src/bin/lttng-sessiond/tsdl-trace-class-visitor.cpp

   1 /*
   2  * Copyright (C) 2022 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #include "tsdl-trace-class-visitor.hpp"
   9 #include "clock-class.hpp"
  10
  11 #include <common/exception.hpp>
  12 #include <common/format.hpp>
  13 #include <common/make-unique.hpp>
  14 #include <common/uuid.hpp>
  15
  16 #include <vendor/optional.hpp>
  17
  18 #include <algorithm>
  19 #include <array>
  20 #include <locale>
  21 #include <queue>
  22 #include <set>
  23 #include <stack>
  24
  25 namespace lst = lttng::sessiond::trace;
  26 namespace tsdl = lttng::sessiond::tsdl;
  27
  28 namespace {
  29 const auto ctf_spec_major = 1;
  30 const auto ctf_spec_minor = 8;
  31
  32 /*
  33  * Although the CTF v1.8 specification recommends ignoring any leading underscore, Some readers,
  34  * such as Babeltrace 1.x, expect special identifiers without a prepended underscore.
  35  */
  36 const std::set<std::string> safe_tsdl_identifiers = {
  37         "stream_id",
  38         "packet_size",
  39         "content_size",
  40         "id",
  41         "v",
  42         "timestamp",
  43         "events_discarded",
  44         "packet_seq_num",
  45         "timestamp_begin",
  46         "timestamp_end",
  47         "cpu_id",
  48         "magic",
  49         "uuid",
  50         "stream_instance_id"
  51 };
  52
  53 /*
  54  * A previous implementation always prepended '_' to the identifiers in order to
  55  * side-step the problem of escaping TSDL keywords and ensuring identifiers
  56  * started with an alphabetic character.
  57  *
  58  * Changing this behaviour to a smarter algorithm would break readers that have
  59  * come to expect this initial underscore.
  60  */
  61 std::string escape_tsdl_identifier(const std::string& original_identifier)
  62 {
  63         if (original_identifier.size() == 0) {
  64                 LTTNG_THROW_ERROR("Invalid 0-length identifier used in trace description");
  65         }
  66
  67         if (safe_tsdl_identifiers.find(original_identifier) != safe_tsdl_identifiers.end()) {
  68                 return original_identifier;
  69         }
  70
  71         std::string new_identifier;
  72         /* Optimisticly assume most identifiers are valid and allocate the same length. */
  73         new_identifier.reserve(original_identifier.size());
  74         new_identifier = "_";
  75
  76         /* Replace illegal characters by '_'. */
  77         std::locale c_locale{"C"};
  78         for (const auto current_char : original_identifier) {
  79                 if (!std::isalnum(current_char, c_locale) && current_char != '_') {
  80                         new_identifier += '_';
  81                 } else {
  82                         new_identifier += current_char;
  83                 }
  84         }
  85
  86         return new_identifier;
  87 }
  88
  89 std::string escape_tsdl_env_string_value(const std::string& original_string)
  90 {
  91         std::string escaped_string;
  92
  93         escaped_string.reserve(original_string.size());
  94
  95         for (const auto c : original_string) {
  96                 switch (c) {
  97                 case '\n':
  98                         escaped_string += "\\n";
  99                         break;
 100                 case '\\':
 101                         escaped_string += "\\\\";
 102                         break;
 103                 case '"':
 104                         escaped_string += "\"";
 105                         break;
 106                 default:
 107                         escaped_string += c;
 108                         break;
 109                 }
 110         }
 111
 112         return escaped_string;
 113 }
 114
 115 class tsdl_field_visitor : public lttng::sessiond::trace::field_visitor,
 116                            public lttng::sessiond::trace::type_visitor {
 117 public:
 118         tsdl_field_visitor(const lst::abi& abi,
 119                         unsigned int indentation_level,
 120                         const nonstd::optional<std::string>& in_default_clock_class_name =
 121                                         nonstd::nullopt) :
 122                 _indentation_level{indentation_level},
 123                 _trace_abi{abi},
 124                 _bypass_identifier_escape{false},
 125                 _default_clock_class_name{in_default_clock_class_name ?
