tskv_parser_read.hpp File Reference

Detailed Description

Definition in file tskv_parser_read.hpp.

Go to the source code of this file.

#include <utility>
#include <userver/compiler/thread_local.hpp>
#include <userver/utils/encoding/tskv_parser.hpp>

Namespaces
namespace	utils
	Utilities.

Functions
template<typename TagConsumer >
TskvParser::RecordStatus	utils::encoding::TskvReadRecord (TskvParser &parser, TagConsumer consumer)
	Read all keys-values for 1 TSKV record.

Function Documentation

TskvReadRecord()

template<typename TagConsumer >

TskvParser::RecordStatus utils::encoding::TskvReadRecord	(	TskvParser &	parser,
		TagConsumer	consumer )

Read all keys-values for 1 TSKV record.

Parameters

parser	parser that should have already found the start of the TSKV record using TskvParser::SkipToRecordBegin
consumer	a lambda with the signature (const std::string&, const std::string&) -> bool; the strings are temporaries, references to them should not be stored; can return false to skip the record and return immediately

Usage example:

struct Record {
  std::vector<std::pair<std::string, std::string>> tags;
};
struct Junk {
  std::string data;
};
struct Incomplete {
  std::string data;
};
using SingleParsedRecord = std::variant<Record, Junk, Incomplete>;
using ParsedRecords = std::vector<SingleParsedRecord>;
 
ParsedRecords ParseTskv(std::string_view in) {
  ParsedRecords result;
  utils::encoding::TskvParser parser{in};
 
  const auto account_incomplete = [&](const char* incomplete_begin) {
    const std::string_view remaining(incomplete_begin,
                                     in.data() + in.size() - incomplete_begin);
    if (!remaining.empty()) {
      result.push_back(Incomplete{std::string(remaining)});
    }
  };
 
  while (true) {
    const char* const junk_begin = parser.GetStreamPosition();
    const char* const record_begin = parser.SkipToRecordBegin();
 
    if (!record_begin) {
      // Note: production code should stop and wait for more data here.
      account_incomplete(junk_begin);
      break;
    }
 
    // Note: accounting for junk in-between records is supported, but is
    // typically not important in production.
    if (record_begin != junk_begin) {
      result.push_back(Junk{std::string(junk_begin, record_begin)});
    }
 
    std::vector<std::pair<std::string, std::string>> tags;
 
    const auto status = utils::encoding::TskvReadRecord(
        parser, [&](const std::string& key, const std::string& value) {
          tags.emplace_back(key, value);
          return true;
        });
 
    if (status == utils::encoding::TskvParser::RecordStatus::kIncomplete) {
      // Note: production code should stop and wait for more data here.
      account_incomplete(record_begin);
      break;
    }
 
    result.push_back(Record{std::move(tags)});
  }
 
  return result;
}

Definition at line 40 of file tskv_parser_read.hpp.