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dqe
0.3.22
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0.4.13
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0.4.8
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0.4.4
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0.1.20
0.1.10
0.1.9
DalmatinerDB query engine
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src/dqe_get.erl
-module(dqe_get).
-behaviour(dflow).
-export([init/1, describe/1, start/2, emit/3, done/2]).
-record(state, {
bucket :: binary(),
key :: binary(),
start :: non_neg_integer(),
count :: non_neg_integer(),
chunk :: pos_integer()
}).
init([Start, Count, Resolution, Bucket, Key]) ->
{ok, Chunk} = application:get_env(dqe, get_chunk),
init([Start, Count, Resolution, Bucket, Key, Chunk]);
init([Start, Count, Resolution, Bucket, KeyL, Chunk]) when is_list(KeyL)->
Key = dproto:metric_from_list(KeyL),
init([Start, Count, Resolution, Bucket, Key, Chunk]);
init([Start, Count, _Resolution, Bucket, Key, Chunk]) ->
{ok, #state{start = Start, count = Count, bucket = Bucket, key = Key,
chunk = Chunk}, []}.
describe(#state{bucket = Bucket, key = Key}) ->
[Bucket, "/", Key].
start(run, State = #state{count = 0}) ->
{done, State};
start(run,
State = #state{start = Start, count = Count, chunk = Chunk,
bucket = Bucket, key = Key}) when
Count >= Chunk ->
%% We do a bit of cheating here this allows us to loop.
State1 = State#state{start = Start + Chunk, count = Count - Chunk},
case ddb_connection:get(Bucket, Key, Start, Chunk) of
{error, _Error} ->
{done, State};
{ok, <<>>} ->
dflow:start(self(), run),
{emit, mmath_bin:realize(mmath_bin:empty(Chunk)), State1};
{ok, Data} ->
dflow:start(self(), run),
{emit, mmath_bin:realize(Data), State1}
end;
start(run, State = #state{start = Start, count = Count,
bucket = Bucket, key = Key}) ->
case ddb_connection:get(Bucket, Key, Start, Count) of
{error, _Error} ->
{done, State};
{ok, <<>>} ->
{done, mmath_bin:realize(mmath_bin:empty(Count)), State};
{ok, Data} ->
{done, mmath_bin:realize(Data), State}
end.
emit(_Child, _Data, State) ->
{ok, State}.
done(_, State) ->
{done, State}.