A DataPoint represents a data resource and is an abstraction of a URL. More...

#include <arc/data/DataPoint.h>

Inheritance diagram for Arc::DataPoint:

Public Types
enum	DataPointAccessLatency { ACCESS_LATENCY_ZERO, ACCESS_LATENCY_SMALL, ACCESS_LATENCY_LARGE }
	Describes the latency to access this URL. More...

enum	DataPointInfoType { INFO_TYPE_MINIMAL = 0, INFO_TYPE_NAME = 1, INFO_TYPE_TYPE = 2, INFO_TYPE_TIMES = 4, INFO_TYPE_CONTENT = 8, INFO_TYPE_ACCESS = 16, INFO_TYPE_STRUCT = 32, INFO_TYPE_REST = 64, INFO_TYPE_ALL = 127 }
	Describes type of information about URL to request. More...

typedef void(*	Callback3rdParty )(unsigned long long int bytes_transferred)
	Callback for use in 3rd party transfer. More...

Public Member Functions
virtual	~DataPoint ()
	Destructor.

virtual const URL &	GetURL () const
	Returns the URL that was passed to the constructor.

virtual const UserConfig &	GetUserConfig () const
	Returns the UserConfig that was passed to the constructor.

virtual bool	SetURL (const URL &url)
	Assigns new URL. More...

virtual std::string	str () const
	Returns a string representation of the DataPoint.

virtual	operator bool () const
	Is DataPoint valid?

virtual bool	operator! () const
	Is DataPoint valid?

virtual DataStatus	PrepareReading (unsigned int timeout, unsigned int &wait_time)
	Prepare DataPoint for reading. More...

virtual DataStatus	PrepareWriting (unsigned int timeout, unsigned int &wait_time)
	Prepare DataPoint for writing. More...

virtual DataStatus	StartReading (DataBuffer &buffer)=0
	Start reading data from URL. More...

virtual DataStatus	StartWriting (DataBuffer &buffer, DataCallback *space_cb=NULL)=0
	Start writing data to URL. More...

virtual DataStatus	StopReading ()=0
	Stop reading. More...

virtual DataStatus	StopWriting ()=0
	Stop writing. More...

virtual DataStatus	FinishReading (bool error=false)
	Finish reading from the URL. More...

virtual DataStatus	FinishWriting (bool error=false)
	Finish writing to the URL. More...

virtual DataStatus	Check (bool check_meta)=0
	Query the DataPoint to check if object is accessible. More...

virtual DataStatus	Remove ()=0
	Remove/delete object at URL.

virtual DataStatus	Stat (FileInfo &file, DataPointInfoType verb=INFO_TYPE_ALL)=0
	Retrieve information about this object. More...

virtual DataStatus	Stat (std::list< FileInfo > &files, const std::list< DataPoint * > &urls, DataPointInfoType verb=INFO_TYPE_ALL)=0
	Retrieve information about several DataPoints. More...

virtual DataStatus	List (std::list< FileInfo > &files, DataPointInfoType verb=INFO_TYPE_ALL)=0
	List hierarchical content of this object. More...

virtual DataStatus	CreateDirectory (bool with_parents=false)=0
	Create a directory. More...

virtual DataStatus	Rename (const URL &newurl)=0
	Rename a URL. More...

virtual void	ReadOutOfOrder (bool v)=0
	Allow/disallow DataPoint to read data out of order. More...

virtual bool	WriteOutOfOrder ()=0
	Returns true if DataPoint supports receiving data out of order during writing.

virtual void	SetAdditionalChecks (bool v)=0
	Allow/disallow additional checks on a source DataPoint before transfer. More...

virtual bool	GetAdditionalChecks () const =0
	Returns true unless SetAdditionalChecks() was set to false.

virtual void	SetSecure (bool v)=0
	Allow/disallow heavy security (data encryption) during data transfer. More...

virtual bool	GetSecure () const =0
	Returns true if heavy security during data transfer is allowed.

virtual void	Passive (bool v)=0
	Set passive transfers for FTP-like protocols. More...

virtual DataStatus	GetFailureReason (void) const
	Returns reason of transfer failure, as reported by callbacks. More...

virtual void	Range (unsigned long long int start=0, unsigned long long int end=0)=0
	Set range of bytes to retrieve. More...

virtual DataStatus	Resolve (bool source)=0
	Resolves index service URL into list of ordinary URLs. More...

