Merge pull request #1406 from TheSobkiewicz/thesobkiewicz/nifs/ets/update_counter

Add ets:update_counter

Currently this solution doesn't support list of UpdateOp to update multiple counters.
Based on:
#1405

https://www.erlang.org/docs/23/man/ets#update_counter-3

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

Author: bettio

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added `esp:partition_read/3`, and documentation for `esp:partition_erase_range/2/3` and `esp:partition_write/3`
 - Added support for list insertion in 'ets:insert/2'.
 - Support to OTP-28
+- Added support for `ets:update_counter/3` and `ets:update_counter/4`.
 
 ### Fixed
 - ESP32: improved sntp sync speed from a cold boot.

libs/estdlib/src/ets.erl

@@ -29,7 +29,9 @@
     insert/2,
     lookup/2,
     lookup_element/3,
-    delete/2
+    delete/2,
+    update_counter/3,
+    update_counter/4
 ]).
 
 -export_type([
@@ -101,3 +103,41 @@ lookup_element(_Table, _Key, _Pos) ->
 -spec delete(Table :: table(), Key :: term()) -> true.
 delete(_Table, _Key) ->
     erlang:nif_error(undefined).
+
+%%-----------------------------------------------------------------------------
+%% @param   Table a reference to the ets table
+%% @param   Key the key used to look up the entry expecting to contain a tuple of integers or a single integer
+%% @param   Params the increment value or a tuple {Pos, Increment} or {Pos, Increment, Treshold, SetValue},
+%%         where Pos is an integer (1-based index) specifying the position in the tuple to increment. Value is clamped to SetValue if it exceeds Threshold after update.
+%% @returns the updated element's value after performing the increment, or the default value if applicable
+%% @doc Updates a counter value at Key in the table. If Params is a single integer, it increments the direct integer value at Key or the first integer in a tuple. If Params is a tuple {Pos, Increment}, it increments the integer at the specified position Pos in the tuple stored at Key.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec update_counter(
+    Table :: table(),
+    Key :: term(),
+    Params ::
+        integer() | {pos_integer(), integer()} | {pos_integer(), integer(), integer(), integer()}
+) -> integer().
+update_counter(_Table, _Key, _Params) ->
+    erlang:nif_error(undefined).
+
+%%-----------------------------------------------------------------------------
+%% @param   Table a reference to the ets table
+%% @param   Key the key used to look up the entry expecting to contain a tuple of integers or a single integer
+%% @param   Params the increment value or a tuple {Pos, Increment} or {Pos, Increment, Treshold, SetValue},
+%%         where Pos is an integer (1-based index) specifying the position in the tuple to increment. If after incrementation value exceeds the Treshold, it is set to SetValue.
+%% @param   Default the default value used if the entry at Key doesn't exist or doesn't contain a valid tuple with a sufficient size or integer at Pos
+%% @returns the updated element's value after performing the increment, or the default value if applicable
+%% @doc Updates a counter value at Key in the table. If Params is a single integer, it increments the direct integer value at Key or the first integer in a tuple. If Params is a tuple {Pos, Increment}, it increments the integer at the specified position Pos in the tuple stored at Key. If the needed element does not exist, uses Default value as a fallback.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec update_counter(
+    Table :: table(),
+    Key :: term(),
+    Params ::
+        integer() | {pos_integer(), integer()} | {pos_integer(), integer(), integer(), integer()},
+    Default :: integer()
+) -> integer().
+update_counter(_Table, _Key, _Params, _Default) ->
+    erlang:nif_error(undefined).

src/libAtomVM/ets.c

@@ -25,6 +25,7 @@
 #include "ets_hashtable.h"
 #include "list.h"
 #include "memory.h"
+#include "overflow_helpers.h"
 #include "term.h"
 
 #ifndef AVM_NO_SMP
@@ -445,3 +446,129 @@ EtsErrorCode ets_delete(term name_or_ref, term key, term *ret, Context *ctx)
 
