Skip to content
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension


Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion .github/workflows/ci.yml
Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,7 @@ jobs:

- name: Run busted tests (under LuaJIT)
run: |
# ffi.load("quickdecode") uses dlopen which respects LD_LIBRARY_PATH,
# ffi.load("qjson") uses dlopen which respects LD_LIBRARY_PATH,
# not LuaJIT's package.cpath. Point dlopen at the release build dir.
LD_LIBRARY_PATH="$PWD/target/release" \
busted --lua=$(which luajit) tests/lua \
Expand Down
28 changes: 14 additions & 14 deletions CLAUDE.md
Original file line number Diff line number Diff line change
Expand Up @@ -4,16 +4,16 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co

## Project

Rust JSON decoder (`cdylib` + `rlib`) exposed to LuaJIT via FFI. Optimized for parse-once / extract-a-few-fields / discard. The competitive edge over `lua-cjson` comes from **never building a Lua table** — Phase 1 records only structural offsets, Phase 2 lazily decodes the fields the caller actually asks for. Crate name in `Cargo.toml` is `lua-quick-decode`; the compiled artifact is `libquickdecode.so`.
Rust JSON decoder (`cdylib` + `rlib`) exposed to LuaJIT via FFI. Optimized for parse-once / extract-a-few-fields / discard. The competitive edge over `lua-cjson` comes from **never building a Lua table** — Phase 1 records only structural offsets, Phase 2 lazily decodes the fields the caller actually asks for. Crate name in `Cargo.toml` is `qjson`; the compiled artifact is `libqjson.so`.

## Common commands

The `Makefile` is the canonical entry point; `make help` lists targets.

```sh
make build # cargo build --release → target/release/libquickdecode.so
make build # cargo build --release → target/release/libqjson.so
make test # cargo test --release + busted Lua tests
make lint # cargo clippy -D warnings + cargo fmt --check
make lint # cargo clippy --release --all-targets -- -D warnings
make bench # OpenResty LuaJIT benchmark vs lua-cjson and simdjson
Comment thread
coderabbitai[bot] marked this conversation as resolved.
```

