Ubuntu 14.04 64bit上玩转graphviz绘图工具
简介
关于Graphviz: Graphviz(英文：Graph Visualization Software的缩写)是一个由AT&T实验室启动的开源工具包，用于绘制DOT语言脚本描述的图形。它也提供了供其它软件使用的库。Graphviz是一个自由软件，其授权为Eclipse Public License。其Mac版本曾经获得2004年的苹果设计奖。
Graphviz是大名鼎鼎的贝尔实验室的几位牛人开发的一个画图工具。它的理念和一般的“所见即所得”的画图工具不一样，是“所想即所得”。Graphviz提供了dot语言来编写绘图脚本。dot的语言专门用来定义关系。我们必须先在某个文件中写上代码，最后调用命令行生成。没有找到可边写边改的集成环境。
关于dot的具体语法参看官方文档，这里就不多说。这里仅用来入门。
http://www.graphviz.org/
另外也有专门渲染DOT脚本的浏览器xdo，直接在窗口渲染，不需要生成图像文件，强烈推荐。
很多图都比较适合用DOT来定义，比如流程图，组织关系图，类图，状态转换图等等。
在刚接触DOT不到3天的时间里，我就分别在代码性能优化，协议栈状态机定义两件事情用到了DOT，感觉非常方便。
性能优化：gprof可以对一个程序运行时进行profiling，生成报告，包括函数调用关系，每个函数被调用的次数，花费的时间。但这个报告是文本的，不够直观。可以通过一个gprof2dot.py脚本，把gprof的输出翻译成一个DOT文件，然后再用Graphviz转成图片或者直接用xdot来查看。
sudo apt-get install graphviz graphviz-doc
dot -Tsvg test.dot -o test.svg
典型示例(更多例子可以参见官方文档)
1.Fancy Graph
digraph G {
edge[fontname="FangSong"];
node[peripheries=2, fontname="FangSong"];
size="16, 16";
main[shape="box"];
main[label="从这里开始"]
main->parse[weight=8]
parse->execute;
main->init[style=dotted];
main->cleanup;
execute->{make_string; printf;}
edge[color=red];
init->make_string[label="1000次的感动"];
main->printf[label="make a \n string"];
node[shape=box,style=filled,color=".7 .3 1.0"];
execute->compare;
}
2.Polygon Graph
digraph G{
size = "4, 4"
a->b->c;
b->d;
a[shape=polygon, sides=5, peripheries=3, color=lightblue, style=filled];
c[shape=polygon, sides=4, skew=0.4, label="hello world"];
d[shape=invtriangle];
e[shape=polygon, side=4, distortion=.7];
}
效果图
3.list Graph
digraph G{
node[shape=record, height=.1];
node0[label=" | G| "];
node1[label=" | E| "];
node2[label=" | B| "];
node3[label=" | F| "];
node4[label=" | R| "];
node5[label=" | H| "];
node6[label=" | Y| "];
node7[label=" | A| "];
node8[label=" | C| "];
"node0":f2->"node4":f1;
"node0":f0->"node1":f1;
"node1":f0->"node2":f1;
"node1":f2->"node3":f1;
"node2":f2->"node8":f1;
"node2":f0->"node7":f1;
"node4":f2->"node6":f1;
"node4":f0->"node5":f1;
}
4.hash table Graph
digraph G {
nodesep=.05;
rankdir=LR;
node[shape=record, width=.1, height=.1];
node0[label=" | | | | | | |", height=2.5]
node[width=1.5];
node1[label="{ n14 | 719 |}"];
node2[label="{ a1 | 719 |}"];
node3[label="{ i9 | 512 |}"];
node4[label="{ e5 | 632 |}"];
node5[label="{ t20 | 959 |}"];
node6[label="{ o15 | 794 |}"];
node7[label="{ s19 | 659 |}"];
node0:f0->node1:n;
node0:f1->node2:n;
node0:f2->node3:n;
node0:f5->node4:n;
node0:f6->node5:n;
node2:p->node6:n;
node4:p->node7:n;
}
5.Process Graph
digraph G {
subgraph cluster0 {
node[style=filled, color=white];
style=filled;
color=lightgrey;
a0->a1->a2->a3;
label="process #1";
}
subgraph cluster1 {
node[style=filled];
color=blue;
b0->b1->b2->b3;
label="process #2";
}
start->a0;
start->b0;
a1->b3;
b2->a3;
a3->end;
b3->end;
start[shape=Mdiamond];
end[shape=Msquare];
} 
6.directed Graph
digraph G {
{a b c} -> {d e f g}
} 
7.化学分子式
graph s{
C_0 -- H_0;
C_0 -- H_1;
C_0 -- H_2;
C_0 -- C_1;
C_1 -- H_3;
C_1 -- H_4;
C_1 -- H_5;
}
8.函数调用关系图
digraph s {
node [shape=ellipse, style=filled, color="#40e0d0"];
edge [color="#606060", penwidth=3];
main [color=green];
main -> init[color=blue, label="hello, I'm \llable of edge"];
main -> mainloop;
main -> exit;
init -> a_init;
init -> b_init;
init -> c_init;
mainloop -> select;
}
这个是有向图(directional graph)， 脚本的第一个词需要换成"digraph"。常用的属性有color, style, shape, penwidth, label等。label中 \r, \l, \n 都表示换行，但对齐方式分别是 右对齐，左对齐，居中 。
