aboutsummaryrefslogtreecommitdiffstats
path: root/lib/stdlib/doc
diff options
context:
space:
mode:
Diffstat (limited to 'lib/stdlib/doc')
-rw-r--r--lib/stdlib/doc/src/ets.xml46
-rw-r--r--lib/stdlib/doc/src/gen_statem.xml232
-rw-r--r--lib/stdlib/doc/src/maps.xml34
-rw-r--r--lib/stdlib/doc/src/notes.xml6
-rw-r--r--lib/stdlib/doc/src/rand.xml110
-rw-r--r--lib/stdlib/doc/src/sys.xml166
6 files changed, 446 insertions, 148 deletions
diff --git a/lib/stdlib/doc/src/ets.xml b/lib/stdlib/doc/src/ets.xml
index ccccf7de88..7594514b29 100644
--- a/lib/stdlib/doc/src/ets.xml
+++ b/lib/stdlib/doc/src/ets.xml
@@ -188,6 +188,31 @@
is used to keep the table fixated during the entire traversal.</p>
</item>
</list>
+ <note>
+ <p>Even though the access of a single object is always guaranteed to be
+ <seealso marker="#concurrency">atomic and isolated</seealso>, each traversal
+ through a table to find the next key is not done with such guarantees. This is often
+ not a problem, but may cause rare subtle "unexpected" effects if a concurrent
+ process inserts objects during a traversal. For example, consider one
+ process doing</p>
+<pre>
+ets:new(t, [ordered_set, named_table]),
+ets:insert(t, {1}),
+ets:insert(t, {2}),
+ets:insert(t, {3}),
+</pre>
+ <p>A concurrent call to <c>ets:first(t)</c>, done by another
+ process, may then in rare cases return <c>2</c> even though
+ <c>2</c> has never existed in the table ordered as the first key. In
+ the same way, a concurrent call to <c>ets:next(t, 1)</c> may return
+ <c>3</c> even though <c>3</c> never existed in the table
+ ordered directly after <c>1</c>.</p>
+ <p>Effects like this are improbable but possible. The probability will
+ further be reduced (if not vanish) if table option
+ <seealso marker="#new_2_write_concurrency"><c>write_concurrency</c></seealso>
+ is not enabled. This can also only be a potential concern for
+ <c>ordered_set</c> where the traversal order is defined.</p>
+ </note>
</section>
<section>
@@ -644,9 +669,8 @@ Error: fun containing local Erlang function calls
</item>
<item>
<p><c>Item=stats, Value=tuple()</c></p>
- <p>Returns internal statistics about <c>set</c>, <c>bag</c>, and
- <c>duplicate_bag</c> tables on an internal format used by OTP
- test suites. Not for production use.</p></item>
+ <p>Returns internal statistics about tables on an internal format
+ used by OTP test suites. Not for production use.</p></item>
</list>
</desc>
</func>
@@ -1175,11 +1199,17 @@ ets:select(Table, MatchSpec),</code>
Functions that makes such promises over many objects (like
<seealso marker="#insert/2"><c>insert/2</c></seealso>)
gain less (or nothing) from this option.</p>
- <p>Table type <c>ordered_set</c> is not affected by this option.
- Also, the memory consumption inflicted by
- both <c>write_concurrency</c> and <c>read_concurrency</c> is a
- constant overhead per table. This overhead can be especially
- large when both options are combined.</p>
+ <p>The memory consumption inflicted by both <c>write_concurrency</c>
+ and <c>read_concurrency</c> is a constant overhead per table for
+ <c>set</c>, <c>bag</c> and <c>duplicate_bag</c>. For
+ <c>ordered_set</c> the memory overhead depends on the number
+ of inserted objects and the amount of actual detected
+ concurrency in runtime. The memory overhead can be especially
+ large when both options are combined.</p>
+ <note>
+ <p>Prior to stdlib-3.7 (OTP-22.0) <c>write_concurrency</c> had no
+ effect on <c>ordered_set</c>.</p>
+ </note>
<marker id="new_2_read_concurrency"></marker>
</item>
<tag><c>{read_concurrency,boolean()}</c></tag>
diff --git a/lib/stdlib/doc/src/gen_statem.xml b/lib/stdlib/doc/src/gen_statem.xml
index aaa26df18d..d678d0436b 100644
--- a/lib/stdlib/doc/src/gen_statem.xml
+++ b/lib/stdlib/doc/src/gen_statem.xml
@@ -167,7 +167,7 @@ erlang:'!' -----> Module:StateName/3
</p>
<marker id="state callback"/>
<p>
- The "<em>state callback</em>" for a specific
+ The <em>state callback</em> for a specific
<seealso marker="#type-state">state</seealso>
in a <c>gen_statem</c> is the callback function that is called
for all events in this state. It is selected depending on which
@@ -179,7 +179,7 @@ erlang:'!' -----> Module:StateName/3
When the
<seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
is <c>state_functions</c>, the state must be an atom and
- is used as the state callback name; see
+ is used as the <em>state callback</em> name; see
<seealso marker="#Module:StateName/3"><c>Module:StateName/3</c></seealso>.
This co-locates all code for a specific state
in one function as the <c>gen_statem</c> engine
@@ -192,7 +192,7 @@ erlang:'!' -----> Module:StateName/3
When the
<seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
is <c>handle_event_function</c>, the state can be any term
- and the state callback name is
+ and the <em>state callback</em> name is
<seealso marker="#Module:handle_event/4"><c>Module:handle_event/4</c></seealso>.
This makes it easy to branch depending on state or event as you desire.
Be careful about which events you handle in which
@@ -200,12 +200,36 @@ erlang:'!' -----> Module:StateName/3
forever creating an infinite busy loop.
</p>
<p>
- The <c>gen_statem</c> enqueues incoming events in order of arrival
- and presents these to the
- <seealso marker="#state callback">state callback</seealso>
- in that order. The state callback can postpone an event
- so it is not retried in the current state.
- After a state change the queue restarts with the postponed events.
+ When <c>gen_statem</c> receives a process message it is
+ converted into an event and the
+ <seealso marker="#state callback"><em>state callback</em></seealso>
+ is called with the event as two arguments: type and content.
