Reading Data

Last updated: 2021-01-04 14:35:23

    Prerequisites

    You have created a cluster, a table group and the PLAYERONLINECNT table.

    The description file table_test.xml of the PLAYERONLINECNT table is as follows:

    <?xml version="1.0" encoding="GBK" standalone="yes" ?>
    <metalib name="tcaplus_tb" tagsetversion="1" version="1">
    <struct name="PLAYERONLINECNT" version="1" primarykey="TimeStamp,GameSvrID" splittablekey="TimeStamp">
        <entry name="TimeStamp"         type="uint32"     desc="Measured in minutes" />
        <entry name="GameSvrID"         type="string"     size="64" />
        <entry name="GameAppID"         type="string"     size="64" desc="gameapp id" />
        <entry name="OnlineCntIOS"      type="uint32"     defaultvalue="0" desc="The number of iOS online users" />
        <entry name="OnlineCntAndroid"  type="uint32"     defaultvalue="0" desc="The number of Android online users" />
        <entry name="BinaryLen"         type="smalluint" defaultvalue="1" desc="Data length of the data source; skip the source check when the length is 0."/>
        <entry name="binary"            type="tinyint"     desc="Binary" count= "1000" refer="BinaryLen" />
        <entry name="binary2"           type="tinyint"     desc="Binary 2" count= "1000" refer="BinaryLen" />
        <entry name="strstr"            type="string"     size="64" desc="String"/>
        <index name="index_id"  column="TimeStamp"/>
    </struct>
    </metalib>

    Step 1: Define configuration parameters

    // Access address of the target cluster
    static const char DIR_URL_ARRAY[][TCAPLUS_MAX_STRING_LENGTH] =
    {
       "tcp://10.191.***.99:9999",
       "tcp://10.191.***.88:9999"
    };
    // The number of target cluster addresses
    static const int32_t DIR_URL_COUNT = 2;
    // Cluster ID of the target business
    static const int32_t APP_ID = 3;
    // Table group ID of the target business
    static const int32_t ZONE_ID = 1;
    // Target business password
    static const char * SIGNATURE = "*******";
    // Table name "PLAYERONLINECNT" of the target business
    static const char * TABLE_NAME = "PLAYERONLINECNT";

    Step 2: Initialize TcaplusAPI log handles

    Log configuration file: tlogconf.xml

    // TCaplus service log class
    TcaplusService::TLogger* g_pstTlogger;
    LPTLOGCATEGORYINST g_pstLogHandler;
    LPTLOGCTX g_pstLogCtx;
    int32_t InitLog()
    {
        // Absolute path of the log configuration file
        const char* sLogConfFile = "tlogconf.xml";
        // Log class name
        const char* sCategoryName = "mytest";
        // Initialize the log handle using the configuration file
        g_pstLogCtx = tlog_init_from_file(sLogConfFile);
        if (NULL == g_pstLogCtx)
        {
            fprintf(stderr, "tlog_init_from_file failed.\n");
            return -1;
        }
        // Get the log class
        g_pstLogHandler = tlog_get_category(g_pstLogCtx, sCategoryName);
        if (NULL == g_pstLogHandler)
        {
            fprintf(stderr, "tlog_get_category(mytest) failed.\n");
            return -2;
        }
        // Initialize the log handle
        g_pstTlogger = new TcaplusService::TLogger(g_pstLogHandler);
        if (NULL == g_pstTlogger)
        {
            fprintf(stderr, "TcaplusService::TLogger failed.\n");
            return -3;
        }
    
        return 0;
    }

    Step 3: Initialize TcaplusAPI client

    // The client main class of the TCaplus service API
    TcaplusService::TcaplusServer g_stTcapSvr;
    // Meta information for the table
    extern unsigned char g_szMetalib_tcaplus_tb[];
    LPTDRMETA g_szTableMeta = NULL;
    int32_t InitServiceAPI()
    {
        // Initialize
        int32_t iRet = g_stTcapSvr.Init(g_pstTlogger, /*module_id*/0, /*app id*/APP_ID, /*zone id*/ZONE_ID, /*signature*/SIGNATURE);
        if (0 != iRet)
        {
            tlog_error(g_pstLogHandler, 0, 0, "g_stTcapSvr.Init failed, iRet: %d.", iRet);
            return iRet;
        }
    
        // Add the directory server
        for (int32_t i = 0; i< DIR_URL_COUNT; i++)
        {
            iRet = g_stTcapSvr.AddDirServerAddress(DIR_URL_ARRAY[i]);
            if (0 != iRet)
            {
                tlog_error(g_pstLogHandler, 0, 0, "g_stTcapSvr.AddDirServerAddress(%s) failed, iRet: %d.", DIR_URL_ARRAY[i], iRet);
                return iRet;
            }
        }  
    
        // Get the meta description of the table
        g_szTableMeta = tdr_get_meta_by_name((LPTDRMETALIB)g_szMetalib_tcaplus_tb, TABLE_NAME);
        if(NULL == g_szTableMeta)
        {
            tlog_error(g_pstLogHandler, 0, 0,"tdr_get_meta_by_name(%s) failed.", TABLE_NAME);
            return -1;
        }
    
        // Register the data table (connect to the directory server, verify the password, and get the table routing) with 10-second timeout period
        iRet = g_stTcapSvr.RegistTable(TABLE_NAME, g_szTableMeta, /*timeout_ms*/10000);
        if(0 != iRet)
        {
            tlog_error(g_pstLogHandler, 0, 0, "g_stTcapSvr.RegistTable(%s) failed, iRet: %d.", TABLE_NAME, iRet);
            return iRet;
        }
    
