// Copyright (C) 2012 Davis E. King (davis@dlib.net)
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_BSP_CPph_
#define DLIB_BSP_CPph_
#include "bsp.h"
#include <memory>
#include <stack>
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
namespace dlib
{
namespace impl1
{
void connect_all (
map_id_to_con& cons,
const std::vector<network_address>& hosts,
unsigned long node_id
)
{
cons.clear();
for (unsigned long i = 0; i < hosts.size(); ++i)
{
std::unique_ptr<bsp_con> con(new bsp_con(hosts[i]));
dlib::serialize(node_id, con->stream); // tell the other end our node_id
unsigned long id = i+1;
cons.add(id, con);
}
}
void connect_all_hostinfo (
map_id_to_con& cons,
const std::vector<hostinfo>& hosts,
unsigned long node_id,
std::string& error_string
)
{
cons.clear();
for (unsigned long i = 0; i < hosts.size(); ++i)
{
try
{
std::unique_ptr<bsp_con> con(new bsp_con(hosts[i].addr));
dlib::serialize(node_id, con->stream); // tell the other end our node_id
con->stream.flush();
unsigned long id = hosts[i].node_id;
cons.add(id, con);
}
catch (std::exception&)
{
std::ostringstream sout;
sout << "Could not connect to " << hosts[i].addr;
error_string = sout.str();
break;
}
}
}
void send_out_connection_orders (
map_id_to_con& cons,
const std::vector<network_address>& hosts
)
{
// tell everyone their node ids
cons.reset();
while (cons.move_next())
{
dlib::serialize(cons.element().key(), cons.element().value()->stream);
}
// now tell them who to connect to
std::vector<hostinfo> targets;
for (unsigned long i = 0; i < hosts.size(); ++i)
{
hostinfo info(hosts[i], i+1);
dlib::serialize(targets, cons[info.node_id]->stream);
targets.push_back(info);
// let the other host know how many incoming connections to expect
const unsigned long num = hosts.size()-targets.size();
dlib::serialize(num, cons[info.node_id]->stream);
cons[info.node_id]->stream.flush();
}
}
// ------------------------------------------------------------------------------------
}
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
namespace impl2
{
// These control bytes are sent before each message between nodes. Note that many
// of these are only sent between the control node (node 0) and the other nodes.
// This is because the controller node is responsible for handling the
// synchronization that needs to happen when all nodes block on calls to
// receive_data()
// at the same time.
// denotes a normal content message.
const static char MESSAGE_HEADER = 0;
// sent to the controller node when someone receives a message via receive_data().
const static char GOT_MESSAGE = 1;
// sent to the controller node when someone sends a message via send().
const static char SENT_MESSAGE = 2;
// sent to the controller node when someone enters a call to receive_data()
const static char IN_WAITING_STATE = 3;
// broadcast when a node terminates itself.
const static char NODE_TERMINATE = 5;
// broadcast by the controller node when it determines that all nodes are blocked
// on calls to receive_data() and there aren't any messages in flight. This is also
// what makes us go to the next epoch.
const static char SEE_ALL_IN_WAITING_STATE = 6;
// This isn't ever transmitted between nodes. It is used internally to indicate
// that an error occurred.
const static char READ_ERROR = 7;
// ------------------------------------------------------------------------------------
void read_thread (
impl1::bsp_con* con,
unsigned long node_id,
unsigned long sender_id,
impl1::thread_safe_message_queue& msg_buffer
)
{
try
{
while(true)
{
impl1::msg_data msg;
deserialize(msg.msg_type, con->stream);
msg.sender_id = sender_id;
if (msg.msg_type == MESSAGE_HEADER)
{
msg.data.reset(new std::vector<char>);
deserialize(msg.epoch, con->stream);
deserialize(*msg.data, con->stream);
}
msg_buffer.push_and_consume(msg);
if (msg.msg_type == NODE_TERMINATE)
break;
}
}
catch (std::exception& e)
{
impl1::msg_data msg;
msg.data.reset(new std::vector<char>);
vectorstream sout(*msg.data);
sout << "An exception was thrown while attempting to receive a message from processing node " << sender_id << ".\n";
sout << " Sending processing node address: " << con->con->get_foreign_ip() << ":" << con->con->get_foreign_port() << std::endl;
sout << " Receiving processing node address: " << con->con->get_local_ip() << ":" << con->con->get_local_port() << std::endl;
sout << " Receiving processing node id: " << node_id << std::endl;
sout << " Error message in the exception: " << e.what() << std::endl;
msg.sender_id = sender_id;
msg.msg_type = READ_ERROR;
msg_buffer.push_and_consume(msg);
}
catch (...)