+ When the
+ <seealso marker="#state callback"><em>state callback</em></seealso>
+ has processed the event it returns to <c>gen_statem</c>
+ which does a <em>state transition</em>.
+ If this <em>state transition</em> is to a different state,
+ that is: <c>NextState =/= State</c>, it is a <em>state change</em>.
+ </p>
+ <p>
+ The
+ <seealso marker="#state callback"><em>state callback</em></seealso>
+ may return
+ <seealso marker="#type-action"><em>transition actions</em></seealso>
+ for <c>gen_statem</c>
+ to execute during the <em>state transition</em>,
+ for example to reply to a
+ <seealso marker="#call/2"><c>gen_statem:call/2,3</c></seealso>.
+ </p>
+ <p>
+ One of the possible <em>transition actions</em>
+ is to postpone the current event.
+ Then it is not retried in the current state.
+ The <c>gen_statem</c> engine keeps a queue of events
+ divided into the postponed events
+ and the events still to process.
+ After a <em>state change</em> the queue restarts
+ with the postponed events.
</p>
<p>
The <c>gen_statem</c> event queue model is sufficient
@@ -215,13 +239,17 @@ erlang:'!' -----> Module:StateName/3
to entering a new receive statement.
</p>
<p>
- The <seealso marker="#state callback">state callback</seealso>
+ The
+ <seealso marker="#state callback"><em>state callback</em></seealso>
can insert events using the
- <seealso marker="#type-action"><c>action()</c></seealso>
+ <seealso marker="#type-action"><em>transition actions</em></seealso>
<c>next_event</c>
- and such an event is inserted as the next to present
- to the state callback. That is, as if it is
- the oldest incoming event. A dedicated
+ and such an event is inserted in the event queue
+ as the next to call the
+ <seealso marker="#state callback"><em>state callback</em></seealso>
+ with.
+ That is, as if it is the oldest incoming event.
+ A dedicated
<seealso marker="#type-event_type"><c>event_type()</c></seealso>
<c>internal</c> can be used for such events making them impossible
to mistake for external events.
@@ -236,24 +264,26 @@ erlang:'!' -----> Module:StateName/3
<p>
The <c>gen_statem</c> engine can automatically
make a specialized call to the
- <seealso marker="#state callback">state callback</seealso>
+ <seealso marker="#state callback"><em>state callback</em></seealso>
whenever a new state is entered; see
<seealso marker="#type-state_enter"><c>state_enter()</c></seealso>.
This is for writing code common to all state entries.
- Another way to do it is to insert an event at the state transition,
- and/or to use a dedicated state transition function,
+ Another way to do it is to explicitly insert an event
+ at the <em>state transition</em>,
+ and/or to use a dedicated <em>state transition</em> function,
but that is something you will have to remember
- at every state transition to the state(s) that need it.
+ at every <em>state transition</em> to the state(s) that need it.
</p>
<note>
<p>If you in <c>gen_statem</c>, for example, postpone
- an event in one state and then call another state callback
- of yours, you have not changed states and hence the postponed event
- is not retried, which is logical but can be confusing.
+ an event in one state and then call another <em>state callback</em>
+ of yours, you have not done a <em>state change</em>
+ and hence the postponed event is not retried,
+ which is logical but can be confusing.
</p>
</note>
<p>
- For the details of a state transition, see type
+ For the details of a <em>state transition</em>, see type
<seealso marker="#type-transition_option"><c>transition_option()</c></seealso>.
</p>
<p>
@@ -276,7 +306,8 @@ erlang:'!' -----> Module:StateName/3
The <c>gen_statem</c> process can go into hibernation; see
<seealso marker="proc_lib#hibernate/3"><c>proc_lib:hibernate/3</c></seealso>.
It is done when a
- <seealso marker="#state callback">state callback</seealso> or
+ <seealso marker="#state callback"><em>state callback</em></seealso>
+ or
<seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
specifies <c>hibernate</c> in the returned
<seealso marker="#type-action"><c>Actions</c></seealso>
@@ -551,7 +582,7 @@ handle_event(_, _, State, Data) ->
<seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
is <c>handle_event_function</c>,
the state can be any term.
- After a state change (<c>NextState =/= State</c>),
+ After a <em>state change</em> (<c>NextState =/= State</c>),
all postponed events are retried.
</p>
</desc>
@@ -564,7 +595,7 @@ handle_event(_, _, State, Data) ->
<seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
is <c>state_functions</c>,
the state must be of this type.
- After a state change (<c>NextState =/= State</c>),
+ After a <em>state change</em> (<c>NextState =/= State</c>),
all postponed events are retried.
</p>
</desc>
@@ -595,7 +626,7 @@ handle_event(_, _, State, Data) ->
</p>
<p>
<c>internal</c> events can only be generated by the
- state machine itself through the state transition action
+ state machine itself through the <em>transition action</em>
<seealso marker="#type-action"><c>next_event</c></seealso>.
</p>
</desc>
@@ -633,9 +664,9 @@ handle_event(_, _, State, Data) ->
This is the return type from
<seealso marker="#Module:callback_mode/0"><c>Module:callback_mode/0</c></seealso>
and selects
- <seealso marker="#type-callback_mode">callback mode</seealso>
+ <seealso marker="#type-callback_mode"><em>callback mode</em></seealso>
and whether to do
- <seealso marker="#type-state_enter">state enter calls</seealso>,
+ <seealso marker="#type-state_enter"><em>state enter calls</em></seealso>,
or not.
</p>
</desc>
@@ -684,13 +715,15 @@ handle_event(_, _, State, Data) ->
If
<seealso marker="#Module:callback_mode/0"><c>Module:callback_mode/0</c></seealso>
returns a list containing <c>state_enter</c>,
- the <c>gen_statem</c> engine will, at every state change,
+ the <c>gen_statem</c> engine will, at every <em>state change</em>,
call the
<seealso marker="#state callback">state callback</seealso>
with arguments <c>(enter, OldState, Data)</c>.
This may look like an event but is really a call
- performed after the previous state callback returned
- and before any event is delivered to the new state callback.
