非阻塞有限状态机的实现 C语言

非阻塞IO – 阻塞IO

IO多路转接

其他读写函数

存储映射IO

文件锁

非阻塞 IO

简单流程：如果一个程序的自然流程是结构化的，就是简单流程。（明确能分析结构流程的）

复杂流程：如果一个程序的自然流程不是结构化的，就是复杂流程。

有限状态机的实现方法：

任务：实现一个数据中继模型。（流式套接字）

​ - - -> 设备1 <——> 设备2 < - - -

目标：

a. 读设备1——写设备2——读设备2——写设备1

如果采用阻塞的方式，假如正在读设备1，且设备1上没有数据，程序就会一直阻塞在读设备1；假设设备2有数据产生，就会无法读设备2并像设备1中写入。这种方案的阻塞是无法实现功能的。

如果采用非阻塞方式，假如在读取某一个设备时没有数据，就会去尝试读取另一个设备，就不会产生上述问题。

a.读设备1——写设备2

b.读设备2——写设备1

这种采用两个线程分工，如果采用阻塞的方式是可以实现功能，但是效果很差。

这种采用两个线程分工，如果采用非阻塞的方式是可以实现功能。

原型：

#mermaid-svg-MGFMrNDLZR8v0rD9 .label{font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family);fill:#333;color:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .label text{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .node rect,#mermaid-svg-MGFMrNDLZR8v0rD9 .node circle,#mermaid-svg-MGFMrNDLZR8v0rD9 .node ellipse,#mermaid-svg-MGFMrNDLZR8v0rD9 .node polygon,#mermaid-svg-MGFMrNDLZR8v0rD9 .node path{fill:#ECECFF;stroke:#9370db;stroke-width:1px}#mermaid-svg-MGFMrNDLZR8v0rD9 .node .label{text-align:center;fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .node.clickable{cursor:pointer}#mermaid-svg-MGFMrNDLZR8v0rD9 .arrowheadPath{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .edgePath .path{stroke:#333;stroke-width:1.5px}#mermaid-svg-MGFMrNDLZR8v0rD9 .flowchart-link{stroke:#333;fill:none}#mermaid-svg-MGFMrNDLZR8v0rD9 .edgeLabel{background-color:#e8e8e8;text-align:center}#mermaid-svg-MGFMrNDLZR8v0rD9 .edgeLabel rect{opacity:0.9}#mermaid-svg-MGFMrNDLZR8v0rD9 .edgeLabel span{color:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .cluster rect{fill:#ffffde;stroke:#aa3;stroke-width:1px}#mermaid-svg-MGFMrNDLZR8v0rD9 .cluster text{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family);font-size:12px;background:#ffffde;border:1px solid #aa3;border-radius:2px;pointer-events:none;z-index:100}#mermaid-svg-MGFMrNDLZR8v0rD9 .actor{stroke:#ccf;fill:#ECECFF}#mermaid-svg-MGFMrNDLZR8v0rD9 text.actor>tspan{fill:#000;stroke:none}#mermaid-svg-MGFMrNDLZR8v0rD9 .actor-line{stroke:grey}#mermaid-svg-MGFMrNDLZR8v0rD9 .messageLine0{stroke-width:1.5;stroke-dasharray:none;stroke:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .messageLine1{stroke-width:1.5;stroke-dasharray:2, 2;stroke:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 #arrowhead path{fill:#333;stroke:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .sequenceNumber{fill:#fff}#mermaid-svg-MGFMrNDLZR8v0rD9 #sequencenumber{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 #crosshead path{fill:#333;stroke:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .messageText{fill:#333;stroke:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .labelBox{stroke:#ccf;fill:#ECECFF}#mermaid-svg-MGFMrNDLZR8v0rD9 .labelText,#mermaid-svg-MGFMrNDLZR8v0rD9 .labelText>tspan{fill:#000;stroke:none}#mermaid-svg-MGFMrNDLZR8v0rD9 .loopText,#mermaid-svg-MGFMrNDLZR8v0rD9 .loopText>tspan{fill:#000;stroke:none}#mermaid-svg-MGFMrNDLZR8v0rD9 .loopLine{stroke-width:2px;stroke-dasharray:2, 2;stroke:#ccf;fill:#ccf}#mermaid-svg-MGFMrNDLZR8v0rD9 .note{stroke:#aa3;fill:#fff5ad}#mermaid-svg-MGFMrNDLZR8v0rD9 .noteText,#mermaid-svg-MGFMrNDLZR8v0rD9 .noteText>tspan{fill:#000;stroke:none}#mermaid-svg-MGFMrNDLZR8v0rD9 .activation0{fill:#f4f4f4;stroke:#666}#mermaid-svg-MGFMrNDLZR8v0rD9 .activation1{fill:#f4f4f4;stroke:#666}#mermaid-svg-MGFMrNDLZR8v0rD9 .activation2{fill:#f4f4f4;stroke:#666}#mermaid-svg-MGFMrNDLZR8v0rD9 .mermaid-main-font{font-family:"trebuchet ms", verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 .section{stroke:none;opacity:0.2}#mermaid-svg-MGFMrNDLZR8v0rD9 .section0{fill:rgba(102,102,255,0.49)}#mermaid-svg-MGFMrNDLZR8v0rD9 .section2{fill:#fff400}#mermaid-svg-MGFMrNDLZR8v0rD9 .section1,#mermaid-svg-MGFMrNDLZR8v0rD9 .section3{fill:#fff;opacity:0.2}#mermaid-svg-MGFMrNDLZR8v0rD9 .sectionTitle0{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .sectionTitle1{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .sectionTitle2{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .sectionTitle3{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .sectionTitle{text-anchor:start;font-size:11px;text-height:14px;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 .grid .tick{stroke:#d3d3d3;opacity:0.8;shape-rendering:crispEdges}#mermaid-svg-MGFMrNDLZR8v0rD9 .grid .tick text{font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 .grid path{stroke-width:0}#mermaid-svg-MGFMrNDLZR8v0rD9 .today{fill:none;stroke:red;stroke-width:2px}#mermaid-svg-MGFMrNDLZR8v0rD9 .task{stroke-width:2}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskText{text-anchor:middle;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskText:not([font-size]){font-size:11px}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskTextOutsideRight{fill:#000;text-anchor:start;font-size:11px;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskTextOutsideLeft{fill:#000;text-anchor:end;font-size:11px}#mermaid-svg-MGFMrNDLZR8v0rD9 .task.clickable{cursor:pointer}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskText.clickable{cursor:pointer;fill:#003163 !important;font-weight:bold}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskTextOutsideLeft.clickable{cursor:pointer;fill:#003163 !important;font-weight:bold}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskTextOutsideRight.clickable{cursor:pointer;fill:#003163 !important;font-weight:bold}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskText0,#mermaid-svg-MGFMrNDLZR8v0rD9 .taskText1,#mermaid-svg-MGFMrNDLZR8v0rD9 .taskText2,#mermaid-svg-MGFMrNDLZR8v0rD9 .taskText3{fill:#fff}#mermaid-svg-MGFMrNDLZR8v0rD9 .task0,#mermaid-svg-MGFMrNDLZR8v0rD9 .task1,#mermaid-svg-MGFMrNDLZR8v0rD9 .task2,#mermaid-svg-MGFMrNDLZR8v0rD9 .task3{fill:#8a90dd;stroke:#534fbc}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskTextOutside0,#mermaid-svg-MGFMrNDLZR8v0rD9 .taskTextOutside2{fill:#000}#mermaid-svg-MGFMrNDLZR8v0rD9 .taskTextOutside1,#mermaid-svg-MGFMrNDLZR8v0rD9 .taskTextOutside3{fill:#000}#mermaid-svg-MGFMrNDLZR8v0rD9 .active0,#mermaid-svg-MGFMrNDLZR8v0rD9 .active1,#mermaid-svg-MGFMrNDLZR8v0rD9 .active2,#mermaid-svg-MGFMrNDLZR8v0rD9 .active3{fill:#bfc7ff;stroke:#534fbc}#mermaid-svg-MGFMrNDLZR8v0rD9 .activeText0,#mermaid-svg-MGFMrNDLZR8v0rD9 .activeText1,#mermaid-svg-MGFMrNDLZR8v0rD9 .activeText2,#mermaid-svg-MGFMrNDLZR8v0rD9 .activeText3{fill:#000 !important}#mermaid-svg-MGFMrNDLZR8v0rD9 .done0,#mermaid-svg-MGFMrNDLZR8v0rD9 .done1,#mermaid-svg-MGFMrNDLZR8v0rD9 .done2,#mermaid-svg-MGFMrNDLZR8v0rD9 .done3{stroke:grey;fill:#d3d3d3;stroke-width:2}#mermaid-svg-MGFMrNDLZR8v0rD9 .doneText0,#mermaid-svg-MGFMrNDLZR8v0rD9 .doneText1,#mermaid-svg-MGFMrNDLZR8v0rD9 .doneText2,#mermaid-svg-MGFMrNDLZR8v0rD9 .doneText3{fill:#000 !important}#mermaid-svg-MGFMrNDLZR8v0rD9 .crit0,#mermaid-svg-MGFMrNDLZR8v0rD9 .crit1,#mermaid-svg-MGFMrNDLZR8v0rD9 .crit2,#mermaid-svg-MGFMrNDLZR8v0rD9 .crit3{stroke:#f88;fill:red;stroke-width:2}#mermaid-svg-MGFMrNDLZR8v0rD9 .activeCrit0,#mermaid-svg-MGFMrNDLZR8v0rD9 .activeCrit1,#mermaid-svg-MGFMrNDLZR8v0rD9 .activeCrit2,#mermaid-svg-MGFMrNDLZR8v0rD9 .activeCrit3{stroke:#f88;fill:#bfc7ff;stroke-width:2}#mermaid-svg-MGFMrNDLZR8v0rD9 .doneCrit0,#mermaid-svg-MGFMrNDLZR8v0rD9 .doneCrit1,#mermaid-svg-MGFMrNDLZR8v0rD9 .doneCrit2,#mermaid-svg-MGFMrNDLZR8v0rD9 .doneCrit3{stroke:#f88;fill:#d3d3d3;stroke-width:2;cursor:pointer;shape-rendering:crispEdges}#mermaid-svg-MGFMrNDLZR8v0rD9 .milestone{transform:rotate(45deg) scale(0.8, 0.8)}#mermaid-svg-MGFMrNDLZR8v0rD9 .milestoneText{font-style:italic}#mermaid-svg-MGFMrNDLZR8v0rD9 .doneCritText0,#mermaid-svg-MGFMrNDLZR8v0rD9 .doneCritText1,#mermaid-svg-MGFMrNDLZR8v0rD9 .doneCritText2,#mermaid-svg-MGFMrNDLZR8v0rD9 .doneCritText3{fill:#000 !important}#mermaid-svg-MGFMrNDLZR8v0rD9 .activeCritText0,#mermaid-svg-MGFMrNDLZR8v0rD9 .activeCritText1,#mermaid-svg-MGFMrNDLZR8v0rD9 .activeCritText2,#mermaid-svg-MGFMrNDLZR8v0rD9 .activeCritText3{fill:#000 !important}#mermaid-svg-MGFMrNDLZR8v0rD9 .titleText{text-anchor:middle;font-size:18px;fill:#000;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 g.classGroup text{fill:#9370db;stroke:none;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family);font-size:10px}#mermaid-svg-MGFMrNDLZR8v0rD9 g.classGroup text .title{font-weight:bolder}#mermaid-svg-MGFMrNDLZR8v0rD9 g.clickable{cursor:pointer}#mermaid-svg-MGFMrNDLZR8v0rD9 g.classGroup rect{fill:#ECECFF;stroke:#9370db}#mermaid-svg-MGFMrNDLZR8v0rD9 g.classGroup line{stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 .classLabel .box{stroke:none;stroke-width:0;fill:#ECECFF;opacity:0.5}#mermaid-svg-MGFMrNDLZR8v0rD9 .classLabel .label{fill:#9370db;font-size:10px}#mermaid-svg-MGFMrNDLZR8v0rD9 .relation{stroke:#9370db;stroke-width:1;fill:none}#mermaid-svg-MGFMrNDLZR8v0rD9 .dashed-line{stroke-dasharray:3}#mermaid-svg-MGFMrNDLZR8v0rD9 #compositionStart{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 #compositionEnd{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 #aggregationStart{fill:#ECECFF;stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 #aggregationEnd{fill:#ECECFF;stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 #dependencyStart{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 #dependencyEnd{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 #extensionStart{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 #extensionEnd{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 .commit-id,#mermaid-svg-MGFMrNDLZR8v0rD9 .commit-msg,#mermaid-svg-MGFMrNDLZR8v0rD9 .branch-label{fill:lightgrey;color:lightgrey;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 .pieTitleText{text-anchor:middle;font-size:25px;fill:#000;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 .slice{font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 g.stateGroup text{fill:#9370db;stroke:none;font-size:10px;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 