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tdelibs/tdecore/network/kresolverworkerbase.h

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/* -*- C++ -*-
* Copyright (C) 2003,2004 Thiago Macieira <thiago.macieira@kdemail.net>
*
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef KRESOLVERWORKERBASE_H
#define KRESOLVERWORKERBASE_H
#include "kresolver.h"
// forward declarations
class TQString;
template <class T> class TQValueList;
namespace KNetwork {
namespace Internal
{
class KResolverThread;
struct InputData;
}
/** @internal
* This class is the base functionality for a resolver worker. That is,
* the class that does the actual work.
*
* In the future, this class might be exposed to allow plug-ins. So, try and
* make it binary compatible.
*
* Note that hostnames are still encoded in Unicode at this point. It's up to
* the worker class to decide which encoding to use. In the case of DNS,
* an ASCII Compatible Encoding (ACE) must be used.
* See @ref KResolver::domainToAscii.
*
* Also specially note that the run method in this class is called in a
* thread that is not the program's main thread. So do not do anything there
* that you shouldn't!
*
* @class KResolverWorkerBase kresolverworkerbase.h kresolverworkerbase.h
*/
class KResolverWorkerBase
{
public:
/**
* Helper class for locking the resolver subsystem.
* Similar to TQMutexLocker.
*
* @author Luís Pedro Coelho
* @since 3.4
*/
class ResolverLocker
{
public:
/**
* Constructor. Acquires a lock.
*/
ResolverLocker(KResolverWorkerBase* parent)
: parent( parent )
{
parent->acquireResolver();
}
/**
* Destructor. Releases the lock.
*/
~ResolverLocker()
{
parent->releaseResolver();
}
/**
* Releases the lock and then reacquires it.
* It may be necessary to call this if the resolving function
* decides to retry.
*/
void openClose()
{
parent->releaseResolver();
parent->acquireResolver();
}
private:
/// @internal
KResolverWorkerBase* parent;
};
private:
// this will be like our d pointer
KNetwork::Internal::KResolverThread *th;
const KNetwork::Internal::InputData *input;
friend class KNetwork::Internal::KResolverThread;
friend class KNetwork::Internal::KResolverManager;
friend class KResolverWorkerBase::ResolverLocker;
int m_finished : 1;
int m_reserved : 31; // reserved
public:
/**
* Derived classes will put their resolved data in this list, or will
* leave it empty in case of error.
*
* Status and error codes should also be stored in this object (the
* @ref setError function does that).
*/
KResolverResults results;
public:
// default constructor
KResolverWorkerBase();
// virtual destructor
virtual ~KResolverWorkerBase();
/**
* This is the hostname to be looked for
*/
TQString nodeName() const;
/**
* And this is the service name
*/
TQString serviceName() const;
/**
* gets the flags
*/
int flags() const;
/**
* gets the family mask
*/
int familyMask() const;
/**
* gets the socket type
*/
int socketType() const;
/**
* gets the protocol number
*/
int protocol() const;
/**
* gets the protocol name, if applicable
*/
TQCString protocolName() const;
/**
* Call this function to indicate that processing
* has finished. This is useful in the preprocessing
* stage, to indicate that @ref run doesn't have to be
* called.
*/
void finished();
protected:
// like a QThread
/**
* This is the function that should be overriden in derived classes.
*
* Derived classes will do their blocking job in this function and return
* either success or failure to work (not the lookup). That is, whether the
* lookup result was a domain found or not, if we got our answer, we should
* indicate success. The error itself must be set with @ref setError.
*
* \b Important: this function gets called in a separate thread!
*
* @return true on success
*/
virtual bool run() = 0;
/**
* This function gets called during pre processing for this class and you must
* override it.
*
* \b Important: this function gets called in the main event thread. And it MUST
* NOT block.
*
* This function can be used for an object to determine if it will be able
* to resolve the given data or not even before launching into a blocking
* operation. This function should return true if the object is capable of
* handling this kind of data; false otherwise. Note that the return value
* of 'true' means that the object's blocking answer will be considered authoritative.
*
* This function MUST NOT queue further requests. Leave that to @ref run.
*
* This function is pure virtual; you must override it.
*
* @return true on success
*/
virtual bool preprocess() = 0;
/**
* This function gets called during post processing for this class.
*
* \b Important: this function gets called in the main event thread. And it MUST
* NOT block.
*
* @returns true on success
*/
virtual bool postprocess();
/**
* Sets the error
*/
inline void setError(int errorcode, int syserror = 0)
{ results.setError(errorcode, syserror); }
/**
* Enqueue the given resolver for post-processing.
*
* Use this function to make the manager call for another resolution.
* This is suitable for workers that do post-processing.
*
* The manager will make sure that any requests enqueued by this function
* are done before calling the postprocessing function, which you should
* override.
*
* \b Important: do use KResolver's own enqueueing functions (i.e., @ref KResolver::start).
* Instead, use this function.
*
* @returns true on successful queueing or false if a problem ocurred
*/
bool enqueue(KResolver* other);
/**
* @overload
*/
bool enqueue(KResolverWorkerBase* worker);
/**
* Checks the resolver subsystem status.
* @returns true if the resolver subsystem changed, false otherwise.
* If this function returns true, it might be necessary to
* restart the resolution altogether.
* @since 3.4
*/
bool checkResolver();
/**
* This function has to be called from the resolver workers that require
* use of the DNS resolver code (i.e., res_* functions, generally in
* libresolv). It indicates that the function is starting a resolution
* and that the resolver backend shouldn't change asynchronously.
*
* If any pending res_init's are required, they will be performed before
* this function returns.
*
* @since 3.4
*/
void acquireResolver();
/**
* This function is the counterpart for @ref acquireResolver: the worker
* thread indicates that it's done with the resolver.
*
* @since 3.4
*/
void releaseResolver();
};
/** @internal
* This class provides functionality for creating and registering worker classes.
*
* @class KResolverWorkerFactoryBase kresolverworkerbase.h kresolverworkerbase.h
*/
class KResolverWorkerFactoryBase
{
public:
// default constructor
KResolverWorkerFactoryBase();
// virtual destructor
virtual ~KResolverWorkerFactoryBase();
virtual KResolverWorkerBase* create() const = 0;
/**
* Wrapper call to register workers
*
* It is NOT thread-safe!
*/
static void registerNewWorker(KResolverWorkerFactoryBase* factory);
};
/** @internal
* This class provides functionality for creating and registering worker classes.
*
* @class KResolverWorkerFactory kresolverworkerbase.h kresolverworkerbase.h
*/
template<class Worker>
class KResolverWorkerFactory: public KResolverWorkerFactoryBase
{
public:
virtual KResolverWorkerBase* create() const
{ return new Worker; }
};
} // namespace KNetwork
#endif