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SimplTransport.cc

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/**************************************************************************
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#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include <string>
#include <deque>

#include <mps/mps.h>
#include <mps/transport_simpl.h>

extern "C" {
#include <simpl.h>
}

#define MPS_MESSAGE_MAXLEN      8192    ///< arbitrary - passed in to simpl

namespace MPS {

SimplTransport *SimplTransport::instance = 0;

///////////////////////////////////////////////////////////////////////////

static string toString(int x) {
  char buf[20];
  sprintf(buf, "%d", x);
  return buf;
}

///////////////////////////////////////////////////////////////////////////

class SimplTransport::SimplIOStream: public MPS::InputStream, public MPS::OutputStream {
private:
  bool useReply;                        ///< Determines if Reply() or Send() will be used to send
  FCID other;                           ///< Handle on our SIMPL interlocutor
  char msg[MPS_MESSAGE_MAXLEN];         ///< Message buffer space. Note yucky fixed size!
  int pos;                              ///< Current read-position
  int msglen;                           ///< Number of valid bytes in msg

protected:
  virtual string referenceTransport() const { return "simpl"; }

public:
  /**
   * Construct a SimplIOStream which will communicate with the
   * nominated target, using Reply() or Send() as per the passed-in
   * boolean.
   *
   * @param target the SIMPL process we are to communicate with
   * @param _u initial setting of useReply */
  SimplIOStream(FCID const &target, bool _u)
    : useReply(_u),
      other(target),
      pos(0),
      msglen(0)
  {}

  /**
   * Wait for a message to arrive from some other SIMPL process, and
   * when it does, construct a SimplIOStream around it. Automatically
   * sets useReply to true, given the nature of the task. */
  SimplIOStream()
    : useReply(true),
      pos(0)
  {
    other = * (FCID *) SimplTransport::popMessage(msg, msglen);

    if (other.slot == -1)
      throw MPS::MPSException("SIMPL Receive failed");
  }

  /// Returns the handle on the SIMPL process at the other end of this link.
  FCID getOther() const { return other; }

  /// Reads a byte from the message this SimplIOStream has read from our interlocutor
  virtual int read() {
    if (pos >= msglen) {
      throw MPS::MPSConnectionClosedException("reading from a SIMPL message");
    }

    return msg[pos++];
  }

  /// Sends our outbound message to our interlocutor
  virtual void flush() {
    if (useReply) {
      if (Reply(&other, (void *) getBody(), getLength()) == -1)
        throw MPS::MPSException("SIMPL Reply failed");
    } else {
      int replylen = Send(&other, const_cast<char *>(getBody()), msg, getLength(), sizeof(msg));

      if (replylen == -1)
        throw MPS::MPSException("SIMPL Send failed");
      if (replylen > 0)
        SimplTransport::pushMessage(&other, msg, replylen);
    }

    MPS::OutputStream::flush();
  }
};

///////////////////////////////////////////////////////////////////////////

class SimplTransport::SimplConnection: public MPS::Connection {
private:
  int oid;                      ///< OID this connection is connected to
  FCID other;                   ///< SIMPL process that holds the object we are connected to

public:
  /**
   * Constructs a connection to the given OID at the named SIMPL process.
   *
   * @param _oid the OID to connect to
   * @param _other the SIMPL process to connect to
   * @param a the MPS::Address to pass on to our superclass, MPS::Connection
   */
  SimplConnection(int _oid, FCID const &_other, MPS::Address const &a)
    : MPS::Connection(a),
           oid(_oid),
           other(_other)
  {}

  /**
   * Returns a writeable-stream that will send a message to the object
   * we are connected to */
  virtual MPS::OutputStream *getOutputStream() {
    MPS::OutputStream *stream = new SimplIOStream(other, false);
    stream->writeint(oid);
    return stream;
  }

  /**
   * Returns a readable-stream that returns bytes from a message we
   * received from the object we are connected to */
  virtual MPS::InputStream *getInputStream() {
    MPS::InputStream *stream = new SimplIOStream();
    int inputOid = stream->readint();

    if (inputOid != oid) {
      throw MPS::MPSException("OID mismatch in SimplTransport::SimplConnection, got " +
                              toString(inputOid) + " expected " + toString(oid));
    }

    return stream;
  }

  virtual void releaseOutputStream(MPS::OutputStream *stream) { delete stream; }
  virtual void releaseInputStream(MPS::InputStream *stream) { delete stream; }
};

