Track IO deltas.

[beam_stats.git] / src / beam_stats_state.erl

diff --git a/src/beam_stats_state.erl b/src/beam_stats_state.erl
new file mode 100644 (file)
index 0000000..552b5b1
--- /dev/null
+++ b/src/beam_stats_state.erl
@@ -0,0 +1,85 @@
+-module(beam_stats_state).
+
+-include("include/beam_stats.hrl").
+
+-export_type(
+    [ t/0
+    ]).
+
+-export(
+    [ new/0
+    , update/1
+    , export/1
+    ]).
+
+-record(?MODULE,
+    { timestamp             :: erlang:timestamp()
+    , node_id               :: atom()
+    , memory                :: [{atom(), 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()
+    }).
+
+-define(T, #?MODULE).
+
+-opaque t() ::
+    ?T{}.
+
+-spec new() ->
+    t().
+new() ->
+    { {input  , CurrentIOBytesIn}
+    , {output , CurrentIOBytesOut}
+    } = erlang:statistics(io),
+    ?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
+    }.
+
+-spec update(t()) ->
+    t().
+update(?T
+    { previous_io_bytes_in  = PreviousIOBytesIn
+    , previous_io_bytes_out = PreviousIOBytesOut
+    }
+) ->
+    { {input  , CurrentIOBytesIn}
+    , {output , CurrentIOBytesOut}
+    } = erlang:statistics(io),
+    ?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
+    }.
+
+-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
+    }
+) ->
+    #beam_stats
+    { timestamp    = Timestamp
+    , node_id      = NodeID
+    , memory       = Memory
+    , io_bytes_in  = CurrentIOBytesIn  - PreviousIOBytesIn
+    , io_bytes_out = CurrentIOBytesOut - PreviousIOBytesOut
+    }.