g.stateGroup text{fill:#9370db;fill:#333;stroke:none;font-size:10px}#mermaid-svg-MGFMrNDLZR8v0rD9 g.statediagram-cluster .cluster-label text{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 g.stateGroup .state-title{font-weight:bolder;fill:#000}#mermaid-svg-MGFMrNDLZR8v0rD9 g.stateGroup rect{fill:#ECECFF;stroke:#9370db}#mermaid-svg-MGFMrNDLZR8v0rD9 g.stateGroup line{stroke:#9370db;stroke-width:1}#mermaid-svg-MGFMrNDLZR8v0rD9 .transition{stroke:#9370db;stroke-width:1;fill:none}#mermaid-svg-MGFMrNDLZR8v0rD9 .stateGroup .composit{fill:white;border-bottom:1px}#mermaid-svg-MGFMrNDLZR8v0rD9 .stateGroup .alt-composit{fill:#e0e0e0;border-bottom:1px}#mermaid-svg-MGFMrNDLZR8v0rD9 .state-note{stroke:#aa3;fill:#fff5ad}#mermaid-svg-MGFMrNDLZR8v0rD9 .state-note text{fill:black;stroke:none;font-size:10px}#mermaid-svg-MGFMrNDLZR8v0rD9 .stateLabel .box{stroke:none;stroke-width:0;fill:#ECECFF;opacity:0.7}#mermaid-svg-MGFMrNDLZR8v0rD9 .edgeLabel text{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .stateLabel text{fill:#000;font-size:10px;font-weight:bold;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-MGFMrNDLZR8v0rD9 .node circle.state-start{fill:black;stroke:black}#mermaid-svg-MGFMrNDLZR8v0rD9 .node circle.state-end{fill:black;stroke:white;stroke-width:1.5}#mermaid-svg-MGFMrNDLZR8v0rD9 #statediagram-barbEnd{fill:#9370db}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-cluster rect{fill:#ECECFF;stroke:#9370db;stroke-width:1px}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-cluster rect.outer{rx:5px;ry:5px}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-state .divider{stroke:#9370db}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-state .title-state{rx:5px;ry:5px}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-cluster.statediagram-cluster .inner{fill:white}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-cluster.statediagram-cluster-alt .inner{fill:#e0e0e0}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-cluster .inner{rx:0;ry:0}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-state rect.basic{rx:5px;ry:5px}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-state rect.divider{stroke-dasharray:10,10;fill:#efefef}#mermaid-svg-MGFMrNDLZR8v0rD9 .note-edge{stroke-dasharray:5}#mermaid-svg-MGFMrNDLZR8v0rD9 .statediagram-note rect{fill:#fff5ad;stroke:#aa3;stroke-width:1px;rx:0;ry:0}:root{--mermaid-font-family: '"trebuchet ms", verdana, arial';--mermaid-font-family: "Comic Sans MS", "Comic Sans", cursive}#mermaid-svg-MGFMrNDLZR8v0rD9 .error-icon{fill:#522}#mermaid-svg-MGFMrNDLZR8v0rD9 .error-text{fill:#522;stroke:#522}#mermaid-svg-MGFMrNDLZR8v0rD9 .edge-thickness-normal{stroke-width:2px}#mermaid-svg-MGFMrNDLZR8v0rD9 .edge-thickness-thick{stroke-width:3.5px}#mermaid-svg-MGFMrNDLZR8v0rD9 .edge-pattern-solid{stroke-dasharray:0}#mermaid-svg-MGFMrNDLZR8v0rD9 .edge-pattern-dashed{stroke-dasharray:3}#mermaid-svg-MGFMrNDLZR8v0rD9 .edge-pattern-dotted{stroke-dasharray:2}#mermaid-svg-MGFMrNDLZR8v0rD9 .marker{fill:#333}#mermaid-svg-MGFMrNDLZR8v0rD9 .marker.cross{stroke:#333} :root { --mermaid-font-family: "trebuchet ms", verdana, arial;} #mermaid-svg-MGFMrNDLZR8v0rD9 { color: rgba(0, 0, 0, 0.75); font: ; } 1 2 Input dev1 dev2 Input 读dev1写dev2读dev2写dev1

