case_clause in process_is_down()

The crash is funny. I don't know how another process could
register the name before the reverse mapping of (presumably) a waiter
is removed. Perhaps some earlier bug caused lingering garbage in the
table? Anyway, I have added a clause to handle the event, so it shouldn't
crash anymore.

doc/gproc.md

@@ -100,7 +100,7 @@ a = aggregate_counter
 
 
 
-<table width="100%" border="1" cellspacing="0" cellpadding="2" summary="function index"><tr><td valign="top"><a href="#add_global_aggr_counter-1">add_global_aggr_counter/1</a></td><td>Registers a global (unique) aggregated counter.</td></tr><tr><td valign="top"><a href="#add_global_counter-2">add_global_counter/2</a></td><td>Registers a global (non-unique) counter.</td></tr><tr><td valign="top"><a href="#add_global_name-1">add_global_name/1</a></td><td>Registers a global (unique) name.</td></tr><tr><td valign="top"><a href="#add_global_property-2">add_global_property/2</a></td><td>Registers a global (non-unique) property.</td></tr><tr><td valign="top"><a href="#add_local_aggr_counter-1">add_local_aggr_counter/1</a></td><td>Registers a local (unique) aggregated counter.</td></tr><tr><td valign="top"><a href="#add_local_counter-2">add_local_counter/2</a></td><td>Registers a local (non-unique) counter.</td></tr><tr><td valign="top"><a href="#add_local_name-1">add_local_name/1</a></td><td>Registers a local (unique) name.</td></tr><tr><td valign="top"><a href="#add_local_property-2">add_local_property/2</a></td><td>Registers a local (non-unique) property.</td></tr><tr><td valign="top"><a href="#audit_process-1">audit_process/1</a></td><td></td></tr><tr><td valign="top"><a href="#await-1">await/1</a></td><td>Equivalent to <a href="#await-2"><tt>await(Key, infinity)</tt></a>.</td></tr><tr><td valign="top"><a href="#await-2">await/2</a></td><td>Wait for a local name to be registered.</td></tr><tr><td valign="top"><a href="#cancel_wait-2">cancel_wait/2</a></td><td></td></tr><tr><td valign="top"><a href="#default-1">default/1</a></td><td></td></tr><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_global_aggr_counter-1">lookup_global_aggr_counter/1</a></td><td>Lookup a global (unique) aggregated counter and returns its value.</td></tr><tr><td valign="top"><a href="#lookup_global_counters-1">lookup_global_counters/1</a></td><td>Look up all global (non-unique) instances of a given Counter.</td></tr><tr><td valign="top"><a href="#lookup_global_name-1">lookup_global_name/1</a></td><td>Lookup a global unique name.</td></tr><tr><td valign="top"><a href="#lookup_global_properties-1">lookup_global_properties/1</a></td><td>Look up all global (non-unique) instances of a given Property.</td></tr><tr><td valign="top"><a href="#lookup_local_aggr_counter-1">lookup_local_aggr_counter/1</a></td><td>Lookup a local (unique) aggregated counter and returns its value.</td></tr><tr><td valign="top"><a href="#lookup_local_counters-1">lookup_local_counters/1</a></td><td>Look up all local (non-unique) instances of a given Counter.</td></tr><tr><td valign="top"><a href="#lookup_local_name-1">lookup_local_name/1</a></td><td>Lookup a local unique name.</td></tr><tr><td valign="top"><a href="#lookup_local_properties-1">lookup_local_properties/1</a></td><td>Look up all local (non-unique) instances of a given Property.</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="#lookup_value-1">lookup_value/1</a></td><td>Lookup the value stored with a key.</td></tr><tr><td valign="top"><a href="#lookup_values-1">lookup_values/1</a></td><td>Retrieve the <code>{Pid,Value}</code> pairs corresponding to 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="#nb_wait-1">nb_wait/1</a></td><td>Wait for a local name to be registered.</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, default(Key))</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>Starts the gproc server.</td></tr><tr><td valign="top"><a href="#table-1">table/1</a></td><td>Equivalent to <a href="#table-2"><tt>table(Context, [])</tt></a>.</td></tr><tr><td valign="top"><a href="#table-2">table/2</a></td><td>QLC table generator for the gproc registry.</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>
+<table width="100%" border="1" cellspacing="0" cellpadding="2" summary="function index"><tr><td valign="top"><a href="#add_global_aggr_counter-1">add_global_aggr_counter/1</a></td><td>Registers a global (unique) aggregated counter.</td></tr><tr><td valign="top"><a href="#add_global_counter-2">add_global_counter/2</a></td><td>Registers a global (non-unique) counter.</td></tr><tr><td valign="top"><a href="#add_global_name-1">add_global_name/1</a></td><td>Registers a global (unique) name.</td></tr><tr><td valign="top"><a href="#add_global_property-2">add_global_property/2</a></td><td>Registers a global (non-unique) property.</td></tr><tr><td valign="top"><a href="#add_local_aggr_counter-1">add_local_aggr_counter/1</a></td><td>Registers a local (unique) aggregated counter.</td></tr><tr><td valign="top"><a href="#add_local_counter-2">add_local_counter/2</a></td><td>Registers a local (non-unique) counter.</td></tr><tr><td valign="top"><a href="#add_local_name-1">add_local_name/1</a></td><td>Registers a local (unique) name.</td></tr><tr><td valign="top"><a href="#add_local_property-2">add_local_property/2</a></td><td>Registers a local (non-unique) property.</td></tr><tr><td valign="top"><a href="#audit_process-1">audit_process/1</a></td><td></td></tr><tr><td valign="top"><a href="#await-1">await/1</a></td><td>Equivalent to <a href="#await-2"><tt>await(Key, infinity)</tt></a>.</td></tr><tr><td valign="top"><a href="#await-2">await/2</a></td><td>Wait for a local name to be registered.</td></tr><tr><td valign="top"><a href="#cancel_wait-2">cancel_wait/2</a></td><td></td></tr><tr><td valign="top"><a href="#default-1">default/1</a></td><td></td></tr><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_global_aggr_counter-1">lookup_global_aggr_counter/1</a></td><td>Lookup a global (unique) aggregated counter and returns its value.</td></tr><tr><td valign="top"><a href="#lookup_global_counters-1">lookup_global_counters/1</a></td><td>Look up all global (non-unique) instances of a given Counter.</td></tr><tr><td valign="top"><a href="#lookup_global_name-1">lookup_global_name/1</a></td><td>Lookup a global unique name.</td></tr><tr><td valign="top"><a href="#lookup_global_properties-1">lookup_global_properties/1</a></td><td>Look up all global (non-unique) instances of a given Property.</td></tr><tr><td valign="top"><a href="#lookup_local_aggr_counter-1">lookup_local_aggr_counter/1</a></td><td>Lookup a local (unique) aggregated counter and returns its value.</td></tr><tr><td valign="top"><a href="#lookup_local_counters-1">lookup_local_counters/1</a></td><td>Look up all local (non-unique) instances of a given Counter.</td></tr><tr><td valign="top"><a href="#lookup_local_name-1">lookup_local_name/1</a></td><td>Lookup a local unique name.</td></tr><tr><td valign="top"><a href="#lookup_local_properties-1">lookup_local_properties/1</a></td><td>Look up all local (non-unique) instances of a given Property.</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="#lookup_values-1">lookup_values/1</a></td><td>Retrieve the <code>{Pid,Value}</code> pairs corresponding to 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="#nb_wait-1">nb_wait/1</a></td><td>Wait for a local name to be registered.</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, default(Key))</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>Starts the gproc server.</td></tr><tr><td valign="top"><a href="#table-1">table/1</a></td><td>Equivalent to <a href="#table-2"><tt>table(Context, [])</tt></a>.</td></tr><tr><td valign="top"><a href="#table-2">table/2</a></td><td>QLC table generator for the gproc registry.</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="#unregister_name-1">unregister_name/1</a></td><td>Equivalent to <tt>unreg / 1</tt>.</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><tr><td valign="top"><a href="#whereis_name-1">whereis_name/1</a></td><td>Equivalent to <tt>where / 1</tt>.</td></tr></table>
 
