n4u
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gproc


			
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<h1>Module gproc</h1>
<ul class="index"><li><a href="#description">Description</a></li><li><a href="#types">Data Types</a></li><li><a href="#index">Function Index</a></li><li><a href="#functions">Function Details</a></li></ul>Extended process registry.

<p><b>Behaviours:</b> <a href="gen_server.html"><tt>gen_server</tt></a>.</p>
<p><b>Authors:</b> Ulf Wiger (<a href="mailto:ulf.wiger@ericsson.com"><tt>ulf.wiger@ericsson.com</tt></a>).</p>

<h2><a name="description">Description</a></h2>Extended process registry
  <p>This module implements an extended process registry</p>
  <p>For a detailed description, see gproc/doc/erlang07-wiger.pdf.</p>
 
<h2><a name="types">Data Types</a></h2>

<h3 class="typedecl"><a name="type-context">context()</a></h3>
<p><tt>context() = {<a href="#type-scope">scope()</a>, <a href="#type-type">type()</a>} | <a href="#type-type">type()</a></tt></p>
<p>Local scope is the default</p>

<h3 class="typedecl"><a name="type-headpat">headpat()</a></h3>
<p><tt>headpat() = {<a href="#type-keypat">keypat()</a>, <a href="#type-pidpat">pidpat()</a>, ValPat}</tt></p>


<h3 class="typedecl"><a name="type-key">key()</a></h3>
<p><tt>key() = {<a href="#type-type">type()</a>, <a href="#type-scope">scope()</a>, any()}</tt></p>


<h3 class="typedecl"><a name="type-keypat">keypat()</a></h3>
<p><tt>keypat() = {<a href="#type-sel_type">sel_type()</a> | <a href="#type-sel_var">sel_var()</a>, l | g | <a href="#type-sel_var">sel_var()</a>, any()}</tt></p>


<h3 class="typedecl"><a name="type-pidpat">pidpat()</a></h3>
<p><tt>pidpat() = pid() | <a href="#type-sel_var">sel_var()</a></tt></p>
<p>sel_var() = DollarVar | '_'.</p>

<h3 class="typedecl"><a name="type-scope">scope()</a></h3>
<p><tt>scope() = l | g</tt></p>
<p>l = local registration; g = global registration</p>

<h3 class="typedecl"><a name="type-sel_pattern">sel_pattern()</a></h3>
<p><tt>sel_pattern() = [{<a href="#type-headpat">headpat()</a>, Guards, Prod}]</tt></p>


<h3 class="typedecl"><a name="type-sel_type">sel_type()</a></h3>
<p><tt>sel_type() = n | p | c | a | names | props | counters | aggr_counters</tt></p>


<h3 class="typedecl"><a name="type-type">type()</a></h3>
<p><tt>type() = n | p | c | a</tt></p>
<p>n = name; p = property; c = counter;
                                 a = aggregate_counter</p>

