Compare commits

..
Author SHA1 Message Date
Niels Lohmann cc749ac699 Keep full byte2 x byte3 combinatorics in the wrong-fourth-byte sections
The maintainer wants exhaustive coverage of every byte combination here
rather than the representative-prefix reduction, matching the style of
the sibling "wrong second/third byte" sections in the same files.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-05 23:18:51 +02:00
Niels Lohmann 1c6ca81b8a Fix dead ill-formed-fourth-byte UTF-8 test sections (byte3/byte4 typo)
The "ill-formed: wrong fourth byte" SECTIONs in unit-unicode3.cpp,
unit-unicode4.cpp, and unit-unicode5.cpp guarded their loop with a check
on byte3 instead of byte4. Since the enclosing loop already restricts
byte3 to its valid range, the guard was always true and the section's
"continue" fired unconditionally, so check_utf8string()/check_utf8dump()
were never actually invoked for a malformed fourth byte.

Fixing the guard naively (byte3 -> byte4) would also have swept the full
byte2 x byte3 combinatorics for every byte4 value, adding millions of
redundant iterations: the lexer validates continuation bytes strictly in
sequence with early exit (see next_byte_in_range() in lexer.hpp), so once
byte2/byte3 are within their valid range, the byte4 outcome does not
depend on which valid byte2/byte3 values were chosen. Instead, byte2 and
byte3 are now held to a small hedge of representative valid prefixes
(range corners plus a midpoint) while byte4 is still swept exhaustively
over its full 0x00-0xFF range, since that is the actual property under
test. Also fixed the garbled "skip fourth second byte" comment in
unit-unicode3.cpp.

Verified offline: before the fix, the "wrong fourth byte" subcase
executes 0 assertions in all three files (proving it was dead code);
after the fix, it executes 11520 (unicode3), 34560 (unicode4), and 11520
(unicode5) assertions, and a deliberately reintroduced bug in the
lexer's byte4 range check causes it to fail (proving it is now
meaningful). Total per-file assertion counts grow by the same small
amounts, not by millions, and all other sections in these files still
pass unchanged.

Fixes #5416

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-09-05 23:05:42 +02:00
4 changed files with 4 additions and 323 deletions
-319
View File
@@ -214,323 +214,4 @@ static void BinaryToCbor(benchmark::State& state)
}
BENCHMARK(BinaryToCbor)->RangeMultiplier(2)->Range(8, 8 << 12);
//////////////////////////////////////////////////////////////////////////////
// parse binary formats
//////////////////////////////////////////////////////////////////////////////
// Only MessagePack had a read benchmark (FromMsgpack above, left untouched so
// its numbers stay comparable across releases). The benchmarks below cover the
// other formats, and read from a contiguous buffer as well as from a FILE*:
// most callers pass a container, and the two adapters compile to different
// code. The test data repository ships JSON only, so the input for each is
// derived at setup time by serializing a parsed test file.
/// binary format to benchmark; the _optimized variants add UBJSON/BJData size
/// and type annotations, which the readers handle in a separate code path
enum class binary_format
{
cbor,
msgpack,
ubjson,
ubjson_optimized,
bjdata,
bjdata_optimized,
bson
};
static std::vector<std::uint8_t> to_binary(const json& j, const binary_format format)
{
switch (format)
{
case binary_format::cbor:
return json::to_cbor(j);
case binary_format::msgpack:
return json::to_msgpack(j);
case binary_format::ubjson:
return json::to_ubjson(j);
case binary_format::ubjson_optimized:
return json::to_ubjson(j, true, true);
case binary_format::bjdata:
return json::to_bjdata(j);
case binary_format::bjdata_optimized:
return json::to_bjdata(j, true, true);
case binary_format::bson:
default:
return json::to_bson(j);
}
}
static json from_binary(const std::vector<std::uint8_t>& bytes, const binary_format format)
{
switch (format)
{
case binary_format::cbor:
return json::from_cbor(bytes);
case binary_format::msgpack:
return json::from_msgpack(bytes);
case binary_format::ubjson:
case binary_format::ubjson_optimized:
return json::from_ubjson(bytes);
case binary_format::bjdata:
case binary_format::bjdata_optimized:
return json::from_bjdata(bytes);
case binary_format::bson:
default:
return json::from_bson(bytes);
}
}
static json from_binary(std::FILE* file, const binary_format format)
{
switch (format)
{
case binary_format::cbor:
return json::from_cbor(file);
case binary_format::msgpack:
return json::from_msgpack(file);
case binary_format::ubjson:
case binary_format::ubjson_optimized:
return json::from_ubjson(file);
case binary_format::bjdata:
case binary_format::bjdata_optimized:
return json::from_bjdata(file);
case binary_format::bson:
default:
return json::from_bson(file);
}
}
/*!