 
 <a name="functions"></a>
@@ -562,21 +562,6 @@ Returns a list of pids with the published key Key
 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.
-<a name="lookup_value-1"></a>
-
-
-<h3>lookup_value/1</h3>
-
-
-
-
-
-<tt>lookup_value(Key) -> Value</tt>
-
-
-
-Lookup the value stored with a key.
-
 <a name="lookup_values-1"></a>
 
 
@@ -860,6 +845,20 @@ See [`http://www.erlang.org/doc/man/qlc.html`](http://www.erlang.org/doc/man/qlc
 
 
 Unregister a name or property.
+<a name="unregister_name-1"></a>
+
+
+<h3>unregister_name/1</h3>
+
+
+
+
+
+`unregister_name(Key) -> any()`
+
+
+
+Equivalent to `unreg / 1`.
 <a name="update_counter-2"></a>
 
 
@@ -900,5 +899,19 @@ Returns the pid registered as Key
 The type of registration entry must be either name or aggregated counter.
 Otherwise this function will exit. Use [`lookup_pids/1`](#lookup_pids-1) in these
 cases.
+<a name="whereis_name-1"></a>
+
+
+<h3>whereis_name/1</h3>
+
+
+
+
+
+`whereis_name(Key) -> any()`
+
+
+
+Equivalent to `where / 1`.
 
