init: init nachos hw01, should pass jenkins os_group_20_hw job but fail on os_group_20_ta job
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TA
344
code/network/post.cc
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344
code/network/post.cc
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// post.cc
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// Routines to deliver incoming network messages to the correct
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// "address" -- a mailbox, or a holding area for incoming messages.
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// This module operates just like the US postal service (in other
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// words, it works, but it's slow, and you can't really be sure if
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// your mail really got through!).
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//
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// Note that once we prepend the MailHdr to the outgoing message data,
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// the combination (MailHdr plus data) looks like "data" to the Network
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// device.
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//
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// The implementation synchronizes incoming messages with threads
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// waiting for those messages.
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//
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// Copyright (c) 1992-1996 The Regents of the University of California.
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// All rights reserved. See copyright.h for copyright notice and limitation
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// of liability and disclaimer of warranty provisions.
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#include "copyright.h"
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#include "post.h"
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//----------------------------------------------------------------------
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// Mail::Mail
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// Initialize a single mail message, by concatenating the headers to
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// the data.
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//
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// "pktH" -- source, destination machine ID's
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// "mailH" -- source, destination mailbox ID's
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// "data" -- payload data
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//----------------------------------------------------------------------
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Mail::Mail(PacketHeader pktH, MailHeader mailH, char *msgData)
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{
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ASSERT(mailH.length <= MaxMailSize);
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pktHdr = pktH;
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mailHdr = mailH;
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bcopy(msgData, data, mailHdr.length);
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}
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//----------------------------------------------------------------------
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// MailBox::MailBox
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// Initialize a single mail box within the post office, so that it
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// can receive incoming messages.
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//
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// Just initialize a list of messages, representing the mailbox.
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//----------------------------------------------------------------------
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MailBox::MailBox()
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{
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messages = new SynchList<Mail *>();
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}
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//----------------------------------------------------------------------
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// MailBox::~MailBox
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// De-allocate a single mail box within the post office.
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//
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// Just delete the mailbox, and throw away all the queued messages
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// in the mailbox.
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//----------------------------------------------------------------------
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MailBox::~MailBox()
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{
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delete messages;
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}
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//----------------------------------------------------------------------
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// PrintHeader
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// Print the message header -- the destination machine ID and mailbox
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// #, source machine ID and mailbox #, and message length.
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//
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// "pktHdr" -- source, destination machine ID's
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// "mailHdr" -- source, destination mailbox ID's
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//----------------------------------------------------------------------
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static void
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PrintHeader(PacketHeader pktHdr, MailHeader mailHdr)
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{
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cout << "From (" << pktHdr.from << ", " << mailHdr.from << ") to (" <<
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pktHdr.to << ", " << mailHdr.to << ") bytes " << mailHdr.length << "\n";
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}
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//----------------------------------------------------------------------
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// MailBox::Put
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// Add a message to the mailbox. If anyone is waiting for message
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// arrival, wake them up!
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//
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// We need to reconstruct the Mail message (by concatenating the headers
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// to the data), to simplify queueing the message on the SynchList.
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//
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// "pktHdr" -- source, destination machine ID's
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// "mailHdr" -- source, destination mailbox ID's
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// "data" -- payload message data
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//----------------------------------------------------------------------
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void
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MailBox::Put(PacketHeader pktHdr, MailHeader mailHdr, char *data)
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{
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Mail *mail = new Mail(pktHdr, mailHdr, data);
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messages->Append(mail); // put on the end of the list of
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// arrived messages, and wake up
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// any waiters
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}
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//----------------------------------------------------------------------
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// MailBox::Get
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// Get a message from a mailbox, parsing it into the packet header,
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// mailbox header, and data.
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//
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// The calling thread waits if there are no messages in the mailbox.
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//
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// "pktHdr" -- address to put: source, destination machine ID's
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// "mailHdr" -- address to put: source, destination mailbox ID's
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// "data" -- address to put: payload message data
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//----------------------------------------------------------------------
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void
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MailBox::Get(PacketHeader *pktHdr, MailHeader *mailHdr, char *data)
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{
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DEBUG(dbgNet, "Waiting for mail in mailbox");
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Mail *mail = messages->RemoveFront(); // remove message from list;
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// will wait if list is empty
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*pktHdr = mail->pktHdr;
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*mailHdr = mail->mailHdr;
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if (debug->IsEnabled('n')) {
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cout << "Got mail from mailbox: ";
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PrintHeader(*pktHdr, *mailHdr);
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}
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bcopy(mail->data, data, mail->mailHdr.length);
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// copy the message data into
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// the caller's buffer
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delete mail; // we've copied out the stuff we
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// need, we can now discard the message
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}
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//----------------------------------------------------------------------
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// PostOfficeInput::PostOfficeInput
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// Initialize the post office input queues as a collection of mailboxes.
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// Also initialize the network device, to allow post offices
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// on different machines to deliver messages to one another.
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//
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// We use a separate thread "the postal worker" to wait for messages
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// to arrive, and deliver them to the correct mailbox. Note that
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// delivering messages to the mailboxes can't be done directly
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// by the interrupt handlers, because it requires a Lock.
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//
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// "nBoxes" is the number of mail boxes in this Post Office
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//----------------------------------------------------------------------
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PostOfficeInput::PostOfficeInput(int nBoxes)
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{
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messageAvailable = new Semaphore("message available", 0);
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numBoxes = nBoxes;
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boxes = new MailBox[nBoxes];
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network = new NetworkInput(this);
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Thread *t = new Thread("postal worker", 1);
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t->Fork(PostOfficeInput::PostalDelivery, this);
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}
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//----------------------------------------------------------------------
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// PostOfficeInput::~PostOfficeInput
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// De-allocate the post office data structures.