virtual DataStatus	Resolve (bool source, const std::list< DataPoint * > &urls)=0
	Resolves several index service URLs. More...

virtual bool	Registered () const =0
	Returns true if file is registered in indexing service (only known after Resolve())

virtual DataStatus	PreRegister (bool replication, bool force=false)=0
	Index service pre-registration. More...

virtual DataStatus	PostRegister (bool replication)=0
	Index service post-registration. More...

virtual DataStatus	PreUnregister (bool replication)=0
	Index service pre-unregistration. More...

virtual DataStatus	Unregister (bool all)=0
	Index service unregistration. More...

virtual bool	CheckSize () const
	Check if meta-information 'size' is available.

virtual void	SetSize (const unsigned long long int val)
	Set value of meta-information 'size'.

virtual unsigned long long int	GetSize () const
	Get value of meta-information 'size'.

virtual bool	CheckCheckSum () const
	Check if meta-information 'checksum' is available.

virtual void	SetCheckSum (const std::string &val)
	Set value of meta-information 'checksum'.

virtual const std::string &	GetCheckSum () const
	Get value of meta-information 'checksum'.

virtual const std::string	DefaultCheckSum () const
	Default checksum type (varies by protocol)

virtual bool	CheckModified () const
	Check if meta-information 'modification time' is available.

virtual void	SetModified (const Time &val)
	Set value of meta-information 'modification time'.

virtual const Time &	GetModified () const
	Get value of meta-information 'modification time'.

virtual bool	CheckValid () const
	Check if meta-information 'validity time' is available.

virtual void	SetValid (const Time &val)
	Set value of meta-information 'validity time'.

virtual const Time &	GetValid () const
	Get value of meta-information 'validity time'.

virtual void	SetAccessLatency (const DataPointAccessLatency &latency)
	Set value of meta-information 'access latency'.

virtual DataPointAccessLatency	GetAccessLatency () const
	Get value of meta-information 'access latency'.

virtual long long int	BufSize () const =0
	Get suggested buffer size for transfers.

virtual int	BufNum () const =0
	Get suggested number of buffers for transfers.

virtual bool	Cache () const
	Returns true if file is cacheable.

virtual bool	Local () const =0
	Returns true if file is local, e.g. file:// urls.

virtual bool	ReadOnly () const =0
	Returns true if file is readonly.

virtual int	GetTries () const
	Returns number of retries left.

virtual void	SetTries (const int n)
	Set number of retries.

virtual void	NextTry ()
	Decrease number of retries left.

virtual bool	RequiresCredentials () const
	Returns true if some kind of credentials are needed to use this DataPoint.

virtual bool	IsIndex () const =0
	Check if URL is an Indexing Service.

virtual bool	IsStageable () const
	Check if URL should be staged or queried for Transport URL (TURL)

virtual bool	AcceptsMeta () const =0
	Check if endpoint can have any use from meta information.

virtual bool	ProvidesMeta () const =0
	Check if endpoint can provide at least some meta information directly.

virtual void	SetMeta (const DataPoint &p)
	Copy meta information from another object. More...

virtual bool	CompareMeta (const DataPoint &p) const
	Compare meta information from another object. More...

virtual std::vector< URL >	TransferLocations () const
	Returns physical file(s) to read/write, if different from CurrentLocation() More...

virtual const URL &	CurrentLocation () const =0
	Returns current (resolved) URL.

virtual const std::string &	CurrentLocationMetadata () const =0
	Returns meta information used to create current URL. More...

virtual DataPoint *	CurrentLocationHandle () const =0
	Returns a pointer to the DataPoint representing the current location.

virtual DataStatus	CompareLocationMetadata () const =0
	Compare metadata of DataPoint and current location. More...

virtual bool	NextLocation ()=0
	Switch to next location in list of URLs. More...

virtual bool	LocationValid () const =0
	Returns false no more locations are left and out of retries.

virtual bool	LastLocation ()=0
	Returns true if the current location is the last.

virtual bool	HaveLocations () const =0
	Returns true if number of resolved URLs is not 0.

virtual DataStatus	AddLocation (const URL &url, const std::string &meta)=0
	Add URL representing physical replica to list of locations. More...

virtual DataStatus	RemoveLocation ()=0
	Remove current URL from list.

virtual DataStatus	RemoveLocations (const DataPoint &p)=0
	Remove locations present in another DataPoint object.

virtual DataStatus	ClearLocations ()=0
	Remove all locations.

virtual int	AddCheckSumObject (CheckSum *cksum)=0
	Add a checksum object which will compute checksum during data transfer. More...

virtual const CheckSum *	GetCheckSumObject (int index) const =0
	Get CheckSum object at given position in list.

virtual void	SortLocations (const std::string &pattern, const URLMap &url_map)=0
	Sort locations according to the specified pattern and URLMap. More...

virtual void	AddURLOptions (const std::map< std::string, std::string > &options)
	Add URL options to this DataPoint's URL object. More...

