v61.03 鸿蒙内核源码分析(忍者ninja) | 忍者的特点就是一个字原创精华

鸿蒙内核源码分析

发布于 2021-11-15 11:14

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ninja | 忍者

ninja是一个叫 Evan Martin的谷歌工程师开源的一个自定义的构建系统,最早是用于 chrome的构建,Martin给它取名 ninja(忍者)的原因是因为它strikes quickly(快速出击).这是忍者的特点,可惜Martin不了解中国文化,不然叫小李飞刀更合适些.究竟有多块呢? 用Martin自己的话说是当一个文件被修改后,ninja从发现到编译速度是make的十倍.有没有十倍不是本篇讨论的重点,人家做出来了,就算是牛皮也该人家吹.本篇是要对鸿蒙如何使用ninja做一个比较详细的阐述.

ninja是一个重视速度的构建系统,与其对标的是Make,它们都依赖于文件的时间戳进行检测重编.

它的设计目的是让更高级别的构建系统生成其输入端文件,其并不希望你手动去编.ninja文件,可以生成.ninja的工具有gn,cmake,premake,甚至你自己都可以写个 ninja 生成工具.
ninja非常高效,可理解为构建系统中的汇编语言。
ninja文件没有分支、循环的流程控制，是被指定了一堆规则的文件，所以要比Makefile简单很多
目前已知的GoogleChrome，Android的一部分，LLVM, V8, 方舟编译器, 鸿蒙等大型系统都使用到了ninja构建.

基本概念

概念	中译	解释
edge	边      即build语句，指定目标（输出）、规则与输入，是编译过程拓扑图中的一条边（edge）。
target	目标	编译过程需要产生的目标，由build语句指定。
output	输出	build语句的前半段，是target的另一种称呼。
input	输入	build语句的后半段，用来产生output的文件或目标，另一种称呼是依赖。
rule	规则	通过指定command与一些内置变量，决定如何从输入产生输出。
pool	池      一组rule或edge，通过指定其depth，可以控制并行上限。
scope	作用域	变量的作用范围，有rule与build语句的块级，也有文件级别。rule也有scope。
--------------------------------------------------------------------------------------------
关键字	  作用
build	  定义一个edge。
rule	  定义一个rule。
pool	  定义一个pool。
default	  指定默认的一个或多个target。
include	  添加一个ninja文件到当前scope。
subninja  添加一个ninja文件，其scope与当前文件不同。
phony     一个内置的特殊规则，指定非文件的target。

简单的ninja

首先 ninja 一定是简单的,呆板的.凡是能被工具生成的东西,一定是在不断的重复某种简单,众多的简单按一定的规则有效叠加起来就能解决复杂的问题,请仔细想想是不是这个道理.ninja简单到没什么语法,只是几个概念和规则. 以至于 ninja参考手册比 gn参考手册简单的太多.

看个示例:

cflags = -Wall -Werror  #全局变量
rule cc
  command = gcc $cflags -c $in -o $out

build foo.o: cc foo.c

build special.o: cc special.c
  cflags = -Wall #局部变量,范围只在编译special.c上有效

解读

cflags:定义一个用户变量,用于给规则传参.
rule:定义一个叫cc的规则.
- command:将生成bash命令,接收外部三个参数
第一个build,将foo.c用cc规则编译成foo.o
- 最终编译选项:gcc -Wall -Werror -c foo.c -o foo.o
第二个build,将special.c用cc规则编译成special.o
- 最终编译选项:gcc -Wall -c foo.c -o foo.o
in,out是ninja的两个内置变量.

phony规则

跟称呼弗拉基米尔·弗拉基米罗维奇·普京为普总一样,
有些文件路径会很长,ninja提供取别名的功能,这仅仅是为了方便.

build ability: phony ./libability.so
build ability_notes: phony obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/ability_notes.stamp
build ability_test: phony obj/foundation/aafwk/aafwk_lite/services/abilitymgr_lite/unittest/ability_test.stamp
build ability_test_pageAbilityTest_group_lv0: phony obj/foundation/aafwk/aafwk_lite/services/abilitymgr_lite/unittest/test_lv0/page_ability_test/ability_test_pageAbilityTest_group_lv0.stamp

有了上面的铺垫,读懂鸿蒙的ninja部分应该没多大障碍了.

