new queue
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Feng Lee
parent
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commit
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@ -20,39 +20,76 @@
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%%% SOFTWARE.
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%%%-----------------------------------------------------------------------------
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%%% @doc
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%%% emqttd simple queue.
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%%% simple message queue.
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%%%
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%%% Notice that MQTT is not an enterprise messaging queue. MQTT assume that client
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%%% should be online in most of the time.
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%%%
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%%% This module wraps an erlang queue to store offline messages temporarily for MQTT
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%%% persistent session.
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%%%
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%%% If the broker restarted or crashed, all the messages stored will be gone.
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%%%
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%%% @end
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%%%-----------------------------------------------------------------------------
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%% TODO: this module should be rewrited...
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-module(emqttd_queue).
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-module(emqttd_mqueue).
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-author("Feng Lee <feng@emqtt.io>").
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-include_lib("emqtt/include/emqtt.hrl").
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-export([new/1, new/2, in/3, all/1, clear/1]).
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-export([new/2, name/1,
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is_empty/1, len/1,
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in/2, out/1,
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peek/1,
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to_list/1]).
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-define(DEFAULT_MAX_LEN, 1000).
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%% in_r/2, out_r/1,
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-record(mqtt_queue_wrapper, {queue = queue:new(),
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max_len = ?DEFAULT_MAX_LEN,
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store_qos0 = false}).
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-define(MAX_LEN, 600).
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-type mqtt_queue() :: #mqtt_queue_wrapper{}.
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-define(HIGH_WM, 0.6).
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-define(LOW_WM, 0.2).
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-record(mqueue, {name,
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len = 0,
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max_len = ?MAX_LEN,
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queue = queue:new(),
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store_qos0 = false,
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high_watermark = ?HIGH_WM,
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low_watermark = ?LOW_WM,
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alert = false}).
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-type mqueue() :: #mqueue{}.
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-type queue_option() :: {max_queued_messages, pos_integer()} %% Max messages queued
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| {high_queue_watermark, float()} %% High watermark
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| {low_queue_watermark, float()} %% Low watermark
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| {queue_qos0_messages, boolean()}. %% Queue Qos0 messages?
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%%------------------------------------------------------------------------------
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%% @doc
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%% New Queue.
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%%
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%% @doc New Queue.
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%% @end
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%%------------------------------------------------------------------------------
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-spec new(non_neg_integer()) -> mqtt_queue().
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new(MaxLen) -> #mqtt_queue_wrapper{max_len = MaxLen}.
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-spec new(binary() | string(), list(queue_option())) -> mqueue().
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new(Name, Opts) ->
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MaxLen = emqttd_opts:g(max_queued_messages, Opts, ?MAX_LEN),
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HighWM = round(MaxLen * emqttd_opts:g(high_queue_watermark, Opts, ?HIGH_WM)),
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LowWM = round(MaxLen * emqttd_opts:g(low_queue_watermark, Opts, ?LOW_WM)),
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#mqueue{name = Name, max_len = MaxLen,
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store_qos0 = emqttd_opts:g(queue_qos0_messages, Opts, false),
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high_watermark = HighWM, low_watermark = LowWM}.
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new(MaxLen, StoreQos0) -> #mqtt_queue_wrapper{max_len = MaxLen, store_qos0 = StoreQos0}.
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name(#mqueue{name = Name}) ->
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Name.
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len(#mqueue{len = Len}) ->
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Len.
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is_empty(#mqueue{len = 0}) -> true;
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is_empty(_Q) -> false.
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%%------------------------------------------------------------------------------
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%% @doc
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@ -60,39 +97,46 @@ new(MaxLen, StoreQos0) -> #mqtt_queue_wrapper{max_len = MaxLen, store_qos0 = Sto
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%%
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%% @end
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%%------------------------------------------------------------------------------
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-spec in(binary(), mqtt_message(), mqtt_queue()) -> mqtt_queue().
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in(ClientId, Message = #mqtt_message{qos = Qos},
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Wrapper = #mqtt_queue_wrapper{queue = Queue, max_len = MaxLen}) ->
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case queue:len(Queue) < MaxLen of
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true ->
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Wrapper#mqtt_queue_wrapper{queue = queue:in(Message, Queue)};
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false -> % full
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if
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Qos =:= ?QOS_0 ->
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lager:error("Queue ~s drop qos0 message: ~p", [ClientId, Message]),
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Wrapper;
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true ->
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{{value, Msg}, Queue1} = queue:drop(Queue),
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lager:error("Queue ~s drop message: ~p", [ClientId, Msg]),
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Wrapper#mqtt_queue_wrapper{queue = queue:in(Message, Queue1)}
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end
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end.
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-spec in(mqtt_message(), mqueue()) -> mqueue().
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in(#mqtt_message{qos = ?QOS_0}, MQ = #mqueue{store_qos0 = false}) ->
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MQ;
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%% queue is full, drop the oldest
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in(Msg, MQ = #mqueue{name = Name, len = Len, max_len = MaxLen, queue = Q}) when Len =:= MaxLen ->
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Q2 = case queue:out(Q) of
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{{value, OldMsg}, Q1} ->
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%%TODO: publish the dropped message to $SYS?
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lager:error("Queue(~s) drop message: ~p", [Name, OldMsg]),
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Q1;
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{empty, Q1} -> %% maybe max_len is 1
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Q1
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end,
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MQ#mqueue{queue = queue:in(Msg, Q2)};
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in(Msg, MQ = #mqueue{len = Len, queue = Q}) ->
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maybe_set_alarm(MQ#mqueue{len = Len+1, queue = queue:in(Msg, Q)}).
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%%------------------------------------------------------------------------------
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%% @doc
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%% Get all messages in queue.
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%%
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%% @end
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%%------------------------------------------------------------------------------
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-spec all(mqtt_queue()) -> list().
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all(#mqtt_queue_wrapper { queue = Queue }) -> queue:to_list(Queue).
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out(MQ = #mqueue{len = 0, queue = _Q}) ->
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{empty, MQ};
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out(MQ = #mqueue{len = Len, queue = Q}) ->
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{Result, Q1} = queue:out(Q),
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{Result, maybe_clear_alarm(MQ#mqueue{len = Len - 1, queue = Q1})}.
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%%------------------------------------------------------------------------------
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%% @doc
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%% Clear queue.
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%%
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%% @end
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%%------------------------------------------------------------------------------
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-spec clear(mqtt_queue()) -> mqtt_queue().
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clear(Queue) -> Queue#mqtt_queue_wrapper{queue = queue:new()}.
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peek(#mqueue{queue = Q}) ->
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queue:peek(Q).
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to_list(#mqueue{queue = Q}) ->
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queue:to_list(Q).
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maybe_set_alarm(MQ = #mqueue{name = Name, len = Len, high_watermark = HighWM, alert = false})
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when Len >= HighWM ->
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AlarmDescr = io_lib:format("len ~p > high_watermark ~p", [Len, HighWM]),
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emqttd_alarm:set_alarm({{queue_high_watermark, Name}, AlarmDescr}),
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MQ#mqueue{alert = true};
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maybe_set_alarm(MQ) ->
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MQ.
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maybe_clear_alarm(MQ = #mqueue{name = Name, len = Len, low_watermark = LowWM, alert = true})
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when Len =< LowWM ->
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emqttd_alarm:clear_alarm({queue_high_watermark, Name}), MQ#mqueue{alert = false};
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maybe_clear_alarm(MQ) ->
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MQ.
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