liuq19 commented 1 year ago

背景

在部分业务场景下，只需要 json 中的特定字段。而 parseondemand api 虽然能按需解析，但是不够灵活。因此，设计一种新的基于 simdskip 的 lazynode。 lazynode 的 api 力求完全与现有的 dynamic node 兼容。

设计

是否需要拷贝 JSON 串？目前，lazynode 的 dom 树默认不拷贝 json 串。dynamicnode 的 dom 树会拷贝整个 json 串做 string buffer。
lazynode 数据结构？ lazynode 带有一个 alloc_ 成员，用以无感知地进行内存分配等操作。因此，lazynode 比 dynamicnode 多 8 bytes 内存占用。
lazynode 的 API 和 dynamicnode 的区别？ API 名字保持一致，但内在实现不同。 lazynode 的 dom 树，parse 时只解析第一层。 lazynode 的 Get 和 Check API，都会进行 node 的展开。

性能测试

codecov-commenter commented 1 year ago

Codecov Report

Merging #55 (949746b) into master (80cdba0) will decrease coverage by 0.11%. The diff coverage is 91.13%.

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@@            Coverage Diff             @@
##           master      #55      +/-   ##
==========================================
- Coverage   95.04%   94.94%   -0.11%     
==========================================
  Files          22       23       +1     
  Lines        2785     3362     +577     
==========================================
+ Hits         2647     3192     +545     
- Misses        138      170      +32

Impacted Files	Coverage Δ
include/sonic/dom/dynamicnode.h	`93.40% <15.38%> (-2.69%)`	:arrow_down:
include/sonic/dom/handler.h	`92.17% <42.85%> (-6.88%)`	:arrow_down:
include/sonic/dom/parser.h	`96.15% <88.34%> (+1.91%)`	:arrow_up:
include/sonic/internal/skip.h	`89.84% <93.33%> (+5.73%)`	:arrow_up:
include/sonic/dom/genericnode.h	`98.26% <93.65%> (-1.37%)`	:arrow_down:
include/sonic/dom/lazynode.h	`94.44% <94.44%> (ø)`
include/sonic/dom/generic_document.h	`95.91% <100.00%> (+0.31%)`	:arrow_up:
include/sonic/dom/serialize.h	`92.72% <100.00%> (-0.67%)`	:arrow_down:
include/sonic/experiment/lazy_update.h	`88.46% <100.00%> (ø)`
include/sonic/allocator.h	`87.96% <0.00%> (-2.48%)`	:arrow_down:
... and 4 more

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liuq19 commented 1 year ago

验证性能收益不及预期，此 pr 暂时关闭。待需要时才开发 lazynode feature。

bytedance / sonic-cpp

feat: support lazynode #55

背景

设计

性能测试

Codecov Report