9.ATS中插件collapsed_connection的流程图，一个更复杂的例子
dot -Tpng collapsed_connection.dot -o collapsed_connection.png
digraph collapsed_connection {
accept -> TS_HTTP_POST_REMAP_HOOK;
TS_HTTP_POST_REMAP_HOOK -> "check request method (and header)";
"check request method (and header)" -> "get CacheUrl hash_key using MurmurHash3" [label = "GET request (required_header present)"];
"check request method (and header)" -> "pass request" [label = "others"];
"get CacheUrl hash_key using MurmurHash3" -> "check hash_key from hashTable";
"check hash_key from hashTable" -> "lock URL in hashTable" [label = "not found"];
"check hash_key from hashTable" -> "pass request" [label = "found, but marked pass"];
"check hash_key from hashTable" -> "check hash_key from hashTable" [label = "locked or unable to get mutex, wait insert_lock_retry_time"];
"lock URL in hashTable" -> TS_HTTP_CACHE_LOOKUP_COMPLETE_HOOK;
TS_HTTP_CACHE_LOOKUP_COMPLETE_HOOK -> "remove URL from hashTable(1)" [label = "hit_fresh or skipped"];
TS_HTTP_CACHE_LOOKUP_COMPLETE_HOOK -> "request origin server" [label = "miss or stale"];
"request origin server" -> TS_HTTP_READ_RESPONSE_HDR_HOOK;
TS_HTTP_READ_RESPONSE_HDR_HOOK -> "remove URL from hashTable(1)" [label = "not 200/OK response"];
TS_HTTP_READ_RESPONSE_HDR_HOOK -> "check read_while_writer config";
"check read_while_writer config" -> "remove URL from hashTable(1)" [label = "enabled"];
"check read_while_writer config" -> TS_HTTP_TXN_CLOSE_HOOK [label = "disabled"];
TS_HTTP_READ_RESPONSE_HDR_HOOK -> "mark pass in hashTable" [label = "non-cacheable"];
"remove URL from hashTable(1)" -> TS_HTTP_TXN_CLOSE_HOOK;
"mark pass in hashTable" -> TS_HTTP_TXN_CLOSE_HOOK;
"pass request" -> TS_HTTP_TXN_CLOSE_HOOK;
TS_HTTP_TXN_CLOSE_HOOK -> "remove URL from hashTable(2)";
TS_HTTP_TXN_CLOSE_HOOK -> "check keep_pass_record_time" [label = "non-cacheable"];
"check keep_pass_record_time" -> "add into KeepPassList" [label = "> 0"];
"check keep_pass_record_time" -> "remove URL from hashTable(2)" [label = "= 0"];
"add into KeepPassList" -> "transaction close";
"remove URL from hashTable(2)" -> "transaction close";
"transaction close" -> accept;
TS_HTTP_POST_REMAP_HOOK [shape = box];
TS_HTTP_CACHE_LOOKUP_COMPLETE_HOOK[shape = box];
TS_HTTP_READ_RESPONSE_HDR_HOOK [shape = box];
TS_HTTP_TXN_CLOSE_HOOK [shape = box];
"check request method (and header)" [shape = diamond];
"check hash_key from hashTable" [shape = diamond];
"check read_while_writer config" [shape = diamond];
"check keep_pass_record_time" [shape = diamond];
} 
10.使用Makefile文件来批量执行
在阅读源码过程中，如果我们编写了大量的dot文件，需要处理和展示，如果逐个编译和操作，未免太为繁琐，我们这里推荐使用一个Makefile来将所有的dot文件都包括过来。
生成图像命令
make png
清除图像命令
make clean
下面是Makefile文件
SVG_FILES = \
HttpProxyServer-callgraph.svg \
HttpSM-callgraph.svg \
HttpTransact-callgraph.svg \
HttpTransact-state-diagram.svg \
HttpTransactAndSM-callgraph.svg
PNG_FILES = $(SVG_FILES:.svg=.png)
PDF_FILES = $(SVG_FILES:.svg=.pdf)
svg: ${SVG_FILES}
png: ${PNG_FILES}
pdf: ${PDF_FILES}
clean:
rm -f ${SVG_FILES} ${PNG_FILES} ${PDF_FILES}
.SUFFIXES: .dot .svg .png .pdf
.dot.svg:
dot -Tsvg $< -o $@
.dot.png:
dot -Tpng $< -o $@
.dot.pdf:
dot -Tpdf $< -o $@截图如下
注意事项
1.中文乱码
graphviz默认情况下对中文支持不好，如果代码中有中文，则必须使用UTF-8的格式保存文件，并且在代码中指定字体。
进一步深究可以查看官方文档
http://www.graphviz.org/Documentation.php
下面给出几个颇具震撼力的效果图，来自官网文档