+ performed after the previous
+ <seealso marker="#state callback"><em>state callback</em></seealso>
+ returned and before any event is delivered to the new
+ <seealso marker="#state callback"><em>state callback</em></seealso>.
See
<seealso marker="#Module:StateName/3"><c>Module:StateName/3</c></seealso>
and
@@ -703,27 +736,27 @@ handle_event(_, _, State, Data) ->
<seealso marker="#type-state_callback_result">
<c>repeat_state_and_data</c>
</seealso>
- tuple from the state callback.
+ tuple from the <em>state callback</em>.
</p>
<p>
If
<seealso marker="#Module:callback_mode/0"><c>Module:callback_mode/0</c></seealso>
- does not return such a list, no state enter calls are done.
+ does not return such a list, no <em>state enter calls</em> are done.
</p>
<p>
If
<seealso marker="#Module:code_change/4"><c>Module:code_change/4</c></seealso>
should transform the state,
- it is regarded as a state rename and not a state change,
- which will not cause a state enter call.
+ it is regarded as a state rename and not a <em>state change</em>,
+ which will not cause a <em>state enter call</em>.
</p>
<p>
- Note that a state enter call <em>will</em> be done
+ Note that a <em>state enter call</em> <em>will</em> be done
right before entering the initial state even though this
- formally is not a state change.
- In this case <c>OldState</c> will be the same as <c>State</c>,
+ actually is not a <em>state change</em>.
+ In this case <c>OldState =:= State</c>,
which can not happen for a subsequent state change,
- but will happen when repeating the state enter call.
+ but will happen when repeating the <em>state enter call</em>.
</p>
</desc>
</datatype>
@@ -733,8 +766,11 @@ handle_event(_, _, State, Data) ->
<p>
Transition options can be set by
<seealso marker="#type-action">actions</seealso>
- and modify the state transition.
- Here are the sequence of steps for a state transition:
+ and modify the <em>state transition</em>.
+ The <em>state transition</em> takes place when the
+ <seealso marker="#state callback"><em>state callback</em></seealso>
+ has processed an event and returns.
+ Here are the sequence of steps for a <em>state transition</em>:
</p>
<list type="ordered">
<item>
@@ -765,7 +801,7 @@ handle_event(_, _, State, Data) ->
returned by the state callback that caused the state entry.
</p>
<p>
- Should this state enter call return any of
+ Should this <em>state enter call</em> return any of
the mentioned <c>repeat_*</c> callback results
it is repeated again, with the updated <c>Data</c>.
</p>
@@ -787,7 +823,8 @@ handle_event(_, _, State, Data) ->
</item>
<item>
<p>
- If the state changes, the queue of incoming events
+ If this is a <em>state change</em>,
+ the queue of incoming events
is reset to start with the oldest postponed.
</p>
</item>
@@ -821,7 +858,7 @@ handle_event(_, _, State, Data) ->
if the event queue is empty.
</p>
<p>
- A state change cancels a
+ A <em>state change</em> cancels a
<seealso marker="#type-state_timeout"><c>state_timeout()</c></seealso>
and any new transition option of this type
belongs to the new state.
@@ -830,7 +867,7 @@ handle_event(_, _, State, Data) ->
<item>
<p>
If there are enqueued events the
- <seealso marker="#state callback">state callback</seealso>
+ <seealso marker="#state callback"><em>state callback</em></seealso>
for the possibly new state
is called with the oldest enqueued event,
and we start again from the top of this list.
@@ -848,7 +885,7 @@ handle_event(_, _, State, Data) ->
the next incoming message awakens the <c>gen_statem</c>,
but if it is a system event it goes right back into hibernation.
When a new message arrives the
- <seealso marker="#state callback">state callback</seealso>
+ <seealso marker="#state callback"><em>state callback</em></seealso>
is called with the corresponding event,
and we start again from the top of this sequence.
</p>
@@ -861,7 +898,7 @@ handle_event(_, _, State, Data) ->
<desc>
<p>
If <c>true</c>, postpones the current event and retries
- it when the state changes
+ it after a <em>state change</em>
(<c>NextState =/= State</c>).
</p>
</desc>
@@ -1021,9 +1058,9 @@ handle_event(_, _, State, Data) ->
<name name="action"/>
<desc>
<p>
- These state transition actions can be invoked by
+ These <em>transition actions</em> can be invoked by
returning them from the
- <seealso marker="#state callback">state callback</seealso>
+ <seealso marker="#state callback"><em>state callback</em></seealso>
when it is called with an
<seealso marker="#type-event_type">event</seealso>,
from
@@ -1054,7 +1091,7 @@ handle_event(_, _, State, Data) ->
<c>transition_option()</c>
</seealso>
<seealso marker="#type-postpone"><c>postpone()</c></seealso>
- for this state transition.
+ for this <em>state transition</em>.
This action is ignored when returned from
<seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
or given to
@@ -1093,9 +1130,9 @@ handle_event(_, _, State, Data) ->
<name name="enter_action"/>
<desc>
<p>
- These state transition actions can be invoked by
+ These <em>transition actions</em> can be invoked by
returning them from the
- <seealso marker="#state callback">state callback</seealso>, from
+ <seealso marker="#state callback"><em>state callback</em></seealso>, from
<seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
or by giving them to
<seealso marker="#enter_loop/5"><c>enter_loop/5,6</c></seealso>.
@@ -1119,7 +1156,7 @@ handle_event(_, _, State, Data) ->
Sets the
<seealso marker="#type-transition_option"><c>transition_option()</c></seealso>
<seealso marker="#type-hibernate"><c>hibernate()</c></seealso>
- for this state transition.
+ for this <em>state transition</em>.
</p>
</item>
</taglist>
@@ -1129,9 +1166,9 @@ handle_event(_, _, State, Data) ->
<name name="timeout_action"/>
<desc>
<p>
- These state transition actions can be invoked by
+ These <em>transition actions</em> can be invoked by
returning them from the
- <seealso marker="#state callback">state callback</seealso>, from
+ <seealso marker="#state callback"><em>state callback</em></seealso>, from
<seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
or by giving them to
<seealso marker="#enter_loop/5"><c>enter_loop/5,6</c></seealso>.