状态机：

#mermaid-svg-oioFW5LCfPy830IW .label{font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family);fill:#333;color:#333}#mermaid-svg-oioFW5LCfPy830IW .label text{fill:#333}#mermaid-svg-oioFW5LCfPy830IW .node rect,#mermaid-svg-oioFW5LCfPy830IW .node circle,#mermaid-svg-oioFW5LCfPy830IW .node ellipse,#mermaid-svg-oioFW5LCfPy830IW .node polygon,#mermaid-svg-oioFW5LCfPy830IW .node path{fill:#ECECFF;stroke:#9370db;stroke-width:1px}#mermaid-svg-oioFW5LCfPy830IW .node .label{text-align:center;fill:#333}#mermaid-svg-oioFW5LCfPy830IW .node.clickable{cursor:pointer}#mermaid-svg-oioFW5LCfPy830IW .arrowheadPath{fill:#333}#mermaid-svg-oioFW5LCfPy830IW .edgePath .path{stroke:#333;stroke-width:1.5px}#mermaid-svg-oioFW5LCfPy830IW .flowchart-link{stroke:#333;fill:none}#mermaid-svg-oioFW5LCfPy830IW .edgeLabel{background-color:#e8e8e8;text-align:center}#mermaid-svg-oioFW5LCfPy830IW .edgeLabel rect{opacity:0.9}#mermaid-svg-oioFW5LCfPy830IW .edgeLabel span{color:#333}#mermaid-svg-oioFW5LCfPy830IW .cluster rect{fill:#ffffde;stroke:#aa3;stroke-width:1px}#mermaid-svg-oioFW5LCfPy830IW .cluster text{fill:#333}#mermaid-svg-oioFW5LCfPy830IW div.mermaidTooltip{position:absolute;text-align:center;max-width:200px;padding:2px;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family);font-size:12px;background:#ffffde;border:1px solid #aa3;border-radius:2px;pointer-events:none;z-index:100}#mermaid-svg-oioFW5LCfPy830IW .actor{stroke:#ccf;fill:#ECECFF}#mermaid-svg-oioFW5LCfPy830IW text.actor>tspan{fill:#000;stroke:none}#mermaid-svg-oioFW5LCfPy830IW .actor-line{stroke:grey}#mermaid-svg-oioFW5LCfPy830IW .messageLine0{stroke-width:1.5;stroke-dasharray:none;stroke:#333}#mermaid-svg-oioFW5LCfPy830IW .messageLine1{stroke-width:1.5;stroke-dasharray:2, 2;stroke:#333}#mermaid-svg-oioFW5LCfPy830IW #arrowhead path{fill:#333;stroke:#333}#mermaid-svg-oioFW5LCfPy830IW .sequenceNumber{fill:#fff}#mermaid-svg-oioFW5LCfPy830IW #sequencenumber{fill:#333}#mermaid-svg-oioFW5LCfPy830IW #crosshead path{fill:#333;stroke:#333}#mermaid-svg-oioFW5LCfPy830IW .messageText{fill:#333;stroke:#333}#mermaid-svg-oioFW5LCfPy830IW .labelBox{stroke:#ccf;fill:#ECECFF}#mermaid-svg-oioFW5LCfPy830IW .labelText,#mermaid-svg-oioFW5LCfPy830IW .labelText>tspan{fill:#000;stroke:none}#mermaid-svg-oioFW5LCfPy830IW .loopText,#mermaid-svg-oioFW5LCfPy830IW .loopText>tspan{fill:#000;stroke:none}#mermaid-svg-oioFW5LCfPy830IW .loopLine{stroke-width:2px;stroke-dasharray:2, 2;stroke:#ccf;fill:#ccf}#mermaid-svg-oioFW5LCfPy830IW .note{stroke:#aa3;fill:#fff5ad}#mermaid-svg-oioFW5LCfPy830IW .noteText,#mermaid-svg-oioFW5LCfPy830IW .noteText>tspan{fill:#000;stroke:none}#mermaid-svg-oioFW5LCfPy830IW .activation0{fill:#f4f4f4;stroke:#666}#mermaid-svg-oioFW5LCfPy830IW .activation1{fill:#f4f4f4;stroke:#666}#mermaid-svg-oioFW5LCfPy830IW .activation2{fill:#f4f4f4;stroke:#666}#mermaid-svg-oioFW5LCfPy830IW .mermaid-main-font{font-family:"trebuchet ms", verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW .section{stroke:none;opacity:0.2}#mermaid-svg-oioFW5LCfPy830IW .section0{fill:rgba(102,102,255,0.49)}#mermaid-svg-oioFW5LCfPy830IW .section2{fill:#fff400}#mermaid-svg-oioFW5LCfPy830IW .section1,#mermaid-svg-oioFW5LCfPy830IW .section3{fill:#fff;opacity:0.2}#mermaid-svg-oioFW5LCfPy830IW .sectionTitle0{fill:#333}#mermaid-svg-oioFW5LCfPy830IW .sectionTitle1{fill:#333}#mermaid-svg-oioFW5LCfPy830IW .sectionTitle2{fill:#333}#mermaid-svg-oioFW5LCfPy830IW .sectionTitle3{fill:#333}#mermaid-svg-oioFW5LCfPy830IW .sectionTitle{text-anchor:start;font-size:11px;text-height:14px;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW .grid .tick{stroke:#d3d3d3;opacity:0.8;shape-rendering:crispEdges}#mermaid-svg-oioFW5LCfPy830IW .grid .tick text{font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW .grid path{stroke-width:0}#mermaid-svg-oioFW5LCfPy830IW .today{fill:none;stroke:red;stroke-width:2px}#mermaid-svg-oioFW5LCfPy830IW .task{stroke-width:2}#mermaid-svg-oioFW5LCfPy830IW .taskText{text-anchor:middle;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW .taskText:not([font-size]){font-size:11px}#mermaid-svg-oioFW5LCfPy830IW .taskTextOutsideRight{fill:#000;text-anchor:start;font-size:11px;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW .taskTextOutsideLeft{fill:#000;text-anchor:end;font-size:11px}#mermaid-svg-oioFW5LCfPy830IW .task.clickable{cursor:pointer}#mermaid-svg-oioFW5LCfPy830IW .taskText.clickable{cursor:pointer;fill:#003163 !important;font-weight:bold}#mermaid-svg-oioFW5LCfPy830IW .taskTextOutsideLeft.clickable{cursor:pointer;fill:#003163 !important;font-weight:bold}#mermaid-svg-oioFW5LCfPy830IW .taskTextOutsideRight.clickable{cursor:pointer;fill:#003163 !important;font-weight:bold}#mermaid-svg-oioFW5LCfPy830IW .taskText0,#mermaid-svg-oioFW5LCfPy830IW .taskText1,#mermaid-svg-oioFW5LCfPy830IW .taskText2,#mermaid-svg-oioFW5LCfPy830IW .taskText3{fill:#fff}#mermaid-svg-oioFW5LCfPy830IW .task0,#mermaid-svg-oioFW5LCfPy830IW .task1,#mermaid-svg-oioFW5LCfPy830IW .task2,#mermaid-svg-oioFW5LCfPy830IW .task3{fill:#8a90dd;stroke:#534fbc}#mermaid-svg-oioFW5LCfPy830IW .taskTextOutside0,#mermaid-svg-oioFW5LCfPy830IW .taskTextOutside2{fill:#000}#mermaid-svg-oioFW5LCfPy830IW .taskTextOutside1,#mermaid-svg-oioFW5LCfPy830IW .taskTextOutside3{fill:#000}#mermaid-svg-oioFW5LCfPy830IW .active0,#mermaid-svg-oioFW5LCfPy830IW .active1,#mermaid-svg-oioFW5LCfPy830IW .active2,#mermaid-svg-oioFW5LCfPy830IW .active3{fill:#bfc7ff;stroke:#534fbc}#mermaid-svg-oioFW5LCfPy830IW .activeText0,#mermaid-svg-oioFW5LCfPy830IW .activeText1,#mermaid-svg-oioFW5LCfPy830IW .activeText2,#mermaid-svg-oioFW5LCfPy830IW .activeText3{fill:#000 !important}#mermaid-svg-oioFW5LCfPy830IW .done0,#mermaid-svg-oioFW5LCfPy830IW .done1,#mermaid-svg-oioFW5LCfPy830IW .done2,#mermaid-svg-oioFW5LCfPy830IW .done3{stroke:grey;fill:#d3d3d3;stroke-width:2}#mermaid-svg-oioFW5LCfPy830IW .doneText0,#mermaid-svg-oioFW5LCfPy830IW .doneText1,#mermaid-svg-oioFW5LCfPy830IW .doneText2,#mermaid-svg-oioFW5LCfPy830IW .doneText3{fill:#000 !important}#mermaid-svg-oioFW5LCfPy830IW .crit0,#mermaid-svg-oioFW5LCfPy830IW .crit1,#mermaid-svg-oioFW5LCfPy830IW .crit2,#mermaid-svg-oioFW5LCfPy830IW .crit3{stroke:#f88;fill:red;stroke-width:2}#mermaid-svg-oioFW5LCfPy830IW .activeCrit0,#mermaid-svg-oioFW5LCfPy830IW .activeCrit1,#mermaid-svg-oioFW5LCfPy830IW .activeCrit2,#mermaid-svg-oioFW5LCfPy830IW .activeCrit3{stroke:#f88;fill:#bfc7ff;stroke-width:2}#mermaid-svg-oioFW5LCfPy830IW .doneCrit0,#mermaid-svg-oioFW5LCfPy830IW .doneCrit1,#mermaid-svg-oioFW5LCfPy830IW .doneCrit2,#mermaid-svg-oioFW5LCfPy830IW .doneCrit3{stroke:#f88;fill:#d3d3d3;stroke-width:2;cursor:pointer;shape-rendering:crispEdges}#mermaid-svg-oioFW5LCfPy830IW .milestone{transform:rotate(45deg) scale(0.8, 0.8)}#mermaid-svg-oioFW5LCfPy830IW .milestoneText{font-style:italic}#mermaid-svg-oioFW5LCfPy830IW .doneCritText0,#mermaid-svg-oioFW5LCfPy830IW .doneCritText1,#mermaid-svg-oioFW5LCfPy830IW .doneCritText2,#mermaid-svg-oioFW5LCfPy830IW .doneCritText3{fill:#000 !important}#mermaid-svg-oioFW5LCfPy830IW .activeCritText0,#mermaid-svg-oioFW5LCfPy830IW .activeCritText1,#mermaid-svg-oioFW5LCfPy830IW .activeCritText2,#mermaid-svg-oioFW5LCfPy830IW .activeCritText3{fill:#000 !important}#mermaid-svg-oioFW5LCfPy830IW .titleText{text-anchor:middle;font-size:18px;fill:#000;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW g.classGroup text{fill:#9370db;stroke:none;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family);font-size:10px}#mermaid-svg-oioFW5LCfPy830IW g.classGroup text .title{font-weight:bolder}#mermaid-svg-oioFW5LCfPy830IW g.clickable{cursor:pointer}#mermaid-svg-oioFW5LCfPy830IW g.classGroup rect{fill:#ECECFF;stroke:#9370db}#mermaid-svg-oioFW5LCfPy830IW g.classGroup line{stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW .classLabel .box{stroke:none;stroke-width:0;fill:#ECECFF;opacity:0.5}#mermaid-svg-oioFW5LCfPy830IW .classLabel .label{fill:#9370db;font-size:10px}#mermaid-svg-oioFW5LCfPy830IW .relation{stroke:#9370db;stroke-width:1;fill:none}#mermaid-svg-oioFW5LCfPy830IW .dashed-line{stroke-dasharray:3}#mermaid-svg-oioFW5LCfPy830IW #compositionStart{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW #compositionEnd{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW #aggregationStart{fill:#ECECFF;stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW #aggregationEnd{fill:#ECECFF;stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW #dependencyStart{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW #dependencyEnd{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW #extensionStart{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW #extensionEnd{fill:#9370db;stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW .commit-id,#mermaid-svg-oioFW5LCfPy830IW .commit-msg,#mermaid-svg-oioFW5LCfPy830IW .branch-label{fill:lightgrey;color:lightgrey;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW .pieTitleText{text-anchor:middle;font-size:25px;fill:#000;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW .slice{font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW g.stateGroup text{fill:#9370db;stroke:none;font-size:10px;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW g.stateGroup text{fill:#9370db;fill:#333;stroke:none;font-size:10px}#mermaid-svg-oioFW5LCfPy830IW g.statediagram-cluster .cluster-label text{fill:#333}#mermaid-svg-oioFW5LCfPy830IW g.stateGroup .state-title{font-weight:bolder;fill:#000}#mermaid-svg-oioFW5LCfPy830IW g.stateGroup rect{fill:#ECECFF;stroke:#9370db}#mermaid-svg-oioFW5LCfPy830IW g.stateGroup line{stroke:#9370db;stroke-width:1}#mermaid-svg-oioFW5LCfPy830IW .transition{stroke:#9370db;stroke-width:1;fill:none}#mermaid-svg-oioFW5LCfPy830IW .stateGroup .composit{fill:white;border-bottom:1px}#mermaid-svg-oioFW5LCfPy830IW .stateGroup .alt-composit{fill:#e0e0e0;border-bottom:1px}#mermaid-svg-oioFW5LCfPy830IW .state-note{stroke:#aa3;fill:#fff5ad}#mermaid-svg-oioFW5LCfPy830IW .state-note text{fill:black;stroke:none;font-size:10px}#mermaid-svg-oioFW5LCfPy830IW .stateLabel .box{stroke:none;stroke-width:0;fill:#ECECFF;opacity:0.7}#mermaid-svg-oioFW5LCfPy830IW .edgeLabel text{fill:#333}#mermaid-svg-oioFW5LCfPy830IW .stateLabel text{fill:#000;font-size:10px;font-weight:bold;font-family:'trebuchet ms', verdana, arial;font-family:var(--mermaid-font-family)}#mermaid-svg-oioFW5LCfPy830IW .node circle.state-start{fill:black;stroke:black}#mermaid-svg-oioFW5LCfPy830IW .node circle.state-end{fill:black;stroke:white;stroke-width:1.5}#mermaid-svg-oioFW5LCfPy830IW #statediagram-barbEnd{fill:#9370db}#mermaid-svg-oioFW5LCfPy830IW .statediagram-cluster rect{fill:#ECECFF;stroke:#9370db;stroke-width:1px}#mermaid-svg-oioFW5LCfPy830IW .statediagram-cluster rect.outer{rx:5px;ry:5px}#mermaid-svg-oioFW5LCfPy830IW .statediagram-state .divider{stroke:#9370db}#mermaid-svg-oioFW5LCfPy830IW .statediagram-state .title-state{rx:5px;ry:5px}#mermaid-svg-oioFW5LCfPy830IW .statediagram-cluster.statediagram-cluster .inner{fill:white}#mermaid-svg-oioFW5LCfPy830IW .statediagram-cluster.statediagram-cluster-alt .inner{fill:#e0e0e0}#mermaid-svg-oioFW5LCfPy830IW .statediagram-cluster .inner{rx:0;ry:0}#mermaid-svg-oioFW5LCfPy830IW .statediagram-state rect.basic{rx:5px;ry:5px}#mermaid-svg-oioFW5LCfPy830IW .statediagram-state rect.divider{stroke-dasharray:10,10;fill:#efefef}#mermaid-svg-oioFW5LCfPy830IW .note-edge{stroke-dasharray:5}#mermaid-svg-oioFW5LCfPy830IW .statediagram-note rect{fill:#fff5ad;stroke:#aa3;stroke-width:1px;rx:0;ry:0}:root{--mermaid-font-family: '"trebuchet ms", verdana, arial';--mermaid-font-family: "Comic Sans MS", "Comic Sans", cursive}#mermaid-svg-oioFW5LCfPy830IW .error-icon{fill:#522}#mermaid-svg-oioFW5LCfPy830IW .error-text{fill:#522;stroke:#522}#mermaid-svg-oioFW5LCfPy830IW .edge-thickness-normal{stroke-width:2px}#mermaid-svg-oioFW5LCfPy830IW .edge-thickness-thick{stroke-width:3.5px}#mermaid-svg-oioFW5LCfPy830IW .edge-pattern-solid{stroke-dasharray:0}#mermaid-svg-oioFW5LCfPy830IW .edge-pattern-dashed{stroke-dasharray:3}#mermaid-svg-oioFW5LCfPy830IW .edge-pattern-dotted{stroke-dasharray:2}#mermaid-svg-oioFW5LCfPy830IW .marker{fill:#333}#mermaid-svg-oioFW5LCfPy830IW .marker.cross{stroke:#333} :root { --mermaid-font-family: "trebuchet ms", verdana, arial;} #mermaid-svg-oioFW5LCfPy830IW { color: rgba(0, 0, 0, 0.75); font: ; } state read EX end write