 126                                                 in_default_clock_class_name->c_str() :
 127                                                 nullptr}
 128         {
 129         }
 130
 131         std::string& get_description()
 132         {
 133                 return _description;
 134         }
 135
 136 private:
 137         virtual void visit(const lst::field& field) override final
 138         {
 139                 /*
 140                  * Hack: keep the name of the field being visited since
 141                  * the tracers can express sequences, variants, and arrays with an alignment
 142                  * constraint, which is not expressible in TSDL. To work around this limitation, an
 143                  * empty structure declaration is inserted when needed to express the aligment
 144                  * constraint. The name of this structure is generated using the field's name.
 145                  */
 146                 _current_field_name.push(_bypass_identifier_escape ?
 147                                 field.name : escape_tsdl_identifier(field.name));
 148
 149                 field._type->accept(*this);
 150                 _description += " ";
 151                 _description += _current_field_name.top();
 152                 _current_field_name.pop();
 153
 154                 /*
 155                  * Some types requires suffixes to be appended (e.g. the length of arrays
 156                  * and sequences, the mappings of enumerations).
 157                  */
 158                 while (!_type_suffixes.empty()) {
 159                         _description += _type_suffixes.front();
 160                         _type_suffixes.pop();
 161                 }
 162
 163                 _description += ";";
 164         }
 165
 166         virtual void visit(const lst::integer_type& type) override final
 167         {
 168                 _description += "integer { ";
 169
 170                 /* Mandatory properties (no defaults). */
 171                 _description += fmt::format("size = {size}; align = {alignment};",
 172                                 fmt::arg("size", type.size),
 173                                 fmt::arg("alignment", type.alignment));
 174
 175                 /* Defaults to unsigned. */
 176                 if (type.signedness_ == lst::integer_type::signedness::SIGNED) {
 177                         _description += " signed = true;";
 178                 }
 179
 180                 /* Defaults to 10. */
 181                 if (type.base_ != lst::integer_type::base::DECIMAL) {
 182                         unsigned int base;
 183
 184                         switch (type.base_) {
 185                         case lst::integer_type::base::BINARY:
 186                                 base = 2;
 187                                 break;
 188                         case lst::integer_type::base::OCTAL:
 189                                 base = 8;
 190                                 break;
 191                         case lst::integer_type::base::HEXADECIMAL:
 192                                 base = 16;
 193                                 break;
 194                         default:
 195                                 LTTNG_THROW_ERROR(fmt::format(
 196                                                 "Unexpected base encountered while serializing integer type to TSDL: base = {}",
 197                                                 (int) type.base_));
 198                         }
 199
 200                         _description += fmt::format(" base = {};", base);
 201                 }
 202
 203                 /* Defaults to the trace's native byte order. */
 204                 if (type.byte_order != _trace_abi.byte_order) {
 205                         const auto byte_order_str = type.byte_order == lst::byte_order::BIG_ENDIAN_ ? "be" : "le";
 206
 207                         _description += fmt::format(" byte_order = {};", byte_order_str);
 208                 }
 209
 210                 if (_current_integer_encoding_override) {
 211                         const char *encoding_str;
 212
 213                         switch (*_current_integer_encoding_override) {
 214                         case lst::string_type::encoding::ASCII:
 215                                 encoding_str = "ASCII";
 216                                 break;
 217                         case lst::string_type::encoding::UTF8:
 218                                 encoding_str = "UTF8";
 219                                 break;
 220                         default:
 221                                 LTTNG_THROW_ERROR(fmt::format(
 222                                                 "Unexpected encoding encountered while serializing integer type to TSDL: encoding = {}",
 223                                                 (int) *_current_integer_encoding_override));
 224                         }
 225
 226                         _description += fmt::format(" encoding = {};", encoding_str);
 227                         _current_integer_encoding_override.reset();
 228                 }
 229
 230                 if (std::find(type.roles_.begin(), type.roles_.end(),
 231                                     lst::integer_type::role::DEFAULT_CLOCK_TIMESTAMP) !=
 232                                                 type.roles_.end() ||
 233                                 std::find(type.roles_.begin(), type.roles_.end(),
 234                                                 lst::integer_type::role::
 235                                                                 PACKET_END_DEFAULT_CLOCK_TIMESTAMP) !=
