Refactor stats tables around descriptor-driven row emission

include/jemalloc/internal/emitter.h

@@ -590,6 +590,99 @@ emitter_sparse_row(emitter_t *emitter, emitter_row_t *row, bool is_gap) {
 	}
 }
 
+/*
+ * Descriptor-driven column tables.  A descriptor array defines table order;
+ * callers provide a separate index array when JSON requires a different
+ * subset or ordering.  The getter lets one engine serve different row types
+ * while keeping derived values (rates, utilization, and so on) with the
+ * table-specific code.  A column is active when all its required_flags are
+ * present in the active_flags supplied by the caller; the emitter assigns no
+ * domain-specific meaning to those bits.
+ */
+typedef struct emitter_col_desc_s emitter_col_desc_t;
+struct emitter_col_desc_s {
+	const char       *json_key;
+	const char       *table_label;
+	emitter_justify_t justify;
+	int               width;
+	emitter_type_t    type;
+	unsigned          required_flags;
+	void            (*get)(const void *row, emitter_col_t *col);
+};
+
+static inline bool
+emitter_col_desc_active(const emitter_col_desc_t *desc,
+    unsigned active_flags) {
+	return (desc->required_flags & ~active_flags) == 0;
+}
+
+static inline void
+emitter_col_table_build(const emitter_col_desc_t *descs, size_t ndescs,
+    unsigned active_flags, emitter_row_t *row, emitter_col_t *cols,
+    emitter_row_t *header_row, emitter_col_t *header_cols) {
+	emitter_row_init(row);
+	emitter_row_init(header_row);
+	for (size_t i = 0; i < ndescs; i++) {
+		if (!emitter_col_desc_active(&descs[i], active_flags)) {
+			continue;
+		}
+
+		emitter_col_init(&cols[i], row);
+		cols[i].justify = descs[i].justify;
+		cols[i].width = descs[i].width;
+		cols[i].type = descs[i].type;
+
+		emitter_col_init(&header_cols[i], header_row);
+		header_cols[i].justify = descs[i].justify;
+		header_cols[i].width = descs[i].width;
+		header_cols[i].type = emitter_type_title;
+		header_cols[i].str_val = descs[i].table_label != NULL
+		    ? descs[i].table_label : descs[i].json_key;
+	}
+}
+
+static inline void
+emitter_col_table_header(emitter_t *emitter, emitter_row_t *header_row,
+    emitter_col_t *first_header_col, const char *table_prefix,
+    const char *json_key) {
+	first_header_col->width -= (int)strlen(table_prefix);
+	emitter_table_printf(emitter, "%s", table_prefix);
+	emitter_table_row(emitter, header_row);
+	emitter_json_array_kv_begin(emitter, json_key);
+}
+
+static inline void
+emitter_col_table_fill(const emitter_col_desc_t *descs, size_t ndescs,
+    unsigned active_flags, emitter_col_t *cols, const void *row) {
+	for (size_t i = 0; i < ndescs; i++) {
+		if (!emitter_col_desc_active(&descs[i], active_flags)) {
+			continue;
+		}
+		cols[i].type = descs[i].type;
+		descs[i].get(row, &cols[i]);
+	}
+}
+
+static inline void
+emitter_col_table_emit_json(emitter_t *emitter,
+    const emitter_col_desc_t *descs, size_t ndescs, unsigned active_flags,
+    emitter_col_t *cols, const unsigned *json_order, size_t json_order_len) {
+	if (!emitter_outputs_json(emitter)) {
+		return;
+	}
+	for (size_t i = 0; i < json_order_len; i++) {
+		unsigned col_ind = json_order[i];
+		assert(col_ind < ndescs);
+		const emitter_col_desc_t *desc = &descs[col_ind];
+		if (!emitter_col_desc_active(desc, active_flags)) {
+			continue;
+		}
+		assert(desc->json_key != NULL);
+		emitter_json_kv(emitter, desc->json_key, cols[col_ind].type,
+		    (const void *)&cols[col_ind].bool_val);
+	}
+}
+
 static inline void
 emitter_begin(emitter_t *emitter) {
 	if (emitter_outputs_json(emitter)) {

test/unit/emitter.c

@@ -668,6 +668,111 @@ static const char *sparse_row_table =
     "     2\n"
     "                     ---\n";
 