鸿蒙 | ninja

在[v60.xx 鸿蒙内核源码分析(gn应用篇) | gn语法及在鸿蒙的使用 ]篇的末尾已说明通过 gn gen生成了以下文件和目录

turing@ubuntu:/home/openharmony/code-v1.1.1-LTS/out/hispark_aries/ipcamera_hispark_aries$ ls
args.gn  build.ninja  build.ninja.d  NOTICE_FILE  obj  test_info  toolchain.ninja

args.gn :一些参数
build.ninja : ninja的主文件
build.ninja.d :记录生成所有.ninja 所依赖的BUILD.gn文件路劲列表,一个BUILD.gn就生成一个.ninja文件
obj :各组件模块构建/编译文件输出地.
toolchain :放置ninja规则,将被 subninja 进 build.ninja

build.ninja

build.ninja内容如下:

ninja_required_version = 1.7.2

rule gn
  command = ../../../../tools/gn --root=../../.. -q --dotfile=../../../build/lite/.gn --script-executable=python3 gen .
  description = Regenerating ninja files

build build.ninja: gn
  generator = 1
  depfile = build.ninja.d

subninja toolchain.ninja


build ability: phony ./libability.so
build ability_notes: phony obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/ability_notes.stamp
build ability_test: phony obj/foundation/aafwk/aafwk_lite/services/abilitymgr_lite/unittest/ability_test.stamp
build ability_test_pageAbilityTest_group_lv0: phony obj/foundation/aafwk/aafwk_lite/services/abilitymgr_lite/unittest/test_lv0/page_ability_test/ability_test_pageAbilityTest_group_lv0.stamp
#此处省略诸多 phony ..

build all: phony $
    ./libcameraApp.so $
    obj/applications/sample/camera/cameraApp/cameraApp_hap.stamp $
    ./libgallery.so $
    ...

default all

解读

前面部分是定义一个 gn规则,用于干嘛呢? 重新生成一遍 *ninja文件
subninja相当于 #include文件
default all,指定默认的一个或多个target

toolchain | 定义规则

toolchain.ninja 定义了编译c,c++,汇编器,链接,静态/动态链接库,时间戳,拷贝等规则. 内容如下:

rule cxx
  command = /root/llvm/bin/clang++ ${defines} ${include_dirs} ${cflags_cc} -c ${in} -o ${out}
  description = clang++ ${out}
  depfile = ${out}.d
  deps = gcc
rule alink
  command = /root/llvm/bin/llvm-ar -cr ${out} @"${out}.rsp"
  description = AR ${out}
  rspfile = ${out}.rsp
  rspfile_content = ${in}
rule link
  command = /root/llvm/bin/clang ${ldflags} ${in} ${libs}   -o ${output_dir}/bin/${target_output_name}${output_extension}
  description = LLVM LINK ${output_dir}/bin/${target_output_name}${output_extension}
  rspfile = ${output_dir}/bin/${target_output_name}${output_extension}.rsp
  rspfile_content = ${in}
rule solink
  command = /root/llvm/bin/clang -shared ${ldflags} ${in} ${libs} -o ${output_dir}/${target_output_name}${output_extension}
  description = SOLINK ${output_dir}/${target_output_name}${output_extension}
  rspfile = ${output_dir}/${target_output_name}${output_extension}.rsp
  rspfile_content = ${in}
rule stamp
  command = /usr/bin/touch ${out}
  description = STAMP ${out}
rule asm
  command = /root/llvm/bin/clang ${include_dirs} ${asmflags} -c ${in} -o ${out}
  description = ASM ${out}
  depfile = ${out}.d
  deps = gcc
rule cc
  command = /root/llvm/bin/clang ${defines} ${include_dirs} ${cflags} ${cflags_c} -c ${in} -o ${out}
  description = clang ${out}
rule copy
  command = cp -afd ${in} ${out}
  description = COPY ${in} ${out}

注意这些规则中的描述description字段,其后面的内容会打到控制台上,每一条输出都是一次 build,如图所示,通过这些描述就知道使用了什么规则去构建.

组件编译

本篇以编译ability组件为例说明 ninja对组件的编译情况.每个组件都有自己的.ninja,描述组件的编译细节.而整个鸿蒙系统就是由众多的类似.ninja构建编译完成的.