        // Connect to all TcaplusDB proxy servers corresponding to the table
        iRet = g_stTcapSvr.ConnectAll(/*timeout_ms*/10000, 0);
        if(0 != iRet)
        {
            tlog_error(g_pstLogHandler, 0, 0, "g_stTcapSvr.ConnectAll failed, iRet: %d.", iRet);
            return iRet;
        }
    
        return 0;
    }

    Step 4. Send a get request via the API

    int32_t SendGetRequest()
    {
        // Request object class
        TcaplusService::TcaplusServiceRequest* pstRequest = g_stTcapSvr.GetRequest(TABLE_NAME);
        if (NULL == pstRequest)
        {
            tlog_error(g_pstLogHandler, 0, 0, "g_stTcapSvr.GetRequest(%s) failed.", TABLE_NAME);
            return -1;
        }
    
        // Initialize the request object
        int iRet = pstRequest->Init(TCAPLUS_API_GET_REQ, NULL, 0, 0, 0, 0);
        if(0 != iRet)
        {
            tlog_error(g_pstLogHandler, 0, 0, "pstRequest->Init(TCAPLUS_API_GET_REQ) failed, iRet: %d.", iRet);
            return iRet;
        }
    
        // Add a record to the table according to the request
        TcaplusService::TcaplusServiceRecord* pstRecord = pstRequest->AddRecord();
        if (NULL == pstRecord)
        {
            tlog_error(g_pstLogHandler, 0, 0, "pstRequest->AddRecord() failed.");
            return -1;
        }
    
        PLAYERONLINECNT stPLAYERONLINECNT;
        memset(&stPLAYERONLINECNT, 0, sizeof(stPLAYERONLINECNT));
    
        // Specify the information of the key to be queried
        stPLAYERONLINECNT.dwTimeStamp = 1;
        snprintf(stPLAYERONLINECNT.szGameSvrID, sizeof(stPLAYERONLINECNT.szGameSvrID), "%s", "mysvrid");
    
        // Set the record based on the TDR description
        iRet = pstRecord->SetData(&stPLAYERONLINECNT, sizeof(stPLAYERONLINECNT));
        if(0 != iRet)
        {
            tlog_error(g_pstLogHandler, 0, 0, "pstRecord->SetData() failed, iRet: %d.", iRet);
            return iRet;
        }
    
        // Send the request packet
        iRet= g_stTcapSvr.SendRequest(pstRequest);
        if(0 != iRet)
        {
            tlog_error(g_pstLogHandler, 0, 0, "g_stTcapSvr.SendRequest failed, iRet: %d.", iRet);
            return iRet;
        }
        return 0;
    }

    Step 5. Receive the response via the API

    int RecvResp(TcaplusServiceResponse*& response)
    {
        // Block the reception of response packets 5,000 times with each block lasting for 1 ms
        unsigned int sleep_us = 1000;
        unsigned int sleep_count = 5000;
        do
        {
            usleep(sleep_us);
            response = NULL;
            int ret = g_stTcapSvr.RecvResponse(response);
            if (ret < 0)
            {
                tlog_error(g_pstLogHandler, 0, 0, "tcaplus_server.RecvResponse failed. ret:%d", ret);
                return ret;
            }
    
            // Receive a response packet
            if (1 == ret)
            {
                 break;
            }
        } while ((--sleep_count) > 0);
    
        // Timeout period: 5 seconds
        if (0 == sleep_count)
        {
            tlog_error(g_pstLogHandler, 0, 0, "tcaplus_server.RecvResponse wait timeout.");
            return -1;
        }
        return 0;
    }

    Samples

    Please refer to main.cpp.

    int main(void) {
        // Initialize the log
        int ret = InitLog();
        if (ret != 0)
        {
            printf("init log failed\n");
            return -1;
        }
    
        // Initialize the API client
        ret = InitServiceAPI();
        if ( ret != 0)
        {
            printf("init InitServiceAPI failed\n");
            return -1;
        }
    
        // Send the request
        ret = SendGetRequest();
        if (0 != ret)
        {
            printf("SendGetRequest failed\n");
            return -1;
        }
    
        // Receive the response
        TcaplusServiceResponse* response = NULL;
        ret = RecvResp(response);
        if (0 != ret)
        {
            printf("RecvResp failed\n");
            return -1;
        }
    
        // Get the result, where "0" indicates success
        int32_t result = response->GetResult();
        if (0 != result)
        {
            printf("the result is %d\n", result);
            return -1;
        }
    
        // Get the record in the response
        // Use "batch" command if there are multiple records in the response
        int count = 0;
        const TcaplusService::TcaplusServiceRecord* const_record = NULL;
        while((count++) < response->GetRecordCount())
        {
            // Read the record
            const_record = NULL;
            printf("---   ---   %3d   ---   ---\n", count - 1);
            ret = response->FetchRecord(const_record);
            if(0 != ret)
            {
                printf("FetchRecord() ret:%d\n", ret);
                continue;
            }
    
            // Assign the record to the structure
            PLAYERONLINECNT stPLAYERONLINECNT;
            memset(&stPLAYERONLINECNT, 0, sizeof(stPLAYERONLINECNT));
            ret = const_record->GetData(&stPLAYERONLINECNT, sizeof(stPLAYERONLINECNT));
            if(0 != ret)
            {
                printf("const_record->GetData() failed, ret: %d.", ret);
                continue;
            }
    
            // Print the values in the structure
            printf("struct dwTimeStamp %d szGameSvrID %s szGameAppID %s dwOnlineCntIOS %d dwOnlineCntAndroid %d \n",
                stPLAYERONLINECNT.dwTimeStamp,
                stPLAYERONLINECNT.szGameSvrID,
                stPLAYERONLINECNT.szGameAppID,
                stPLAYERONLINECNT.dwOnlineCntIOS,
                stPLAYERONLINECNT.dwOnlineCntAndroid);
        }
        return 0;
    }