ceph/src/messages/MForward.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2010 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  * Client requests often need to get forwarded from some monitor
  14  * to the leader. This class encapsulates the original message
  15  * along with the client's caps so the leader can do proper permissions
  16  * checking.
  17  */
  18
  19 #ifndef CEPH_MFORWARD_H
  20 #define CEPH_MFORWARD_H
  21
  22 #include "msg/Message.h"
  23 #include "mon/MonCap.h"
  24 #include "include/encoding.h"
  25 #include "include/stringify.h"
  26
  27 struct MForward : public Message {
  28   uint64_t tid;
  29   entity_inst_t client;
  30   MonCap client_caps;
  31   uint64_t con_features;
  32   EntityName entity_name;
  33   PaxosServiceMessage *msg;   // incoming or outgoing message
  34
  35   string msg_desc;  // for operator<< only
  36
  37   static const int HEAD_VERSION = 3;
  38   static const int COMPAT_VERSION = 3;
  39
  40   MForward() : Message(MSG_FORWARD, HEAD_VERSION, COMPAT_VERSION),
  41                tid(0), con_features(0), msg(NULL) {}
  42   //the message needs to have caps filled in!
  43   MForward(uint64_t t, PaxosServiceMessage *m, uint64_t feat) :
  44     Message(MSG_FORWARD, HEAD_VERSION, COMPAT_VERSION),
  45     tid(t), msg(NULL) {
  46     client = m->get_source_inst();
  47     client_caps = m->get_session()->caps;
  48     con_features = feat;
  49     // we may need to reencode for the target mon
  50     msg->clear_payload();
  51     msg = (PaxosServiceMessage*)m->get();
  52   }
  53   MForward(uint64_t t, PaxosServiceMessage *m, uint64_t feat,
  54            const MonCap& caps) :
  55     Message(MSG_FORWARD, HEAD_VERSION, COMPAT_VERSION),
  56     tid(t), client_caps(caps), msg(NULL) {
  57     client = m->get_source_inst();
  58     con_features = feat;
  59     msg = (PaxosServiceMessage*)m->get();
  60   }
  61 private:
  62   ~MForward() override {
  63     if (msg) {
  64       // message was unclaimed
  65       msg->put();
  66       msg = NULL;
  67     }
  68   }
  69
  70 public:
  71   void encode_payload(uint64_t features) override {
  72     ::encode(tid, payload);
  73     ::encode(client, payload, features);
  74     ::encode(client_caps, payload, features);
  75     // Encode client message with intersection of target and source
  76     // features.  This could matter if the semantics of the encoded
  77     // message are changed when reencoding with more features than the
  78     // client had originally.  That should never happen, but we may as
  79     // well be defensive here.
  80     if (con_features != features) {
  81       msg->clear_payload();
  82     }
  83     encode_message(msg, features & con_features, payload);
  84     ::encode(con_features, payload);
  85     ::encode(entity_name, payload);
  86   }
  87
  88   void decode_payload() override {
  89     bufferlist::iterator p = payload.begin();
  90     ::decode(tid, p);
  91     ::decode(client, p);
  92     ::decode(client_caps, p);
  93     msg = (PaxosServiceMessage *)decode_message(NULL, 0, p);
  94     ::decode(con_features, p);
  95     ::decode(entity_name, p);
  96   }
  97
  98   PaxosServiceMessage *claim_message() {
  99     // let whoever is claiming the message deal with putting it.
 100     assert(msg);
 101     msg_desc = stringify(*msg);
 102     PaxosServiceMessage *m = msg;
 103     msg = NULL;
 104     return m;
 105   }
 106
 107   const char *get_type_name() const override { return "forward"; }
 108   void print(ostream& o) const override {
 109     o << "forward(";
 110     if (msg) {
 111       o << *msg;
 112     } else {
 113       o << msg_desc;
 114     }
 115     o << " caps " << client_caps
 116       << " tid " << tid
 117       << " con_features " << con_features << ")";
 118   }
 119 };
 120
 121 #endif