Expand All @@ -37,7 +37,7 @@ cargo test --release --no-default-features
cargo test --features test-panic --release
```

`ffi.load("quickdecode")` uses `dlopen`, which respects `LD_LIBRARY_PATH` — **not** LuaJIT's `package.cpath`. The Makefile sets `LD_LIBRARY_PATH=target/release` for `test`/`bench`; if you invoke `busted` or `luajit` directly, set it yourself.
`ffi.load("qjson")` uses `dlopen`, which respects `LD_LIBRARY_PATH` — **not** LuaJIT's `package.cpath`. The Makefile sets `LD_LIBRARY_PATH=target/release` for `test`/`bench`; if you invoke `busted` or `luajit` directly, set it yourself.

`make lint` runs clippy only (with `-D warnings`); `cargo fmt --check` is intentionally **not** part of the lint gate because the codebase uses manual column alignment in struct definitions and compact single-line literals that default rustfmt would reflow. See the README "Roadmap / Deferred" entry on fmt for context.

Expand All @@ -50,39 +50,39 @@ cargo test --features test-panic --release
- `Avx2Scanner` (gated by the `avx2` cargo feature, default-on) when both `avx2` and `pclmulqdq` are detected at runtime.
- `ScalarScanner` otherwise.

Validation level depends on `qjd_options.mode`. **EAGER** (default): a post-scan pass walks `indices` and validates RFC 8259 number ABNF, string content (no unescaped control chars), and UTF-8 — parse fails on any value-level violation. **LAZY** (opt-in): bracket/quote balance + max-depth only; value-level errors surface when the offending field is accessed (lua-cjson-equivalent behavior). Trailing-content rejection and value-level validation are eager-only; max-depth (default 1024, configurable up to 4096) is enforced in both modes.
Validation level depends on `qjson_options.mode`. **EAGER** (default): a post-scan pass walks `indices` and validates RFC 8259 number ABNF, string content (no unescaped control chars), and UTF-8 — parse fails on any value-level violation. **LAZY** (opt-in): bracket/quote balance + max-depth only; value-level errors surface when the offending field is accessed (lua-cjson-equivalent behavior). Trailing-content rejection and value-level validation are eager-only; max-depth (default 1024, configurable up to 4096) is enforced in both modes.

**Phase 2** (`src/cursor.rs`, `src/path.rs`, `src/decode/`): path strings are parsed by a zero-alloc `PathIter` into `PathSeg::Key | Idx`. A `Cursor` (a `(idx_start, idx_end)` pair into `doc.indices`) is walked to the target, optionally caching sibling spans in `doc.skip` (`SkipCache`) so repeated lookups on the same container skip brace-counting. Strings are decoded into `doc.scratch` only when they contain escapes; otherwise the original buffer slice is handed back.

### Critical invariants (these will bite you if violated)

- **`get_str` pointer lifetime.** The `(ptr, len)` returned by `qjd_get_str` / `qjd_cursor_get_str` points into either the original input buffer or `doc.scratch`. **Any subsequent `*_get_str` call on the same doc may invalidate prior pointers** (scratch buffer reuse). The LuaJIT wrapper preserves this contract by calling `ffi.string(ptr, len)` immediately to copy into a Lua string — do not change that.
- **Buffer lifetime.** `Document<'a>` borrows the input slice. `qjd_parse` transmutes `'a` to `'static` and trusts the caller to keep the buffer alive for the document's lifetime. The LuaJIT wrapper enforces this by stashing the original string under `_hold` on the Doc table so Lua GC keeps it pinned.
- **`get_str` pointer lifetime.** The `(ptr, len)` returned by `qjson_get_str` / `qjson_cursor_get_str` points into either the original input buffer or `doc.scratch`. **Any subsequent `*_get_str` call on the same doc may invalidate prior pointers** (scratch buffer reuse). The LuaJIT wrapper preserves this contract by calling `ffi.string(ptr, len)` immediately to copy into a Lua string — do not change that.
- **Buffer lifetime.** `Document<'a>` borrows the input slice. `qjson_parse` transmutes `'a` to `'static` and trusts the caller to keep the buffer alive for the document's lifetime. The LuaJIT wrapper enforces this by stashing the original string under `_hold` on the Doc table so Lua GC keeps it pinned.
- **`indices` stores offsets only, not types.** Token type is recovered from `buf[indices[i]]`. Do not add a type tag — the 25% memory win is intentional.
- **Single-threaded.** `qjd_doc` is not Sync/Send across threads; `RefCell` is used for `scratch` and `skip`.
- **FFI panic barrier.** Every `pub unsafe extern "C"` function in `src/ffi.rs` wraps its body in `catch_unwind` and converts a panic into `QJD_OOM`. Preserve this pattern on any new export — a panic crossing the FFI boundary is undefined behavior.
- **Single-threaded.** `qjson_doc` is not Sync/Send across threads; `RefCell` is used for `scratch` and `skip`.
- **FFI panic barrier.** Every `pub unsafe extern "C"` function in `src/ffi.rs` wraps its body in `catch_unwind` and converts a panic into `QJSON_OOM`. Preserve this pattern on any new export — a panic crossing the FFI boundary is undefined behavior.

### Layout

```
src/
lib.rs crate root
ffi.rs extern "C" surface, qjd_* symbols, panic barrier
ffi.rs extern "C" surface, qjson_* symbols, panic barrier
doc.rs Document (indices + scratch + skip cache)
cursor.rs Cursor + path resolution + skip-cache walk
path.rs zero-alloc path-string iterator
decode/ lazy string / number decode
scan/ ScalarScanner, Avx2Scanner, runtime dispatch
skip_cache.rs Phase 2 sibling-skip cache
error.rs qjd_err + qjd_type enums (must stay in sync with include/lua_quick_decode.h and lua/quickdecode.lua)
error.rs qjson_err + qjson_type enums (must stay in sync with include/qjson.h and lua/qjson.lua)

