[thirdparty/squid.git] / src / base / Subscription.h

#ifndef _SQUID_BASE_SUBSCRIPTION_H
#define _SQUID_BASE_SUBSCRIPTION_H

#include "base/AsyncCall.h"

/** API for creating a series of AsyncCalls.
 * This is necessary because the same AsyncCall callback must not be
 * fired multiple times.
 *
 * The call producer needs to accept and store a Subscription::Pointer.
 * It also should provide some mechanism for adding/removing/changing
 * the stored Subscription::Pointer.
 *
 * The callback() method of Subscription::Pointer will spawn AsyncCall
 * to be filled out and scheduled as needed.
 */
class Subscription: public RefCountable
{
public:
    typedef RefCount<Subscription> Pointer;

    /** returns a call object to be used for the next call back.
     * Child implementations must ensure the Call pointer produced
     * is not NULL.
     */
    virtual AsyncCall::Pointer callback() const = 0;
};

/** Implements Subscription API using Call's copy constructor.
 *
 * The subscriber creates one of these using a specific callback
 * type and instance. The subscription object is then passed to a
 * producer/factory which will use this API to generate calls.
 * A subscription may be passed to multiple producers.
 *
 * Call_ must have a copy constructor.
 * A pointer to Call_ must be convertable to AsyncCall::Pointer
 */
template<class Call_>
class CallSubscription: public Subscription
{
public:
    /// Must be passed an object. nil pointers are not permitted.
    explicit CallSubscription(const RefCount<Call_> &aCall) : call(aCall) { assert(aCall != NULL); }
    virtual AsyncCall::Pointer callback() const { return new Call_(call); }

private:
    const RefCount<Call_> call; ///< gets copied to create callback calls
};

#endif /* _SQUID_BASE_SUBSCRIPTION_H */
Commit	Line	Data
3cb19943 AJ	1	#ifndef _SQUID_BASE_SUBSCRIPTION_H
	2	#define _SQUID_BASE_SUBSCRIPTION_H
	3
	4	#include "base/AsyncCall.h"
	5
	6	/** API for creating a series of AsyncCalls.
	7	* This is necessary because the same AsyncCall callback must not be
	8	* fired multiple times.
	9	*
	10	* The call producer needs to accept and store a Subscription::Pointer.
	11	* It also should provide some mechanism for adding/removing/changing
	12	* the stored Subscription::Pointer.
	13	*
	14	* The callback() method of Subscription::Pointer will spawn AsyncCall
	15	* to be filled out and scheduled as needed.
	16	*/
	17	class Subscription: public RefCountable
	18	{
	19	public:
	20	typedef RefCount<Subscription> Pointer;
	21
	22	/** returns a call object to be used for the next call back.
	23	* Child implementations must ensure the Call pointer produced
	24	* is not NULL.
	25	*/
	26	virtual AsyncCall::Pointer callback() const = 0;
	27	};
	28
	29	/** Implements Subscription API using Call's copy constructor.
	30	*
	31	* The subscriber creates one of these using a specific callback
	32	* type and instance. The subscription object is then passed to a
	33	* producer/factory which will use this API to generate calls.
	34	* A subscription may be passed to multiple producers.
	35	*
	36	* Call_ must have a copy constructor.
	37	* A pointer to Call_ must be convertable to AsyncCall::Pointer
	38	*/
	39	template<class Call_>
	40	class CallSubscription: public Subscription
	41	{
	42	public:
	43	/// Must be passed an object. nil pointers are not permitted.
	44	explicit CallSubscription(const RefCount<Call_> &aCall) : call(aCall) { assert(aCall != NULL); }
	45	virtual AsyncCall::Pointer callback() const { return new Call_(call); }
	46
	47	private:
	48	const RefCount<Call_> call; ///< gets copied to create callback calls
	49	};
	50
	51	#endif /* _SQUID_BASE_SUBSCRIPTION_H */