aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--erts/emulator/beam/bif.tab1
-rw-r--r--erts/emulator/beam/erl_db.c28
-rw-r--r--lib/stdlib/doc/src/ets.xml31
-rw-r--r--lib/stdlib/src/ets.erl11
-rw-r--r--lib/stdlib/test/ets_SUITE.erl35
5 files changed, 98 insertions, 8 deletions
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index c0d5e8ce74..b5725e4185 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -696,3 +696,4 @@ bif erlang:iolist_to_iovec/1
bif erts_internal:new_connection/1
bif erts_internal:abort_connection/2
bif erts_internal:map_next/3
+bif ets:whereis/1
diff --git a/erts/emulator/beam/erl_db.c b/erts/emulator/beam/erl_db.c
index 3ba0886464..1ab1c4a363 100644
--- a/erts/emulator/beam/erl_db.c
+++ b/erts/emulator/beam/erl_db.c
@@ -1753,6 +1753,28 @@ BIF_RETTYPE ets_new_2(BIF_ALIST_2)
BIF_RET(ret);
}
+/*
+** Retrieves the tid() of a named ets table.
+*/
+BIF_RETTYPE ets_whereis_1(BIF_ALIST_1)
+{
+ DbTable* tb;
+ Eterm res;
+
+ if (is_not_atom(BIF_ARG_1)) {
+ BIF_ERROR(BIF_P, BADARG);
+ }
+
+ if ((tb = db_get_table(BIF_P, BIF_ARG_1, DB_INFO, LCK_READ)) == NULL) {
+ BIF_RET(am_undefined);
+ }
+
+ res = make_tid(BIF_P, tb);
+ db_unlock(tb, LCK_READ);
+
+ BIF_RET(res);
+}
+
/*
** The lookup BIF
*/
@@ -3126,7 +3148,8 @@ BIF_RETTYPE ets_info_1(BIF_ALIST_1)
static Eterm fields[] = {am_protection, am_keypos, am_type, am_named_table,
am_node, am_size, am_name, am_heir, am_owner, am_memory, am_compressed,
am_write_concurrency,
- am_read_concurrency};
+ am_read_concurrency,
+ am_id};
Eterm results[sizeof(fields)/sizeof(Eterm)];
DbTable* tb;
Eterm res;
@@ -4016,7 +4039,10 @@ static Eterm table_info(Process* p, DbTable* tb, Eterm What)
ret = is_table_named(tb) ? am_true : am_false;
} else if (What == am_compressed) {
ret = tb->common.compress ? am_true : am_false;
+ } else if (What == am_id) {
+ ret = make_tid(p, tb);
}
+
/*
* For debugging purposes
*/
diff --git a/lib/stdlib/doc/src/ets.xml b/lib/stdlib/doc/src/ets.xml
index 1b31a1ec9d..305376a425 100644
--- a/lib/stdlib/doc/src/ets.xml
+++ b/lib/stdlib/doc/src/ets.xml
@@ -487,6 +487,11 @@ Error: fun containing local Erlang function calls
<p>The pid of the heir of the table, or <c>none</c> if no heir
is set.</p>
</item>
+ <tag><c>{id,</c><seealso marker="#type-tid">
+ <c>tid()</c></seealso><c>}</c></tag>
+ <item>
+ <p>The table identifier.</p>
+ </item>
<tag><c>{keypos, integer() >= 1}</c></tag>
<item>
<p>The key position.</p>
@@ -1074,10 +1079,13 @@ ets:select(Table, MatchSpec),</code>
</item>
<tag><c>named_table</c></tag>
<item>
- <p>If this option is present, name <c><anno>Name</anno></c> is
- associated with the table identifier. The name can then
- be used instead of the table identifier in subsequent
- operations.</p>
+ <p>If this option is present, the table is registered under its
+ <c><anno>Name</anno></c> which can then be used instead of the
+ table identifier in subsequent operations.</p>
+ <p>The function will also return the <c><anno>Name</anno></c>
+ instead of the table identifier. To get the table identifier of a
+ named table, use
+ <seealso marker="#whereis/1"><c>whereis/1</c></seealso>.</p>
</item>
<tag><c>{keypos,<anno>Pos</anno>}</c></tag>
<item>
@@ -2037,6 +2045,21 @@ true</pre>
</list>
</desc>
</func>
+
+ <func>
+ <name name="whereis" arity="1"/>
+ <fsummary>Retrieves the tid() of a named table.</fsummary>
+ <desc>
+ <p>This function returns the
+ <seealso marker="#type-tid"><c>tid()</c></seealso> of the named table
+ identified by <c><anno>TableName</anno></c>, or <c>undefined</c> if
+ no such table exists. The <c>tid()</c> can be used in place of the
+ table name in all operations, which is slightly faster since the name
+ does not have to be resolved on each call.</p>
+ <p>If the table is deleted, the <c>tid()</c> will be invalid even if
+ another named table is created with the same name.</p>
+ </desc>
+ </func>
</funcs>
</erlref>
diff --git a/lib/stdlib/src/ets.erl b/lib/stdlib/src/ets.erl
index 039ab45868..6a559f0be5 100644
--- a/lib/stdlib/src/ets.erl
+++ b/lib/stdlib/src/ets.erl
@@ -73,7 +73,8 @@
select_count/2, select_delete/2, select_replace/2, select_reverse/1,
select_reverse/2, select_reverse/3, setopts/2, slot/2,
take/2,
- update_counter/3, update_counter/4, update_element/3]).