{
impl1::msg_data msg;
msg.data.reset(new std::vector<char>);
vectorstream sout(*msg.data);
sout << "An exception was thrown while attempting to receive a message from processing node " << sender_id << ".\n";
sout << " Sending processing node address: " << con->con->get_foreign_ip() << ":" << con->con->get_foreign_port() << std::endl;
sout << " Receiving processing node address: " << con->con->get_local_ip() << ":" << con->con->get_local_port() << std::endl;
sout << " Receiving processing node id: " << node_id << std::endl;
msg.sender_id = sender_id;
msg.msg_type = READ_ERROR;
msg_buffer.push_and_consume(msg);
}
}
// ------------------------------------------------------------------------------------
}
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
// IMPLEMENTATION OF bsp_context OBJECT MEMBERS
// ----------------------------------------------------------------------------------------
// ----------------------------------------------------------------------------------------
void bsp_context::
close_all_connections_gracefully(
)
{
if (node_id() != 0)
{
_cons.reset();
while (_cons.move_next())
{
// tell the other end that we are intentionally dropping the connection
serialize(impl2::NODE_TERMINATE,_cons.element().value()->stream);
_cons.element().value()->stream.flush();
}
}
impl1::msg_data msg;
// now wait for all the other nodes to terminate
while (num_terminated_nodes < _cons.size() )
{
if (node_id() == 0 && num_waiting_nodes + num_terminated_nodes == _cons.size() && outstanding_messages == 0)
{
num_waiting_nodes = 0;
broadcast_byte(impl2::SEE_ALL_IN_WAITING_STATE);
++current_epoch;
}
if (!msg_buffer.pop(msg))
throw dlib::socket_error("Error reading from msg_buffer in dlib::bsp_context.");
if (msg.msg_type == impl2::NODE_TERMINATE)
{
++num_terminated_nodes;
_cons[msg.sender_id]->terminated = true;
}
else if (msg.msg_type == impl2::READ_ERROR)
{
throw dlib::socket_error(msg.data_to_string());
}
else if (msg.msg_type == impl2::MESSAGE_HEADER)
{
throw dlib::socket_error("A BSP node received a message after it has terminated.");
}
else if (msg.msg_type == impl2::GOT_MESSAGE)
{
--num_waiting_nodes;
--outstanding_messages;
}
else if (msg.msg_type == impl2::SENT_MESSAGE)
{
++outstanding_messages;
}
else if (msg.msg_type == impl2::IN_WAITING_STATE)
{
++num_waiting_nodes;
}
}
if (node_id() == 0)
{
_cons.reset();
while (_cons.move_next())
{
// tell the other end that we are intentionally dropping the connection
serialize(impl2::NODE_TERMINATE,_cons.element().value()->stream);
_cons.element().value()->stream.flush();
}
if (outstanding_messages != 0)
{
std::ostringstream sout;
sout << "A BSP job was allowed to terminate before all sent messages have been received.\n";
sout << "There are at least " << outstanding_messages << " messages still in flight. Make sure all sent messages\n";
sout << "have a corresponding call to receive().";
throw dlib::socket_error(sout.str());
}
}
}
// ----------------------------------------------------------------------------------------
bsp_context::
~bsp_context()
{
_cons.reset();
while (_cons.move_next())
{
_cons.element().value()->con->shutdown();
}
msg_buffer.disable();
// this will wait for all the threads to terminate
threads.clear();
}
// ----------------------------------------------------------------------------------------
bsp_context::
bsp_context(
unsigned long node_id_,
impl1::map_id_to_con& cons_
) :
outstanding_messages(0),
num_waiting_nodes(0),
num_terminated_nodes(0),
current_epoch(1),
_cons(cons_),
_node_id(node_id_)
{
// spawn a bunch of read threads, one for each connection
_cons.reset();
while (_cons.move_next())
{
std::unique_ptr<thread_function> ptr(new thread_function(&impl2::read_thread,
_cons.element().value().get(),
_node_id,
_cons.element().key(),
ref(msg_buffer)));
threads.push_back(ptr);
}
}
// ----------------------------------------------------------------------------------------
bool bsp_context::
receive_data (
std::shared_ptr<std::vector<char> >& item,
unsigned long& sending_node_id
)
{
notify_control_node(impl2::IN_WAITING_STATE);
while (true)
{
// If there aren't any nodes left to give us messages then return right now.