@@ -1147,7 +1184,7 @@ handle_event(_, _, State, Data) ->
Short for <c>{timeout,Time,Time}</c>, that is,
the time-out message is the time-out time.
This form exists to make the
- <seealso marker="#state callback">state callback</seealso>
+ <seealso marker="#state callback"><em>state callback</em></seealso>
return value <c>{next_state,NextState,NewData,Time}</c>
allowed like for <c>gen_fsm</c>.
</p>
@@ -1193,9 +1230,9 @@ handle_event(_, _, State, Data) ->
<name name="reply_action"/>
<desc>
<p>
- This state transition action can be invoked by
+ This <em>transition action</em> can be invoked by
returning it from the
- <seealso marker="#state callback">state callback</seealso>, from
+ <seealso marker="#state callback"><em>state callback</em></seealso>, from
<seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
or by giving it to
<seealso marker="#enter_loop/5"><c>enter_loop/5,6</c></seealso>.
@@ -1210,7 +1247,7 @@ handle_event(_, _, State, Data) ->
<c><anno>From</anno></c> must be the term from argument
<seealso marker="#type-event_type"><c>{call,<anno>From</anno>}</c></seealso>
in a call to a
- <seealso marker="#state callback">state callback</seealso>.
+ <seealso marker="#state callback"><em>state callback</em></seealso>.
</p>
<p>
Note that using this action from
@@ -1219,7 +1256,7 @@ handle_event(_, _, State, Data) ->
<seealso marker="#enter_loop/5"><c>enter_loop/5,6</c></seealso>
would be weird on the border of witchcraft
since there has been no earlier call to a
- <seealso marker="#state callback">state callback</seealso>
+ <seealso marker="#state callback"><em>state callback</em></seealso>
in this server.
</p>
</desc>
@@ -1239,7 +1276,7 @@ handle_event(_, _, State, Data) ->
The <seealso marker="#type-action"><c>Actions</c></seealso>
are executed when entering the first
<seealso marker="#type-state">state</seealso> just as for a
- <seealso marker="#state callback">state callback</seealso>,
+ <seealso marker="#state callback"><em>state callback</em></seealso>,
except that the action <c>postpone</c> is forced to
<c>false</c> since there is no event to postpone.
</p>
@@ -1256,7 +1293,7 @@ handle_event(_, _, State, Data) ->
<desc>
<p>
<c><anno>State</anno></c> is the current state
- and it can not be changed since the state callback
+ and it cannot be changed since the state callback
was called with a
<seealso marker="#type-state_enter"><em>state enter call</em></seealso>.
</p>
@@ -1292,11 +1329,13 @@ handle_event(_, _, State, Data) ->
<tag><c>next_state</c></tag>
<item>
<p>
- The <c>gen_statem</c> does a state transition to
+ The <c>gen_statem</c> does a <em>state transition</em> to
<c><anno>NextState</anno></c>
(which can be the same as the current state),
sets <c><anno>NewData</anno></c>,
and executes all <c><anno>Actions</anno></c>.
+ If <c><anno>NextState</anno> =/= CurrentState</c>
+ the <em>state transition</em> is a <em>state change</em>.
</p>
</item>
</taglist>
@@ -1318,54 +1357,33 @@ handle_event(_, _, State, Data) ->
<tag><c>keep_state</c></tag>
<item>
<p>
- The <c>gen_statem</c> keeps the current state, or
- does a state transition to the current state if you like,
- sets <c><anno>NewData</anno></c>,
- and executes all <c><anno>Actions</anno></c>.
- This is the same as
+ The same as
<c>{next_state,CurrentState,<anno>NewData</anno>,<anno>Actions</anno>}</c>.
</p>
</item>
<tag><c>keep_state_and_data</c></tag>
<item>
<p>
- The <c>gen_statem</c> keeps the current state or
- does a state transition to the current state if you like,
- keeps the current server data,
- and executes all <c><anno>Actions</anno></c>.
- This is the same as
- <c>{next_state,CurrentState,CurrentData,<anno>Actions</anno>}</c>.
+ The same as
+ <c>{keep_state,CurrentData,<anno>Actions</anno>}</c>.
</p>
</item>
<tag><c>repeat_state</c></tag>
<item>
<p>
- The <c>gen_statem</c> keeps the current state, or
- does a state transition to the current state if you like,
- sets <c><anno>NewData</anno></c>,
- and executes all <c><anno>Actions</anno></c>.
If the <c>gen_statem</c> runs with
<seealso marker="#type-state_enter"><em>state enter calls</em></seealso>,
- the state enter call is repeated, see type
+ the <em>state enter call</em> is repeated, see type
<seealso marker="#type-transition_option"><c>transition_option()</c></seealso>,
- otherwise <c>repeat_state</c> is the same as
+ other than that <c>repeat_state</c> is the same as
<c>keep_state</c>.
</p>
</item>
<tag><c>repeat_state_and_data</c></tag>
<item>
<p>
- The <c>gen_statem</c> keeps the current state and data, or
- does a state transition to the current state if you like,
- and executes all <c><anno>Actions</anno></c>.
- This is the same as
+ The same as
<c>{repeat_state,CurrentData,<anno>Actions</anno>}</c>.
- If the <c>gen_statem</c> runs with
- <seealso marker="#type-state_enter"><em>state enter calls</em></seealso>,
- the state enter call is repeated, see type
- <seealso marker="#type-transition_option"><c>transition_option()</c></seealso>,
- otherwise <c>repeat_state_and_data</c> is the same as
- <c>keep_state_and_data</c>.
</p>
</item>
<tag><c>stop</c></tag>
@@ -1408,14 +1426,15 @@ handle_event(_, _, State, Data) ->
by sending a request
and waiting until its reply arrives.
The <c>gen_statem</c> calls the
- <seealso marker="#state callback">state callback</seealso> with
+ <seealso marker="#state callback"><em>state callback</em></seealso>
+ with
<seealso marker="#type-event_type"><c>event_type()</c></seealso>
<c>{call,From}</c> and event content
<c><anno>Request</anno></c>.