<h2><a name="index">Function Index</a></h2>
<table width="100%" border="1" cellspacing="0" cellpadding="2" summary="function index"><tr><td valign="top"><a href="#first-1">first/1</a></td><td>Behaves as ets:first(Tab) for a given type of registration object.</td></tr>
<tr><td valign="top"><a href="#get_value-1">get_value/1</a></td><td>Read the value stored with a key registered to the current process.</td></tr>
<tr><td valign="top"><a href="#info-1">info/1</a></td><td>Similar to <code>process_info(Pid)</code> but with additional gproc info.</td></tr>
<tr><td valign="top"><a href="#info-2">info/2</a></td><td>Similar to process_info(Pid, Item), but with additional gproc info.</td></tr>
<tr><td valign="top"><a href="#last-1">last/1</a></td><td>Behaves as ets:last(Tab) for a given type of registration object.</td></tr>
<tr><td valign="top"><a href="#lookup_pid-1">lookup_pid/1</a></td><td>Lookup the Pid stored with a key.</td></tr>
<tr><td valign="top"><a href="#lookup_pids-1">lookup_pids/1</a></td><td>Returns a list of pids with the published key Key.</td></tr>
<tr><td valign="top"><a href="#mreg-3">mreg/3</a></td><td>Register multiple {Key,Value} pairs of a given type and scope.</td></tr>
<tr><td valign="top"><a href="#next-2">next/2</a></td><td>Behaves as ets:next(Tab,Key) for a given type of registration object.</td></tr>
<tr><td valign="top"><a href="#prev-2">prev/2</a></td><td>Behaves as ets:prev(Tab,Key) for a given type of registration object.</td></tr>
<tr><td valign="top"><a href="#reg-1">reg/1</a></td><td>Equivalent to <a href="#reg-2"><tt>reg(Key, undefined)</tt></a>.
</td></tr>
<tr><td valign="top"><a href="#reg-2">reg/2</a></td><td>Register a name or property for the current process.</td></tr>
<tr><td valign="top"><a href="#select-1">select/1</a></td><td>Equivalent to <a href="#select-2"><tt>select(all, Pat)</tt></a>.
</td></tr>
<tr><td valign="top"><a href="#select-2">select/2</a></td><td>Perform a select operation on the process registry.</td></tr>
<tr><td valign="top"><a href="#select-3">select/3</a></td><td>Like <a href="#select-2"><code>select/2</code></a> but returns Limit objects at a time.</td></tr>
<tr><td valign="top"><a href="#send-2">send/2</a></td><td>Sends a message to the process, or processes, corresponding to Key.</td></tr>
<tr><td valign="top"><a href="#set_value-2">set_value/2</a></td><td>Sets the value of the registeration entry given by Key.</td></tr>
<tr><td valign="top"><a href="#start_link-0">start_link/0</a></td><td></td></tr>
<tr><td valign="top"><a href="#table-1">table/1</a></td><td></td></tr>
<tr><td valign="top"><a href="#table-2">table/2</a></td><td></td></tr>
<tr><td valign="top"><a href="#unreg-1">unreg/1</a></td><td>Unregister a name or property.</td></tr>
<tr><td valign="top"><a href="#update_counter-2">update_counter/2</a></td><td>Updates the counter registered as Key for the current process.</td></tr>
<tr><td valign="top"><a href="#where-1">where/1</a></td><td>Returns the pid registered as Key.</td></tr>
</table>

<h2><a name="functions">Function Details</a></h2>

<h3 class="function"><a name="first-1">first/1</a></h3>
<div class="spec">
<p><tt>first(Type::<a href="#type-type">type()</a>) -&gt; <a href="#type-key">key()</a> | '$end_of_table'</tt></p>
</div><p><p>Behaves as ets:first(Tab) for a given type of registration object.</p>
 
  See <a href="http://www.erlang.org/doc/man/ets.html#first-1" target="_top"><tt>http://www.erlang.org/doc/man/ets.html#first-1</tt></a>.
   The registry behaves as an ordered_set table.</p>

<h3 class="function"><a name="get_value-1">get_value/1</a></h3>
<div class="spec">
<p><tt>get_value(Key) -&gt; Value</tt></p>
</div><p><p>Read the value stored with a key registered to the current process.</p>
 
  If no such key is registered to the current process, this function exits.</p>

<h3 class="function"><a name="info-1">info/1</a></h3>
<div class="spec">
<p><tt>info(Pid::pid()) -&gt; ProcessInfo</tt>
<ul class="definitions"><li><tt>ProcessInfo = [{gproc, [{Key, Value}]} | ProcessInfo]</tt></li>
</ul></p>
</div><p><p>Similar to <code>process_info(Pid)</code> but with additional gproc info.</p>
 
  Returns the same information as process_info(Pid), but with the
  addition of a <code>gproc</code> information item, containing the <code>{Key,Value}</code>
  pairs registered to the process.</p>

<h3 class="function"><a name="info-2">info/2</a></h3>
<div class="spec">
<p><tt>info(Pid::pid(), Item::atom()) -&gt; {Item, Info}</tt></p>
</div><p><p>Similar to process_info(Pid, Item), but with additional gproc info.</p>
 
