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https://github.com/nlohmann/json.git
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Niels Lohmann
c391abccb1
Parsing from a FILE* reads one character at a time with std::fgetc, which locks and unlocks the FILE object for every character. file_input_adapter now locks the file once when it is created and unlocks it when it is destroyed - also when parsing throws - and reads with the unlocked stdio functions in between: flockfile/getc_unlocked/funlockfile with glibc, Apple, Android, and the BSDs, and _lock_file/_fgetc_nolock/_unlock_file with the Microsoft C runtime. Other C libraries keep std::fgetc. The lock is recursive, so fread() in the binary readers and stdio calls of a SAX handler or parser callback on the same thread keep working. On an Apple M1 Max, parsing from a FILE* is 2.9 to 4.0 times as fast (twitter.json 14.3 -> 4.1 ms, citm_catalog.json 35.4 -> 8.8 ms); with glibc, whose locking is cheaper, 1.1 to 1.3 times. The values and the position of the file after parsing are unchanged. Other threads that use the same FILE object now wait until parsing is done instead of interleaving their reads with the parser's. JSON_DISABLE_UNLOCKED_FILE_IO restores std::fgetc, for programs in which a SAX handler waits for another thread that uses the same FILE. The new tests check from a second thread that the lock is released after success and after a parse error, and run again with the macro. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
54 lines
1.6 KiB
C++
54 lines
1.6 KiB
C++
// __ _____ _____ _____
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// __| | __| | | | JSON for Modern C++
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// | | |__ | | | | | | version 3.12.0
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// |_____|_____|_____|_|___| https://github.com/nlohmann/json
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//
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// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
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// SPDX-License-Identifier: MIT
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#pragma once
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// clean up
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#undef JSON_ASSERT
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#undef JSON_INTERNAL_CATCH
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#undef JSON_THROW
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#undef JSON_PRIVATE_UNLESS_TESTED
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#undef NLOHMANN_BASIC_JSON_TPL_DECLARATION
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#undef NLOHMANN_BASIC_JSON_TPL
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#undef JSON_EXPLICIT
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#undef NLOHMANN_CAN_CALL_STD_FUNC_IMPL
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#undef JSON_INLINE_VARIABLE
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#undef JSON_NO_UNIQUE_ADDRESS
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#undef JSON_DISABLE_ENUM_SERIALIZATION
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#undef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
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#undef JSON_DISABLE_STREAM_BULK_SCAN
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#undef JSON_DISABLE_UNLOCKED_FILE_IO
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#undef JSON_UNLOCKED_FILE_IO
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#ifndef JSON_TEST_KEEP_MACROS
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#undef JSON_CATCH
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#undef JSON_TRY
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#undef JSON_HAS_CPP_11
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#undef JSON_HAS_CPP_14
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#undef JSON_HAS_CPP_17
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#undef JSON_HAS_CPP_20
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#undef JSON_HAS_CPP_23
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#undef JSON_HAS_CPP_26
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#undef JSON_HAS_FILESYSTEM
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#undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
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#undef JSON_HAS_THREE_WAY_COMPARISON
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#undef JSON_HAS_RANGES
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#undef JSON_HAS_RANGE_VIEW_CONVERSION
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#undef JSON_HAS_STD_FORMAT
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#undef JSON_HAS_STATIC_RTTI
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#undef JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON
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#undef JSON_BRACE_INIT_COPY_SEMANTICS
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#undef JSON_PRECISE_STREAM_POSITION
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#undef JSON_STRICT_NUL_HANDLING
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#undef JSON_STRICT_BINARY_UTF8
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#undef JSON_DELETE_DEPRECATED_FUNCTIONS
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#undef JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS
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#endif
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#include <nlohmann/thirdparty/hedley/hedley_undef.hpp>
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