├── foundation
│   ├── aafwk
│   │   └── aafwk_lite
│   │       ├── frameworks
│   │       │   ├── ability_lite
│   │       │   │   └── ability.ninja

ability.ninja内容如下:

defines = -DOHOS_APPEXECFWK_BMS_BUNDLEMANAGER \
          -D_XOPEN_SOURCE=700 -DOHOS_DEBUG \
          -D_FORTIFY_SOURCE=2 \
          -D__LITEOS__ -D__LITEOS_A__
include_dirs = -I../../../foundation/aafwk/aafwk_lite/frameworks/abilitymgr_lite/include \
               -I../../../foundation/aafwk/aafwk_lite/frameworks/want_lite/include \
               -I../../../foundation/aafwk/aafwk_lite/interfaces/innerkits/abilitymgr_lite \
               -I../../../foundation/aafwk/aafwk_lite/interfaces/kits/want_lite \
               -I../../../foundation/aafwk/aafwk_lite/interfaces/kits/ability_lite \
               -I../../../foundation/appexecfwk/appexecfwk_lite/utils/bundle_lite \
               -I../../../foundation/appexecfwk/appexecfwk_lite/interfaces/kits/bundle_lite \
               -I../../../foundation/appexecfwk/appexecfwk_lite/frameworks/bundle_lite/include \
               -I../../../foundation/graphic/ui/frameworks -I../../../foundation/graphic/surface/interfaces/kits \
               -I../../../foundation/distributedschedule/samgr_lite/interfaces/kits/registry \
               -I../../../foundation/distributedschedule/samgr_lite/interfaces/kits/samgr \
               -I../../../foundation/communication/ipc_lite/frameworks/liteipc/include \
               -I../../../kernel/liteos_a/kernel/include \
               -I../../../kernel/liteos_a/kernel/common \
               -I../../../third_party/bounds_checking_function/include \
               -I../../../third_party/freetype/include \
               -I../../../utils/native/lite/kv_store/innerkits \
               -I../../../utils/native/lite/include \
               -I../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/include \
               -I../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite \
               -I/root/llvm/include/c++/v1 \
               -I../../../prebuilts/lite/sysroot/usr/include/arm-liteos \
               -I../../../base/hiviewdfx/hilog_lite/interfaces/native/innerkits/hilog \
               -I../../../base/hiviewdfx/hilog_lite/interfaces/native/innerkits \
               -I../../../third_party/bounds_checking_function/include \
               -I../../../third_party/bounds_checking_function/include \
               -I../../../foundation/communication/ipc_lite/interfaces/kits \
               -I../../../utils/native/lite/include
cflags = -Wall -Wno-format -Wno-format-extra-args -fPIC \
          --target=arm-liteos \
          --sysroot=/home/openharmony/prebuilts/lite/sysroot \
          -Oz -flto -mfloat-abi=softfp -mcpu=cortex-a7 -nostdlib -fno-common -fno-builtin -fno-strict-aliasing -Wall -fsigned-char -mno-unaligned-access -fno-omit-frame-pointer -fstack-protector-all -fPIC
cflags_cc = -Wall -Wno-format -Wno-format-extra-args -fPIC \
            --target=arm-liteos \
            --sysroot=/home/openharmony/prebuilts/lite/sysroot \
            -Oz -flto -mfloat-abi=softfp -mcpu=cortex-a7 -nostdlib -fno-common -fno-builtin -fno-strict-aliasing -Wall -mno-unaligned-access -fno-omit-frame-pointer -fstack-protector-all -fexceptions -std=c++11 -fPIC
target_output_name = libability

build obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability.o: cxx ../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/ability.cpp
build obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_context.o: cxx ../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/ability_context.cpp
build obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_env.o: cxx ../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/ability_env.cpp
build obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_env_impl.o: cxx ../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/ability_env_impl.cpp
build obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_event_handler.o: cxx ../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/ability_event_handler.cpp
build obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_loader.o: cxx ../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/ability_loader.cpp
build obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_main.o: cxx ../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/ability_main.cpp
build obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_scheduler.o: cxx ../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/ability_scheduler.cpp
build obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_thread.o: cxx ../../../foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/ability_thread.cpp