 236                                                 type.roles_.end()) {
 237                         LTTNG_ASSERT(_default_clock_class_name);
 238                         _description += fmt::format(
 239                                         " map = clock.{}.value;", _default_clock_class_name);
 240                 }
 241
 242                 _description += " }";
 243         }
 244
 245         virtual void visit(const lst::floating_point_type& type) override final
 246         {
 247                 _description += fmt::format(
 248                                 "floating_point {{ align = {alignment}; mant_dig = {mantissa_digits}; exp_dig = {exponent_digits};",
 249                                 fmt::arg("alignment", type.alignment),
 250                                 fmt::arg("mantissa_digits", type.mantissa_digits),
 251                                 fmt::arg("exponent_digits", type.exponent_digits));
 252
 253                 /* Defaults to the trace's native byte order. */
 254                 if (type.byte_order != _trace_abi.byte_order) {
 255                         const auto byte_order_str = type.byte_order == lst::byte_order::BIG_ENDIAN_ ? "be" : "le";
 256
 257                         _description += fmt::format(" byte_order = {};", byte_order_str);
 258                 }
 259
 260                 _description += " }";
 261         }
 262
 263         template <class EnumerationType>
 264         void visit_enumeration(const EnumerationType& type)
 265         {
 266                 /* name follows, when applicable. */
 267                 _description += "enum : ";
 268
 269                 tsdl_field_visitor integer_visitor{_trace_abi, _indentation_level};
 270
 271                 integer_visitor.visit(static_cast<const lst::integer_type&>(type));
 272                 _description += integer_visitor.get_description() + " {\n";
 273
 274                 const auto mappings_indentation_level = _indentation_level + 1;
 275
 276                 bool first_mapping = true;
 277                 for (const auto& mapping : *type._mappings) {
 278                         if (!first_mapping) {
 279                                 _description += ",\n";
 280                         }
 281
 282                         _description.resize(_description.size() + mappings_indentation_level, '\t');
 283                         if (!mapping.range) {
 284                                 _description += fmt::format("\"{}\"", mapping.name);
 285                         } else if (mapping.range->begin == mapping.range->end) {
 286                                 _description += fmt::format(
 287                                                 "\"{mapping_name}\" = {mapping_value}",
 288                                                 fmt::arg("mapping_name", mapping.name),
 289                                                 fmt::arg("mapping_value", mapping.range->begin));
 290                         } else {
 291                                 _description += fmt::format(
 292                                                 "\"{mapping_name}\" = {mapping_range_begin} ... {mapping_range_end}",
 293                                                 fmt::arg("mapping_name", mapping.name),
 294                                                 fmt::arg("mapping_range_begin",
 295                                                                 mapping.range->begin),
 296                                                 fmt::arg("mapping_range_end", mapping.range->end));
 297                         }
 298
 299                         first_mapping = false;
 300                 }
 301
 302                 _description += "\n";
 303                 _description.resize(_description.size() + _indentation_level, '\t');
 304                 _description += "}";
 305         }
 306
 307         virtual void visit(const lst::signed_enumeration_type& type) override final
 308         {
 309                 visit_enumeration(type);
 310         }
 311
 312         virtual void visit(const lst::unsigned_enumeration_type& type) override final
 313         {
 314                 visit_enumeration(type);
 315         }
 316
 317         virtual void visit(const lst::static_length_array_type& type) override final
 318         {
 319                 if (type.alignment != 0) {
 320                         LTTNG_ASSERT(_current_field_name.size() > 0);
 321                         _description += fmt::format(
 322                                         "struct {{ }} align({alignment}) {field_name}_padding;\n",
 323                                         fmt::arg("alignment", type.alignment),
 324                                         fmt::arg("field_name", _current_field_name.top()));
 325                         _description.resize(_description.size() + _indentation_level, '\t');
 326                 }
 327
 328                 type.element_type->accept(*this);
 329                 _type_suffixes.emplace(fmt::format("[{}]", type.length));
 330         }
 331
 332         virtual void visit(const lst::dynamic_length_array_type& type) override final
 333         {
 334                 if (type.alignment != 0) {
 335                         /*
 336                          * Note that this doesn't support nested sequences. For
 337                          * the moment, tracers can't express those. However, we
 338                          * could wrap nested sequences in structures, which
 339                          * would allow us to express alignment constraints.