</p>
<p>
A <c><anno>Reply</anno></c> is generated when a
- <seealso marker="#state callback">state callback</seealso>
+ <seealso marker="#state callback"><em>state callback</em></seealso>
returns with
<c>{reply,From,<anno>Reply</anno>}</c> as one
<seealso marker="#type-action"><c>action()</c></seealso>,
@@ -1484,7 +1503,8 @@ handle_event(_, _, State, Data) ->
ignoring if the destination node or <c>gen_statem</c>
does not exist.
The <c>gen_statem</c> calls the
- <seealso marker="#state callback">state callback</seealso> with
+ <seealso marker="#state callback"><em>state callback</em></seealso>
+ with
<seealso marker="#type-event_type"><c>event_type()</c></seealso>
<c>cast</c> and event content
<c><anno>Msg</anno></c>.
@@ -1598,18 +1618,18 @@ handle_event(_, _, State, Data) ->
<seealso marker="#call/2"><c>call/2</c></seealso>
when the reply cannot be defined in
the return value of a
- <seealso marker="#state callback">state callback</seealso>.
+ <seealso marker="#state callback"><em>state callback</em></seealso>.
</p>
<p>
<c><anno>From</anno></c> must be the term from argument
<seealso marker="#type-event_type"><c>{call,<anno>From</anno>}</c></seealso>
to the
- <seealso marker="#state callback">state callback</seealso>.
+ <seealso marker="#state callback"><em>state callback</em></seealso>.
A reply or multiple replies canalso be sent
using one or several
<seealso marker="#type-reply_action"><c>reply_action()</c></seealso>s
from a
- <seealso marker="#state callback">state callback</seealso>.
+ <seealso marker="#state callback"><em>state callback</em></seealso>.
</p>
<note>
<p>
@@ -1826,7 +1846,7 @@ handle_event(_, _, State, Data) ->
for efficiency reasons, so this function is only called
once after server start and after code change,
but before the first
- <seealso marker="#state callback">state callback</seealso>
+ <seealso marker="#state callback"><em>state callback</em></seealso>
in the current code version is called.
More occasions may be added in future versions
of <c>gen_statem</c>.
@@ -1883,7 +1903,7 @@ handle_event(_, _, State, Data) ->
<p>
This callback is optional, so callback modules need not export it.
If a release upgrade/downgrade with
- <c>Change={advanced,Extra}</c>
+ <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>.
@@ -1893,7 +1913,7 @@ handle_event(_, _, State, Data) ->
This function is called by a <c>gen_statem</c> when it is to
update its internal state during a release upgrade/downgrade,
that is, when the instruction <c>{update,Module,Change,...}</c>,
- where <c>Change={advanced,Extra}</c>, is specified in the
+ where <c>Change = {advanced,Extra}</c>, is specified in the
<seealso marker="sasl:appup"><c>appup</c></seealso>
file. For more information, see
<seealso marker="doc/design_principles:release_handling#instr">OTP Design Principles</seealso>.
@@ -1922,7 +1942,7 @@ handle_event(_, _, State, Data) ->
<p>
If the function returns a failure <c>Reason</c>, the ongoing
upgrade fails and rolls back to the old release.
- Note that <c>Reason</c> can not be an <c>{ok,_,_}</c> tuple
+ Note that <c>Reason</c> cannot be an <c>{ok,_,_}</c> tuple
since that will be regarded as a
<c>{ok,NewState,NewData}</c> tuple,
and that a tuple matching <c>{ok,_}</c>
@@ -1933,13 +1953,13 @@ handle_event(_, _, State, Data) ->
<p>
Also note when upgrading a <c>gen_statem</c>,
this function and hence
- the <c>Change={advanced,Extra}</c> parameter in the
+ the <c>Change = {advanced,Extra}</c> parameter in the
<seealso marker="sasl:appup"><c>appup</c></seealso> file
is not only needed to update the internal state
or to act on the <c>Extra</c> argument.
It is also needed if an upgrade or downgrade should change
<seealso marker="#type-callback_mode"><em>callback mode</em></seealso>,
- or else the callback mode after the code change
+ or else the <em>callback mode</em> after the code change
will not be honoured,
most probably causing a server crash.
</p>
@@ -2148,7 +2168,7 @@ init(Args) -> erlang:error(not_implemented, [Args]).</pre>
<seealso marker="#type-event_type"><c>{call,From}</c></seealso>,
the caller waits for a reply. The reply can be sent
from this or from any other
- <seealso marker="#state callback">state callback</seealso>
+ <seealso marker="#state callback"><em>state callback</em></seealso>
by returning with <c>{reply,From,Reply}</c> in
<seealso marker="#type-action"><c>Actions</c></seealso>, in
<seealso marker="#type-reply_action"><c>Replies</c></seealso>,
@@ -2173,9 +2193,9 @@ init(Args) -> erlang:error(not_implemented, [Args]).</pre>
</p>
<p>
When the <c>gen_statem</c> runs with
- <seealso marker="#type-state_enter">state enter calls</seealso>,
+ <seealso marker="#type-state_enter"><em>state enter calls</em></seealso>,
these functions are also called with arguments
- <c>(enter, OldState, ...)</c> whenever the state changes.
+ <c>(enter, OldState, ...)</c> during every <em>state change</em>.
In this case there are some restrictions on the
<seealso marker="#type-enter_action">actions</seealso>
that may be returned:
@@ -2208,7 +2228,7 @@ init(Args) -> erlang:error(not_implemented, [Args]).</pre>
<seealso marker="erts:erlang#throw/1"><c>throw</c></seealso>
to return the result, which can be useful.
For example to bail out with <c>throw(keep_state_and_data)</c>
- from deep within complex code that can not
+ from deep within complex code that cannot
return <c>{next_state,State,Data}</c> because
<c>State</c> or <c>Data</c> is no longer in scope.
