diff options
Diffstat (limited to 'lib/stdlib/doc/src/gen_statem.xml')
| -rw-r--r-- | lib/stdlib/doc/src/gen_statem.xml | 190 |
1 files changed, 146 insertions, 44 deletions
diff --git a/lib/stdlib/doc/src/gen_statem.xml b/lib/stdlib/doc/src/gen_statem.xml index 18089a8191..17a3a3c83c 100644 --- a/lib/stdlib/doc/src/gen_statem.xml +++ b/lib/stdlib/doc/src/gen_statem.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>2016-2017</year> + <year>2016</year><year>2017</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -67,13 +67,16 @@ It has the same features and adds some really useful: </p> <list type="bulleted"> - <item>State code is gathered.</item> - <item>The state can be any term.</item> - <item>Events can be postponed.</item> - <item>Events can be self-generated.</item> - <item>Automatic state enter code can be called.</item> - <item>A reply can be sent from a later state.</item> - <item>There can be multiple <c>sys</c> traceable replies.</item> + <item>Gathered state code.</item> + <item>Arbitrary term state.</item> + <item>Event postponing.</item> + <item>Self-generated events.</item> + <item>State time-out.</item> + <item>Multiple generic named time-outs.</item> + <item>Absolute time-out time.</item> + <item>Automatic state enter calls.</item> + <item>Reply from other state than the request.</item> + <item>Multiple <c>sys</c> traceable replies.</item> </list> <p> The callback model(s) for <c>gen_statem</c> differs from @@ -148,7 +151,7 @@ erlang:'!' -----> Module:StateName/3 This gathers all code for a specific state in one function as the <c>gen_statem</c> engine branches depending on state name. - Notice the fact that there is a mandatory callback function + Note the fact that the callback function <seealso marker="#Module:terminate/3"><c>Module:terminate/3</c></seealso> makes the state name <c>terminate</c> unusable in this mode. </p> @@ -533,10 +536,12 @@ handle_event(_, _, State, Data) -> originate from the corresponding API functions. For calls, the event contains whom to reply to. 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>state_timeout</c>, - and <c>internal</c> to itself. + to the <c>gen_statem</c>. The state machine + implementation can, in addition to the above, + generate + <seealso marker="#type-event_type"><c>events of types</c></seealso> + <c>timeout</c>, <c>{timeout,<anno>Name</anno>}</c>, + <c>state_timeout</c>, and <c>internal</c> to itself. </p> </desc> </datatype> @@ -703,13 +708,14 @@ handle_event(_, _, State, Data) -> </item> <item> <p> - Timeout timers - <seealso marker="#type-state_timeout"><c>state_timeout()</c></seealso> + Time-out timers + <seealso marker="#type-event_timeout"><c>event_timeout()</c></seealso>, + <seealso marker="#type-generic_timeout"><c>generic_timeout()</c></seealso> and - <seealso marker="#type-event_timeout"><c>event_timeout()</c></seealso> + <seealso marker="#type-state_timeout"><c>state_timeout()</c></seealso> are handled. Time-outs with zero time are guaranteed to be delivered to the state machine before any external - not yet received event so if there is such a timeout requested, + not yet received event so if there is such a time-out requested, the corresponding time-out zero event is enqueued as the newest event. </p> @@ -787,49 +793,102 @@ handle_event(_, _, State, Data) -> <name name="event_timeout"/> <desc> <p> - Generates an event of + Starts a timer set by + <seealso marker="#type-enter_action"><c>enter_action()</c></seealso> + <c>timeout</c>. + When the timer expires an event of <seealso marker="#type-event_type"><c>event_type()</c></seealso> - <c>timeout</c> - after this time (in milliseconds) unless another - event arrives or has arrived - in which case this time-out is cancelled. + <c>timeout</c> will be generated. + See + <seealso marker="erts:erlang#start_timer/4"><c>erlang:start_timer/4</c></seealso> + for how <c>Time</c> and + <seealso marker="#type-timeout_option"><c>Options</c></seealso> + are interpreted. Future <c>erlang:start_timer/4</c> <c>Options</c> + will not necessarily be supported. + </p> + <p> + Any event that arrives cancels this time-out. Note that a retried or inserted event counts as arrived. So does a state time-out zero event, if it was generated - before this timer is requested. + before this time-out is requested. </p> <p> - If the value is <c>infinity</c>, no timer is started, as - it never would trigger anyway. + If <c>Time</c> is <c>infinity</c>, + no timer is started, as it never would expire anyway. </p> <p> - If the value is <c>0</c> no timer is actually started, + If <c>Time</c> is relative and <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, + Note that it is not possible nor needed to cancel this time-out, as it is cancelled automatically by any other event. </p> </desc> </datatype> <datatype> + <name name="generic_timeout"/> + <desc> + <p> + Starts a timer set by + <seealso marker="#type-enter_action"><c>enter_action()</c></seealso> + <c>{timeout,Name}</c>. + When the timer expires an event of + <seealso marker="#type-event_type"><c>event_type()</c></seealso> + <c>{timeout,Name}</c> will be generated. + See + <seealso marker="erts:erlang#start_timer/4"><c>erlang:start_timer/4</c></seealso> + for how <c>Time</c> and + <seealso marker="#type-timeout_option"><c>Options</c></seealso> + are interpreted. Future <c>erlang:start_timer/4</c> <c>Options</c> + will not necessarily be supported. + </p> + <p> + If <c>Time</c> is <c>infinity</c>, + no timer is started, as it never would expire anyway. + </p> + <p> + If <c>Time</c> is relative and <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 a timer with the same <c>Name</c> while it is running + will restart it with the new time-out value. + Therefore it is possible to cancel + a specific time-out by setting it to <c>infinity</c>. + </p> + </desc> + </datatype> + <datatype> <name name="state_timeout"/> <desc> <p> - Generates an event of + Starts a timer set by + <seealso marker="#type-enter_action"><c>enter_action()</c></seealso> + <c>state_timeout</c>. + When the timer expires 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. + <c>state_timeout</c> will be generated. + See + <seealso marker="erts:erlang#start_timer/4"><c>erlang:start_timer/4</c></seealso> + for how <c>Time</c> and + <seealso marker="#type-timeout_option"><c>Options</c></seealso> + are interpreted. Future <c>erlang:start_timer/4</c> <c>Options</c> + will not necessarily be supported. </p> <p> - If the value is <c>infinity</c>, no timer is started, as - it never would trigger anyway. + If <c>Time</c> is <c>infinity</c>, + no timer is started, as it never would expire anyway. </p> <p> - If the value is <c>0</c> no timer is actually started, + If <c>Time</c> is relative and <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. @@ -842,6 +901,20 @@ handle_event(_, _, State, Data) -> </desc> </datatype> <datatype> + <name name="timeout_option"/> + <desc> + <p> + If <c>Abs</c> is <c>true</c> an absolute timer is started, + and if it is <c>false</c> a relative, which is the default. + See + <seealso marker="erts:erlang#start_timer/4"><c>erlang:start_timer/4</c></seealso> + for details. + </p> + <p> + </p> + </desc> + </datatype> + <datatype> <name name="action"/> <desc> <p> @@ -955,7 +1028,21 @@ handle_event(_, _, State, Data) -> Sets the <seealso marker="#type-transition_option"><c>transition_option()</c></seealso> <seealso marker="#type-event_timeout"><c>event_timeout()</c></seealso> - to <c><anno>Time</anno></c> with <c><anno>EventContent</anno></c>. + to <c><anno>Time</anno></c> with <c><anno>EventContent</anno></c> + and time-out options + <seealso marker="#type-timeout_option"><c><anno>Options</anno></c></seealso>. + </p> + </item> + <tag><c>{timeout,<anno>Name</anno>}</c></tag> + <item> + <p> + Sets the + <seealso marker="#type-transition_option"><c>transition_option()</c></seealso> + <seealso marker="#type-generic_timeout"><c>generic_timeout()</c></seealso> + to <c><anno>Time</anno></c> for <c><anno>Name</anno></c> + with <c><anno>EventContent</anno></c> + and time-out options + <seealso marker="#type-timeout_option"><c><anno>Options</anno></c></seealso>. </p> </item> <tag><c>state_timeout</c></tag> @@ -964,7 +1051,9 @@ handle_event(_, _, State, Data) -> 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>. + to <c><anno>Time</anno></c> with <c><anno>EventContent</anno></c> + and time-out options + <seealso marker="#type-timeout_option"><c><anno>Options</anno></c></seealso>. </p> </item> </taglist> @@ -1236,7 +1325,7 @@ handle_event(_, _, State, Data) -> to avoid that the calling process dies when the call times out, you will have to be prepared to handle a late reply. - So why not just allow the calling process to die? + So why not just let the calling process die? </p> </note> <p> @@ -1645,6 +1734,16 @@ handle_event(_, _, State, Data) -> <v>Reason = term()</v> </type> <desc> + <note> + <p> + This callback is optional, so callback modules need not export it. + If a release upgrade/downgrade with + <c>Change={advanced,Extra}</c> + specified in the <c>.appup</c> file is made + when <c>code_change/4</c> is not implemented + the process will crash with exit reason <c>undef</c>. + </p> + </note> <p> This function is called by a <c>gen_statem</c> when it is to update its internal state during a release upgrade/downgrade, @@ -1705,7 +1804,7 @@ handle_event(_, _, State, Data) -> <func> <name>Module:init(Args) -> Result(StateType)</name> <fsummary> - Optional function for initializing process and internal state. + Initializing process and internal state. </fsummary> <type> <v>Args = term()</v> @@ -1721,7 +1820,7 @@ handle_event(_, _, State, Data) -> <seealso marker="#start_link/3"><c>start_link/3,4</c></seealso> or <seealso marker="#start/3"><c>start/3,4</c></seealso>, - this optional function is called by the new process to initialize + this function is called by the new process to initialize the implementation state and server data. </p> <p> @@ -1730,13 +1829,16 @@ handle_event(_, _, State, Data) -> </p> <note> <p> - This callback is optional, so a callback module does not need - to export it, but most do. If this function is not exported, - the <c>gen_statem</c> should be started through + Note that if the <c>gen_statem</c> is started trough <seealso marker="proc_lib"><c>proc_lib</c></seealso> and - <seealso marker="#enter_loop/4"><c>enter_loop/4-6</c></seealso>. + <seealso marker="#enter_loop/4"><c>enter_loop/4-6</c></seealso>, + this callback will never be called. + Since this callback is not optional it can + in that case be implemented as: </p> + <pre> +init(Args) -> erlang:error(not_implemented, [Args]).</pre> </note> </desc> </func> |