 340                          */
 341                         LTTNG_ASSERT(_current_field_name.size() > 0);
 342                         _description += fmt::format(
 343                                         "struct {{ }} align({alignment}) {field_name}_padding;\n",
 344                                         fmt::arg("alignment", type.alignment),
 345                                         fmt::arg("field_name", _current_field_name.top()));
 346                         _description.resize(_description.size() + _indentation_level, '\t');
 347                 }
 348
 349                 type.element_type->accept(*this);
 350                 _type_suffixes.emplace(fmt::format("[{}]",
 351                                 _bypass_identifier_escape ?
 352                                                 type.length_field_name :
 353                                                       escape_tsdl_identifier(type.length_field_name)));
 354         }
 355
 356         virtual void visit(const lst::static_length_blob_type& type) override final
 357         {
 358                 /* This type doesn't exist in CTF 1.x, express it as a static length array of uint8_t. */
 359                 std::unique_ptr<const lst::type> uint8_element = lttng::make_unique<lst::integer_type>(8,
 360                                 _trace_abi.byte_order, 8, lst::integer_type::signedness::UNSIGNED,
 361                                 lst::integer_type::base::HEXADECIMAL);
 362                 const auto array = lttng::make_unique<lst::static_length_array_type>(
 363                                 type.alignment, std::move(uint8_element), type.length_bytes);
 364
 365                 visit(*array);
 366         }
 367
 368         virtual void visit(const lst::dynamic_length_blob_type& type) override final
 369         {
 370                 /* This type doesn't exist in CTF 1.x, express it as a dynamic length array of uint8_t. */
 371                 std::unique_ptr<const lst::type> uint8_element = lttng::make_unique<lst::integer_type>(0,
 372                                 _trace_abi.byte_order, 8, lst::integer_type::signedness::UNSIGNED,
 373                                 lst::integer_type::base::HEXADECIMAL);
 374                 const auto array = lttng::make_unique<lst::dynamic_length_array_type>(
 375                                 type.alignment, std::move(uint8_element), type.length_field_name);
 376
 377                 visit(*array);
 378         }
 379
 380         virtual void visit(const lst::null_terminated_string_type& type) override final
 381         {
 382                 /* Defaults to UTF-8. */
 383                 if (type.encoding_ == lst::null_terminated_string_type::encoding::ASCII) {
 384                         _description += "string { encoding = ASCII }";
 385                 } else {
 386                         _description += "string";
 387                 }
 388         }
 389
 390         virtual void visit(const lst::structure_type& type) override final
 391         {
 392                 _indentation_level++;
 393                 _description += "struct {";
 394
 395                 const auto previous_bypass_identifier_escape = _bypass_identifier_escape;
 396                 _bypass_identifier_escape = false;
 397                 for (const auto& field : type._fields) {
 398                         _description += "\n";
 399                         _description.resize(_description.size() + _indentation_level, '\t');
 400                         field->accept(*this);
 401                 }
 402
 403                 _bypass_identifier_escape = previous_bypass_identifier_escape;
 404
 405                 _indentation_level--;
 406                 if (type._fields.size() != 0) {
 407                         _description += "\n";
 408                         _description.resize(_description.size() + _indentation_level, '\t');
 409                 }
 410
 411                 _description += "}";
 412         }
 413
 414         virtual void visit(const lst::variant_type& type) override final
 415         {
 416                 if (type.alignment != 0) {
 417                         LTTNG_ASSERT(_current_field_name.size() > 0);
 418                         _description += fmt::format(
 419                                         "struct {{ }} align({alignment}) {field_name}_padding;\n",
 420                                         fmt::arg("alignment", type.alignment),
 421                                         fmt::arg("field_name", _current_field_name.top()));
 422                         _description.resize(_description.size() + _indentation_level, '\t');
 423                 }
 424
 425                 _indentation_level++;
 426                 _description += fmt::format("variant <{}> {{\n",
 427                                 _bypass_identifier_escape ?
