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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */ |
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2 /* |
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3 * Copyright (c) 2007 INRIA |
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4 * All rights reserved. |
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5 * |
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6 * This program is free software; you can redistribute it and/or modify |
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7 * it under the terms of the GNU General Public License version 2 as |
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8 * published by the Free Software Foundation; |
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9 * |
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10 * This program is distributed in the hope that it will be useful, |
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11 * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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13 * GNU General Public License for more details. |
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14 * |
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15 * You should have received a copy of the GNU General Public License |
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16 * along with this program; if not, write to the Free Software |
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17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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18 * |
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19 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr> |
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20 */ |
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21 #ifndef TRACE_ROOT_H |
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22 #define TRACE_ROOT_H |
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23 |
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24 #include <string> |
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25 #include "ns3/callback.h" |
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26 |
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27 /** |
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28 * \defgroup tracing Tracing |
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29 * |
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30 * The low-level tracing framework is built around a few very simple |
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31 * concepts: |
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32 * - There can be any number of trace source objects. Each trace source |
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33 * object can generate any number of trace events. The current |
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34 * trace source objects are: ns3::CallbackTraceSourceSource, ns3::UVTraceSource, |
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35 * ns3::SVTraceSource, and, ns3::FVTraceSource. |
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36 * - Each trace source can be connected to any number of trace sinks. |
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37 * A trace sink is a ns3::Callback with a very special signature. Its |
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38 * first argument is always a ns3::TraceContext. |
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39 * - Every trace source is uniquely identified by a ns3::TraceContext. Every |
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40 * trace sink can query a ns3::TraceContext for information. This allows |
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41 * a trace sink which is connected to multiple trace sources to identify |
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42 * from which source each event is coming from. |
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43 * |
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44 * To allow the user to connect his own trace sinks to each trace source |
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45 * defined by any of the models he is using, the tracing framework defines |
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46 * a hierarchical namespace. The root of this namespace is accessed through |
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47 * the ns3::TraceRoot class. The namespace is represented as a string made |
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48 * of multiple elements, each of which is separated from the other elements |
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49 * by the '/' character. A namespace string always starts with a '/'. |
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50 * |
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51 * By default, the simulation models provide a '/nodes' tracing root. This |
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52 * '/nodes' namespace is structured as follows: |
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53 * \code |
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54 * /nodes/n/udp |
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55 * /nodes/n/ipv4 |
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56 * /tx |
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57 * /rx |
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58 * /drop |
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59 * /interfaces/n/netdevice |
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60 * (NetDevice only) /queue/ |
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61 * /enque |
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62 * /deque |
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63 * /drop |
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64 * /nodes/n/arp |
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65 * \endcode |
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66 * |
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67 * The 'n' element which follows the /nodes and /interfaces namespace elements |
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68 * identify a specific node and interface through their index within the |
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69 * ns3::NodeList and ns3::Ipv4 objects respectively. |
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70 * |
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71 * To connect a trace sink to a trace source identified by a namespace string, |
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72 * a user can call the ns3::TraceRoot::Connect method (the ns3::TraceRoot::Disconnect |
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73 * method does the symmetric operation). This connection method can accept |
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74 * fully-detailed namespace strings but it can also perform pattern matching |
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75 * on the user-provided namespace strings to connect multiple trace sources |
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76 * to a single trace sink in a single connection operation. |
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77 * |
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78 * The syntax of the pattern matching rules are loosely based on regular |
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79 * expressions: |
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80 * - the '*' character matches every element |
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81 * - the (a|b) construct matches element 'a' or 'b' |
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82 * - the [ss-ee] construct matches all numerical values which belong |
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83 * to the interval which includes ss and ee |
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84 * |
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85 * For example, the user could use the following to connect a single sink |
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86 * to the ipv4 tx, rx, and drop trace events: |
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87 * |
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88 * \code |
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89 * void MyTraceSink (TraceContext const &context, Packet &packet); |
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90 * TraceRoot::Connect ("/nodes/ * /ipv4/ *", MakeCallback (&MyTraceSink)); |
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91 * \endcode |
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92 * |