+typedef struct {
+	size_t   size;
+	uint64_t count;
+	uint64_t prof_count;
+	uint64_t requests;
+} col_table_test_row_t;
+
+#define COL_TABLE_TEST_GETTER(name, member, value_member)                     \
+	static void                                                            \
+	col_table_test_get_##name(const void *vrow, emitter_col_t *col) {       \
+		const col_table_test_row_t *row = vrow;                          \
+		col->value_member = row->member;                                 \
+	}
+COL_TABLE_TEST_GETTER(size, size, size_val)
+COL_TABLE_TEST_GETTER(count, count, uint64_val)
+COL_TABLE_TEST_GETTER(prof_count, prof_count, uint64_val)
+COL_TABLE_TEST_GETTER(requests, requests, uint64_val)
+#undef COL_TABLE_TEST_GETTER
+
+enum {
+	COL_TABLE_TEST_SIZE,
+	COL_TABLE_TEST_COUNT,
+	COL_TABLE_TEST_PROF_COUNT,
+	COL_TABLE_TEST_REQUESTS,
+	COL_TABLE_TEST_NCOLS
+};
+
+#define COL_TABLE_TEST_FLAG_PROF (1U << 0)
+
+static const emitter_col_desc_t col_table_test_descs[] = {
+	{NULL, "size", emitter_justify_right, 8, emitter_type_size, 0,
+	    col_table_test_get_size},
+	{"count", "count", emitter_justify_right, 8, emitter_type_uint64,
+	    0, col_table_test_get_count},
+	{"prof_count", "prof", emitter_justify_right, 6, emitter_type_uint64,
+	    COL_TABLE_TEST_FLAG_PROF, col_table_test_get_prof_count},
+	{"requests", "requests", emitter_justify_right, 10,
+	    emitter_type_uint64, 0, col_table_test_get_requests},
+};
+_Static_assert(
+    sizeof(col_table_test_descs) / sizeof(col_table_test_descs[0]) ==
+    COL_TABLE_TEST_NCOLS,
+    "col_table_test_descs must match COL_TABLE_TEST_NCOLS");
+
+TEST_BEGIN(test_col_desc_flags) {
+	expect_true(emitter_col_desc_active(
+	    &col_table_test_descs[COL_TABLE_TEST_COUNT], 0),
+	    "A column without requirements should always be active");
+	expect_false(emitter_col_desc_active(
+	    &col_table_test_descs[COL_TABLE_TEST_PROF_COUNT], 0),
+	    "A column with an unmet requirement should be inactive");
+	expect_true(emitter_col_desc_active(
+	    &col_table_test_descs[COL_TABLE_TEST_PROF_COUNT],
+	    COL_TABLE_TEST_FLAG_PROF),
+	    "A column with a satisfied requirement should be active");
+}
+TEST_END
+
+static const unsigned col_table_test_json_order[] = {
+	COL_TABLE_TEST_REQUESTS,
+	COL_TABLE_TEST_PROF_COUNT,
+	COL_TABLE_TEST_COUNT,
+};
+
+static void
+emit_col_table(emitter_t *emitter) {
+	col_table_test_row_t value = {42, 7, 100, 9};
+	emitter_row_t row, header_row;
+	emitter_col_t cols[COL_TABLE_TEST_NCOLS];
+	emitter_col_t header_cols[COL_TABLE_TEST_NCOLS];
+
+	emitter_begin(emitter);
+	emitter_col_table_build(col_table_test_descs, COL_TABLE_TEST_NCOLS,
+	    COL_TABLE_TEST_FLAG_PROF, &row, cols, &header_row, header_cols);
+	emitter_col_table_header(
+	    emitter, &header_row, &header_cols[0], "mock:", "rows");
+	emitter_col_table_fill(col_table_test_descs, COL_TABLE_TEST_NCOLS,
+	    COL_TABLE_TEST_FLAG_PROF, cols, &value);
+	emitter_json_object_begin(emitter);
+	emitter_col_table_emit_json(emitter, col_table_test_descs,
+	    COL_TABLE_TEST_NCOLS, COL_TABLE_TEST_FLAG_PROF, cols,
+	    col_table_test_json_order, sizeof(col_table_test_json_order) /
+	        sizeof(col_table_test_json_order[0]));
+	emitter_json_object_end(emitter);
+	emitter_table_row(emitter, &row);
+	emitter_json_array_end(emitter);
+	emitter_end(emitter);
+}
+
+static const char *col_table_json =
+    "{\n"
+    "\t\"rows\": [\n"
+    "\t\t{\n"
+    "\t\t\t\"requests\": 9,\n"
+    "\t\t\t\"prof_count\": 100,\n"
+    "\t\t\t\"count\": 7\n"
+    "\t\t}\n"
+    "\t]\n"
+    "}\n";
+static const char *col_table_json_compact =
+    "{\"rows\":[{\"requests\":9,\"prof_count\":100,\"count\":7}]}";
+static const char *col_table_table =
+    "mock:size   count  prof  requests\n"
+    "      42       7   100         9\n";
+
 #define GENERATE_TEST(feature)                                                 \
 	TEST_BEGIN(test_##feature) {                                           \
 		expect_emit_output(emit_##feature, feature##_json,             \
@@ -685,10 +790,12 @@ GENERATE_TEST(json_nested_array)
 GENERATE_TEST(table_row)
 GENERATE_TEST(row)
 GENERATE_TEST(sparse_row)
+GENERATE_TEST(col_table)
 
 int
 main(void) {
 	return test_no_reentrancy(test_dict, test_table_printf,
 	    test_nested_dict, test_types, test_modal, test_json_array,
-	    test_json_nested_array, test_table_row, test_row, test_sparse_row);
+	    test_json_nested_array, test_table_row, test_row, test_sparse_row,
+	    test_col_table, test_col_desc_flags);
 }