     return EtsOk;
 }
+
+static bool operation_to_tuple4(term operation, size_t default_pos, term *position, term *increment, term *threshold, term *set_value)
+{
+    if (term_is_integer(operation)) {
+        *increment = operation;
+        *position = term_from_int(default_pos);
+        *threshold = term_invalid_term();
+        *set_value = term_invalid_term();
+        return true;
+    }
+
+    if (UNLIKELY(!term_is_tuple(operation))) {
+        return false;
+    }
+    int n = term_get_tuple_arity(operation);
+    if (UNLIKELY(n != 2 && n != 4)) {
+        return false;
+    }
+
+    term pos = term_get_tuple_element(operation, 0);
+    term incr = term_get_tuple_element(operation, 1);
+    if (UNLIKELY(!term_is_integer(pos) || !term_is_integer(incr))) {
+        return false;
+    }
+
+    if (n == 2) {
+        *position = pos;
+        *increment = incr;
+        *threshold = term_invalid_term();
+        *set_value = term_invalid_term();
+        return true;
+    }
+
+    term tresh = term_get_tuple_element(operation, 2);
+    term set_val = term_get_tuple_element(operation, 3);
+    if (UNLIKELY(!term_is_integer(tresh) || !term_is_integer(set_val))) {
+        return false;
+    }
+
+    *position = pos;
+    *increment = incr;
+    *threshold = tresh;
+    *set_value = set_val;
+    return true;
+}
+
+EtsErrorCode ets_update_counter(term ref, term key, term operation, term default_value, term *ret, Context *ctx)
+{
+    struct EtsTable *ets_table = term_is_atom(ref)
+        ? ets_get_table_by_name(&ctx->global->ets, ref, TableAccessWrite)
+        : ets_get_table_by_ref(&ctx->global->ets, term_to_ref_ticks(ref), TableAccessWrite);
+    if (IS_NULL_PTR(ets_table)) {
+        return EtsTableNotFound;
+    }
+
+    term list;
+    EtsErrorCode result = ets_table_lookup(ets_table, key, &list, ctx);
+    if (UNLIKELY(result != EtsOk)) {
+        SMP_UNLOCK(ets_table);
+        return result;
+    }
+
+    term to_insert;
+    if (term_is_nil(list)) {
+        if (term_is_invalid_term(default_value)) {
+            SMP_UNLOCK(ets_table);
+            return EtsBadEntry;
+        }
+        to_insert = default_value;
+    } else {
+        to_insert = term_get_list_head(list);
+    }
+
+    if (UNLIKELY(!term_is_tuple(to_insert))) {
+        SMP_UNLOCK(ets_table);
+        return EtsBadEntry;
+    }
+    term position_term;
+    term increment_term;
+    term threshold_term;
+    term set_value_term;
+    // +1 to position, +1 to elem after key
+    size_t default_pos = (ets_table->keypos + 1) + 1;
+
+    if (UNLIKELY(!operation_to_tuple4(operation, default_pos, &position_term, &increment_term, &threshold_term, &set_value_term))) {
+        SMP_UNLOCK(ets_table);
+        return EtsBadEntry;
+    }
+    int arity = term_get_tuple_arity(to_insert);
+    avm_int_t position = term_to_int(position_term) - 1;
+    if (UNLIKELY(arity <= position || position < 1)) {
+        SMP_UNLOCK(ets_table);
+        return EtsBadEntry;
+    }
+
+    term elem = term_get_tuple_element(to_insert, position);
+    if (UNLIKELY(!term_is_integer(elem))) {
+        SMP_UNLOCK(ets_table);
+        return EtsBadEntry;
+    }
+    avm_int_t increment = term_to_int(increment_term);
+    avm_int_t elem_value;
+    if (BUILTIN_ADD_OVERFLOW_INT(increment, term_to_int(elem), &elem_value)) {
+        SMP_UNLOCK(ets_table);
+        return EtsOverlfow;
+    }
+    if (!term_is_invalid_term(threshold_term) && !term_is_invalid_term(set_value_term)) {
+        avm_int_t threshold = term_to_int(threshold_term);
+        avm_int_t set_value = term_to_int(set_value_term);
+
+        if (increment >= 0 && elem_value > threshold) {
+            elem_value = set_value;
+        } else if (increment < 0 && elem_value < threshold) {
+            elem_value = set_value;
+        }
+    }
+
+    term final_value = term_from_int(elem_value);
+    term_put_tuple_element(to_insert, position, final_value);
+    EtsErrorCode insert_result = ets_table_insert(ets_table, to_insert, ctx);
+    if (insert_result == EtsOk) {
+        *ret = final_value;
+    }
+    SMP_UNLOCK(ets_table);
+    return insert_result;
+}

src/libAtomVM/ets.h

@@ -57,7 +57,8 @@ typedef enum EtsErrorCode
     EtsBadEntry,
     EtsAllocationFailure,
     EtsEntryNotFound,
-    EtsBadPosition
+    EtsBadPosition,
+    EtsOverlfow
 } EtsErrorCode;
 struct Ets
 {
@@ -77,7 +78,7 @@ EtsErrorCode ets_insert(term ref, term entry, Context *ctx);
 EtsErrorCode ets_lookup(term ref, term key, term *ret, Context *ctx);
 EtsErrorCode ets_lookup_element(term ref, term key, size_t pos, term *ret, Context *ctx);
 EtsErrorCode ets_delete(term ref, term key, term *ret, Context *ctx);
-
+EtsErrorCode ets_update_counter(term ref, term key, term value, term pos, term *ret, Context *ctx);
 #ifdef __cplusplus
 }
 #endif