build ./libability.so: solink \
  obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability.o \
  obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_context.o \
  obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_env.o \
  obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_env_impl.o \
  obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_event_handler.o \
  obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_loader.o \
  obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_main.o \
  obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_scheduler.o \
  obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite/src/libability.ability_thread.o \
  ./libabilitymanager.so ./libbundle.so ./libhilog_shared.so ./libliteipc_adapter.so \
  ./libsec_shared.so ./libutils_kv_store.so || obj/utils/native/lite/kv_store/kv_store.stamp
  ldflags = -lstdc++ \
  --target=arm-liteos \
  --sysroot=/home/openharmony/prebuilts/lite/sysroot \
  -L/root/llvm/lib/arm-liteos/c++ \
  -L/home/openharmony/prebuilts/lite/sysroot/usr/lib/arm-liteos \
  -L/root/llvm/lib/clang/9.0.0/lib/arm-liteos \
  -lclang_rt.builtins -lc -lc++ -lc++abi \
  --sysroot=/home/openharmony/prebuilts/lite/sysroot \
  -mcpu=cortex-a7 -lc \
  -L/home/openharmony/out/hispark_aries/ipcamera_hispark_aries \
  -Wl,-rpath-link=/home/openharmony/out/hispark_aries/ipcamera_hispark_aries -Wl,-z,now -Wl,-z,relro -Wl,-z,noexecstack
  libs =
  frameworks =
  output_extension = .so
  output_dir = .

解读

defines,include_dirs,cflags_cc都是用户自定义变量,为了给 rule cxx准备参数,对.cpp的编译使用了这个规则

rule cxx
  command = /root/llvm/bin/clang++ ${defines} ${include_dirs} ${cflags_cc} -c ${in} -o ${out}
  description = clang++ ${out}
  depfile = ${out}.d
  deps = gcc

in,out是两个内置变量,无须定义,值由build提供,如此就编译成了一个个的 .o文件.

在最后在当前目录下使用了solink规则,生成一个动态链接库libability.so.

rule solink
  command = /root/llvm/bin/clang -shared ${ldflags} ${in} ${libs} -o ${output_dir}/${target_output_name}${output_extension}
  description = SOLINK ${output_dir}/${target_output_name}${output_extension}
  rspfile = ${output_dir}/${target_output_name}${output_extension}.rsp
  rspfile_content = ${in}

ability | 最终生成文件

turing@ubuntu:/home/openharmony/code-v1.1.1-LTS/out/hispark_aries/ipcamera_hispark_aries/obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite$ tree
.
├── aafwk_abilitykit_lite.stamp
├── ability.ninja
├── ability_notes.stamp
└── src
    ├── libability.ability_context.o
    ├── libability.ability_env_impl.o
    ├── libability.ability_env.o
    ├── libability.ability_event_handler.o
    ├── libability.ability_loader.o
    ├── libability.ability_main.o
    ├── libability.ability.o
    ├── libability.ability_scheduler.o
    └── libability.ability_thread.o

1 directory, 12 files
turing@ubuntu:/home/openharmony/code-v1.1.1-LTS/out/hispark_aries/ipcamera_hispark_aries/obj/foundation/aafwk/aafwk_lite/frameworks/ability_lite$ stat ability_notes.stamp 
  File: ability_notes.stamp
  Size: 0         	Blocks: 0          IO Block: 4096   regular empty file
Device: 805h/2053d	Inode: 1217028     Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/  turing)   Gid: (    0/    root)
Access: 2021-07-21 00:38:52.237373740 -0700
Modify: 2021-07-21 00:34:30.207312566 -0700
Change: 2021-07-21 00:34:30.207312566 -0700

百篇博客分析.深挖内核地基

给鸿蒙内核源码加注释过程中，整理出以下文章。内容立足源码，常以生活场景打比方尽可能多的将内核知识点置入某种场景，具有画面感，容易理解记忆。说别人能听得懂的话很重要! 百篇博客绝不是百度教条式的在说一堆诘屈聱牙的概念，那没什么意思。更希望让内核变得栩栩如生，倍感亲切.确实有难度，自不量力，但已经出发，回头已是不可能的了。　😛
与代码有bug需不断debug一样，文章和注解内容会存在不少错漏之处，请多包涵，但会反复修正，持续更新，v**.xx 代表文章序号和修改的次数，精雕细琢，言简意赅，力求打造精品内容。

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