Static Public Member Functions
static DataStatus	Transfer3rdParty (const URL &source, const URL &destination, const UserConfig &usercfg, Callback3rdParty callback=NULL)
	Perform third party transfer. More...

Protected Member Functions
	DataPoint (const URL &url, const UserConfig &usercfg, PluginArgument *parg)
	Constructor. More...

virtual DataStatus	Transfer3rdParty (const URL &source, const URL &destination, Callback3rdParty callback=NULL)
	Perform third party transfer. More...

Protected Attributes
URL	url
	URL supplied in constructor.

const UserConfig	usercfg
	UserConfig supplied in constructor.

unsigned long long int	size
	Size of object represented by DataPoint.

std::string	checksum
	Checksum of object represented by DataPoint.

Time	modified
	Modification time of object represented by DataPoint.

Time	valid
	Validity time of object represented by DataPoint.

DataPointAccessLatency	access_latency
	Access latency of object represented by DataPoint.

int	triesleft
	Retries left for data transfer.

DataStatus	failure_code
	Result of data read/write carried out in separate thread.

bool	cache
	Whether this DataPoint is cacheable.

bool	stageable
	Whether this DataPoint requires staging.

std::set< std::string >	valid_url_options
	Valid URL options. Subclasses should add their own specific options to this list.

Static Protected Attributes
static Logger	logger
	Logger object.

Detailed Description

A DataPoint represents a data resource and is an abstraction of a URL.

DataPoint uses ARC's Plugin mechanism to dynamically load the required Data Manager Component (DMC) when necessary. A DMC typically defines a subclass of DataPoint (e.g. DataPointHTTP) and is responsible for a specific protocol (e.g. http). DataPoints should not be used directly, instead the DataHandle wrapper class should be used, which automatically loads the correct DMC. Examples of how to use DataPoint methods are shown in the DataHandle documentation.

DataPoint defines methods for access to the data resource. To transfer data between two DataPoints, DataMover::Transfer() can be used.

There are two subclasses of DataPoint, DataPointDirect and DataPointIndex. None of these three classes can be instantiated directly. DataPointDirect and its subclasses handle "physical" resources through protocols such as file, http and gsiftp. These classes implement methods such as StartReading() and StartWriting(). DataPointIndex and its subclasses handle resources such as indexes and catalogs and implement methods like Resolve() and PreRegister().

When creating a new DMC, a subclass of either DataPointDirect or DataPointIndex should be created, and the appropriate methods implemented. DataPoint itself has no direct external dependencies, but plugins may rely on third-party components. The new DMC must also add itself to the list of available plugins and provide an Instance() method which returns a new instance of itself, if the supplied arguments are valid for the protocol. Here is an example skeleton implementation of a new DMC for protocol MyProtocol which represents a physical resource accessible through protocol my://

