Additional API Calls in libVTcs

VT_abort

int VT_abort (void)

Description

Abort a VT_initialize() or VT_finalize() call running concurrently in a different thread.

This call will not block, but it might still take a while before the aborted calls actually return. They will return either successfully (if they have completed without aborting) or with an error code.

Return values

0 if abort request was sent successfully, error code otherwise

 

VT_clientinit

int VT_clientinit(int procid, const char * clientname, const char * contact)

Description

Initializes communication in a client/server application.

Must be called before VT_initialize() in the client of the application. There are three possibilities:

  • client is initialized first, which produces a contact string that must be passed to the server (*contact == NULL)

  • the server was started first, its contact string is passed to the clients (*contact == <result of VT_serverinit() with the prefix "S" - this prefix must be added by the application>)

  • a process spawns children dynamically, its contact string is given to its children (*contact == <result of VT_serverinit() or VT_clientinit()>)

Parameters

procid All clients must be enumerated by the application. This will become the process id of the local client inside its VT_COMM_WORLD. If the VTserver is used, then enumeration must start at 1 because VTserver always gets rank 0. Threads can be enumerated automatically by Intel® Trace Collector or by the client by calling VT_registerthread().

clientname The name of the client. Currently only used for error messages. Copied by Intel® Trace Collector.

Return values

contact Will be set to a string which tells other processes how to contact this process. Guaranteed not to contain spaces. The client may copy this string, but doesn't have to, because Intel® Trace Collector will not free this string until VT_finalize() is called.

Returns error code.

 

VT_serverinit

int VT_serverinit(const char * servername, int numcontacts, const char * contacts[], const char ** contact)

Description

Initializes one process as the server that contacts the other processes and coordinates trace file writing.

The calling process always gets rank 0.

There are two possibilities:

  1. Collect all information from the clients and pass them here (numcontacts >= 0, contacts != NULL)

  2. Start the server first, pass its contact string to the clients (numcontacts >= 0, contacts == NULL)

This call replaces starting the VTserver executable in a separate process. Parameters that used to be passed to the VTserver to control tracing and trace writing can be passed to VT_initialize() instead.

Parameters

servername similar to clientname in VT_clientinit(): the name of the server. Currently only used for error messages. Copied by Intel® Trace Collector.

numcontacts number of client processes

contacts contact string for each client process (order is irrelevant); copied by Intel® Trace Collector

Return values

contact will be set to a string which tells spawned children how to contact this server. Guaranteed not to contain spaces. The server may copy this string, but doesn't have to, because Intel® Trace Collector will not free this string until VT_finalize() is called. contact must have been set to NULL before calling this function.

Returns error code.

 

VT_attach

int VT_attach(int root, int comm, int numchildren, int * childcomm)

Description

Connect to several new processes.

These processes must have been spawned already and need to know the contact string of the root process when calling VT_clientinit().

comm == VT_COMM_WORLD is currently not implemented. It has some design problems: if several children want to use VT_COMM_WORLD to recursively spawn more processes, then their parents must also call VT_attach(), because they are part of this communicator. If the VTserver is part of the initial VT_COMM_WORLD, then VT_attach() with VT_COMM_WORLD won't work, because the VTserver does not know about the spawned processes and never calls VT_attach().

Parameters

root rank of the process that the spawned processes will contact

comm either VT_COMM_SELF or VT_COMM_WORLD: in the first case root must be 0 and the spawned processes are connected to just the calling process. In the latter case all processes that share this VT_COMM_WORLD must call VT_attach() and are included in the new communicator. root then indicates whose contact infos were given to the children.

numchildren number of children that the spawning processes will wait for

Return values

childcomm an identifier for a new communicator that includes the parent processes in the same order as in their VT_COMM_WORLD, followed by the child processes in the order specified by their procid argument in VT_clientinit(). The spawned processes will have access to this communicator through VT_get_parent().

Returns error code.

 

VT_get_parent

int VT_get_parent (int * parentcomm)

Description

Returns the communicator that connects the process with its parent, or VT_COMM_INVALID if not spawned.

Return values

parentcomm set to the communicator number that can be used to log communication with parents

Returns error code.

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