Internal - instance storage

libmqmsgque is using a class-attribute as instance-storage.

Collaboration diagram for Internal - instance storage:

libmqmsgque is using a class-attribute as instance-storage.

To create a new instance-storage 3 steps are reqired:

Step 1. - Define new class-type "MyLoopServerC" with attribute "mydata"

typedef struct MyLoopServerS {
  struct MqContextS mqctx;    ///< link to the \libmqmsgque object
  #define mydata_size 30
  char mydata[mydata_size];   ///< define the "mydata" attribute
} MyLoopServerC;  

Step 2. - Initialize the class-type "MyLoopServerCTT" with base-class "MyContextSTT"

  // initialize the MyLoopServer class-type with existing MqContextC_TT class-type
  MyLoopServerCTT = MkTypeDup2(MqContextC_TT,"MyLoopServerC");
  MyLoopServerCTT->objsize = sizeof(struct MyLoopServerS);

Step 3. - Create a new instance from class-type "MyLoopServerCTT" using "MqContextCreate"

enum MkErrorE
MyLoopServerFactory ( MQ_CALLBACK_FACTORY_CTOR_ARGS )
{ 
  // create new instance using the MyLoopServerCTT class-type
  MQ_CTX const mqctx = *contextP = MqContextCreate(MyLoopServerCTT,tmpl);

  // initialize the new context
  MqConfigSetServerSetup (mqctx, ServerSetup, NULL, NULL, NULL);

  // cast the libmqmsgque-context into the MyLoopServerC-context
  MyLoopServerC* mqctxC = (MyLoopServerC*)mqctx;

  // initialize the "mydata" attribute
  strncpy(mqctxC->mydata,"Hello World",mydata_size);
  mqctxC->mydata[mydata_size-1] = '\0';

  return MK_OK;
}

See also

MkObjectC ContextCreate

Example from MyLoopServer.c → create and access class-attribute mydata as instance-storage

#include "common.h"

// [MyLoopServerC_Define]
typedef struct MyLoopServerS {
  struct MqContextS mqctx;    ///< link to the \libmqmsgque object
  #define mydata_size 30
  char mydata[mydata_size];   ///< define the "mydata" attribute
} MyLoopServerC;  
// [MyLoopServerC_Define]

// the MyLoopServerC class-type
static MkThreadLocal MK_TYP MyLoopServerCTT = NULL;

// service to serve all EXTERNAL requests for token "HLWO"
static enum MkErrorE HLWO_srv ( MQ_SERVICE_CALL_ARGS ) {
  // get the "loopback" context
  MQ_CTX loop = MqSlaveGet_e(mqctx,MQ_SLAVE_LOOPBACK);
  // call the LOOP service on the SAME server
  MqSend_E(loop,"W","LOOP");
  // answer HLWO with string-return from LOOP
  MqSend_E(mqctx, "R", "C", MqReadSTR_e(loop));
  return MK_OK;
error:
  return MqSendRETURN(mqctx);
}

// service to serve all INTERNAL requests for token "LOOP
static enum MkErrorE LOOP_srv ( MQ_SERVICE_CALL_ARGS ) {
  // get the "master" context 
  MyLoopServerC* master = (MyLoopServerC*)MqSlaveGetMaster(mqctx);
  // answer LOOP with data from MASTER->mydata attribute
  return MqSend(mqctx, "R", "C", master->mydata);
}

// define a service as link between the token "HLWO" and the callback "HLWO_srv"
static enum MkErrorE ServerSetup ( MQ_SERVICE_CALL_ARGS ) {
  // EXTERNAL: link the "HLWO" service with "HLWO_srv"
  MqServiceCreate_E(mqctx, "HLWO", HLWO_srv, NULL, NULL, NULL);
  // INTERNAL: link the "LOOP" service with "LOOP_srv"
  MqServiceCreate_E(MqSlaveGet_e(mqctx,MQ_SLAVE_LOOPBACK), "LOOP", LOOP_srv, NULL, NULL, NULL);
  return MK_OK;
error:
  return MkErrorStack_1X(mqctx);
}

// [MyLoopServerC_Create]
enum MkErrorE
MyLoopServerFactory ( MQ_CALLBACK_FACTORY_CTOR_ARGS )
{ 
  // create new instance using the MyLoopServerCTT class-type
  MQ_CTX const mqctx = *contextP = MqContextCreate(MyLoopServerCTT,tmpl);

  // initialize the new context
  MqConfigSetServerSetup (mqctx, ServerSetup, NULL, NULL, NULL);

  // cast the libmqmsgque-context into the MyLoopServerC-context
  MyLoopServerC* mqctxC = (MyLoopServerC*)mqctx;

  // initialize the "mydata" attribute
  strncpy(mqctxC->mydata,"Hello World",mydata_size);
  mqctxC->mydata[mydata_size-1] = '\0';

  return MK_OK;
}
// [MyLoopServerC_Create]

int main (int argc, MK_STRN argv[]) 
{
  AllRtSetup_NULL;

  // [MyLoopServerC_Init]
  // initialize the MyLoopServer class-type with existing MqContextC_TT class-type
  MyLoopServerCTT = MkTypeDup2(MqContextC_TT,"MyLoopServerC");
  MyLoopServerCTT->objsize = sizeof(struct MyLoopServerS);
  // [MyLoopServerC_Init]

  // setup commandline arguments for later use
  MK_BFL largv = MkBufferListCreateVC(argc, argv);
  MQ_CTX mqctx = NULL;

  // create "MyLoopServer" factory… and make it to the default.
  MqFactoryDefault(MqFactoryAdd_2(MyLoopServerFactory,"MyLoopServer"));
  // inspect commandline-argument for the "factory" to choose… and create a object
  MqFactoryNew_E (MqFactoryGetCalledL(largv), NULL, &mqctx);

  // start listen for incoming call's
  MqLinkCreate_E (mqctx, largv);
  MqCheckForLeftOverArguments_E (mqctx, largv);
  MqProcessEvent_E (mqctx,MQ_WAIT_FOREVER,MK_TIMEOUT_DEFAULT);
error:
  MkBufferListDelete(largv);
  MqExit_1(mqctx);
}