src/libAtomVM/nifs.c

@@ -153,6 +153,7 @@ static term nif_ets_insert(Context *ctx, int argc, term argv[]);
 static term nif_ets_lookup(Context *ctx, int argc, term argv[]);
 static term nif_ets_lookup_element(Context *ctx, int argc, term argv[]);
 static term nif_ets_delete(Context *ctx, int argc, term argv[]);
+static term nif_ets_update_counter(Context *ctx, int argc, term argv[]);
 static term nif_erlang_pid_to_list(Context *ctx, int argc, term argv[]);
 static term nif_erlang_ref_to_list(Context *ctx, int argc, term argv[]);
 static term nif_erlang_fun_to_list(Context *ctx, int argc, term argv[]);
@@ -680,6 +681,12 @@ static const struct Nif ets_delete_nif =
     .nif_ptr = nif_ets_delete
 };
 
+static const struct Nif ets_update_counter_nif =
+{
+    .base.type = NIFFunctionType,
+    .nif_ptr = nif_ets_update_counter
+};
+
 static const struct Nif atomvm_add_avm_pack_binary_nif =
 {
     .base.type = NIFFunctionType,
@@ -3294,6 +3301,39 @@ static term nif_ets_delete(Context *ctx, int argc, term argv[])
     }
 }
 
+static term nif_ets_update_counter(Context *ctx, int argc, term argv[])
+{
+    term ref = argv[0];
+    VALIDATE_VALUE(ref, is_ets_table_id);
+
+    term key = argv[1];
+    term operation = argv[2];
+    term default_value;
+    if (argc == 4) {
+        default_value = argv[3];
+        VALIDATE_VALUE(default_value, term_is_tuple);
+        term_put_tuple_element(default_value, 0, key);
+    } else {
+        default_value = term_invalid_term();
+    }
+    term ret;
+    EtsErrorCode result = ets_update_counter(ref, key, operation, default_value, &ret, ctx);
+    switch (result) {
+        case EtsOk:
+            return ret;
+        case EtsTableNotFound:
+        case EtsPermissionDenied:
+        case EtsBadEntry:
+            RAISE_ERROR(BADARG_ATOM);
+        case EtsAllocationFailure:
+            RAISE_ERROR(OUT_OF_MEMORY_ATOM);
+        case EtsOverlfow:
+            RAISE_ERROR(OVERFLOW_ATOM);
+        default:
+            UNREACHABLE();
+    }
+}
+
 static term nif_erts_debug_flat_size(Context *ctx, int argc, term argv[])
 {
     UNUSED(ctx);

src/libAtomVM/nifs.gperf

@@ -130,6 +130,8 @@ ets:insert/2, &ets_insert_nif
 ets:lookup/2, &ets_lookup_nif
 ets:lookup_element/3, &ets_lookup_element_nif
 ets:delete/2, &ets_delete_nif
+ets:update_counter/3, &ets_update_counter_nif
+ets:update_counter/4, &ets_update_counter_nif
 atomvm:add_avm_pack_binary/2, &atomvm_add_avm_pack_binary_nif
 atomvm:add_avm_pack_file/2, &atomvm_add_avm_pack_file_nif
 atomvm:close_avm_pack/2, &atomvm_close_avm_pack_nif

tests/erlang_tests/test_ets.erl

@@ -32,6 +32,7 @@ start() ->
     ok = test_public_access(),
     ok = test_lookup_element(),
     ok = test_insert_list(),
+    ok = test_update_counter(),
     0.
 
 test_basic() ->
@@ -367,3 +368,21 @@ test_insert_list() ->
     end),
     expect_failure(fun() -> ets:insert(Tid, [{}]) end),
     ok.
+
+test_update_counter() ->
+    Tid = ets:new(test_lookup_element, []),
+    true = ets:insert(Tid, {foo, 1, 2, 3}),
+    3 = ets:update_counter(Tid, foo, 2),
+    expect_failure(fun() -> ets:update_counter(Tid, tapas, 2) end),
+    5 = ets:update_counter(Tid, tapas, 2, {batat, 3}),
+    [] = ets:lookup(Tid, batat),
+    [{tapas, 5}] = ets:lookup(Tid, tapas),
+    0 = ets:update_counter(Tid, foo, {3, -2}),
+    expect_failure(fun() -> ets:update_counter(Tid, foo, {-3, -2}) end),
+    expect_failure(fun() -> ets:update_counter(Tid, foo, {30, -2}) end),
+    expect_failure(fun() -> ets:update_counter(Tid, patatas, {3, -2}, {cow, 1}) end),
+    0 = ets:update_counter(Tid, patatas, {3, -2}, {cow, 1, 2, 3}),
+    0 = ets:update_counter(Tid, patatas, {3, -2, 0, 0}),
+    10 = ets:update_counter(Tid, patatas, {3, 10, 10, 0}),
+    0 = ets:update_counter(Tid, patatas, {3, 10, 10, 0}),
+    ok.