</p>
diff --git a/lib/stdlib/doc/src/maps.xml b/lib/stdlib/doc/src/maps.xml
index e2a62cb397..8e88882b56 100644
--- a/lib/stdlib/doc/src/maps.xml
+++ b/lib/stdlib/doc/src/maps.xml
@@ -35,9 +35,10 @@
<datatypes>
<datatype>
- <name name="iterator"/>
+ <name name="iterator" n_vars="2"/>
<desc>
- <p>An iterator representing the key value associations in a map.</p>
+ <p>An iterator representing the associations in a map with keys of type
+ <c><anno>Key</anno></c> and values of type <c><anno>Value</anno></c>.</p>
<p>Created using <seealso marker="#iterator-1"><c>maps:iterator/1</c></seealso>.</p>
<p>Consumed by <seealso marker="#next-1"><c>maps:next/1</c></seealso>,
<seealso marker="#filter-2"><c>maps:filter/2</c></seealso>,
@@ -45,6 +46,10 @@
<seealso marker="#map-2"><c>maps:map/2</c></seealso>.</p>
</desc>
</datatype>
+
+ <datatype>
+ <name name="iterator" n_vars="0"/>
+ </datatype>
</datatypes>
<funcs>
@@ -90,13 +95,13 @@
<name name="fold" arity="3" since="OTP 17.0"/>
<fsummary></fsummary>
<desc>
- <p>Calls <c>F(K, V, AccIn)</c> for every <c><anno>K</anno></c> to value
- <c><anno>V</anno></c> association in <c><anno>MapOrIter</anno></c> in
- any order. Function <c>fun F/3</c> must return a new
- accumulator, which is passed to the next successive call.
- This function returns the final value of the accumulator. The initial
- accumulator value <c><anno>Init</anno></c> is returned if the map is
- empty.</p>
+ <p>Calls <c>F(Key, Value, AccIn)</c> for every <c><anno>Key</anno></c>
+ to value <c><anno>Value</anno></c> association in
+ <c><anno>MapOrIter</anno></c> in any order. Function <c>fun F/3</c>
+ must return a new accumulator, which is passed to the next successive
+ call. This function returns the final value of the accumulator.
+ The initial accumulator value <c><anno>Init</anno></c> is returned
+ if the map is empty.</p>
<p>The call fails with a <c>{badmap,Map}</c> exception if
<c><anno>MapOrIter</anno></c> is not a map or valid iterator,
or with <c>badarg</c> if <c><anno>Fun</anno></c> is not a
@@ -234,11 +239,12 @@ none</code>
<fsummary></fsummary>
<desc>
<p>Produces a new map <c><anno>Map</anno></c> by calling function
- <c>fun F(K, V1)</c> for every <c><anno>K</anno></c> to value
- <c><anno>V1</anno></c> association in <c><anno>MapOrIter</anno></c> in
- any order. Function <c>fun F/2</c> must return value
- <c><anno>V2</anno></c> to be associated with key <c><anno>K</anno></c>
- for the new map <c><anno>Map</anno></c>.</p>
+ <c>fun F(Key, Value1)</c> for every <c><anno>Key</anno></c> to value
+ <c><anno>Value1</anno></c> association in
+ <c><anno>MapOrIter</anno></c> in any order. Function <c>fun Fun/2</c>
+ must return value <c><anno>Value2</anno></c> to be associated with
+ key <c><anno>Key</anno></c> for the new map
+ <c><anno>Map</anno></c>.</p>
<p>The call fails with a <c>{badmap,Map}</c> exception if
<c><anno>MapOrIter</anno></c> is not a map or valid iterator,
or with <c>badarg</c> if <c><anno>Fun</anno></c> is not a
diff --git a/lib/stdlib/doc/src/notes.xml b/lib/stdlib/doc/src/notes.xml
index 7ba19a98ea..a682811c6d 100644
--- a/lib/stdlib/doc/src/notes.xml
+++ b/lib/stdlib/doc/src/notes.xml
@@ -3803,7 +3803,7 @@
you use erlang:halt/2 with an integer first argument and
an option list containing {flush,false} as the second
argument. Note that now is flushing not dependant of the
- exit code, and you can not only flush async threads
+ exit code, and you cannot only flush async threads
operations which we deemed as a strange behaviour anyway.
</p>
<p>Also, erlang:halt/1,2 has gotten a new feature: If the
@@ -4317,9 +4317,9 @@
Supervisors should not save child-specs for temporary
processes when they terminate as they should not be
restarted. Saving the temporary child spec will result in
- that you can not start a new temporary process with the
+ that you cannot start a new temporary process with the
same child spec as an already terminated temporary
- process. Since R14B02 you can not restart a temporary
+ process. Since R14B02 you cannot restart a temporary
temporary process as arguments are no longer saved, it
has however always been semantically incorrect to restart
a temporary process. Thanks to Filipe David Manana for
diff --git a/lib/stdlib/doc/src/rand.xml b/lib/stdlib/doc/src/rand.xml
index 27d2d99f3c..b4737b48f8 100644
--- a/lib/stdlib/doc/src/rand.xml
+++ b/lib/stdlib/doc/src/rand.xml
@@ -38,25 +38,71 @@
<p>
This module provides a pseudo random number generator.
The module contains a number of algorithms.
- The uniform distribution algorithms use the
+ The uniform distribution algorithms are based on the
<url href="http://xorshift.di.unimi.it">
- xoroshiro116+ and xorshift1024* algorithms by Sebastiano Vigna.
+ Xoroshiro and Xorshift algorithms
</url>
+ by Sebastiano Vigna.
The normal distribution algorithm uses the
<url href="http://www.jstatsoft.org/v05/i08">
Ziggurat Method by Marsaglia and Tsang
</url>
on top of the uniform distribution algorithm.
</p>
- <p>For some algorithms, jump functions are provided for generating
- non-overlapping sequences for parallel computations.
- The jump functions perform calculations
- equivalent to perform a large number of repeated calls
- for calculating new states. </p>
+ <p>
+ For most algorithms, jump functions are provided for generating
+ non-overlapping sequences for parallel computations.
+ The jump functions perform calculations
+ equivalent to perform a large number of repeated calls
+ for calculating new states.