  For <code>Item = gproc</code>, this function returns a list of <code>{Key, Value}</code> pairs
  registered to the process Pid. For other values of Item, it returns the
  same as <a href="http://www.erlang.org/doc/man/erlang.html#process_info-2" target="_top"><tt>http://www.erlang.org/doc/man/erlang.html#process_info-2</tt></a>.</p>

<h3 class="function"><a name="last-1">last/1</a></h3>
<div class="spec">
<p><tt>last(Context::<a href="#type-context">context()</a>) -&gt; <a href="#type-key">key()</a> | '$end_of_table'</tt></p>
</div><p><p>Behaves as ets:last(Tab) for a given type of registration object.</p>
 
  See <a href="http://www.erlang.org/doc/man/ets.html#last-1" target="_top"><tt>http://www.erlang.org/doc/man/ets.html#last-1</tt></a>.
  The registry behaves as an ordered_set table.</p>

<h3 class="function"><a name="lookup_pid-1">lookup_pid/1</a></h3>
<div class="spec">
<p><tt>lookup_pid(Key) -&gt; Pid</tt></p>
</div><p>Lookup the Pid stored with a key.
 </p>

<h3 class="function"><a name="lookup_pids-1">lookup_pids/1</a></h3>
<div class="spec">
<p><tt>lookup_pids(Key::<a href="#type-key">key()</a>) -&gt; [pid()]</tt></p>
</div><p><p>Returns a list of pids with the published key Key</p>
 
  If the type of registration entry is either name or aggregated counter,
  this function will return either an empty list, or a list of one pid.
  For non-unique types, the return value can be a list of any length.</p>

<h3 class="function"><a name="mreg-3">mreg/3</a></h3>
<div class="spec">
<p><tt>mreg(T::<a href="#type-type">type()</a>, X2::<a href="#type-scope">scope()</a>, KVL::[{Key::any(), Value::any()}]) -&gt; true</tt></p>
</div><p><p>Register multiple {Key,Value} pairs of a given type and scope.</p>
 
  This function is more efficient than calling <a href="#reg-2"><code>reg/2</code></a> repeatedly.</p>

<h3 class="function"><a name="next-2">next/2</a></h3>
<div class="spec">
<p><tt>next(Context::<a href="#type-context">context()</a>, Key::<a href="#type-key">key()</a>) -&gt; <a href="#type-key">key()</a> | '$end_of_table'</tt></p>
</div><p><p>Behaves as ets:next(Tab,Key) for a given type of registration object.</p>
 
  See <a href="http://www.erlang.org/doc/man/ets.html#next-2" target="_top"><tt>http://www.erlang.org/doc/man/ets.html#next-2</tt></a>.
  The registry behaves as an ordered_set table.</p>

<h3 class="function"><a name="prev-2">prev/2</a></h3>
<div class="spec">
<p><tt>prev(Context::<a href="#type-context">context()</a>, Key::<a href="#type-key">key()</a>) -&gt; <a href="#type-key">key()</a> | '$end_of_table'</tt></p>
</div><p><p>Behaves as ets:prev(Tab,Key) for a given type of registration object.</p>
 
  See <a href="http://www.erlang.org/doc/man/ets.html#prev-2" target="_top"><tt>http://www.erlang.org/doc/man/ets.html#prev-2</tt></a>.
  The registry behaves as an ordered_set table.</p>

<h3 class="function"><a name="reg-1">reg/1</a></h3>
<div class="spec">
<p><tt>reg(Key::<a href="#type-key">key()</a>) -&gt; true</tt></p>
</div><p>Equivalent to <a href="#reg-2"><tt>reg(Key, undefined)</tt></a>.</p>


<h3 class="function"><a name="reg-2">reg/2</a></h3>
<div class="spec">
<p><tt>reg(Key::<a href="#type-key">key()</a>, Value) -&gt; true</tt></p>
</div><p><p>Register a name or property for the current process</p>
 