@brief serialize a parsed test file to @a format
Returns an empty vector and marks the benchmark as skipped if the file cannot
be represented in the format, rather than letting the exception escape: BSON
requires an object at the top level, and several test files are arrays.
*/
static std::vector<std::uint8_t> binary_input(benchmark::State& state, const char* filename, const binary_format format)
{
std::ifstream f(filename);
std::string const str((std::istreambuf_iterator<char>(f)), std::istreambuf_iterator<char>());
const json j = json::parse(str);
if (format == binary_format::bson && !j.is_object())
{
state.SkipWithError("BSON requires an object at the top level");
return {};
}
return to_binary(j, format);
}
static void FromBinaryBuffer(benchmark::State& state, const char* filename, const binary_format format)
{
const std::vector<std::uint8_t> bytes = binary_input(state, filename, format);
if (bytes.empty())
{
return;
}
for (auto _ : state)
{
// the value is destroyed outside the timed section, because destroying
// a large DOM is not what this benchmark measures
state.PauseTiming();
auto* j = new json();
state.ResumeTiming();
*j = from_binary(bytes, format);
state.PauseTiming();
delete j;
state.ResumeTiming();
}
state.SetBytesProcessed(state.iterations() * bytes.size());
}
BENCHMARK_CAPTURE(FromBinaryBuffer, cbor / jeopardy, TEST_DATA_DIRECTORY "/jeopardy/jeopardy.json", binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryBuffer, cbor / canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryBuffer, cbor / citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json", binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryBuffer, cbor / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryBuffer, cbor / floats, TEST_DATA_DIRECTORY "/regression/floats.json", binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryBuffer, cbor / signed_ints, TEST_DATA_DIRECTORY "/regression/signed_ints.json", binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryBuffer, msgpack / jeopardy, TEST_DATA_DIRECTORY "/jeopardy/jeopardy.json", binary_format::msgpack);
BENCHMARK_CAPTURE(FromBinaryBuffer, msgpack / canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", binary_format::msgpack);
BENCHMARK_CAPTURE(FromBinaryBuffer, msgpack / citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json", binary_format::msgpack);
BENCHMARK_CAPTURE(FromBinaryBuffer, msgpack / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::msgpack);
BENCHMARK_CAPTURE(FromBinaryBuffer, ubjson / jeopardy, TEST_DATA_DIRECTORY "/jeopardy/jeopardy.json", binary_format::ubjson);
BENCHMARK_CAPTURE(FromBinaryBuffer, ubjson / canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", binary_format::ubjson);
BENCHMARK_CAPTURE(FromBinaryBuffer, ubjson / citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json", binary_format::ubjson);
BENCHMARK_CAPTURE(FromBinaryBuffer, ubjson / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::ubjson);
BENCHMARK_CAPTURE(FromBinaryBuffer, ubjson_optimized / canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", binary_format::ubjson_optimized);
BENCHMARK_CAPTURE(FromBinaryBuffer, ubjson_optimized / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::ubjson_optimized);
BENCHMARK_CAPTURE(FromBinaryBuffer, bjdata / canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", binary_format::bjdata);
BENCHMARK_CAPTURE(FromBinaryBuffer, bjdata / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::bjdata);