+ </p>
<p>The following algorithms are provided:</p>
<taglist>
+ <tag><c>exsss</c></tag>
+ <item>
+ <p>Xorshift116**, 58 bits precision and period of 2^116-1</p>
+ <p>Jump function: equivalent to 2^64 calls</p>
+ <p>
+ This is the Xorshift116 generator combined with the StarStar scrambler
+ from the 2018 paper by David Blackman and Sebastiano Vigna:
+ <url href="http://vigna.di.unimi.it/ftp/papers/ScrambledLinear.pdf">
+ Scrambled Linear Pseudorandom Number Generators
+ </url>
+ </p>
+ <p>
+ The generator does not need 58-bit rotates so it is faster
+ than the Xoroshiro116 generator, and when combined with
+ the StarStar scrambler it does not have any weak low bits
+ like <c>exrop</c> (Xoroshiro116+).
+ </p>
+ <p>
+ Alas, this combination is about 10% slower than <c>exrop</c>,
+ but is despite that the default algorithm thanks to its
+ statistical qualities.
+ </p>
+ </item>
+ <tag><c>exro928ss</c></tag>
+ <item>
+ <p>Xoroshiro928**, 58 bits precision and a period of 2^928-1</p>
+ <p>Jump function: equivalent to 2^512 calls</p>
+ <p>
+ This is a 58 bit version of Xoroshiro1024**,
+ from the 2018 paper by David Blackman and Sebastiano Vigna:
+ <url href="http://vigna.di.unimi.it/ftp/papers/ScrambledLinear.pdf">
+ Scrambled Linear Pseudorandom Number Generators
+ </url>
+ that on a 64 bit Erlang system executes only about 40% slower than
+ the default <c>exsss</c> algorithm but with much longer period
+ and better statistical properties, and on the flip side
+ a larger state.
+ </p>
+ <p>
+ Many thanks to Sebastiano Vigna for his help with
+ the 58 bit adaption.
+ </p>
+ </item>
<tag><c>exrop</c></tag>
<item>
<p>Xoroshiro116+, 58 bits precision and period of 2^116-1</p>
@@ -83,7 +129,7 @@
</taglist>
<p>
- The default algorithm is <c>exrop</c> (Xoroshiro116+).
+ The default algorithm is <c>exsss</c> (Xorshift116**).
If a specific algorithm is
required, ensure to always use <seealso marker="#seed-1">
<c>seed/1</c></seealso> to initialize the state.
@@ -154,19 +200,19 @@ R1 = rand:uniform(),</pre>
<p>Use a specified algorithm:</p>
<pre>
-_ = rand:seed(exs1024s),
+_ = rand:seed(exs928ss),
R2 = rand:uniform(),</pre>
<p>Use a specified algorithm with a constant seed:</p>
<pre>
-_ = rand:seed(exs1024s, {123, 123534, 345345}),
+_ = rand:seed(exs928ss, {123, 123534, 345345}),
R3 = rand:uniform(),</pre>
<p>Use the functional API with a non-constant seed:</p>
<pre>
-S0 = rand:seed_s(exrop),
+S0 = rand:seed_s(exsss),
{R4, S1} = rand:uniform_s(S0),</pre>
<p>Textbook basic form Box-Muller standard normal deviate</p>
@@ -195,8 +241,9 @@ SND0 = math:sqrt(-2 * math:log(R5)) * math:cos(math:pi() * R6)</pre>
</note>
<p>
- For all these generators the lowest bit(s) has got
- a slightly less random behaviour than all other bits.
+ For all these generators except <c>exro928ss</c> and <c>exsss</c>
+ the lowest bit(s) has got a slightly less
+ random behaviour than all other bits.
1 bit for <c>exrop</c> (and <c>exsp</c>),
and 3 bits for <c>exs1024s</c>.
See for example the explanation in the
@@ -211,7 +258,7 @@ up to (and included) 16TB, with the exception of binary rank tests,
which fail due to the lowest bit being an LFSR; all other bits pass all
tests. We suggest to use a sign test to extract a random Boolean value.</pre>
<p>
- If this is a problem; to generate a boolean
+ If this is a problem; to generate a boolean with these algorithms
use something like this:
</p>
<pre>(rand:uniform(16) > 8)</pre>
@@ -254,21 +301,50 @@ tests. We suggest to use a sign test to extract a random Boolean value.</pre>
</desc>
</datatype>
<datatype>
- <name name="exs64_state"/>
- <desc><p>Algorithm specific internal state</p></desc>
+ <name name="seed"/>
+ <desc>
+ <p>
+ A seed value for the generator.
+ </p>
+ <p>
+ A list of integers sets the generator's internal state directly,
+ after algorithm-dependent checks of the value
+ and masking to the proper word size.
+ </p>
+ <p>
+ An integer is used as the initial state for a SplitMix64 generator.
+ The output values of that is then used for setting
+ the generator's internal state
+ after masking to the proper word size
+ and if needed avoiding zero values.
+ </p>
+ <p>
+ A traditional 3-tuple of integers seed is passed through
+ algorithm-dependent hashing functions to create
+ the generator's initial state.
+ </p>
+ </desc>
</datatype>
<datatype>
<name name="exsplus_state"/>
<desc><p>Algorithm specific internal state</p></desc>
</datatype>
<datatype>
- <name name="exs1024_state"/>
+ <name name="exro928_state"/>
<desc><p>Algorithm specific internal state</p></desc>
</datatype>
<datatype>
<name name="exrop_state"/>
<desc><p>Algorithm specific internal state</p></desc>
</datatype>
+ <datatype>
+ <name name="exs1024_state"/>
+ <desc><p>Algorithm specific internal state</p></desc>
+ </datatype>
+ <datatype>
+ <name name="exs64_state"/>
+ <desc><p>Algorithm specific internal state</p></desc>
+ </datatype>
</datatypes>
<funcs>
diff --git a/lib/stdlib/doc/src/sys.xml b/lib/stdlib/doc/src/sys.xml
index 6fc508b853..c5075f31c5 100644
--- a/lib/stdlib/doc/src/sys.xml
+++ b/lib/stdlib/doc/src/sys.xml
@@ -114,6 +114,154 @@
</datatype>
<datatype>
<name name="system_event"/>
+ <desc>
+ <taglist>
+ <tag><c>{in,<anno>Msg</anno>}</c></tag>
+ <item>
+ <p>
+ Is produced by <c>gen_server</c> and <c>gen_event</c>
+ when the message <c>Msg</c> arrives.