#include <arc/data/DataPointDirect.h>
namespace Arc {
// DMC implementation for my protocol
class DataPointMyProtocol : public DataPointDirect {
 public:
  // Constructor should never be used directly
  DataPointMyProtocol(const URL& url, const UserConfig& usercfg, PluginArgument* parg);
  // Instance is called by the DataPointPluginLoader to get the correct DMC
  // instance. If returns a DataPointMyProtocol if the URL is of the form my://
  // or NULL otherwise.
  static Plugin* Instance(PluginArgument *arg);
  // The following methods from DataPoint must be implemented
  virtual DataStatus Check(bool check_meta);
  virtual DataStatus Remove();
  virtual DataStatus CreateDirectory(bool with_parents=false) { return DataStatus(DataStatus::UnimplementedError, EOPNOTSUPP); };
  virtual DataStatus Stat(FileInfo& file, DataPoint::DataPointInfoType verb);
  virtual DataStatus List(std::list<FileInfo>& file, DataPoint::DataPointInfoType verb);
  virtual DataStatus Rename(const URL& newurl) { return DataStatus(DataStatus::UnimplementedError, EOPNOTSUPP); };
  virtual DataStatus StartReading(DataBuffer& buffer);
  virtual DataStatus StartWriting(DataBuffer& buffer,
                                  DataCallback *space_cb = NULL);
  virtual DataStatus StopReading();
  virtual DataStatus StopWriting();
};
DataPointMyProtocol::DataPointMyProtocol(const URL& url, const UserConfig& usercfg, PluginArgument* parg)
 : DataPointDirect(url, usercfg, parg) {}
DataStatus DataPointMyProtocol::Check(bool check_meta) { return DataStatus::Success; }
DataStatus DataPointMyProtocol::Remove() { return DataStatus::Success; }
DataStatus DataPointMyProtocol::Stat(FileInfo& file,
                                     DataPoint::DataPointInfoType verb) { return DataStatus::Success; }
DataStatus DataPointMyProtocol::List(std::list<FileInfo>& file,
                                     DataPoint::DataPointInfoType verb) { return DataStatus::Success; }
DataStatus DataPointMyProtocol::StartReading(DataBuffer& buffer) { return DataStatus::Success; }
DataStatus DataPointMyProtocol::StartWriting(DataBuffer& buffer,
                                             DataCallback *space_cb) { return DataStatus::Success; }
DataStatus DataPointMyProtocol::StopReading() { return DataStatus::Success; }
DataStatus DataPointMyProtocol::StopWriting() { return DataStatus::Success; }
Plugin* DataPointMyProtocol::Instance(PluginArgument *arg) {
  DataPointPluginArgument *dmcarg = dynamic_cast<DataPointPluginArgument*>(arg);
  if (!dmcarg)
    return NULL;
  if (((const URL &)(*dmcarg)).Protocol() != "my")
    return NULL;
  return new DataPointMyProtocol(*dmcarg, *dmcarg, dmcarg);
}
} // namespace Arc
// Add this plugin to the plugin descriptor table
Arc::PluginDescriptor ARC_PLUGINS_TABLE_NAME[] = {
  { "my", "HED:DMC", "My protocol", 0, &Arc::DataPointMyProtocol::Instance },
  { NULL, NULL, NULL, 0, NULL }
};

Member Typedef Documentation

typedef void(* Arc::DataPoint::Callback3rdParty)(unsigned long long int bytes_transferred)

Callback for use in 3rd party transfer.

Will be called periodically during the transfer with the number of bytes transferred so far.

Parameters

bytes_transferred the number of bytes transferred so far

Member Enumeration Documentation

enum Arc::DataPoint::DataPointAccessLatency

Describes the latency to access this URL.

For now this value is one of a small set specified by the enumeration. In the future with more sophisticated protocols or information it could be replaced by a more fine-grained list of possibilities such as an int value.

Enumerator
ACCESS_LATENCY_ZERO	URL can be accessed instantly.
ACCESS_LATENCY_SMALL	URL has low (but non-zero) access latency, for example staged from disk.
ACCESS_LATENCY_LARGE	URL has a large access latency, for example staged from tape.

enum Arc::DataPoint::DataPointInfoType

Describes type of information about URL to request.

Enumerator
INFO_TYPE_MINIMAL	Whatever protocol can get with no additional effort.
INFO_TYPE_NAME	Only name of object (relative).
INFO_TYPE_TYPE	Type of object - currently file or dir.
INFO_TYPE_TIMES	Timestamps associated with object.
INFO_TYPE_CONTENT	Metadata describing content, like size, checksum, etc.
INFO_TYPE_ACCESS	Access control - ownership, permission, etc.
INFO_TYPE_STRUCT	Fine structure - replicas, transfer locations, redirections.
INFO_TYPE_REST	All the other parameters.
INFO_TYPE_ALL	All the parameters.

Constructor & Destructor Documentation

Arc::DataPoint::DataPoint	(	const URL &	url,
		const UserConfig &	usercfg,
		PluginArgument *	parg
	)

protected

Constructor.

Constructor is protected because DataPoints should not be created directly. Subclasses should however call this in their constructors to set various common attributes.

Parameters

url	The URL representing the DataPoint
usercfg	User configuration object
parg	plugin argument

Member Function Documentation

virtual int Arc::DataPoint::AddCheckSumObject ( CheckSum * cksum )

pure virtual

Add a checksum object which will compute checksum during data transfer.

