Simple service that allows to read files independently from the storage. More...

#include <VFSSvc.h>

Inheritance diagram for VFSSvc:

Collaboration diagram for VFSSvc:

Public Member Functions
virtual StatusCode	initialize ()
	Initialize Service.
virtual StatusCode	finalize ()
	Finalize Service.
virtual std::auto_ptr < std::istream >	open (const std::string &url)
virtual const std::vector < std::string > &	protocols () const
Protected Member Functions
	VFSSvc (const std::string &name, ISvcLocator *svcloc)
	Standard constructor.
virtual	~VFSSvc ()
	Destructor.
Private Attributes
std::vector< std::string >	m_urlHandlersNames
	Names of the handlers to use.
std::vector< std::string >	m_protocols
	Protocols registered.
std::string	m_fallBackProtocol
	Protocol to use in case there is not a specific tool to handle the URL.
GaudiUtils::HashMap < std::string, IFileAccess * >	m_urlHandlers
	Map of the tools handling the known protocols.
SmartIF< IToolSvc >	m_toolSvc
	Handle to the tool service.
std::list< IAlgTool * >	m_acquiredTools
	List of acquired tools (needed to release them).
Friends
class	SvcFactory< VFSSvc >

Detailed Description

Simple service that allows to read files independently from the storage.

The service uses tools to resolve URLs and serve the files as input streams. The basic implementations read from the filesystem, and simple extensions allow to read from databases, web...

Author:: Marco Clemencic

Date:: 2008-01-18

Definition at line 28 of file VFSSvc.h.

Constructor & Destructor Documentation

VFSSvc::VFSSvc	(	const std::string &	name,
		ISvcLocator *	svcloc
	)		`[protected]`

Standard constructor.

Definition at line 11 of file VFSSvc.cpp.

                                                     :
  base_class(name,svc) {

  m_urlHandlersNames.push_back("FileReadTool");

  declareProperty("FileAccessTools",m_urlHandlersNames,
                  "List of tools implementing the IFileAccess interface.");

  declareProperty("FallBackProtocol",m_fallBackProtocol = "file",
                  "URL prefix to use if the prefix is not present.");
}

VFSSvc::~VFSSvc ( ) [protected, virtual]

Destructor.

Definition at line 23 of file VFSSvc.cpp.

{}

Member Function Documentation

StatusCode VFSSvc::finalize ( void ) [virtual]

Finalize Service.

Reimplemented from Service.

Definition at line 77 of file VFSSvc.cpp.

                            {
  m_urlHandlers.clear(); // clear the map
  m_protocols.clear();

  if (m_toolSvc) {
    // release the acquired tools (from the last acquired one)
    while ( m_acquiredTools.begin() != m_acquiredTools.end() ){
      m_toolSvc->releaseTool(*m_acquiredTools.begin()).ignore();
      m_acquiredTools.pop_front();
    }
    m_toolSvc->release(); // release the tool service
    m_toolSvc = 0;
  }
  return Service::finalize();
}

StatusCode VFSSvc::initialize ( void ) [virtual]

Initialize Service.

Reimplemented from Service.

Definition at line 25 of file VFSSvc.cpp.

                              {
  StatusCode sc = Service::initialize();
  if (sc.isFailure()){
    return sc;
  }

  MsgStream log(msgSvc(), name());

  m_toolSvc = serviceLocator()->service("ToolSvc");
  if (!m_toolSvc.isValid()){
    log << MSG::ERROR << "Cannot locate ToolSvc" << endmsg;
    return StatusCode::FAILURE;
  }

  IAlgTool *tool;
  IFileAccess *hndlr;
  std::vector<std::string>::iterator i;
  for(i = m_urlHandlersNames.begin(); i != m_urlHandlersNames.end(); ++i){
    // retrieve the tool and the pointer to the interface
    sc = m_toolSvc->retrieve(*i,IAlgTool::interfaceID(),tool,0,true);
    if (sc.isFailure()){
      log << MSG::ERROR << "Cannot get tool " << *i << endmsg;
      return sc;
    }
    m_acquiredTools.push_front(tool); // this is one tool that we will have to release
    sc = tool->queryInterface(IFileAccess::interfaceID(),pp_cast<void>(&hndlr));
    if (sc.isFailure()){
      log << MSG::ERROR << *i << " does not implement IFileAccess" << endmsg;
      return sc;
    }
    // We do not need to increase the reference count for the IFileAccess interface
    // because we hold the tool by its IAlgTool interface.
    hndlr->release();
    // loop over the list of supported protocols and add them to the map (for quick access)
    for ( std::vector<std::string>::const_iterator prot = hndlr->protocols().begin();
          prot != hndlr->protocols().end(); ++prot ){
      m_urlHandlers[*prot] = hndlr;
    }
  }

  // Now let's check if we can handle the fallback protocol
  if ( m_urlHandlers.find(m_fallBackProtocol) == m_urlHandlers.end() ) {
    log << MSG::ERROR << "No handler specified for fallback protocol prefix "
        << m_fallBackProtocol << endmsg;
    return StatusCode::FAILURE;
  }

  // Note: the list of handled protocols will be filled only if requested

  return sc;
}

std::auto_ptr< std::istream > VFSSvc::open ( const std::string & url ) [virtual]

See also:: IFileAccess::open

Implements IFileAccess.

Definition at line 93 of file VFSSvc.cpp.

                                                        {

  // get the url prefix endpos
  std::string::size_type pos = url.find("://");

  if (std::string::npos == pos) { // no url prefix
    return m_urlHandlers[m_fallBackProtocol]->open(url);
  }

  std::string url_prefix(url,0,pos);
  if ( m_urlHandlers.find(url_prefix) == m_urlHandlers.end() ) {
    // if we do not have a handler for the URL prefix,
    // use the fall back one and pass only the path
    return m_urlHandlers[m_fallBackProtocol]->open(url.substr(pos+3));
  }
  return m_urlHandlers[url_prefix]->open(url);
}

const std::vector< std::string > & VFSSvc::protocols ( ) const [virtual]

See also:: IFileAccess::protocols

Implements IFileAccess.

Definition at line 128 of file VFSSvc.cpp.

{
  if (m_protocols.empty()){
    // prepare the list of handled protocols
    std::for_each(m_urlHandlers.begin(),m_urlHandlers.end(),
                  append_key<std::vector<std::string> >(const_cast<VFSSvc*>(this)->m_protocols));
  }
  return m_protocols;
}