+ update_counter/3, update_counter/4, update_element/3,
+ whereis/1]).
%% internal exports
-export([internal_request_all/0]).
@@ -145,6 +146,7 @@ give_away(_, _, _) ->
InfoList :: [InfoTuple],
InfoTuple :: {compressed, boolean()}
| {heir, pid() | none}
+ | {id, tid()}
| {keypos, pos_integer()}
| {memory, non_neg_integer()}
| {name, atom()}
@@ -162,7 +164,7 @@ info(_) ->
-spec info(Tab, Item) -> Value | undefined when
Tab :: tab(),
- Item :: compressed | fixed | heir | keypos | memory
+ Item :: compressed | fixed | heir | id | keypos | memory
| name | named_table | node | owner | protection
| safe_fixed | safe_fixed_monotonic_time | size | stats | type
| write_concurrency | read_concurrency,
@@ -512,6 +514,11 @@ update_counter(_, _, _, _) ->
update_element(_, _, _) ->
erlang:nif_error(undef).
+-spec whereis(TableName) -> tid() | undefined when
+ TableName :: atom().
+whereis(_) ->
+ erlang:nif_error(undef).
+
%%% End of BIFs
-opaque comp_match_spec() :: reference().
diff --git a/lib/stdlib/test/ets_SUITE.erl b/lib/stdlib/test/ets_SUITE.erl
index 0cfb1b5516..8b651f4b43 100644
--- a/lib/stdlib/test/ets_SUITE.erl
+++ b/lib/stdlib/test/ets_SUITE.erl
@@ -78,6 +78,7 @@
-export([ets_all/1]).
-export([massive_ets_all/1]).
-export([take/1]).
+-export([whereis_table/1]).
-export([init_per_testcase/2, end_per_testcase/2]).
%% Convenience for manual testing
@@ -137,7 +138,8 @@ all() ->
otp_9423,
ets_all,
massive_ets_all,
- take].
+ take,
+ whereis_table].
groups() ->
[{new, [],
@@ -4099,6 +4101,7 @@ info_do(Opts) ->
{value, {keypos, 2}} = lists:keysearch(keypos, 1, Res),
{value, {protection, protected}} =
lists:keysearch(protection, 1, Res),
+ {value, {id, Tab}} = lists:keysearch(id, 1, Res),
true = ets:delete(Tab),
undefined = ets:info(non_existing_table_xxyy),
undefined = ets:info(non_existing_table_xxyy,type),
@@ -5892,6 +5895,36 @@ take(Config) when is_list(Config) ->
ets:delete(T3),
ok.
+whereis_table(Config) when is_list(Config) ->
+ %% Do we return 'undefined' when the named table doesn't exist?
+ undefined = ets:whereis(whereis_test),
+
+ %% Does the tid() refer to the same table as the name?
+ whereis_test = ets:new(whereis_test, [named_table]),
+ Tid = ets:whereis(whereis_test),
+
+ ets:insert(whereis_test, [{hello}, {there}]),
+
+ [[{hello}],[{there}]] = ets:match(whereis_test, '$1'),
+ [[{hello}],[{there}]] = ets:match(Tid, '$1'),
+
+ true = ets:delete_all_objects(Tid),
+
+ [] = ets:match(whereis_test, '$1'),
+ [] = ets:match(Tid, '$1'),
+
+ %% Does the name disappear when deleted through the tid()?
+ true = ets:delete(Tid),
+ undefined = ets:info(whereis_test),
+ {'EXIT',{badarg, _}} = (catch ets:match(whereis_test, '$1')),
+
+ %% Is the old tid() broken when the table is re-created with the same
+ %% name?
+ whereis_test = ets:new(whereis_test, [named_table]),
+ [] = ets:match(whereis_test, '$1'),
+ {'EXIT',{badarg, _}} = (catch ets:match(Tid, '$1')),
+
+ ok.
%%
%% Utility functions:
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 14:26:14 +0000