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93 * Of course, this code would work only if the signature of the trace sink |
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94 * is exactly equal to the signature of all the trace sources which match |
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95 * the namespace string (if one of the matching trace source does not match |
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96 * exactly, a fatal error will be triggered at runtime during the connection |
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97 * process). The ns3::TraceContext extra argument contains |
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98 * information on where the trace source is located in the namespace tree. |
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99 * In that example, if there are multiple nodes in this scenario, each |
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100 * call to the MyTraceSink function would receive a different TraceContext, |
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101 * each of which would contain a different NodeList::Index object. |
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102 * |
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103 * It is important to understand exactly what an ns3::TraceContext |
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104 * is. It is a container for a number of type instances. Each instance of |
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105 * a ns3::TraceContext contains one and only one instance of a given type. |
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106 * ns3::TraceContext::Add can be called to add a type instance into a |
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107 * TraceContext instance and ns3::TraceContext::Get can be called to get |
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108 * a copy of a type instance stored into the ns3::TraceContext. If ::Get |
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109 * cannot retrieve the requested type, a fatal error is triggered at |
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110 * runtime. The values stored into an ns3::TraceContext attached to a |
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111 * trace source are automatically determined during the namespace |
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112 * resolution process. To retrieve a value from a ns3::TraceContext, the |
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113 * code can be as simple as this: |
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114 * \code |
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115 * void MyTraceSink (TraceContext const &context, Packet &packet) |
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116 * { |
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117 * NodeList::Index index; |
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118 * context.Get (index); |
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119 * std::cout << "node id=" << NodeList::GetNode (index)->GetId () << std::endl; |
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120 * } |
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121 * \endcode |
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122 * |
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123 * To define new trace sources, a model author needs to instante one trace source |
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124 * object for each kind of tracing event he wants to export. The trace source objects |
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125 * currently defined are: |
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126 * - ns3::CallbackTraceSourceSource: this trace source can be used to convey any kind of |
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127 * trace event to the user. It is a functor, that is, it is a variable |
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128 * which behaves like a function which will forward every event to every |
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129 * connected trace sink (i.e., ns3::Callback). This trace source takes |
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130 * up to four arguments and forwards these 4 arguments together with the |
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131 * ns3::TraceContext which identifies this trace source to the connected |
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132 * trace sinks. |
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133 * - ns3::UVTraceSource: this trace source is used to convey key state variable |
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134 * changes to the user. It behaves like a normal integer unsigned variable: |
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135 * you can apply every normal arithmetic operator to it. It will forward |
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136 * every change in the value of the variable back to every connected trace |
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137 * sink by providing a TraceContext, the old value and the new value. |
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138 * - ns3::SVTraceSource: this is the signed integer equivalent of |
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139 * ns3::UVTraceSource. |
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140 * - ns3::FVTraceSource: this is the floating point equivalent of |
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141 * ns3::UVTraceSource and ns3::SVTraceSource. |
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142 * |
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143 * Once the model author has instantiated these objects and has wired them |
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144 * in his simulation code (that is, he calls them wherever he wants to |
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145 * trigger a trace event), he needs to hook these trace sources into the |
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146 * global tracing namespace. The first step to do this is to define a method |
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147 * which returns a pointer to a ns3::TraceResolver object and which takes |
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148 * as argument a reference to a const ns3::TraceContext. The name of this method |
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149 * depends on how you will hook into the global tracing namespace. Before |
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150 * we get there, you need to implement this method. To do this, you could |
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151 * attempt to do everything by hand: define a subclass of the |
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152 * ns3::TraceResolver base class and implement its DoConnect, DoDisconnect |
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153 * and DoLookup methods. Because doing this can be a bit tedious, our |
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154 * tracing framework provides a number of helper template classes which |
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155 * should save you from having to implement your own in most cases: |
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156 * - ns3::CompositeTraceResolver: this subclass of ns3::TraceResolver |
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157 * can be used to aggregate together multiple trace sources and |
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158 * multiple other ns3::TraceResolver instances. |
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159 * - ns3::ArrayTraceResolver: this subclass of ns3::TraceResolver |
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160 * can be used to match any number of elements within an array |
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161 * where every element is identified by its index. |
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162 * |
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163 * Once you can instantiate your own ns3::TraceResolver object instance, |
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164 * you have to hook it up into the global namespace. There are two ways |
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165 * to do this: |
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166 * - you can hook your ns3::TraceResolver creation method as a new trace |
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167 * root by using the ns3::TraceRoot::Register method |
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168 * - you can hook your new ns3::TraceResolver creation method into |