Parameters

cksum object which will compute checksum. Should not be destroyed until DataPointer itself.

Returns: integer position in the list of checksum objects.

Implemented in Arc::DataPointIndex, and Arc::DataPointDirect.

virtual DataStatus Arc::DataPoint::AddLocation	(	const URL &	url,
		const std::string &	meta
	)

pure virtual

Add URL representing physical replica to list of locations.

Parameters

url	Location URL to add.
meta	Location meta information.

Returns: LocationAlreadyExistsError if location already exists, otherwise success

Implemented in Arc::DataPointDirect, and Arc::DataPointIndex.

virtual void Arc::DataPoint::AddURLOptions ( const std::map< std::string, std::string > & options )

virtual

Add URL options to this DataPoint's URL object.

Invalid options for the specific DataPoint instance will not be added.

Parameters

options map of option, value pairs

virtual DataStatus Arc::DataPoint::Check ( bool check_meta )

pure virtual

Query the DataPoint to check if object is accessible.

If check_meta is true this method will also try to provide meta information about the object. Note that for many protocols an access check also provides meta information and so check_meta may have no effect.

Parameters

check_meta If true then the method will try to retrieve meta data during the check.

Returns: success if the object is accessible by the caller.

Implemented in Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::CompareLocationMetadata ( ) const

pure virtual

Compare metadata of DataPoint and current location.

Returns: inconsistency error or error encountered during operation, or success

Implemented in Arc::DataPointDirect, and Arc::DataPointIndex.

virtual bool Arc::DataPoint::CompareMeta ( const DataPoint & p ) const

virtual

Compare meta information from another object.

Undefined values are not used for comparison.

Parameters

p	object to which to compare.

virtual DataStatus Arc::DataPoint::CreateDirectory ( bool with_parents = false )

pure virtual

Create a directory.

If the protocol supports it, this method creates the last directory in the path to the URL. It assumes the last component of the path is a file-like object and not a directory itself, unless the path ends in a directory separator. If with_parents is true then all missing parent directories in the path will also be created. The access control on the new directories is protocol-specific and may vary depending on protocol.

Parameters

with_parents If true then all missing directories in the path are created

Returns: success if the directory was created

virtual const std::string& Arc::DataPoint::CurrentLocationMetadata ( ) const

pure virtual

Returns meta information used to create current URL.

Usage differs between different indexing services.

Implemented in Arc::DataPointDirect, and Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::FinishReading ( bool error = false )

virtual

Finish reading from the URL.

Must be called after transfer of physical file has completed if PrepareReading() was called, to free resources, release requests that were made during preparation etc.

Parameters

error If true then action is taken depending on the error.

Returns: success if source was released properly

Reimplemented in Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::FinishWriting ( bool error = false )

virtual

Finish writing to the URL.

Must be called after transfer of physical file has completed if PrepareWriting() was called, to free resources, release requests that were made during preparation etc.

Parameters

error if true then action is taken depending on the error, for example cleaning the file from the storage

Returns: success if destination was released properly

Reimplemented in Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::GetFailureReason ( void ) const

virtual

Returns reason of transfer failure, as reported by callbacks.

This could be different from the failure returned by the methods themselves.

virtual DataStatus Arc::DataPoint::List	(	std::list< FileInfo > &	files,
		DataPointInfoType	verb = `INFO_TYPE_ALL`
	)

pure virtual

List hierarchical content of this object.

If the DataPoint represents a directory or something similar its contents will be listed and put into files. If the DataPoint is file- like an error will be returned.

Parameters

files	will contain list of file names and requested attributes. There may be more attributes than requested. There may be less if object can't provide particular information.
verb	defines attribute types which method must try to retrieve. It is not a failure if some attributes could not be retrieved due to limitation of protocol or access control.

Returns: success if DataPoint is a directory-like object and could be listed.

virtual bool Arc::DataPoint::NextLocation ( )

pure virtual

Switch to next location in list of URLs.

At last location switch to first if number of allowed retries is not exceeded.

Returns: false if no retries left.

Implemented in Arc::DataPointDirect, and Arc::DataPointIndex.

virtual void Arc::DataPoint::Passive ( bool v )

pure virtual

Set passive transfers for FTP-like protocols.

Parameters

v	true if passive should be used.

