CaptureStreamAbortHandler Class Reference

Small class to handle std::abort() calls by external libraries. More...

Collaboration diagram for CaptureStreamAbortHandler:

Public Member Functions
	CaptureStreamAbortHandler (const CaptureStreamAbortHandler &)=delete
	Singleton, no copy construction.
	CaptureStreamAbortHandler (CaptureStreamAbortHandler &&)=delete
	Singleton, no move construction.
CaptureStreamAbortHandler &	operator= (const CaptureStreamAbortHandler &)=delete
	Singleton, no assignment.
void	addObject (CaptureStream *obj)
	Add a CaptureStream object to guard against SIGABRT.
void	removeObject (CaptureStream *obj)
	Remove a CaptureStream object to no longer guard against SIGABRT.

Static Public Member Functions
static CaptureStreamAbortHandler &	getInstance ()
	Return the singleton instance.

Private Member Functions
	CaptureStreamAbortHandler ()
	Register handler.

Static Private Member Functions
static void	handle (int signal)
	signal handler: print all pending redirection buffers and exit

Private Attributes
std::set< CaptureStream * >	m_objects
	list of all active stream redirections

Detailed Description

Small class to handle std::abort() calls by external libraries.

External libraries like EvtGen seem to prefer calling abort() on error which means destructors are not called and so interception is never finished and thus the error message are lost.

This class installs a SIGABRT handler which is the only way to do something once std::abort() is called and dump all the output intercepted so far back on the original output (stdout or stderr) to basically "reverse" the redirection.

This seems like the best choice since calling abort means the user needs to be able to see the messages

Definition at line 34 of file IOIntercept.cc.

Constructor & Destructor Documentation

CaptureStreamAbortHandler()

CaptureStreamAbortHandler ( )

inlineprivate

Register handler.

Definition at line 54 of file IOIntercept.cc.

    {
      auto result = std::signal(SIGABRT, &CaptureStreamAbortHandler::handle);
      if (result == SIG_ERR) B2FATAL("Cannot register abort handler");
    }

Member Function Documentation

addObject()

void addObject ( CaptureStream *  obj )

inline

Add a CaptureStream object to guard against SIGABRT.

Definition at line 49 of file IOIntercept.cc.

{ m_objects.emplace(obj); }

getInstance()

static CaptureStreamAbortHandler & getInstance ( )

inlinestatic

Return the singleton instance.

Definition at line 43 of file IOIntercept.cc.

    {
      static CaptureStreamAbortHandler instance;
      return instance;
    }

handle()

void handle ( int  signal )

staticprivate

signal handler: print all pending redirection buffers and exit

Definition at line 65 of file IOIntercept.cc.

  {
    // move set of registered objects in here so we can call finish when
    // looping over them without invalidating the iterators
    std::set<CaptureStream*> objects;
    std::swap(CaptureStreamAbortHandler::getInstance().m_objects, objects);
    // loop over all registered instances and print the content in their
    // buffer to the original file descriptor
    for (CaptureStream* stream : objects) {
      // close the write end of the pipe
      close(stream->m_replacementFD);
      // read all content
      if (stream->finish()) {
        const std::string& out = stream->getOutput();
        // and write it to the original file descriptor
        if (out.size()) write(stream->m_savedFD, out.c_str(), out.size());
      }
    }
    // write error message and signal error
    write(STDERR_FILENO, "abort() called, exiting\n", 24);
    std::_Exit(EXIT_FAILURE);
  }

removeObject()

void removeObject ( CaptureStream *  obj )

inline

Remove a CaptureStream object to no longer guard against SIGABRT.

Definition at line 51 of file IOIntercept.cc.

{ m_objects.erase(obj); }

Member Data Documentation

m_objects

std::set<CaptureStream*> m_objects

private

list of all active stream redirections

Definition at line 62 of file IOIntercept.cc.

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The documentation for this class was generated from the following file:

• framework/utilities/src/IOIntercept.cc