-_Generated by EDoc, Mar 4 2011, 18:56:59._
+_Generated by EDoc, Mar 4 2011, 19:33:29._

doc/gproc_app.md

@@ -64,4 +64,4 @@ __Behaviours:__ [`application`](application.md).
 
 
 
-_Generated by EDoc, Mar 4 2011, 18:56:59._
+_Generated by EDoc, Mar 4 2011, 19:33:29._

doc/gproc_dist.md

@@ -329,4 +329,4 @@ Scope = l | g (global or local)
 
 
 
-_Generated by EDoc, Mar 4 2011, 18:56:59._
+_Generated by EDoc, Mar 4 2011, 19:33:29._

doc/gproc_init.md

@@ -50,4 +50,4 @@ Module gproc_init
 
 
 
-_Generated by EDoc, Mar 4 2011, 18:56:59._
+_Generated by EDoc, Mar 4 2011, 19:33:29._

doc/gproc_lib.md

@@ -22,4 +22,4 @@ This module implements an extended process registry
 
 For a detailed description, see gproc/doc/erlang07-wiger.pdf.
 
-_Generated by EDoc, Mar 4 2011, 18:56:59._
+_Generated by EDoc, Mar 4 2011, 19:33:29._

doc/gproc_sup.md

@@ -54,4 +54,4 @@ The main GPROC supervisor.
 
 
 
-_Generated by EDoc, Mar 4 2011, 18:56:59._
+_Generated by EDoc, Mar 4 2011, 19:33:29._

src/gproc.erl

@@ -49,7 +49,6 @@
          cancel_wait/2,
          lookup_pid/1,
          lookup_pids/1,
-         lookup_value/1,
          lookup_values/1,
          update_counter/2,
          send/2,
@@ -79,6 +78,10 @@
          lookup_local_aggr_counter/1,
          lookup_global_aggr_counter/1]).
 
+%% Callbacks for behaviour support
+-export([whereis_name/1,
+	 unregister_name/1]).
+
 -export([default/1]).
 
 %%% internal exports
@@ -408,6 +411,10 @@ unreg(Key) ->
             end
     end.
 
+%% @equiv unreg/1
+unregister_name(Key) ->
+    unreg(Key).
+
 %% @spec (select_pattern()) -> list(sel_object())
 %% @doc
 %% @equiv select(all, Pat)
@@ -519,9 +526,6 @@ lookup_pid({_T,_,_} = Key) ->
         P -> P
     end.
 
-%% @spec (Key) -> Value
-%% @doc Lookup the value stored with a key.
-%%
 lookup_value({T,_,_} = Key) ->
     if T==n orelse T==a ->
             ets:lookup_element(?TAB, {Key,T}, 3);
@@ -554,6 +558,10 @@ where({T,_,_}=Key) ->
             erlang:error(badarg)
     end.
 
+%% @equiv where/1
+whereis_name(Key) ->
+    where(Key).
+
 %% @spec (Key::key()) -> [pid()]
 %%
 %% @doc Returns a list of pids with the published key Key
@@ -955,6 +963,10 @@ process_is_down(Pid) ->
               case ets:lookup(?TAB, Key) of
                   [{_, Pid, _}] ->
                       ets:delete(?TAB, Key);
+		  [{_, OtherPid, _}] when OtherPid =/= Pid ->
+		      %% Has been known to happen, possibly due to a lingering
+		      %% reverse mapping
+		      true;
                   [{_, Waiters}] ->
                       case [W || {P,_} = W <- Waiters,
                                  P =/= Pid] of

test/eqc/gproc_eqc_tests.erl

@@ -11,6 +11,9 @@
 
 -include_lib("eqc/include/eqc.hrl").
 -include_lib("eqc/include/eqc_statem.hrl").
+-ifdef(TEST).
+-include_lib("eunit/include/eunit.hrl").
+-endif.
 
 -compile(export_all).