Implemented in Arc::DataPointIndex, and Arc::DataPointDirect.

virtual DataStatus Arc::DataPoint::PostRegister ( bool replication )

pure virtual

Index service post-registration.

Used for same purpose as PreRegister. Should be called after actual transfer of file successfully finished to finalise registration in an index service.

Parameters

replication if true, the file is being replicated between two locations registered in Indexing Service under the same name.

Returns: success if post-registration succeeded

Implemented in Arc::DataPointDirect.

virtual DataStatus Arc::DataPoint::PrepareReading	(	unsigned int	timeout,
		unsigned int &	wait_time
	)

virtual

Prepare DataPoint for reading.

This method should be implemented by protocols which require preparation or staging of physical files for reading. It can act synchronously or asynchronously (if protocol supports it). In the first case the method will block until the file is prepared or the specified timeout has passed. In the second case the method can return with a ReadPrepareWait status before the file is prepared. The caller should then wait some time (a hint from the remote service may be given in wait_time) and call PrepareReading() again to poll for the preparation status, until the file is prepared. In this case it is also up to the caller to decide when the request has taken too long and if so cancel it by calling FinishReading(). When file preparation has finished, the physical file(s) to read from can be found from TransferLocations().

Parameters

timeout	If non-zero, this method will block until either the file has been prepared successfully or the timeout has passed. A zero value means that the caller would like to call and poll for status.
wait_time	If timeout is zero (caller would like asynchronous operation) and ReadPrepareWait is returned, a hint for how long to wait before a subsequent call may be given in wait_time.

Returns: Status of the operation

Reimplemented in Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::PrepareWriting	(	unsigned int	timeout,
		unsigned int &	wait_time
	)

virtual

Prepare DataPoint for writing.

This method should be implemented by protocols which require preparation of physical files for writing. It can act synchronously or asynchronously (if protocol supports it). In the first case the method will block until the file is prepared or the specified timeout has passed. In the second case the method can return with a WritePrepareWait status before the file is prepared. The caller should then wait some time (a hint from the remote service may be given in wait_time) and call PrepareWriting() again to poll for the preparation status, until the file is prepared. In this case it is also up to the caller to decide when the request has taken too long and if so cancel or abort it by calling FinishWriting(true). When file preparation has finished, the physical file(s) to write to can be found from TransferLocations().

Parameters

timeout	If non-zero, this method will block until either the file has been prepared successfully or the timeout has passed. A zero value means that the caller would like to call and poll for status.
wait_time	If timeout is zero (caller would like asynchronous operation) and WritePrepareWait is returned, a hint for how long to wait before a subsequent call may be given in wait_time.

Returns: Status of the operation

Reimplemented in Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::PreRegister	(	bool	replication,
		bool	force = `false`
	)

pure virtual

Index service pre-registration.

This function registers the physical location of a file into an indexing service. It should be called before the actual transfer to that location happens.

Parameters

replication	if true, the file is being replicated between two locations registered in the indexing service under the same name.
force	if true, perform registration of a new file even if it already exists. Should be used to fix failures in indexing service.

Returns: success if pre-registration succeeded

Implemented in Arc::DataPointDirect.

virtual DataStatus Arc::DataPoint::PreUnregister ( bool replication )

pure virtual

Index service pre-unregistration.

Should be called if file transfer failed. It removes changes made by PreRegister().

Parameters

replication if true, the file is being replicated between two locations registered in Indexing Service under the same name.

Returns: success if pre-unregistration succeeded

Implemented in Arc::DataPointDirect.

virtual void Arc::DataPoint::Range	(	unsigned long long int	start = `0`,
		unsigned long long int	end = `0`
	)

pure virtual

Set range of bytes to retrieve.

Default values correspond to whole file. Both start and end bytes are included in the range, i.e. start - end + 1 bytes will be read.

Parameters

start	byte to start from
end	byte to end at

Implemented in Arc::DataPointIndex, and Arc::DataPointDirect.

virtual void Arc::DataPoint::ReadOutOfOrder ( bool v )

pure virtual

Allow/disallow DataPoint to read data out of order.

If set to true then data may be read from source out of order or in parallel from multiple threads. For a transfer between two DataPoints this should only be set to true if WriteOutOfOrder() returns true for the destination. Only certain protocols support this option.

Parameters

v	true if allowed (default is false).

Implemented in Arc::DataPointIndex, and Arc::DataPointDirect.

virtual DataStatus Arc::DataPoint::Rename ( const URL & newurl )

pure virtual

Rename a URL.

