer(), non_neg_integer(), qistate()}).
--spec(recover/1 :: ([rabbit_amqqueue:name()]) ->
-                        {[[any()]], startup_fun_state()}).
+-spec(recover/1 :: ([rabbit_amqqueue:name()]) -> {[[any()]], {walker(A), A}}).
 
 -spec(add_queue_ttl/0 :: () -> 'ok').
 
diff --git a/src/rabbit_types.erl b/src/rabbit_types.erl
index ab2300c0..899291f2 100644
--- a/src/rabbit_types.erl
+++ b/src/rabbit_types.erl
@@ -21,7 +21,7 @@
 -ifdef(use_specs).
 
 -export_type([txn/0, maybe/1, info/0, infos/0, info_key/0, info_keys/0,
-              message/0, basic_message/0,
+              message/0, msg_id/0, basic_message/0,
               delivery/0, content/0, decoded_content/0, undecoded_content/0,
               unencoded_content/0, encoded_content/0, message_properties/0,
               vhost/0, ctag/0, amqp_error/0, r/1, r2/2, r3/3, listener/0,
@@ -62,11 +62,12 @@
                properties_bin        :: binary(),
                payload_fragments_rev :: [binary()]}).
 -type(content() :: undecoded_content() | decoded_content()).
+-type(msg_id() :: rabbit_guid:guid()).
 -type(basic_message() ::
       #basic_message{exchange_name  :: rabbit_exchange:name(),
                      routing_keys   :: [rabbit_router:routing_key()],
                      content        :: content(),
-                     guid           :: rabbit_guid:guid(),
+                     guid           :: msg_id(),
                      is_persistent  :: boolean()}).
 -type(message() :: basic_message()).
 -type(delivery() ::