 428                                                 type.tag_name :
 429                                                       escape_tsdl_identifier(type.tag_name));
 430
 431                 /*
 432                  * The CTF 1.8 specification only recommends that implementations ignore
 433                  * leading underscores in field names. Both babeltrace 1 and 2 expect the
 434                  * variant choice and enumeration mapping name to match perfectly. Given that we
 435                  * don't have access to the tag in this context, we have to assume they match.
 436                  */
 437                 const auto previous_bypass_identifier_escape = _bypass_identifier_escape;
 438                 _bypass_identifier_escape = true;
 439                 for (const auto& field : type._choices) {
 440                         _description.resize(_description.size() + _indentation_level, '\t');
 441                         field->accept(*this);
 442                         _description += fmt::format("\n", field->name);
 443                 }
 444
 445                 _bypass_identifier_escape = previous_bypass_identifier_escape;
 446
 447                 _indentation_level--;
 448                 _description.resize(_description.size() + _indentation_level, '\t');
 449                 _description += "}";
 450         }
 451
 452         lst::type::cuptr create_character_type(enum lst::string_type::encoding encoding)
 453         {
 454                 _current_integer_encoding_override = encoding;
 455                 return lttng::make_unique<lst::integer_type>(8, _trace_abi.byte_order, 8,
 456                                 lst::integer_type::signedness::UNSIGNED,
 457                                 lst::integer_type::base::DECIMAL);
 458         }
 459
 460         virtual void visit(const lst::static_length_string_type& type) override final
 461         {
 462                 /*
 463                  * TSDL expresses static-length strings as arrays of 8-bit integer with
 464                  * an encoding specified.
 465                  */
 466                 const auto char_array = lttng::make_unique<lst::static_length_array_type>(
 467                                 type.alignment, create_character_type(type.encoding_), type.length);
 468
 469                 visit(*char_array);
 470         }
 471
 472         virtual void visit(const lst::dynamic_length_string_type& type) override final
 473         {
 474                 /*
 475                  * TSDL expresses dynamic-length strings as arrays of 8-bit integer with
 476                  * an encoding specified.
 477                  */
 478                 const auto char_sequence = lttng::make_unique<lst::dynamic_length_array_type>(
 479                                 type.alignment, create_character_type(type.encoding_),
 480                                 type.length_field_name);
 481
 482                 visit(*char_sequence);
 483         }
 484
 485         std::stack<std::string> _current_field_name;
 486         /*
 487          * Encoding to specify for the next serialized integer type.
 488          * Since the integer_type does not allow an encoding to be specified (it is a TSDL-specific
 489          * concept), this attribute is used when expressing static or dynamic length strings as
 490          * arrays/sequences of bytes with an encoding.
