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-rw-r--r--erts/doc/src/persistent_term.xml16
-rw-r--r--erts/emulator/beam/bif.tab1
-rw-r--r--erts/emulator/beam/erl_bif_persistent.c17
-rw-r--r--erts/emulator/test/persistent_term_SUITE.erl5
-rw-r--r--erts/preloaded/ebin/persistent_term.beambin1692 -> 1836 bytes
-rw-r--r--erts/preloaded/src/persistent_term.erl9
6 files changed, 45 insertions, 3 deletions
diff --git a/erts/doc/src/persistent_term.xml b/erts/doc/src/persistent_term.xml
index 1eda7f8d76..9d3c9afd80 100644
--- a/erts/doc/src/persistent_term.xml
+++ b/erts/doc/src/persistent_term.xml
@@ -256,6 +256,22 @@ will be slower as the number of persistent terms increases.</pre>
</func>
<func>
+ <name name="get" arity="2" since="OTP 21.3"/>
+ <fsummary>Get the value for a persistent term.</fsummary>
+ <desc>
+ <p>Retrieve the value for the persistent term associated with
+ the key <c><anno>Key</anno></c>. The lookup will be made in
+ constant time and the value will not be copied to the heap
+ of the calling process.</p>
+ <p>This function returns <c><anno>Default</anno></c> if no
+ term has been stored with the key <c><anno>Key</anno></c>.</p>
+ <p>If the calling process holds on to the value of the
+ persistent term and the persistent term is deleted in the future,
+ the term will be copied to the process.</p>
+ </desc>
+ </func>
+
+ <func>
<name name="info" arity="0" since="OTP 21.2"/>
<fsummary>Get information about persistent terms.</fsummary>
<desc>
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index c96278b10c..8419244832 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -738,3 +738,4 @@ bif erts_internal:spawn_system_process/3
bif erlang:integer_to_list/2
bif erlang:integer_to_binary/2
+bif persistent_term:get/2
diff --git a/erts/emulator/beam/erl_bif_persistent.c b/erts/emulator/beam/erl_bif_persistent.c
index 9dca768a18..5a78a043ce 100644
--- a/erts/emulator/beam/erl_bif_persistent.c
+++ b/erts/emulator/beam/erl_bif_persistent.c
@@ -332,6 +332,23 @@ BIF_RETTYPE persistent_term_get_1(BIF_ALIST_1)
BIF_ERROR(BIF_P, BADARG);
}
+BIF_RETTYPE persistent_term_get_2(BIF_ALIST_2)
+{
+ Eterm key = BIF_ARG_1;
+ Eterm result = BIF_ARG_2;
+ HashTable* hash_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+ Uint entry_index;
+ Eterm term;
+
+ entry_index = lookup(hash_table, key);
+ term = hash_table->term[entry_index];
+ if (is_boxed(term)) {
+ ASSERT(is_tuple_arity(term, 2));
+ result = tuple_val(term)[2];
+ }
+ BIF_RET(result);
+}
+
BIF_RETTYPE persistent_term_erase_1(BIF_ALIST_1)
{
Eterm key = BIF_ARG_1;
diff --git a/erts/emulator/test/persistent_term_SUITE.erl b/erts/emulator/test/persistent_term_SUITE.erl
index 58038e24b7..93eb026ced 100644
--- a/erts/emulator/test/persistent_term_SUITE.erl
+++ b/erts/emulator/test/persistent_term_SUITE.erl
@@ -6,7 +6,7 @@
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
-%5
+%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
@@ -60,7 +60,8 @@ basic(_Config) ->
Key = {?MODULE,{key,I}},
true = persistent_term:erase(Key),
false = persistent_term:erase(Key),
- {'EXIT',{badarg,_}} = (catch persistent_term:get(Key))
+ {'EXIT',{badarg,_}} = (catch persistent_term:get(Key)),
+ {not_present,Key} = persistent_term:get(Key, {not_present,Key})
end || I <- Seq],
[] = [P || {{?MODULE,_},_}=P <- pget(Chk)],
chk(Chk).
diff --git a/erts/preloaded/ebin/persistent_term.beam b/erts/preloaded/ebin/persistent_term.beam
index e94ef983be..c882e4fad4 100644
--- a/erts/preloaded/ebin/persistent_term.beam
+++ b/erts/preloaded/ebin/persistent_term.beam
Binary files differ
diff --git a/erts/preloaded/src/persistent_term.erl b/erts/preloaded/src/persistent_term.erl
index 5d0c266127..ee7e49b6cb 100644
--- a/erts/preloaded/src/persistent_term.erl
+++ b/erts/preloaded/src/persistent_term.erl
@@ -19,7 +19,7 @@
%%
-module(persistent_term).
--export([erase/1,get/0,get/1,info/0,put/2]).
+-export([erase/1,get/0,get/1,get/2,info/0,put/2]).
-type key() :: term().
-type value() :: term().
@@ -41,6 +41,13 @@ get() ->
get(_Key) ->
erlang:nif_error(undef).
+-spec get(Key, Default) -> Value when
+ Key :: key(),
+ Default :: value(),
+ Value :: value().
+get(_Key, _Default) ->
+ erlang:nif_error(undef).
+
-spec info() -> Info when
Info :: #{'count':=Count,'memory':=Memory},
Count :: non_neg_integer(),