 </p>

<h3 class="function"><a name="select-1">select/1</a></h3>
<div class="spec">
<p><tt>select(Pat::<a href="#type-select_pattern">select_pattern()</a>) -&gt; list(<a href="#type-sel_object">sel_object()</a>)</tt></p>
</div><p>Equivalent to <a href="#select-2"><tt>select(all, Pat)</tt></a>.</p>


<h3 class="function"><a name="select-2">select/2</a></h3>
<div class="spec">
<p><tt>select(Type::<a href="#type-sel_type">sel_type()</a>, Pat::<a href="#type-sel_pattern">sel_pattern()</a>) -&gt; [{Key, Pid, Value}]</tt></p>
</div><p><p>Perform a select operation on the process registry.</p>
 
  The physical representation in the registry may differ from the above,
  but the select patterns are transformed appropriately.</p>

<h3 class="function"><a name="select-3">select/3</a></h3>
<div class="spec">
<p><tt>select(Type::<a href="#type-sel_type">sel_type()</a>, Pat::<a href="#type-sel_patten">sel_patten()</a>, Limit::integer()) -&gt; [{Key, Pid, Value}]</tt></p>
</div><p><p>Like <a href="#select-2"><code>select/2</code></a> but returns Limit objects at a time.</p>
 
  See <a href="http://www.erlang.org/doc/man/ets.html#select-3" target="_top"><tt>http://www.erlang.org/doc/man/ets.html#select-3</tt></a>.</p>

<h3 class="function"><a name="send-2">send/2</a></h3>
<div class="spec">
<p><tt>send(Key::<a href="#type-key">key()</a>, Msg::any()) -&gt; Msg</tt></p>
</div><p><p>Sends a message to the process, or processes, corresponding to Key.</p>
 
  If Key belongs to a unique object (name or aggregated counter), this
  function will send a message to the corresponding process, or fail if there
  is no such process. If Key is for a non-unique object type (counter or
  property), Msg will be send to all processes that have such an object.</p>

<h3 class="function"><a name="set_value-2">set_value/2</a></h3>
<div class="spec">
<p><tt>set_value(Key::<a href="#type-key">key()</a>, Value) -&gt; true</tt></p>
</div><p><p>Sets the value of the registeration entry given by Key</p>
 
  <p>Key is assumed to exist and belong to the calling process.  
If it doesn't, this function will exit.</p>
 
  Value can be any term, unless the object is a counter, in which case
  it must be an integer.</p>

<h3 class="function"><a name="start_link-0">start_link/0</a></h3>
<div class="spec">
<p><tt>start_link() -&gt; any()</tt></p>
</div>

<h3 class="function"><a name="table-1">table/1</a></h3>
<div class="spec">
<p><tt>table(Type) -&gt; any()</tt></p>
</div>

<h3 class="function"><a name="table-2">table/2</a></h3>
<div class="spec">
<p><tt>table(T, Opts) -&gt; any()</tt></p>
</div>

<h3 class="function"><a name="unreg-1">unreg/1</a></h3>
<div class="spec">
<p><tt>unreg(Key::<a href="#type-key">key()</a>) -&gt; true</tt></p>
</div><p>Unregister a name or property.</p>

<h3 class="function"><a name="update_counter-2">update_counter/2</a></h3>
<div class="spec">
<p><tt>update_counter(Key::<a href="#type-key">key()</a>, Incr::integer()) -&gt; integer()</tt></p>
</div><p><p>Updates the counter registered as Key for the current process.</p>
 
  This function works like ets:update_counter/3
  (see <a href="http://www.erlang.org/doc/man/ets.html#update_counter-3" target="_top"><tt>http://www.erlang.org/doc/man/ets.html#update_counter-3</tt></a>), but
  will fail if the type of object referred to by Key is not a counter.</p>

<h3 class="function"><a name="where-1">where/1</a></h3>
<div class="spec">
<p><tt>where(Key::<a href="#type-key">key()</a>) -&gt; pid()</tt></p>
</div><p><p>Returns the pid registered as Key</p>
 
  The type of registration entry must be either name or aggregated counter.
  Otherwise this function will exit. Use <a href="#lookup_pids-1"><code>lookup_pids/1</code></a> in these
  cases.</p>
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