Project: TDengine (App Definition and Development / Database)
File: scratch.md

```plantuml @startuml create_table skinparam sequenceMessageAlign center skinparam responseMessageBelowArrow true participant APP as app box "dnode1" participant RPC as rpc participant VNODE as vnode participant SYNC as sync end box box "dnode2" participant SYNC as sync2 participant VNODE as vnode2 end box box "dnode3" participant SYNC as sync3 participant VNODE as vnode3 end box ' APP send request to dnode and RPC in dnode recv the request app ->rpc: create table req ' RPC call vnodeProcessReq() function to process the request rpc -> vnode: vnodeProcessReq note right callback function run in RPC module threads. The function only puts the request to a vnode queue. end note ' VNODE call vnodeProcessReqs() function to integrate requests and process as a whole vnode -> vnode: vnodeProcessReqs() note right integrate reqs and process as a whole end note ' sync the request to other nodes vnode -> sync: syncProcessReqs() ' make request persistent ' sync -->vnode: walWrite()\n(callback function) ' replicate requests to other DNODES sync -> sync2: replication req sync -> sync3: replication req sync2 -> vnode2: walWrite()\n(callback function) sync2 --> sync: replication rsp\n(confirm) sync3 -> vnode3: walWrite()\n(callback function) sync3 --> sync: replication rsp\n(confirm) ' send apply request sync -> sync2: apply req sync -> sync3: apply req ' vnode apply sync2 -> vnode2: vnodeApplyReqs() sync3 -> vnode3: vnodeApplyReqs() ' call apply request sync --> vnode: vnodeApplyReqs()\n(callback function) ' send response vnode --> rpc: rpcSendRsp() ' dnode send response to APP rpc --> app: create table rsp @enduml ``` ```plantuml @startuml leaderprocessstict_consistency box "dnode1" participant CRPC as crpc participant VNODE as vnode participant SYNC as sync end box -> crpc: create table/submit req ' In CRPC threads group #pink "In CRPC threads" crpc -> vnode:vnodeProcessReq() note right A callback function run by CRPC thread to put the request to a vnode queue end note end ' In VNODE worker threads

#lightblue "In VNODE worker threads" vnode -> vnode: vnodeProcessReqs() note right VNODE process requests accumulated in a vnode write queue and process the batch reqs as a whole end note vnode -> sync: syncProcessReqs() sync -> : replication req1 sync -> : replication req2 end group #red "SYNC threads" sync <- : replication rsp1 sync <- : replication rsp2 sync -> vnode: notify apply sync -> : apply rsp1 sync -> : apply rsp2 end group #lightblue "In VNODE worker threads" vnode -> vnode: vnodeApplyReqs() vnode -> crpc: end <- crpc: create table/submit rsp @enduml ``` ```plantuml @startuml followerprocessstrict_consistency participant SYNC as sync participant VNODE as vnode group #pink "SYNC threads" -> sync: replication req sync -> sync: syncProcessReqs() note right In the replication only data is persisted and response is sent back end note <- sync: replication rsp -> sync: apply req sync -> vnode: notify apply end group #lightblue "VNODE worker threads" vnode -> vnode: vnodeApplyReqs() end @enduml ``` ```plantuml @startuml leaderprocesseventual_consistency box "dnode1" participant CRPC as crpc participant VNODE as vnode participant SYNC as sync end box -> crpc: create table/submit req ' In CRPC threads group #pink "In CRPC threads" crpc -> vnode:vnodeProcessReq() note right A callback function run by CRPC thread to put the request to a vnode queue end note end ' In VNODE worker threads group #lightblue "In VNODE worker threads" vnode -> vnode: vnodeProcessReqs() note right VNODE process requests accumulated in a vnode write queue and process the batch reqs as a whole end note vnode -> sync: syncProcessReqs() sync -> : replication req1 sync -> : replication req2 sync -> vnode: notify apply end group #lightblue "In VNODE worker threads" vnode -> vnode: vnodeApplyReqs() vnode -> crpc: end <- crpc: create table/submit rsp @enduml ``` ```plantuml @startuml followerprocesseventual_consistency participant SYNC as sync participant VNODE as vnode group #pink "SYNC threads" -> sync: replication rsp sync -> sync: syncProcessReqs() sync -> vnode: notify VNODE \nthread to process\n the reqs end group #lightblue "VNODE worker threads" vnode -> vnode: vnodeApplyReqs() end @enduml ```