 491          */
 492         nonstd::optional<enum lst::string_type::encoding> _current_integer_encoding_override;
 493
 494         unsigned int _indentation_level;
 495         const lst::abi& _trace_abi;
 496
 497         std::queue<std::string> _type_suffixes;
 498
 499         /* Description in TSDL format. */
 500         std::string _description;
 501
 502         bool _bypass_identifier_escape;
 503         const char *_default_clock_class_name;
 504 };
 505 } /* namespace */
 506
 507 tsdl::trace_class_visitor::trace_class_visitor(const lst::abi& trace_abi,
 508                 tsdl::append_metadata_fragment_function append_metadata_fragment) :
 509         _trace_abi{trace_abi},
 510         _append_metadata_fragment(append_metadata_fragment)
 511 {
 512 }
 513
 514 void tsdl::trace_class_visitor::append_metadata_fragment(const std::string& fragment) const
 515 {
 516         _append_metadata_fragment(fragment);
 517 }
 518
 519 void tsdl::trace_class_visitor::visit(const lttng::sessiond::trace::trace_class& trace_class)
 520 {
 521         tsdl_field_visitor packet_header_visitor(trace_class.abi, 1);
 522
 523         trace_class.get_packet_header()->accept(packet_header_visitor);
 524
 525         /* Declare type aliases, trace class, and packet header. */
 526         auto trace_class_tsdl = fmt::format(
 527                         "/* CTF {ctf_major}.{ctf_minor} */\n\n"
 528                         "trace {{\n"
 529                         "       major = {ctf_major};\n"
 530                         "       minor = {ctf_minor};\n"
 531                         "       uuid = \"{uuid}\";\n"
 532                         "       byte_order = {byte_order};\n"
 533                         "       packet.header := {packet_header_layout};\n"
 534                         "}};\n\n",
 535                         fmt::arg("ctf_major", ctf_spec_major),
 536                         fmt::arg("ctf_minor", ctf_spec_minor),
 537                         fmt::arg("uint8_t_alignment", trace_class.abi.uint8_t_alignment),
 538                         fmt::arg("uint16_t_alignment", trace_class.abi.uint16_t_alignment),
 539                         fmt::arg("uint32_t_alignment", trace_class.abi.uint32_t_alignment),
 540                         fmt::arg("uint64_t_alignment", trace_class.abi.uint64_t_alignment),
 541                         fmt::arg("long_alignment", trace_class.abi.long_alignment),
 542                         fmt::arg("long_size", trace_class.abi.long_alignment),
 543                         fmt::arg("bits_per_long", trace_class.abi.bits_per_long),
 544                         fmt::arg("uuid", lttng::utils::uuid_to_str(trace_class.uuid)),
 545                         fmt::arg("byte_order",
 546                                         trace_class.abi.byte_order == lst::byte_order::BIG_ENDIAN_ ? "be" : "le"),
 547                         fmt::arg("packet_header_layout", packet_header_visitor.get_description()));
 548
 549         /* Declare trace scope and type aliases. */
 550         append_metadata_fragment(std::move(trace_class_tsdl));
 551 }
 552
 553 void tsdl::trace_class_visitor::visit(const lttng::sessiond::trace::clock_class& clock_class)
 554 {
 555         auto uuid_str = clock_class.uuid ?