实现

简单实现：relay.c

/****************************************************************************** * @file relay.c * @brief 非阻塞有限状态机数据中继简单实现，可以通过状态机实现两个终端的数据同步 * @author wangs7__ * @date 2020/10/05 * *******************************************************************************/ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <errno.h> #define TTY1 "/dev/tty11" //设备1 #define TTY2 "/dev/tty12" //设备2 #define BUFSIZE 1024 //缓冲区大小 //状态图 enum{ STATE_R = 1, //写状态 STATE_W , //读状态 STATE_Ex, //出错状态 STATE_T //退出态 }; //状态机结构体 struct fsm_st { int state; //状态描述变量 int sfd; //源文件描述符 int dfd; //目标文件描述符 int len; //读取的字节数 int pos; //写指针 char buf[BUFSIZE]; //读写缓冲区 char *errstr; //报错提示 }; /** * @name fsm_driver * @brief 状态机驱动函数，推动状态机运转 * @param fsm 状态机结构体指针 * @return void */ static void fsm_driver(struct fsm_st *fsm){ int ret; //写函数返回值 //开关选择语句 状态机分支 switch (fsm->state) { //R态------------------------------------------------------------------- case STATE_R: fsm->len = read(fsm->sfd, fsm->buf, BUFSIZE);//从源文件读取字符 if(fsm->len == 0){ //读取文件为空 转T态 fsm->state = STATE_T; } else if (fsm->len < 0){ //读取失败 if(errno == EAGAIN){ //假错 保持R态 fsm->state = STATE_R; } else{ //真错 转Ex态 fsm->errstr = "read()"; fsm->state = STATE_Ex; } } else{ //读成功 转W态 fsm->pos = 0; //写指针初始化 fsm->state = STATE_W; } break; //W态------------------------------------------------------------------- case STATE_W: ret = write(fsm->dfd, fsm->buf+fsm->pos, fsm->len);//从缓冲区向目标文件写入 if(ret < 0){ //写错误 if(errno == EAGAIN){ //假错 保持写 fsm->state = STATE_W; } else{ //真错 转Ex态 fsm->errstr = "write()"; fsm->state = STATE_Ex; } } else{ //写成功 fsm->len -= ret; //写剩余长度 fsm->pos += ret; //写指针位置更新 if(fsm->len == 0){ //写完 转读态 fsm->state = STATE_R; } else{ //未写完 保持写 fsm->state = STATE_W; } } break; //Ex态------------------------------------------------------------------ case STATE_Ex: perror(fsm->errstr); //报错提示 fsm->state = STATE_T; //转T态 break; //T态------------------------------------------------------------------- case STATE_T: /* do something */ break; //--------------------------------------------------------------------- default: abort(); break; } } /** * @name relay * @brief 数据中继函数 * @param fd1 设备1文件描述符 * @param fd2 设备2文件描述符 * @return void */ void relay(int fd1, int fd2){ int fd1_save, fd2_save; //原始文件打开状态 struct fsm_st fsm12, fsm21; //1->>2状态机 和 2->1状态机 //添加非阻塞打开方式 fd1_save = fcntl(fd1, F_GETFL); fcntl(fd1, F_SETFL, fd1_save | O_NONBLOCK); fd2_save = fcntl(fd2, F_GETFL); fcntl(fd2, F_SETFL, fd2_save | O_NONBLOCK); //初始化状态机 fsm12.state = STATE_R; fsm12.sfd = fd1; fsm12.dfd = fd2; fsm21.state = STATE_R; fsm21.sfd = fd2; fsm21.dfd = fd1; //状态机运转 while (fsm12.state != STATE_T ||fsm21.state != STATE_T){ fsm_driver(&fsm12);//驱动 1->2 fsm_driver(&fsm21);//驱动 2->1 } //回复文件原始打开状态 fcntl(fd1, F_SETFL, fd1_save); fcntl(fd2, F_SETFL, fd2_save); } //主函数 int main(int argc, char *argv[]){ int fd1, fd2; fd1 = open(TTY1, O_RDWR); /* 如果出错 */ write(fd1, "TTY1\n", 5); fd2 = open(TTY2, O_RDWR | O_NONBLOCK); /* 如果出错 */ write(fd2, "TTY2\n", 5); //数据中继驱动函数 relay(fd1, fd2); close(fd1); close(fd2); exit(0); }