This method renames the file or directory specified in the constructor to the new name specified in newurl. It only performs namespace operations using the paths of the two URLs and in general ignores any differences in protocol and host between them. It is assumed that checks that the URLs are consistent are done by the caller of this method. This method does not do any data transfer and is only implemented for protocols which support renaming as an atomic namespace operation.

Parameters

newurl The new name for the URL

Returns: success if the object was renamed

virtual DataStatus Arc::DataPoint::Resolve ( bool source )

pure virtual

Resolves index service URL into list of ordinary URLs.

Also obtains meta information about the file if possible. Resolve should be called for both source and destination URLs before a transfer. If source is true an error is returned if the file does not exist.

Parameters

source true if DataPoint object represents source of information.

Returns: success if DataPoint was successfully resolved

Implemented in Arc::DataPointDirect.

virtual DataStatus Arc::DataPoint::Resolve	(	bool	source,
		const std::list< DataPoint * > &	urls
	)

pure virtual

Resolves several index service URLs.

Can use bulk calls if protocol allows. The protocols and hosts of all the DataPoints in urls must be the same and the same as this DataPoint's protocol and host. This method can be called on any of the urls, for example urls.front()->Resolve(true, urls);

Parameters

source	true if DataPoint objects represent source of information
urls	List of DataPoints to resolve. Protocols and hosts must match and match this DataPoint's protocol and host.

Returns: success if any DataPoint was successfully resolved

Implemented in Arc::DataPointDirect.

virtual void Arc::DataPoint::SetAdditionalChecks ( bool v )

pure virtual

Allow/disallow additional checks on a source DataPoint before transfer.

If set to true, extra checks will be performed in DataMover::Transfer() before data transfer starts on for example existence of the source file (and probably other checks too).

Parameters

v	true if allowed (default is true).

Implemented in Arc::DataPointIndex, and Arc::DataPointDirect.

virtual void Arc::DataPoint::SetMeta ( const DataPoint & p )

virtual

Copy meta information from another object.

Already defined values are not overwritten.

Parameters

p	object from which information is taken.

Reimplemented in Arc::DataPointIndex.

virtual void Arc::DataPoint::SetSecure ( bool v )

pure virtual

Allow/disallow heavy security (data encryption) during data transfer.

Parameters

v	true if allowed (default depends on protocol).

Implemented in Arc::DataPointIndex, and Arc::DataPointDirect.

virtual bool Arc::DataPoint::SetURL ( const URL & url )

virtual

Assigns new URL.

The main purpose of this method is to reuse an existing connection for accessing a different object on the same server. The DataPoint implementation does not have to implement this method. If the supplied URL is not suitable or method is not implemented false is returned.

Parameters

url New URL

Returns: true if switching to new URL is supported and succeeded

virtual void Arc::DataPoint::SortLocations	(	const std::string &	pattern,
		const URLMap &	url_map
	)

pure virtual

Sort locations according to the specified pattern and URLMap.

See DataMover::set_preferred_pattern for a more detailed explanation of pattern matching. Locations present in url_map are preferred over others.

Parameters

pattern	a set of strings, separated by \|, to match against.
url_map	map of URLs to local URLs

Implemented in Arc::DataPointDirect, and Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::StartReading ( DataBuffer & buffer )

pure virtual

Start reading data from URL.

A separate thread to transfer data will be created. No other operation can be performed while reading is in progress. Progress of the transfer should be followed using the DataBuffer object.

Parameters

buffer operation will use this buffer to put information into. Should not be destroyed before StopReading() was called and returned. If StopReading() is not called explicitly to release buffer it will be released in destructor of DataPoint which also usually calls StopReading().

Returns: success if a thread was successfully started to start reading

Implemented in Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::StartWriting	(	DataBuffer &	buffer,
		DataCallback *	space_cb = `NULL`
	)

pure virtual

Start writing data to URL.

A separate thread to transfer data will be created. No other operation can be performed while writing is in progress. Progress of the transfer should be followed using the DataBuffer object.

Parameters

buffer	operation will use this buffer to get information from. Should not be destroyed before StopWriting() was called and returned. If StopWriting() is not called explicitly to release buffer it will be released in destructor of DataPoint which also usually calls StopWriting().
space_cb	callback which is called if there is not enough space to store data. May not implemented for all protocols.

