From 2351b41f119835d7e9f4d1e07a47375a48367a50 Mon Sep 17 00:00:00 2001
From: Feng Lee <feng@emqx.io>
Date: Thu, 30 Aug 2018 11:40:53 +0800
Subject: [PATCH] Add is_expired/1, check_expiry/1, check_expiry/2

---
 src/emqx_message.erl | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/src/emqx_message.erl b/src/emqx_message.erl
index 8b49d44d6..d700c2aee 100644
--- a/src/emqx_message.erl
+++ b/src/emqx_message.erl
@@ -22,6 +22,7 @@
 -export([get_flag/2, get_flag/3, set_flag/2, set_flag/3, unset_flag/2]).
 -export([set_headers/2]).
 -export([get_header/2, get_header/3, set_header/3]).
+-export([is_expired/1, check_expiry/1, check_expiry/2]).
 -export([format/1]).
 
 -type(flag() :: atom()).
@@ -93,6 +94,31 @@ set_header(Hdr, Val, Msg = #message{headers = undefined}) ->
 set_header(Hdr, Val, Msg = #message{headers = Headers}) ->
     Msg#message{headers = maps:put(Hdr, Val, Headers)}.
 
+-spec(is_expired(emqx_types:message()) -> boolean()).
+is_expired(#message{headers = #{'Message-Expiry-Interval' := Interval}, timestamp = CreatedAt}) ->
+    elapsed(CreatedAt) > Interval;
+is_expired(_Msg) ->
+    false.
+
+-spec(check_expiry(emqx_types:message()) -> {ok, pos_integer()} | expired | false).
+check_expiry(Msg = #message{timestamp = CreatedAt}) ->
+    check_expiry(Msg, CreatedAt);
+check_expiry(_Msg) ->
+    false.
+
+-spec(check_expiry(emqx_types:message(), erlang:timestamp()) -> {ok, pos_integer()} | expired | false).
+check_expiry(#message{headers = #{'Message-Expiry-Interval' := Interval}}, Since) ->
+    case Interval - elapsed(Since) of
+        I when I > 0 -> {ok, I};
+        _ -> expired
+    end;
+check_expiry(_Msg, _Since) ->
+    false.
+
+elapsed(Since) ->
+    Secs = timer:now_diff(os:timestamp(), Since) div 1000,
+    if Secs < 0 -> 0; true -> Secs end.
+
 format(#message{id = Id, qos = QoS, topic = Topic, from = From, flags = Flags, headers = Headers}) ->
     io_lib:format("Message(Id=~s, QoS=~w, Topic=~s, From=~s, Flags=~s, Headers=~s)",
                   [Id, QoS, Topic, From, format(flags, Flags), format(headers, Headers)]).