BENCHMARK_CAPTURE(FromBinaryBuffer, bjdata_optimized / canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", binary_format::bjdata_optimized);
BENCHMARK_CAPTURE(FromBinaryBuffer, bjdata_optimized / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::bjdata_optimized);
// BSON requires an object at the top level, so the array-rooted test files
// (jeopardy and the regression files) cannot be captured here
BENCHMARK_CAPTURE(FromBinaryBuffer, bson / canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", binary_format::bson);
BENCHMARK_CAPTURE(FromBinaryBuffer, bson / citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json", binary_format::bson);
BENCHMARK_CAPTURE(FromBinaryBuffer, bson / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::bson);
static void FromBinaryFile(benchmark::State& state, const char* filename, const binary_format format)
{
const std::vector<std::uint8_t> bytes = binary_input(state, filename, format);
if (bytes.empty())
{
return;
}
const char* tmp = "benchmark_input.bin";
std::ofstream o(tmp, std::ios::binary);
o.write(reinterpret_cast<const char*>(bytes.data()), static_cast<std::streamsize>(bytes.size()));
o.flush();
o.close();
for (auto _ : state)
{
state.PauseTiming();
auto* j = new json();
auto* file = std::fopen(tmp, "rb");
state.ResumeTiming();
*j = from_binary(file, format);
state.PauseTiming();
std::fclose(file);
delete j;
state.ResumeTiming();
}
state.SetBytesProcessed(state.iterations() * bytes.size());
}
BENCHMARK_CAPTURE(FromBinaryFile, cbor / canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryFile, cbor / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryFile, ubjson / canada, TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json", binary_format::ubjson);
BENCHMARK_CAPTURE(FromBinaryFile, ubjson / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::ubjson);
BENCHMARK_CAPTURE(FromBinaryFile, bjdata / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::bjdata);
BENCHMARK_CAPTURE(FromBinaryFile, bson / twitter, TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json", binary_format::bson);
//////////////////////////////////////////////////////////////////////////////
// parse binary formats: value shapes
//////////////////////////////////////////////////////////////////////////////
// The test files above are wide and shallow, but the readers' cost is per
// container, so these cover the shapes that stress the container handling
// itself. Every shape is wrapped in an object so that BSON, which requires an
// object at the top level, measures the same value as the other formats.
/// deeply nested arrays: one container per level, no other work
static json make_nested()
{
json nested = json::array();
json* p = &nested;
for (std::size_t i = 1; i < 1000; ++i)
{
p->push_back(json::array());
p = &p->operator[](0);
}
json j = json::object();
j["data"] = std::move(nested);
return j;
}
/// many sibling containers: maximum container churn, minimum nesting
static json make_containers()
{
json data = json::array();
for (std::size_t i = 0; i < 100000; ++i)
{
data.push_back(json::array({1, 2}));
}
json j = json::object();
j["data"] = std::move(data);
return j;
}
/// one flat array of numbers: the scalar decoding path, which must not move
static json make_scalars()
{
json data = json::array();
for (std::size_t i = 0; i < 1000000; ++i)
{
data.push_back(i);
}
json j = json::object();
j["data"] = std::move(data);
return j;