Returns: success if a thread was successfully started to start writing

Implemented in Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::Stat	(	FileInfo &	file,
		DataPointInfoType	verb = `INFO_TYPE_ALL`
	)

pure virtual

Retrieve information about this object.

If the DataPoint represents a directory or something similar, information about the object itself and not its contents will be obtained.

Parameters

file	will contain object name and requested attributes. There may be more attributes than requested. There may be less if object can't provide particular information.
verb	defines attribute types which method must try to retrieve. It is not a failure if some attributes could not be retrieved due to limitation of protocol or access control.

Returns: success if any information could be retrieved

virtual DataStatus Arc::DataPoint::Stat	(	std::list< FileInfo > &	files,
		const std::list< DataPoint * > &	urls,
		DataPointInfoType	verb = `INFO_TYPE_ALL`
	)

pure virtual

Retrieve information about several DataPoints.

If a DataPoint represents a directory or something similar, information about the object itself and not its contents will be obtained. This method can use bulk operations if the protocol supports it. The protocols and hosts of all the DataPoints in urls must be the same and the same as this DataPoint's protocol and host. This method can be called on any of the urls, for example urls.front()->Stat(files, urls); Calling this method with an empty list of urls returns success if the protocol supports bulk Stat, and an error if it does not and this can be used as a check for bulk support.

Parameters

files	will contain objects' names and requested attributes. There may be more attributes than requested. There may be less if objects can't provide particular information. The order of this list matches the order of urls. If a stat of any url fails then the corresponding FileInfo in this list will evaluate to false.
urls	list of DataPoints to stat. Protocols and hosts must match and match this DataPoint's protocol and host.
verb	defines attribute types which method must try to retrieve. It is not a failure if some attributes could not be retrieved due to limitation of protocol or access control.

Returns: success if any information could be retrieved for any DataPoint

Implemented in Arc::DataPointDirect.

virtual DataStatus Arc::DataPoint::StopReading ( )

pure virtual

Stop reading.

Must be called after corresponding StartReading() method, either after all data is transferred or to cancel transfer. Use buffer object to find out when data is transferred.

Returns: outcome of stopping reading (not outcome of transfer itself)

Implemented in Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::StopWriting ( )

pure virtual

Stop writing.

Must be called after corresponding StartWriting() method, either after all data is transferred or to cancel transfer. Use buffer object to find out when data is transferred.

Returns: outcome of stopping writing (not outcome of transfer itself)

Implemented in Arc::DataPointIndex.

static DataStatus Arc::DataPoint::Transfer3rdParty	(	const URL &	source,
		const URL &	destination,
		const UserConfig &	usercfg,
		Callback3rdParty	callback = `NULL`
	)

static

Perform third party transfer.

Credentials are delegated to the destination and it pulls data from the source, i.e. data flows directly between source and destination instead of through the client. A callback function can be supplied to monitor progress. This method blocks until the transfer is complete. It is static because third party transfer requires different DMC plugins than those loaded by DataHandle for the same protocol. The third party transfer plugins are loaded internally in this method.

Parameters

source	Source URL to pull data from
destination	Destination URL which pulls data to itself
usercfg	Configuration information
callback	Optional monitoring callback

Returns: outcome of transfer

virtual DataStatus Arc::DataPoint::Transfer3rdParty	(	const URL &	source,
		const URL &	destination,
		Callback3rdParty	callback = `NULL`
	)

protectedvirtual

Perform third party transfer.

This method is protected because the static version should be used instead to load the correct DMC plugin for third party transfer.

Parameters

source	Source URL to pull data from
destination	Destination URL which pulls data to itself
callback	Optional monitoring callback

Returns: outcome of transfer

virtual std::vector<URL> Arc::DataPoint::TransferLocations ( ) const

virtual

Returns physical file(s) to read/write, if different from CurrentLocation()

To be used with protocols which re-direct to different URLs such as Transport URLs (TURLs). The list is initially filled by PrepareReading and PrepareWriting. If this list is non-empty then real transfer should use a URL from this list. It is up to the caller to choose the best URL and instantiate new DataPoint for handling it. For consistency protocols which do not require redirections return original URL. For protocols which need redirection calling StartReading and StartWriting will use first URL in the list.

Reimplemented in Arc::DataPointIndex.

virtual DataStatus Arc::DataPoint::Unregister ( bool all )

pure virtual

Index service unregistration.

Remove information about file registered in indexing service.

Parameters