 556                         fmt::format("   uuid = \"{}\";\n",
 557                                         lttng::utils::uuid_to_str(*clock_class.uuid)) :
 558                               "";
 559
 560         /* Assumes a single clock that maps to specific stream class fields/roles. */
 561         auto clock_class_str = fmt::format(
 562                         "clock {{\n"
 563                         "       name = \"{name}\";\n"
 564                         /* Optional uuid. */
 565                         "{uuid}"
 566                         "       description = \"{description}\";\n"
 567                         "       freq = {frequency};\n"
 568                         "       offset = {offset};\n"
 569                         "}};\n"
 570                         "\n",
 571                         fmt::arg("name", clock_class.name),
 572                         fmt::arg("uuid", uuid_str),
 573                         fmt::arg("description", clock_class.description),
 574                         fmt::arg("frequency", clock_class.frequency),
 575                         fmt::arg("offset", clock_class.offset));
 576
 577         append_metadata_fragment(std::move(clock_class_str));
 578 }
 579
 580 void tsdl::trace_class_visitor::visit(const lttng::sessiond::trace::stream_class& stream_class)
 581 {
 582         auto stream_class_str = fmt::format("stream {{\n"
 583                 "       id = {};\n", stream_class.id);
 584
 585         const auto *event_header = stream_class.get_event_header();
 586         if (event_header) {
 587                 auto event_header_visitor = tsdl_field_visitor(
 588                                 _trace_abi, 1, stream_class.default_clock_class_name);
 589
 590                 event_header->accept(event_header_visitor);
 591                 stream_class_str += fmt::format("       event.header := {};\n",
 592                                 event_header_visitor.get_description());
 593         }
 594
 595         const auto *packet_context = stream_class.get_packet_context();
 596         if (packet_context) {
 597                 auto packet_context_visitor = tsdl_field_visitor(
 598                                 _trace_abi, 1, stream_class.default_clock_class_name);
 599
 600                 packet_context->accept(packet_context_visitor);
 601                 stream_class_str += fmt::format("       packet.context := {};\n",
 602                                 packet_context_visitor.get_description());
 603         }
 604
 605         const auto *event_context = stream_class.get_event_context();
 606         if (event_context) {
 607                 auto event_context_visitor = tsdl_field_visitor(_trace_abi, 1);
 608
 609                 event_context->accept(event_context_visitor);
 610                 stream_class_str += fmt::format("       event.context := {};\n",
 611                                 event_context_visitor.get_description());
 612         }
 613
 614         stream_class_str += "};\n\n";
 615
 616         append_metadata_fragment(stream_class_str);
 617 }
 618
 619 void tsdl::trace_class_visitor::visit(const lttng::sessiond::trace::event_class& event_class)
 620 {
 621         auto event_class_str = fmt::format("event {{\n"
 622                                            "    name = \"{name}\";\n"
 623                                            "    id = {id};\n"
 624                                            "    stream_id = {stream_class_id};\n"
 625                                            "    loglevel = {log_level};\n",
 626                         fmt::arg("name", event_class.name),
 627                         fmt::arg("id", event_class.id),
 628                         fmt::arg("stream_class_id", event_class.stream_class_id),
 629                         fmt::arg("log_level", event_class.log_level));
 630
 631         if (event_class.model_emf_uri) {
 632                 event_class_str += fmt::format(
 633                                 "       model.emf.uri = \"{}\";\n", *event_class.model_emf_uri);
 634         }
 635
 636         auto payload_visitor = tsdl_field_visitor(_trace_abi, 1);
 637
 638         event_class.payload->accept(static_cast<lst::type_visitor&>(payload_visitor));
 639
 640         event_class_str += fmt::format(
 641                         "       fields := {};\n}};\n\n", payload_visitor.get_description());
 642
 643         append_metadata_fragment(event_class_str);
 644 }
 645
 646 void tsdl::trace_class_visitor::environment_begin()
 647 {
 648         _environment += "env {\n";
 649 }
 650
 651 void tsdl::trace_class_visitor::visit(
 652                 const lttng::sessiond::trace::environment_field<int64_t>& field)
 653 {
 654         _environment += fmt::format("   {} = {};\n", field.name, field.value);
 655 }
 656
 657 void tsdl::trace_class_visitor::visit(
 658                 const lttng::sessiond::trace::environment_field<const char *>& field)
 659 {
 660         _environment += fmt::format(
 661                         "       {} = \"{}\";\n", field.name, escape_tsdl_env_string_value(field.value));
 662 }
 663
 664 void tsdl::trace_class_visitor::environment_end()
 665 {
 666         _environment += "};\n\n";
 667         append_metadata_fragment(_environment);
 668         _environment.clear();
 669 }