+ </p>
+ </item>
+ <tag><c>{in,<anno>Msg</anno>,<anno>State</anno>}</c></tag>
+ <item>
+ <p>
+ Is produced by <c>gen_statem</c>
+ when the message <c>Msg</c> arrives in state <c>State</c>.
+ </p>
+ <p>
+ For <c>gen_statem</c> the <c><anno>Msg</anno></c> term is
+ an <c>{EventType,EventContent}</c> tuple.
+ </p>
+ </item>
+ <tag><c>{out,<anno>Msg</anno>,<anno>To</anno>}</c></tag>
+ <item>
+ <p>
+ Is produced by <c>gen_statem</c> when the reply <c>Msg</c>
+ is sent back to <c>To</c> by returning
+ a <c>{reply,To,Msg}</c> action from the callback module.
+ </p>
+ <p>
+ <c><anno>To</anno></c> is of the same type
+ as the first argument to <c>gen_statem:reply/2</c>.
+ </p>
+ </item>
+ <tag>
+ <c>{out,<anno>Msg</anno>,<anno>To</anno>,<anno>State</anno>}</c>
+ </tag>
+ <item>
+ <p>
+ Is produced by <c>gen_server</c>
+ when the reply <c><anno>Msg</anno></c>
+ is sent back to <c><anno>To</anno></c>
+ by returning a <c>{reply,...}</c> tuple
+ from the callback module.
+ </p>
+ <p>
+ <c><anno>To</anno></c> is of the same type
+ as the first argument to <c>gen_server:reply/2</c>.
+ </p>
+ <p>
+ <c><anno>State</anno></c> is the new server state.
+ </p>
+ </item>
+ <tag>
+ <c>{noreply,<anno>State</anno>}</c>
+ </tag>
+ <item>
+ <p>
+ Is produced by <c>gen_server</c>
+ when a <c>{noreply,...}</c> tuple is returned
+ from the callback module.
+ </p>
+ <p>
+ <c><anno>State</anno></c> is the new server state.
+ </p>
+ </item>
+ <tag>
+ <c>{continue,<anno>Continuation</anno>}</c>
+ </tag>
+ <item>
+ <p>
+ Is produced by <c>gen_server</c>
+ when a <c>{continue,<anno>Continuation</anno>}</c>
+ tuple is returned from the callback module.
+ </p>
+ </item>
+ <tag>
+ <c>{code_change,<anno>Event</anno>,<anno>State</anno>}</c>
+ </tag>
+ <item>
+ <p>
+ Is produced by <c>gen_statem</c>
+ when the message <c><anno>Event</anno></c>
+ arrives in state <c><anno>State</anno></c>
+ as the first event after a code change.
+ </p>
+ <p>
+ <c><anno>Event</anno></c> is
+ an <c>{EventType,EventContent}</c> tuple.
+ </p>
+ </item>
+ <tag>
+ <c>
+ {postpone,<anno>Event</anno>,<anno>State</anno>,<anno>NextState</anno>}
+ </c>
+ </tag>
+ <item>
+ <p>
+ Is produced by <c>gen_statem</c>
+ when the message <c><anno>Event</anno></c>
+ is postponed in state <c><anno>State</anno></c>.
+ <c><anno>NextState</anno></c> is the new state.
+ </p>
+ <p>
+ <c><anno>Event</anno></c> is
+ an <c>{EventType,EventContent}</c> tuple.
+ </p>
+ </item>
+ <tag>
+ <c>
+ {consume,<anno>Event</anno>,<anno>State</anno>,<anno>NextState</anno>}
+ </c>
+ </tag>
+ <item>
+ <p>
+ Is produced by <c>gen_statem</c>
+ when the message <c><anno>Event</anno></c>
+ is consumed in state <c><anno>State</anno></c>.
+ <c><anno>NextState</anno></c> is the new state.
+ </p>
+ <p>
+ <c><anno>Event</anno></c> is
+ an <c>{EventType,EventContent}</c> tuple.
+ </p>
+ </item>
+ <tag>
+ <c>
+ {enter,<anno>State</anno>}
+ </c>
+ </tag>
+ <item>
+ <p>
+ Is produced by <c>gen_statem</c>
+ when the first state <c><anno>State</anno></c> is entered.
+ </p>
+ </item>
+ <tag>
+ <c>
+ {terminate,<anno>Reason</anno>,<anno>State</anno>}
+ </c>
+ </tag>
+ <item>
+ <p>
+ Is produced by <c>gen_statem</c>
+ when it terminates with reason <c><anno>Reason</anno></c>
+ in state <c><anno>State</anno></c>.
+ </p>
+ </item>
+ </taglist>
+ </desc>
</datatype>
<datatype>
<name name="dbg_opt"/>
@@ -532,6 +680,12 @@
<name name="get_debug" arity="3" since=""/>
<fsummary>Get the data associated with a debug option.</fsummary>
<desc>
+ <warning>
+ <p>
+ <c>get_debug/3</c> is deprecated since it returns
+ data of an internal type only useful for debugging.
+ </p>
+ </warning>
<p>Gets the data associated with a debug option.
<c><anno>Default</anno></c>
is returned if <c><anno>Item</anno></c> is not found. Can be
@@ -605,6 +759,18 @@
</func>
<func>
+ <name name="get_log" arity="1" since="OTP-22.0"/>
+ <fsummary>Return the logged events in the debug structure.</fsummary>
+ <desc>
+ <p>
+ Returns the logged system events in the debug structure,
+ that is the last argument to
+ <seealso marker="#handle_debug/4"><c>handle_debug/4</c></seealso>.
+ </p>
+ </desc>
+ </func>
+
+ <func>
<name since="">Module:system_code_change(Misc, Module, OldVsn, Extra) ->
{ok, NMisc}</name>
<fsummary>Called when the process is to perform a code change.</fsummary>