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authorRaimo Niskanen <[email protected]>2016-09-30 18:00:38 +0200
committerRaimo Niskanen <[email protected]>2016-10-12 11:27:34 +0200
commit77e175589b0ee3c1a4c94aef3cdcdf54cd84c53c (patch)
treec1f5fa31d25e4e3f8974448f131f980a798bfbeb /lib/stdlib/doc/src
parent800265f49f912dcf66846b13aa8032bf2f380caf (diff)
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Implement state timeouts
Diffstat (limited to 'lib/stdlib/doc/src')
-rw-r--r--lib/stdlib/doc/src/gen_statem.xml105
1 files changed, 73 insertions, 32 deletions
diff --git a/lib/stdlib/doc/src/gen_statem.xml b/lib/stdlib/doc/src/gen_statem.xml
index bba2de5e77..c0631c8448 100644
--- a/lib/stdlib/doc/src/gen_statem.xml
+++ b/lib/stdlib/doc/src/gen_statem.xml
@@ -527,7 +527,8 @@ handle_event(_, _, State, Data) ->
Type <c>info</c> originates from regular process messages sent
to the <c>gen_statem</c>. Also, the state machine
implementation can generate events of types
- <c>timeout</c>, <c>enter</c> and <c>internal</c> to itself.
+ <c>timeout</c>, <c>state_timeout</c>, <c>enter</c>,
+ and <c>internal</c> to itself.
</p>
</desc>
</datatype>
@@ -657,8 +658,7 @@ handle_event(_, _, State, Data) ->
All events stored with
<seealso marker="#type-action"><c>action()</c></seealso>
<c>next_event</c>
- are inserted in the queue to be processed before
- other events.
+ are inserted to be processed before the other queued events.
</p>
</item>
<item>
@@ -668,35 +668,36 @@ handle_event(_, _, State, Data) ->
are used, the <c>gen_statem</c> calls
the new state function with arguments
<seealso marker="#type-state_enter">(enter, OldState, Data)</seealso>.
- If this call returns any
+ Any
<seealso marker="#type-enter_action"><c>actions</c></seealso>
- that sets transition options
- they are merged with the current
- That is: <c>hibernate</c> and <c>timeout</c> overrides
- the current and <c>reply</c> sends a reply.
- This has the same effect as if you would have appended
- the actions from this state enter call to the actions
+ returned from this call are handled as if they were
+ appended to the actions
returned by the state function that changed states.
</p>
</item>
<item>
<p>
- If an
- <seealso marker="#type-event_timeout"><c>event_timeout()</c></seealso>
- is set through
- <seealso marker="#type-action"><c>action()</c></seealso>
- <c>timeout</c>,
- an event timer is started if the value is less than
- <c>infinity</c> or a time-out zero event
- is enqueued if the value is zero.
+ If there are enqueued events the (possibly new)
+ <seealso marker="#state_function">state function</seealso>
+ is called with the oldest enqueued event,
+ and we start again from the top of this list.
</p>
</item>
<item>
<p>
- The (possibly new)
+ Timeout timers
+ <seealso marker="#type-state_timeout"><c>state_timeout()</c></seealso>
+ and
+ <seealso marker="#type-event_timeout"><c>event_timeout()</c></seealso>
+ are handled. This may lead to a time-out zero event
+ being generated to the
<seealso marker="#state_function">state function</seealso>
- is called with the oldest enqueued event if there is any,
- otherwise the <c>gen_statem</c> goes into <c>receive</c>
+ and we start again from the top of this list.
+ </p>
+ </item>
+ <item>
+ <p>
+ Otherwise the <c>gen_statem</c> goes into <c>receive</c>
or hibernation
(if
<seealso marker="#type-hibernate"><c>hibernate()</c></seealso>
@@ -704,8 +705,11 @@ handle_event(_, _, State, Data) ->
to wait for the next message. In hibernation the next
non-system event awakens the <c>gen_statem</c>, or rather
the next incoming message awakens the <c>gen_statem</c>,
- but if it is a system event
- it goes right back into hibernation.
+ but if it is a system event it goes right back into hibernation.
+ When a new message arrives the
+ <seealso marker="#state_function">state function</seealso>
+ is called with the corresponding event,
+ and we start again from the top of this list.
</p>
</item>
</list>
@@ -747,20 +751,20 @@ handle_event(_, _, State, Data) ->
<seealso marker="#type-event_type"><c>event_type()</c></seealso>
<c>timeout</c>
after this time (in milliseconds) unless another
- event arrives in which case this time-out is cancelled.
- Notice that a retried or inserted event
- counts like a new in this respect.
+ event arrives or has arrived
+ in which case this time-out is cancelled.
+ Note that a retried, inserted or state time-out zero
+ events counts as arrived.
</p>
<p>
If the value is <c>infinity</c>, no timer is started, as
- it never triggers anyway.
+ it never would trigger anyway.
</p>
<p>
- If the value is <c>0</c>, the time-out event is immediately enqueued
- unless there already are enqueued events, as the
- time-out is then immediately cancelled.
- This is a feature ensuring that a time-out <c>0</c> event
- is processed before any not yet received external event.
+ If the value is <c>0</c> no timer is actually started,
+ instead the the time-out event is enqueued to ensure
+ that it gets processed before any not yet
+ received external event.
</p>
<p>
Note that it is not possible or needed to cancel this time-out,
@@ -769,6 +773,34 @@ handle_event(_, _, State, Data) ->
</desc>
</datatype>
<datatype>
+ <name name="state_timeout"/>
+ <desc>
+ <p>
+ Generates an event of
+ <seealso marker="#type-event_type"><c>event_type()</c></seealso>
+ <c>state_timeout</c>
+ after this time (in milliseconds) unless the <c>gen_statem</c>
+ changes states (<c>NewState =/= OldState</c>)
+ which case this time-out is cancelled.
+ </p>
+ <p>
+ If the value is <c>infinity</c>, no timer is started, as
+ it never would trigger anyway.
+ </p>
+ <p>
+ If the value is <c>0</c> no timer is actually started,
+ instead the the time-out event is enqueued to ensure
+ that it gets processed before any not yet
+ received external event.
+ </p>
+ <p>
+ Setting this timer while it is running will restart it with
+ the new time-out value. Therefore it is possible to cancel
+ this timeout by setting it to <c>infinity</c>.
+ </p>
+ </desc>
+ </datatype>
+ <datatype>
<name name="action"/>
<desc>
<p>
@@ -886,6 +918,15 @@ handle_event(_, _, State, Data) ->
to <c><anno>Time</anno></c> with <c><anno>EventContent</anno></c>.
</p>
</item>
+ <tag><c>state_timeout</c></tag>
+ <item>
+ <p>
+ Sets the
+ <seealso marker="#type-transition_option"><c>transition_option()</c></seealso>
+ <seealso marker="#type-state_timeout"><c>state_timeout()</c></seealso>
+ to <c><anno>Time</anno></c> with <c><anno>EventContent</anno></c>.
+ </p>
+ </item>
</taglist>
</desc>
</datatype>