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169 * the container of your model. |
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170 * For example, if you wrote a new l3 protocol, all you have to do |
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171 * to hook into your container L3Demux class is to implement |
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172 * the pure virtual method inherited from the L3Protocol class |
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173 * whose name is ns3::L3protocol::CreateTraceResolver. |
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174 * |
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175 * If you really want to have fun and implement your own ns3::TraceResolver |
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176 * subclass, you need to understand the basic Connection and Disconnection |
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177 * algorithm. The code of that algorithm is wholy contained in the |
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178 * ns3::TraceResolver::Connect and ns3::TraceResolver::Disconnect methods. |
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179 * The idea is that we recursively parse the input namespace string by removing |
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180 * the first namespace element. This element is 'resolved' is calling |
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181 * the ns3::TraceResolver::DoLookup method which returns a list of |
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182 * TraceResolver instances. Each of the returned TraceResolver instance is |
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183 * then given what is left of the namespace by calling ns3::TraceResolver::Connect |
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184 * until the last namespace element is processed. At this point, we invoke |
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185 * the ns3::TraceResolver::DoConnect or ns3::TraceResolver::DoDisconnect |
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186 * methods to break the recursion. A good way to understand this algorithm |
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187 * is to trace its behavior. Let's say that you want to connect to |
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188 * '/nodes/ * /ipv4/interfaces/ * /netdevice/queue/ *'. It would generate |
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189 * the following call traces: |
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190 * |
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191 * \code |
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192 * TraceRoot::Connect (/nodes/ * /ipv4/interfaces/ * /netdevice/queue/ *); |
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193 * resolver = NodeList::CreateTraceResolver (); |
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194 * resolver->Connect (/nodes/ * /ipv4/interfaces/ * /netdevice/queue/ *); |
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195 * list = CompositeTraceResolver::DoLookup ('nodes'); |
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196 * resolver->Connect (/ * /ipv4/interfaces/ * /netdevice/queue/ *); |
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197 * list = ArrayTraceResolver::DoLookup ('*'); |
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198 * resolver->Connect ('/ipv4/interfaces/ * /netdevice/queue/ *'); |
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199 * list = CompositeTraceResolver::DoLookup ('ipv4'); |
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200 * resolver->Connect ('/interfaces/ * /netdevice/queue/ *'); |
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201 * list = CompositeTraceResolver::DoLookup ('interfaces'); |
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202 * resolver->Connect ('/ * /netdevice/queue/ *'); |
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203 * list = ArrayTraceResolver::DoLookup ('*'); |
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204 * resolver->Connect ('/netdevice/queue/ *'); |
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205 * list = CompositeTraceResolver::DoLookup ('netdevice'); |
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206 * resolver->Connect ('/queue/ *'); |
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207 * list = CompositeTraceResolver::DoLookup ('queue'); |
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208 * resolver->Connect ('/ *'); |
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209 * list = CompositeTraceResolver::DoLookup ('*'); |
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210 * resolver->DoConnect (); |
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211 * \endcode |
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212 * |
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213 * This namespace resolution algorithm makes sure that each subpart of the |
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214 * namespace is resolved separately by each component. It allows you to |
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215 * never have to know the entire namespace structure to resolve a namespace |
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216 * string. All namespace knowledge is local which makes it very easy to plug |
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217 * in new components and have them extend the global tracing namespace. |
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218 * |
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219 * What is central to this namespace parsing and resolution algorithm is the |
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220 * construction of an ns3::TraceContext for each trace source during the |
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221 * connection process. The root trace context is intialized to be empty and |
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222 * TraceResolver::DoLookup method is responsible for incrementally constructing |
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223 * the TraceContext assigned to each terminal TraceSource object. |
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224 */ |
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225 |
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226 namespace ns3 { |
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227 |
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228 class CompositeTraceResolver; |
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229 class TraceResolver; |
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230 class TraceContext; |
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231 class CallbackBase; |
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232 |
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233 /** |
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234 * \brief The main class used to access tracing functionality for |
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235 * a user. |
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236 * |
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237 * \ingroup tracing |
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238 */ |
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239 class TraceRoot |
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240 { |
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241 public: |
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242 static void Connect (std::string path, CallbackBase const &cb); |
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243 static void Disconnect (std::string path, CallbackBase const &cb); |
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244 static void Register (std::string name, |
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245 Callback<TraceResolver *,TraceContext const &> createResolver); |
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246 private: |
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247 static CompositeTraceResolver *GetComposite (void); |
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248 enum TraceType { |
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249 NOTHING, |
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250 }; |
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251 }; |
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252 |
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253 }// namespace ns3 |
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254 |
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255 #endif /* TRACE_ROOT_H */ |