lua/quickdecode.lua LuaJIT wrapper (ffi.cdef + Doc/Cursor metatables)
include/lua_quick_decode.h public C header
lua/qjson.lua LuaJIT wrapper (ffi.cdef + Doc/Cursor metatables)
include/qjson.h public C header
tests/ Rust integration tests + tests/lua/ busted suite
benches/ lua_bench.lua vs lua-cjson/simdjson; fixtures/ has small_api.json + medium_resp.json
```

The enum values in `src/error.rs` are duplicated in `include/lua_quick_decode.h` and `lua/quickdecode.lua` (the latter only encodes the `T_*` type tags and `NOT_FOUND = 2`). Keep all three in sync when adding/renumbering codes.
The enum values in `src/error.rs` are duplicated in `include/qjson.h` and `lua/qjson.lua` (the latter only encodes the `T_*` type tags and `NOT_FOUND = 2`). Keep all three in sync when adding/renumbering codes.

### CI gates worth knowing

Expand Down
9 changes: 6 additions & 3 deletions Cargo.toml
Original file line number Diff line number Diff line change
@@ -1,11 +1,14 @@
[package]
name = "lua-quick-decode"
name = "qjson"
version = "0.1.0"
edition = "2021"
publish = false
description = "Fast JSON decoder for LuaJIT FFI consumers"
license = "Apache-2.0"
repository = "https://github.com/api7/lua-qjson"
homepage = "https://github.com/api7/lua-qjson"

[lib]
name = "quickdecode"
name = "qjson"
crate-type = ["cdylib", "rlib"]

[features]
Expand Down
176 changes: 176 additions & 0 deletions LICENSE
Original file line number Diff line number Diff line change
@@ -0,0 +1,176 @@
Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/

TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

1. Definitions.

"License" shall mean the terms and conditions for use, reproduction,
and distribution as defined by Sections 1 through 9 of this document.

"Licensor" shall mean the copyright owner or entity authorized by
the copyright owner that is granting the License.

"Legal Entity" shall mean the union of the acting entity and all
other entities that control, are controlled by, or are under common
control with that entity. For the purposes of this definition,
"control" means (i) the power, direct or indirect, to cause the
direction or management of such entity, whether by contract or
otherwise, or (ii) ownership of fifty percent (50%) or more of the
outstanding shares, or (iii) beneficial ownership of such entity.

"You" (or "Your") shall mean an individual or Legal Entity
exercising permissions granted by this License.

"Source" form shall mean the preferred form for making modifications,
including but not limited to software source code, documentation
source, and configuration files.

"Object" form shall mean any form resulting from mechanical
transformation or translation of a Source form, including but
not limited to compiled object code, generated documentation,
and conversions to other media types.

"Work" shall mean the work of authorship, whether in Source or
Object form, made available under the License, as indicated by a
copyright notice that is included in or attached to the work
(an example is provided in the Appendix below).

"Derivative Works" shall mean any work, whether in Source or Object
form, that is based on (or derived from) the Work and for which the
editorial revisions, annotations, elaborations, or other modifications
represent, as a whole, an original work of authorship. For the purposes
of this License, Derivative Works shall not include works that remain
separable from, or merely link (or bind by name) to the interfaces of,
the Work and Derivative Works thereof.

"Contribution" shall mean any work of authorship, including
the original version of the Work and any modifications or additions
to that Work or Derivative Works thereof, that is intentionally
submitted to Licensor for inclusion in the Work by the copyright owner
or by an individual or Legal Entity authorized to submit on behalf of
the copyright owner. For the purposes of this definition, "submitted"
means any form of electronic, verbal, or written communication sent
to the Licensor or its representatives, including but not limited to
communication on electronic mailing lists, source code control systems,
and issue tracking systems that are managed by, or on behalf of, the
Licensor for the purpose of discussing and improving the Work, but
excluding communication that is conspicuously marked or otherwise
designated in writing by the copyright owner as "Not a Contribution."

"Contributor" shall mean Licensor and any individual or Legal Entity
on behalf of whom a Contribution has been received by Licensor and
subsequently incorporated within the Work.

2. Grant of Copyright License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
copyright license to reproduce, prepare Derivative Works of,
publicly display, publicly perform, sublicense, and distribute the
Work and such Derivative Works in Source or Object form.

3. Grant of Patent License. Subject to the terms and conditions of
this License, each Contributor hereby grants to You a perpetual,
worldwide, non-exclusive, no-charge, royalty-free, irrevocable
(except as stated in this section) patent license to make, have made,
use, offer to sell, sell, import, and otherwise transfer the Work,
where such license applies only to those patent claims licensable
by such Contributor that are necessarily infringed by their
Contribution(s) alone or by combination of their Contribution(s)
with the Work to which such Contribution(s) was submitted. If You
institute patent litigation against any entity (including a
