ACE_Remote_Token_Proxy(3)

NAME

ACE_Remote_Token_Proxy - Proxy for acquiring, renewing, and releasing a distributed synchronization token.

SYNOPSIS

#include <ACE/Remote_Tokens.h>
class ACE_Remote_Token_Proxy : public ACE_Token_Proxy
{
  public:
    ACE_Remote_Token_Proxy (void);
    virtual ~ACE_Remote_Token_Proxy (void);
    int open (
        const ASYS_TCHAR *name,
        int ignore_deadlock = 0,
        int debug = 0
        );
    int initiate_connection (void);
    virtual int acquire (int notify = 0, void (*sleep_hook)(
        void *) = 0,
        ACE_Synch_Options &options = ACE_Synch_Options::synch
        );
    virtual int tryacquire (void (*sleep_hook)(void *) = 0);
    virtual int renew (
        int requeue_position = 0,
        ACE_Synch_Options &options = ACE_Synch_Options::synch
        );
    ACE_Synch_Options::synch);
    ACE_Synch_Options::synch);
    virtual void token_acquired (ACE_TPQ_Entry *);
    virtual const ASYS_TCHAR* owner_id (void);
    static void set_server_address (
        const ACE_INET_Addr &server_address
        );
    void dump (void) const;
  protected:
    int ignore_shadow_deadlock_;
    int request_reply (
        ACE_Token_Request &request,
        ACE_Synch_Options &options
        );
};

DESCRIPTION

The Remote_Token_Proxy class implements the mechanisms for distributed token operations. It is similar to the ACE_Token_Proxy.

PUBLIC MEMBERS

ACE_Remote_Token_Proxy (void);

Null construction.

virtual ~ACE_Remote_Token_Proxy (void);

Death.

int open (
    const ASYS_TCHAR *name,
    int ignore_deadlock = 0,
    int debug = 0
    );

Same as Token_Proxy. name is the string uniquely identifying the token. ignore_deadlock can be 1 to disable deadlock notifications. debug prints debug messages.

int initiate_connection (void);

Open a connection with the token server. This only need be used when the user wishes to explicitly open a connection to check if the server exists. Connections are stored in the ACE_Token_Connections singleton as thread-specific data. That is, every thread has only one connection that is used for all remote tokens.

virtual int acquire (int notify = 0, void (*sleep_hook)(
    void *) = 0,
    ACE_Synch_Options &options = ACE_Synch_Options::synch
    );

Acquire the distributed token. If notify is specified and the token is already held, the owner is notified. options contains the timeout value for the acquire call. The timer is kept at the token server. Asynchronous operations are not supported. Returns 0 on success, -1 on failure with errno == problem.

virtual int tryacquire (void (*sleep_hook)(void *) = 0);

Try to acquire the distributed token. If the token is already held, the call returns without queueing the caller as a waiter. Returns 0 on success (the token was acquired), and -1 with EWOULDBLOCK if the token was already held.

virtual int renew (
    int requeue_position = 0,
    ACE_Synch_Options &options = ACE_Synch_Options::synch
    );

Renew the token by offering to release it if there are any other waiters, otherwise get the token back immediately. This renew has the same semantics as ACE_Local_Mutex release. It is semantically equivalent to release followed by acquire, but it is faster. options contains the timeout value used if renew blocks. As with acquire, the timer is maintained at the token server. If there are waiters and requeue_position == -1, the caller is queued at the rear of the waiter list. Otherwise, requeue_position specifies the number of waiters to "let by" before reacquiring the token (effectively, the position in the waiter list.)

ACE_Synch_Options::synch);

Release the distributed token. Similar to ACE_Local_Mutex, if the caller is not the owner, it is removed from the waiter list (if applicable.) Returns 0 on success, -1 on failure with errno == problem.

ACE_Synch_Options::synch);

Become interface compliant for ACE_Guard. This has no functionality.

virtual void token_acquired (ACE_TPQ_Entry *);

Override the default to do nothing.

virtual const ASYS_TCHAR* owner_id (void);

the client id of the current token holder

static void set_server_address (const ACE_INET_Addr &server_address);

sets the server address for all instances of ACE_Remote_Token_Proxy If this isn't called, the environment variable TOKEN_SERVER is checked for the server address. If that is not specified, all ACE_Remote_** operations will fail.

void dump (void) const;

Dump the state of the class.

PROTECTED MEMBERS

int ignore_shadow_deadlock_;

if shadows report deadlock, go remote anyway

int request_reply (
    ACE_Token_Request &request,
    ACE_Synch_Options &options
    );

Perform the request and wait for the reply.

AUTHOR

Douglas C. Schmidt ([email protected]) and Tim Harrison ([email protected])

BUGS

Distributed sleep_hooks have not been implemented. owner_id is not implemented.

LIBRARY

ACE