// We need to check the msg_buffer size to make sure there aren't any
// unprocessed message there. Recall that this can happen because status
// messages always jump to the front of the message buffer. So we might have
// learned about the node terminations before processing their messages for us.
if (num_terminated_nodes == _cons.size() && msg_buffer.size() == 0)
{
return false;
}
// if all running nodes are currently blocking forever on receive_data()
if (node_id() == 0 && outstanding_messages == 0 && num_terminated_nodes + num_waiting_nodes == _cons.size())
{
num_waiting_nodes = 0;
broadcast_byte(impl2::SEE_ALL_IN_WAITING_STATE);
// Note that the reason we have this epoch counter is so we can tell if a
// sent message is from before or after one of these "all nodes waiting"
// synchronization events. If we didn't have the epoch count we would have
// a race condition where one node gets the SEE_ALL_IN_WAITING_STATE
// message before others and then sends out a message to another node
// before that node got the SEE_ALL_IN_WAITING_STATE message. Then that
// node would think the normal message came before SEE_ALL_IN_WAITING_STATE
// which would be bad.
++current_epoch;
return false;
}
impl1::msg_data data;
if (!msg_buffer.pop(data, current_epoch))
throw dlib::socket_error("Error reading from msg_buffer in dlib::bsp_context.");
switch(data.msg_type)
{
case impl2::MESSAGE_HEADER: {
item = data.data;
sending_node_id = data.sender_id;
notify_control_node(impl2::GOT_MESSAGE);
return true;
} break;
case impl2::IN_WAITING_STATE: {
++num_waiting_nodes;
} break;
case impl2::GOT_MESSAGE: {
--outstanding_messages;
--num_waiting_nodes;
} break;
case impl2::SENT_MESSAGE: {
++outstanding_messages;
} break;
case impl2::NODE_TERMINATE: {
++num_terminated_nodes;
_cons[data.sender_id]->terminated = true;
} break;
case impl2::SEE_ALL_IN_WAITING_STATE: {
++current_epoch;
return false;
} break;
case impl2::READ_ERROR: {
throw dlib::socket_error(data.data_to_string());
} break;
default: {
throw dlib::socket_error("Unknown message received by dlib::bsp_context");
} break;
} // end switch()
} // end while (true)
}
// ----------------------------------------------------------------------------------------
void bsp_context::
notify_control_node (
char val
)
{
if (node_id() == 0)
{
using namespace impl2;
switch(val)
{
case SENT_MESSAGE: {
++outstanding_messages;
} break;
case GOT_MESSAGE: {
--outstanding_messages;
} break;
case IN_WAITING_STATE: {
// nothing to do in this case
} break;
default:
DLIB_CASSERT(false,"This should never happen");
}
}
else
{
serialize(val, _cons[0]->stream);
_cons[0]->stream.flush();
}
}
// ----------------------------------------------------------------------------------------
void bsp_context::
broadcast_byte (
char val
)
{
for (unsigned long i = 0; i < number_of_nodes(); ++i)
{
// don't send to yourself or to terminated nodes
if (i == node_id() || _cons[i]->terminated)
continue;
serialize(val, _cons[i]->stream);
_cons[i]->stream.flush();
}
}
// ----------------------------------------------------------------------------------------
void bsp_context::
send_data(
const std::vector<char>& item,
unsigned long target_node_id
)
{
using namespace impl2;
if (_cons[target_node_id]->terminated)
throw socket_error("Attempt to send a message to a node that has terminated.");
serialize(MESSAGE_HEADER, _cons[target_node_id]->stream);
serialize(current_epoch, _cons[target_node_id]->stream);
serialize(item, _cons[target_node_id]->stream);
_cons[target_node_id]->stream.flush();
notify_control_node(SENT_MESSAGE);
}
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_BSP_CPph_