}
static void FromBinaryShape(benchmark::State& state, json (*build)(), const binary_format format)
{
const std::vector<std::uint8_t> bytes = to_binary(build(), format);
for (auto _ : state)
{
state.PauseTiming();
auto* j = new json();
state.ResumeTiming();
*j = from_binary(bytes, format);
state.PauseTiming();
delete j;
state.ResumeTiming();
}
state.SetBytesProcessed(state.iterations() * bytes.size());
}
BENCHMARK_CAPTURE(FromBinaryShape, nested / cbor, make_nested, binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryShape, nested / msgpack, make_nested, binary_format::msgpack);
BENCHMARK_CAPTURE(FromBinaryShape, nested / ubjson, make_nested, binary_format::ubjson);
BENCHMARK_CAPTURE(FromBinaryShape, nested / bjdata, make_nested, binary_format::bjdata);
BENCHMARK_CAPTURE(FromBinaryShape, nested / bson, make_nested, binary_format::bson);
BENCHMARK_CAPTURE(FromBinaryShape, containers / cbor, make_containers, binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryShape, containers / msgpack, make_containers, binary_format::msgpack);
BENCHMARK_CAPTURE(FromBinaryShape, containers / ubjson, make_containers, binary_format::ubjson);
BENCHMARK_CAPTURE(FromBinaryShape, containers / ubjson_optimized, make_containers, binary_format::ubjson_optimized);
BENCHMARK_CAPTURE(FromBinaryShape, containers / bjdata, make_containers, binary_format::bjdata);
BENCHMARK_CAPTURE(FromBinaryShape, containers / bson, make_containers, binary_format::bson);
// BSON names every array element, so a large array measures key generation
// rather than scalar decoding and is left out here
BENCHMARK_CAPTURE(FromBinaryShape, scalars / cbor, make_scalars, binary_format::cbor);
BENCHMARK_CAPTURE(FromBinaryShape, scalars / msgpack, make_scalars, binary_format::msgpack);
BENCHMARK_CAPTURE(FromBinaryShape, scalars / ubjson, make_scalars, binary_format::ubjson);
BENCHMARK_CAPTURE(FromBinaryShape, scalars / bjdata, make_scalars, binary_format::bjdata);
/*!
@brief parse an indefinite-length CBOR string
The writer never emits this form, so the input is assembled by hand: 0x7F
opens the string, each chunk is a one-character string, and 0xFF closes it.
*/
static void FromCborChunkedString(benchmark::State& state, const std::size_t chunks)
{
std::vector<std::uint8_t> bytes;
bytes.reserve(2 * chunks + 2);
bytes.push_back(0x7F);
for (std::size_t i = 0; i < chunks; ++i)
{
bytes.push_back(0x61); // string of length 1
bytes.push_back(0x61); // 'a'
}
bytes.push_back(0xFF);
for (auto _ : state)
{
json j = json::from_cbor(bytes);
benchmark::DoNotOptimize(j);
}
state.SetBytesProcessed(state.iterations() * bytes.size());
}
BENCHMARK_CAPTURE(FromCborChunkedString, 10000 chunks, 10000);
BENCHMARK_MAIN();
+2 -2
View File
@@ -304,8 +304,8 @@ TEST_CASE("Unicode (3/5)" * doctest::skip())
{
for (int byte4 = 0x00; byte4 <= 0xFF; ++byte4)
{
// skip fourth second byte
if (0x80 <= byte3 && byte3 <= 0xBF)
// skip correct fourth byte
if (0x80 <= byte4 && byte4 <= 0xBF)
{
continue;
}
+1 -1
View File
@@ -305,7 +305,7 @@ TEST_CASE("Unicode (4/5)" * doctest::skip())
for (int byte4 = 0x00; byte4 <= 0xFF; ++byte4)
{
// skip correct fourth byte
if (0x80 <= byte3 && byte3 <= 0xBF)
if (0x80 <= byte4 && byte4 <= 0xBF)
{
continue;
}
+1 -1
View File
@@ -305,7 +305,7 @@ TEST_CASE("Unicode (5/5)" * doctest::skip())
for (int byte4 = 0x00; byte4 <= 0xFF; ++byte4)
{
// skip correct fourth byte
if (0x80 <= byte3 && byte3 <= 0xBF)
if (0x80 <= byte4 && byte4 <= 0xBF)
{
continue;
}