Refactor beam_stats_state

diff --git a/src/beam_stats_state.erl b/src/beam_stats_state.erl
index 1fd6e9d..f21f231 100644 (file)
--- a/src/beam_stats_state.erl
+++ b/src/beam_stats_state.erl
@@ -12,21 +12,37 @@
     , export/1
     ]).
 
--record(?MODULE,
-    { timestamp             :: erlang:timestamp()
-    , node_id               :: atom()
-    , memory                :: [{atom(), non_neg_integer()}]
+-record(snapshots,
+    { memory     :: [{atom(), non_neg_integer()}]
+    , run_queue  :: non_neg_integer()
+    }).
 
-    , previous_io_bytes_in  :: non_neg_integer()
-    , previous_io_bytes_out :: non_neg_integer()
-    , current_io_bytes_in   :: non_neg_integer()
-    , current_io_bytes_out  :: non_neg_integer()
+-type snapshots() ::
+    #snapshots{}.
+
+-record(deltas,
+    { reductions :: non_neg_integer()
+    }).
+
+-type deltas() ::
+    #deltas{}.
+
+-record(totals,
+    { io_bytes_in      :: non_neg_integer()
+    , io_bytes_out     :: non_neg_integer()
+    , context_switches :: non_neg_integer()
+    }).
 
-    , previous_context_switches :: non_neg_integer()
-    ,  current_context_switches :: non_neg_integer()
+-type totals() ::
+    #totals{}.
 
-    , reductions                :: non_neg_integer()
-    , run_queue                 :: non_neg_integer()
+-record(?MODULE,
+    { timestamp       :: erlang:timestamp()
+    , node_id         :: atom()
+    , snapshots       :: snapshots()  % Current state
+    , deltas          :: deltas()     % Accumulated since last check
+    , totals_previous :: totals()     % Accumulated since VM start, as of last state
+    , totals_current  :: totals()     % Accumulated since VM start, as of this state
     }).
 
 -define(T, #?MODULE).
@@ -37,78 +53,92 @@
 -spec new() ->
     t().
 new() ->
-    { {input  , CurrentIOBytesIn}
-    , {output , CurrentIOBytesOut}
-    } = erlang:statistics(io),
-    {CurrentContextSwitches, 0} = erlang:statistics(context_switches),
-    {_ReductionsTotal, ReductionsDelta} = erlang:statistics(reductions),
-    RunQueue = erlang:statistics(run_queue),
+    TotalsPrevious = totals_empty(),
+    new(TotalsPrevious).
+
+-spec new(TotalsPrevious :: totals()) ->
+    t().
+new(#totals{}=TotalsPrevious) ->
     ?T
-    { timestamp             = os:timestamp()
-    , node_id               = erlang:node()
-    , memory                = erlang:memory()
-    , previous_io_bytes_in  = 0
-    , previous_io_bytes_out = 0
-    , current_io_bytes_in   = CurrentIOBytesIn
-    , current_io_bytes_out  = CurrentIOBytesOut
-    , previous_context_switches = 0
-    ,  current_context_switches = CurrentContextSwitches
-    , reductions                = ReductionsDelta
-    , run_queue                 = RunQueue
+    { timestamp       = os:timestamp()
+    , node_id         = erlang:node()
+    , snapshots       = snapshots_new()
+    , deltas          = deltas_new()
+    , totals_previous = TotalsPrevious
+    , totals_current  = totals_new()
     }.
 
 -spec update(t()) ->
     t().
-update(?T
-    { current_io_bytes_in      = PreviousIOBytesIn
-    , current_io_bytes_out     = PreviousIOBytesOut
-    , current_context_switches = PreviousContextSwitches
-    }
-) ->
-    { {input  , CurrentIOBytesIn}
-    , {output , CurrentIOBytesOut}
-    } = erlang:statistics(io),
-    {CurrentContextSwitches, 0} = erlang:statistics(context_switches),
-    {_ReductionsTotal, ReductionsDelta} = erlang:statistics(reductions),
-    RunQueue = erlang:statistics(run_queue),
-    ?T
-    { timestamp             = os:timestamp()
-    , node_id               = erlang:node()
-    , memory                = erlang:memory()
-    , previous_io_bytes_in  = PreviousIOBytesIn
-    , previous_io_bytes_out = PreviousIOBytesOut
-    , current_io_bytes_in   = CurrentIOBytesIn
-    , current_io_bytes_out  = CurrentIOBytesOut
-    , previous_context_switches = PreviousContextSwitches
-    ,  current_context_switches = CurrentContextSwitches
-    , reductions                = ReductionsDelta
-    , run_queue                 = RunQueue
-    }.
+update(?T{totals_current=TotalsPrevious}) ->
+    new(TotalsPrevious).
 
 -spec export(t()) ->
     beam_stats:t().
 export(
     ?T
-    { timestamp             = Timestamp
-    , node_id               = NodeID
-    , memory                = Memory
-    , previous_io_bytes_in  = PreviousIOBytesIn
-    , previous_io_bytes_out = PreviousIOBytesOut
-    , current_io_bytes_in   = CurrentIOBytesIn
-    , current_io_bytes_out  = CurrentIOBytesOut
-    , previous_context_switches = PreviousContextSwitches
-    ,  current_context_switches = CurrentContextSwitches
-    , reductions                = Reductions
-    , run_queue                 = RunQueue
+    { timestamp = Timestamp
+    , node_id   = NodeID
+    , snapshots =
+        #snapshots
+        { memory    = Memory
+        , run_queue = RunQueue
+        }
+    , deltas =
+        #deltas
+        { reductions = Reductions
+        }
+    , totals_previous =
+        #totals
+        { io_bytes_in      = PreviousIOBytesIn
+        , io_bytes_out     = PreviousIOBytesOut
+        , context_switches = PreviousContextSwitches
+        }
+    , totals_current =
+        #totals
+        { io_bytes_in      = CurrentIOBytesIn
+        , io_bytes_out     = CurrentIOBytesOut
+        , context_switches = CurrentContextSwitches
+        }
     }
 ) ->
     #beam_stats
-    { timestamp    = Timestamp
-    , node_id      = NodeID
-    , memory       = Memory
-    , io_bytes_in  = CurrentIOBytesIn  - PreviousIOBytesIn
-    , io_bytes_out = CurrentIOBytesOut - PreviousIOBytesOut
+    { timestamp        = Timestamp
+    , node_id          = NodeID
+    , memory           = Memory
+    , io_bytes_in      = CurrentIOBytesIn  - PreviousIOBytesIn
+    , io_bytes_out     = CurrentIOBytesOut - PreviousIOBytesOut
     , context_switches = CurrentContextSwitches - PreviousContextSwitches
     , reductions       = Reductions
     , run_queue        = RunQueue
     }.
+
+snapshots_new() ->
+    #snapshots
+    { memory     = erlang:memory()
+    , run_queue  = erlang:statistics(run_queue)
+    }.
+
+deltas_new() ->
+    {_ReductionsTotal, ReductionsDelta} = erlang:statistics(reductions),
+    #deltas
+    { reductions = ReductionsDelta
+    }.
+
+totals_new() ->
+    { {input  , IOBytesIn}
+    , {output , IOBytesOut}
+    } = erlang:statistics(io),
+    {ContextSwitches, 0} = erlang:statistics(context_switches),
+    #totals
+    { io_bytes_in      = IOBytesIn
+    , io_bytes_out     = IOBytesOut
+    , context_switches = ContextSwitches
+    }.
+
+totals_empty() ->
+    #totals
+    { io_bytes_in      = 0
+    , io_bytes_out     = 0
+    , context_switches = 0
+    }.