<<extern>>

The <<extern>> directive allows for reflecting pre-existing data types and functions.

For example the PersistStore library uses the following declarations to reflect LSS data types

$struct+ LssSettings <<extern>>
{
    $int32 flushTimeMilliSec;
    $float64 cleanerUtilisationPercent;
    $bool enableFileBuffering;
    $bool enableWriteThrough;
    $int32 maxNumSegmentsInCache;
    $int32 numSegmentsPerCheckPoint;
    $int32 segmentSize;
    $bool forceIncrementMSSN;
    $bool validateSUTDuringCheckPoint;
};

$enum+ EOpenMode <<extern>>
{
    OM_CREATE_NEW,
    OM_CREATE_ALWAYS,
    OM_OPEN_EXISTING,
    OM_OPEN_EXISTING_READ_ONLY,
    OM_OPEN_EXISTING_SHARED_READ,
    OM_OPEN_ALWAYS,
    OM_DELETE_EXISTING,
};

As another example the cxWorkingSetIpc has the following declarations to reflect datatypes and functions defined in the cxMessage library:

$struct+ MessageWriterSettings <<extern>>
{
    $ssize_t lowerHysteresisSendSize;
    $ssize_t upperHysteresisSendSize;
    $ssize_t normalCommitBufferSize;
    $ssize_t sendSizeUntilBackToNormalBufferSize;
    $ssize_t maxSendSize;
};

$struct+ MessageReaderSettings <<extern>>
{
    $ssize_t normalCommitBufferSize;
    $ssize_t maxMsgSize;
    $ssize_t maxRecvSize;
};

$struct+ TcpSettings <<extern>>
{
    $ssize_t sendBufSize;
    $ssize_t recBufSize;
    $bool enableNagle;
    $bool enableKeepAlive;
    $int32 keepalivetime;
    $int32 keepaliveinterval;
};

$struct+ TcpMsgSessionSettings <<extern>>
{
    $TcpSettings tcpSettings;
    $MessageReaderSettings msgReaderSettings;
    $MessageWriterSettings msgWriterSettings;
};

$enum+ EProtocol <<extern>>
{
    TCP_IPv4,
    TCP_IPv6
};

$enum+ ESessionFailureType <<extern>>
{
    Session,
    SessionRead,
    SessionWrite
};

$enum+ EEndPointFailureType <<extern>>
{
    Open,
    Close,
    SetOption,
    Bind,
    Listen,
    Accept,
    Connect
};

$struct+ ITcpMsgEndPoint <<extern -dc -copy>> {};
$class+ IoContextPool {};
$class+ TcpMsgServer {};
$class+ TcpMsgClient {};

$function+ <<extern>> IoContextPool* CreateIoContextPool(int32 numThreads);

$function+ void CloseIoContextPool(IoContextPool* pool);

$function+ <<extern>> TcpMsgServer* CreateTcpMsgServer(
    IoContextPool* pool,
    EProtocol protocol,
    int32 port,
    bool reuse_addr, 
    ITcpMsgEndPoint& ep,
    const TcpMsgSessionSettings& sessionSettings);

$function+ void CloseTcpMsgServer(TcpMsgServer* server);

$function+ <<extern>> TcpMsgClient* CreateTcpMsgClient(
    IoContextPool* pool,
    ConstStringZ host,
    ConstStringZ service,
    ITcpMsgEndPoint& ep,
    const TcpMsgSessionSettings& sessionSettings);

$function+ void CloseTcpMsgClient(TcpMsgClient* client);