cross-claim or counterclaim in a lawsuit) alleging that the Work
or a Contribution incorporated within the Work constitutes direct
or contributory patent infringement, then any patent licenses
granted to You under this License for that Work shall terminate
as of the date such litigation is filed.

4. Redistribution. You may reproduce and distribute copies of the
Work or Derivative Works thereof in any medium, with or without
modifications, and in Source or Object form, provided that You
meet the following conditions:

(a) You must give any other recipients of the Work or
Derivative Works a copy of this License; and

(b) You must cause any modified files to carry prominent notices
stating that You changed the files; and

(c) You must retain, in the Source form of any Derivative Works
that You distribute, all copyright, patent, trademark, and
attribution notices from the Source form of the Work,
excluding those notices that do not pertain to any part of
the Derivative Works; and

(d) If the Work includes a "NOTICE" text file as part of its
distribution, then any Derivative Works that You distribute must
include a readable copy of the attribution notices contained
within such NOTICE file, excluding those notices that do not
pertain to any part of the Derivative Works, in at least one
of the following places: within a NOTICE text file distributed
as part of the Derivative Works; within the Source form or
documentation, if provided along with the Derivative Works; or,
within a display generated by the Derivative Works, if and
wherever such third-party notices normally appear. The contents
of the NOTICE file are for informational purposes only and
do not modify the License. You may add Your own attribution
notices within Derivative Works that You distribute, alongside
or as an addendum to the NOTICE text from the Work, provided
that such additional attribution notices cannot be construed
as modifying the License.

You may add Your own copyright statement to Your modifications and
may provide additional or different license terms and conditions
for use, reproduction, or distribution of Your modifications, or
for any such Derivative Works as a whole, provided Your use,
reproduction, and distribution of the Work otherwise complies with
the conditions stated in this License.

5. Submission of Contributions. Unless You explicitly state otherwise,
any Contribution intentionally submitted for inclusion in the Work
by You to the Licensor shall be under the terms and conditions of
this License, without any additional terms or conditions.
Notwithstanding the above, nothing herein shall supersede or modify
the terms of any separate license agreement you may have executed
with Licensor regarding such Contributions.

6. Trademarks. This License does not grant permission to use the trade
names, trademarks, service marks, or product names of the Licensor,
except as required for reasonable and customary use in describing the
origin of the Work and reproducing the content of the NOTICE file.

7. Disclaimer of Warranty. Unless required by applicable law or
agreed to in writing, Licensor provides the Work (and each
Contributor provides its Contributions) on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied, including, without limitation, any warranties or conditions
of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
PARTICULAR PURPOSE. You are solely responsible for determining the
appropriateness of using or redistributing the Work and assume any
risks associated with Your exercise of permissions under this License.

8. Limitation of Liability. In no event and under no legal theory,
whether in tort (including negligence), contract, or otherwise,
unless required by applicable law (such as deliberate and grossly
negligent acts) or agreed to in writing, shall any Contributor be
liable to You for damages, including any direct, indirect, special,
incidental, or consequential damages of any character arising as a
result of this License or out of the use or inability to use the
Work (including but not limited to damages for loss of goodwill,
work stoppage, computer failure or malfunction, or any and all
other commercial damages or losses), even if such Contributor
has been advised of the possibility of such damages.

9. Accepting Warranty or Additional Liability. While redistributing
the Work or Derivative Works thereof, You may choose to offer,
and charge a fee for, acceptance of support, warranty, indemnity,
or other liability obligations and/or rights consistent with this
License. However, in accepting such obligations, You may act only
on Your own behalf and on Your sole responsibility, not on behalf
of any other Contributor, and only if You agree to indemnify,
defend, and hold each Contributor harmless for any liability
incurred by, or claims asserted against, such Contributor by reason
of your accepting any such warranty or additional liability.

END OF TERMS AND CONDITIONS
2 changes: 1 addition & 1 deletion Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ help: ## Show this help
@# Consequence: targets whose prerequisite list contains `#` won't render — none today.
@awk 'BEGIN {FS = ":[^#]*## "} /^[a-zA-Z_-]+:[^#]*## / {printf " \033[36m%-10s\033[0m — %s\n", $$1, $$2}' $(MAKEFILE_LIST)

build: ## Build the release cdylib (target/release/libquickdecode.so)
build: ## Build the release cdylib (target/release/libqjson.so)
cargo build --release

test: build ## Run cargo tests + busted Lua tests
Expand Down
Loading
Loading