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//
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// Since the postal helper is waiting on the "messageAvail" semaphore,
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// we don't deallocate it! This leaves garbage lying about,
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// but the alternative is worse!
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//----------------------------------------------------------------------
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PostOfficeInput::~PostOfficeInput()
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{
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delete network;
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delete [] boxes;
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}
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//----------------------------------------------------------------------
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// PostOffice::PostalDelivery
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// Wait for incoming messages, and put them in the right mailbox.
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//
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// Incoming messages have had the PacketHeader stripped off,
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// but the MailHeader is still tacked on the front of the data.
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//----------------------------------------------------------------------
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void
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PostOfficeInput::PostalDelivery(void* data)
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{
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PostOfficeInput* _this = (PostOfficeInput*)data;
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PacketHeader pktHdr;
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MailHeader mailHdr;
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char *buffer = new char[MaxPacketSize];
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for (;;) {
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// first, wait for a message
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_this->messageAvailable->P();
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pktHdr = _this->network->Receive(buffer);
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mailHdr = *(MailHeader *)buffer;
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if (debug->IsEnabled('n')) {
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cout << "Putting mail into mailbox: ";
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PrintHeader(pktHdr, mailHdr);
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}
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// check that arriving message is legal!
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ASSERT(0 <= mailHdr.to && mailHdr.to < _this->numBoxes);
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ASSERT(mailHdr.length <= MaxMailSize);
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// put into mailbox
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_this->boxes[mailHdr.to].Put(pktHdr, mailHdr, buffer + sizeof(MailHeader));
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}
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}
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//----------------------------------------------------------------------
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// PostOfficeInput::Receive
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// Retrieve a message from a specific box if one is available,
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// otherwise wait for a message to arrive in the box.
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//
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// Note that the MailHeader + data looks just like normal payload
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// data to the Network.
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//
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//
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// "box" -- mailbox ID in which to look for message
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// "pktHdr" -- address to put: source, destination machine ID's
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// "mailHdr" -- address to put: source, destination mailbox ID's
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// "data" -- address to put: payload message data
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//----------------------------------------------------------------------
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void
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PostOfficeInput::Receive(int box, PacketHeader *pktHdr,
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MailHeader *mailHdr, char* data)
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{
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ASSERT((box >= 0) && (box < numBoxes));
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boxes[box].Get(pktHdr, mailHdr, data);
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ASSERT(mailHdr->length <= MaxMailSize);
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}
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//----------------------------------------------------------------------
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// PostOffice::CallBack
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// Interrupt handler, called when a packet arrives from the network.
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//
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// Signal the PostalDelivery routine that it is time to get to work!
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//----------------------------------------------------------------------
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void
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PostOfficeInput::CallBack()
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{
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messageAvailable->V();
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}
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//----------------------------------------------------------------------
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// PostOfficeOutput::PostOfficeOutput
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// Initialize the post office output queue.
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//
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// "reliability" is the probability that a network packet will
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// be delivered (e.g., reliability = 1 means the network never
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// drops any packets; reliability = 0 means the network never
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// delivers any packets)
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//----------------------------------------------------------------------
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PostOfficeOutput::PostOfficeOutput(double reliability)
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{
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messageSent = new Semaphore("message sent", 0);
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sendLock = new Lock("message send lock");
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network = new NetworkOutput(reliability, this);
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}
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//----------------------------------------------------------------------
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// PostOfficeOutput::~PostOfficeOutput
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// De-allocate the post office data structures.
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//----------------------------------------------------------------------
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PostOfficeOutput::~PostOfficeOutput()
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{
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delete network;
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delete messageSent;
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delete sendLock;
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}
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//----------------------------------------------------------------------
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// PostOfficeOutput::Send
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// Concatenate the MailHeader to the front of the data, and pass
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// the result to the Network for delivery to the destination machine.
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//
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// Note that the MailHeader + data looks just like normal payload
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// data to the Network.
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//
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// "pktHdr" -- source, destination machine ID's
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// "mailHdr" -- source, destination mailbox ID's
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// "data" -- payload message data
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//----------------------------------------------------------------------
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void
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PostOfficeOutput::Send(PacketHeader pktHdr, MailHeader mailHdr, char* data)
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{
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char* buffer = new char[MaxPacketSize]; // space to hold concatenated
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// mailHdr + data
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if (debug->IsEnabled('n')) {
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cout << "Post send: ";
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PrintHeader(pktHdr, mailHdr);
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}
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ASSERT(mailHdr.length <= MaxMailSize);
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ASSERT(0 <= mailHdr.to);
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// fill in pktHdr, for the Network layer
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pktHdr.from = kernel->hostName;
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pktHdr.length = mailHdr.length + sizeof(MailHeader);
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// concatenate MailHeader and data
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bcopy((char *)&mailHdr, buffer, sizeof(MailHeader));
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bcopy(data, buffer + sizeof(MailHeader), mailHdr.length);
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sendLock->Acquire(); // only one message can be sent
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// to the network at any one time
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network->Send(pktHdr, buffer);
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messageSent->P(); // wait for interrupt to tell us
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// ok to send the next message
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sendLock->Release();
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delete [] buffer; // we've sent the message, so
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// we can delete our buffer
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}
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//----------------------------------------------------------------------
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// PostOfficeOutput::CallBack
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// Interrupt handler, called when the next packet can be put onto the
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// network.
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//
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// Called even if the previous packet was dropped.
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//----------------------------------------------------------------------
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void
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PostOfficeOutput::CallBack()
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{
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messageSent->V();
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}
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