///////////////////////////////////////////////////////////////////////////

SimplTransport::SimplTransport(string const &_simplName)
  : Transport("simpl"),
    nextOid(1),
    simplName(_simplName),
    serverMap()
{
  if (name_attach(const_cast<char *>(simplName.c_str()), MPS_MESSAGE_MAXLEN, 0) == -1)
    throw MPSException("Could not attach to SIMPL name " + simplName);
}

///////////////////////////////////////////////////////////////////////////

ref<Connection> SimplTransport::connectTo(Address const &connectionSpec)
{
  if (connectionSpec.getParamCount() != 2)
    throw MPS::MPSException("Simpl transport requires 2 Address parameters");

  string remoteName = connectionSpec.getParam(0);
  int oid = atoi(connectionSpec.getParam(1).c_str());

  FCID other = name_locate(const_cast<char *>(remoteName.c_str()));
  if (other.slot == -1)
    throw MPS::MPSException("Simpl name_locate of " + remoteName + " failed");

  return new SimplConnection(oid, other, connectionSpec);
}

string SimplTransport::registerServer(Server *server, Address const &spec)
{
  if (spec.getParamCount() > 0) {
    throw MPS::MPSException("Simpl transport does not allow self-selection of simplName or OID");
  }

  int thisOid = nextOid++;

  serverMap[thisOid] = server;

  Address newSpec("mps:simpl");
  newSpec.setParam(0, instance->simplName);
  newSpec.setParam(1, toString(thisOid));

  return newSpec.getResolvedName();
}

string SimplTransport::deregisterServer(Server *server, Address const &spec) {
  // how embarrassing.
  throw MPSException("SimplTransport::deregisterServer not yet implemented");
}

///////////////////////////////////////////////////////////////////////////

struct QueuedMessage_t {
  FCID sender;
  char *msg;
  int msglen;

  QueuedMessage_t()
    : msg(0),
      msglen(0)
  {}

  QueuedMessage_t(FCID const &s, char const *m, int len)
    : sender(s),
      msg(new char[len]),
      msglen(len)
  {
    memcpy(msg, m, len);
  }

  ~QueuedMessage_t() {
    clean();
  }

private:
  QueuedMessage_t(QueuedMessage_t const &other);
  QueuedMessage_t const &operator=(QueuedMessage_t const &other);

  void clean() {
    if (msg) {
      delete [] msg;
      msg = 0;
    }
  }
};

static deque<QueuedMessage_t *> msgQueue;

void SimplTransport::pushMessage(void *sender, char const *msg, int msglen) {
  msgQueue.push_back(new QueuedMessage_t(* (FCID *) sender, msg, msglen));
}

void *SimplTransport::popMessage(char *msg, int &msglen) {
  static FCID sender;

  if (msgQueue.empty()) {
    sender = Receive(msg, &msglen);
  } else {
    QueuedMessage_t *qm = msgQueue.front();
    msgQueue.pop_front();

    msglen = qm->msglen;
    memcpy(msg, qm->msg, msglen);
    sender = qm->sender;

    delete qm;
  }

  return &sender;
}

void SimplTransport::mainloop() {
  while (1) {
    SimplIOStream input;
    int oid = input.readint();

    serverMap_t::iterator i = instance->serverMap.find(oid);
    if (i == instance->serverMap.end()) {
      throw MPSException("Unknown OID " + toString(oid) + " received");
    }

    Server *server = (*i).second;
    FCID sender = input.getOther();

    SimplIOStream output(sender, true);
    output.writeint(oid);
    int pos = output.getLength();

    server->dispatch(input, output);

    if (output.getLength() > pos) {
      output.flush();
    } else {
      if (Reply(&sender, 0, 0) == -1)
        throw MPS::MPSException("SIMPL Reply failed in mainloop");
    }
  }
}

}

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