add dev doc (#27)

Signed-off-by: wfan <wfan@yahoo-corp.jp>

docs/development/sia-goroutine-and-channel.md

@@ -0,0 +1,116 @@
+# SIA goroutine and channel
+
+```mermaid
+sequenceDiagram
+    participant OS as OS
+    box main
+    participant mgo as goroutine
+    participant mc1 as ch
+    participant mc2 as certificateChan
+    end
+    box CertificateD
+    participant cdgo as goroutine
+    participant cdc1 as sdChan
+    participant cdc2 as tokenChan
+    participant cdc3 as metricsChan
+    participant cdc4 as healthcheckChan
+    end
+    box TokenD
+    participant tdgo as goroutine
+    participant tdc1 as sdChan
+    end
+    box MetricsD
+    participant mdgo as goroutine
+    participant mdc1 as sdChan
+    end
+    box HealthcheckD
+    participant hdgo as goroutine
+    participant hdc1 as sdChan
+    end
+    
+    rect rgb(77, 77, 77)
+    note right of OS: SIA startup
+    
+    mc2->>mc2: make
+    mc1->>mc1: make
+    mc2->cdc1: exchange
+
+    cdc2->>cdc2: make
+    cdc2->tdc1: exchange
+    tdc1->>tdc1: make
+    tdgo->>tdgo: go func()
+    loop run
+        tdgo->>tdgo: start server
+    end
+    loop run
+        tdgo->>tdgo: on every idConfig.tokenRefresh
+        tdgo-->>cdc2: listen close
+    end
+
+    cdc3->>cdc3: make
+    cdc3->mdc1: exchange
+    mdc1->>mdc1: make
+    mdgo->>mdgo: go func()
+    loop run
+        mdgo->>mdgo: start server
+    end
+    loop run
+        mdgo-->>cdc3: listen close
+    end
+
+    cdc4->>cdc4: make
+    cdc4->hdc1: exchange
+    hdc1->>hdc1: make
+    hdgo->>hdgo: go func()
+    loop run
+        hdgo->>hdgo: start server
+    end
+    loop run
+        hdgo-->>cdc4: listen close
+    end
+
+    cdc1->>cdc1: make
+    cdgo->>cdgo: go func()
+    loop run
+        cdgo->>cdgo: on every idConfig.Refresh
+        cdgo-->>mc2: listen close
+    end
+
+
+    mgo-->>OS: listen os.Signal
+    end
+
+    rect rgb(77, 77, 77)
+    note right of OS: SIA shutdown
+    OS->>mc1: syscall.SIGTERM, os.Interruptos.Signal
+    mc1->>mgo: ACK close
+    mgo->>mc2: close
+    mc2->>cdgo: ACK close
+    mgo-->>cdc1: listen close
+
+    cdgo->>cdgo: deleteRequest()
+    par ACK all channels
+    cdgo->>cdc4: close
+    cdc4->>hdgo: ACK close
+    cdgo->>cdc3: close
+    cdc3->>mdgo: ACK close
+    cdgo->>cdc2: close
+    cdc2->>tdgo: ACK close
+    end
+    cdgo-->>tdc1: listen close
+    cdgo-->>mdc1: listen close
+    cdgo-->>hdc1: listen close
+    hdgo->>hdgo: sync Shutdown(timeout=ShutdownTimeout)
+    hdgo->>hdc1: close
+    hdc1->>cdgo: ACK close
+    mdgo->>mdgo: sync Shutdown(context.Background())
+    mdgo->>mdc1: close
+    mdc1->>cdgo: ACK close
+    tdgo->>tdgo: Sleep(idConfig.ShutdownDelay)
+    tdgo->>tdgo: sync Shutdown(timeout=ShutdownTimeout)
+    tdgo->>tdc1: close
+    tdc1->>cdgo: ACK close
+    cdgo->>cdc1: close
+    cdc1->>mgo: ACK close
+    end
+```