--- /dev/null
+/* Copyright (c) 2014-2016. The SimGrid Team. All rights reserved. */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+#ifndef SIMGRID_ROUTING_CLUSTER_FAT_TREE_HPP_
+#define SIMGRID_ROUTING_CLUSTER_FAT_TREE_HPP_
+
+#include "src/routing/AsCluster.hpp"
+
+namespace simgrid {
+namespace routing {
+
+class XBT_PRIVATE FatTreeLink;
+
+/** \brief A node in a fat tree (@ref AsClusterFatTree).
+ * A FatTreeNode can either be a switch or a processing node. Switches are
+ * identified by a negative ID. This class is closely related to fat
+ */
+class XBT_PRIVATE FatTreeNode {
+public:
+ /** Unique ID which identifies every node. */
+ int id;
+ /* Level into the tree, with 0 being the leafs.
+ */
+ unsigned int level;
+ /* \brief Position into the level, starting from 0.
+ */
+ unsigned int position;
+ /** In order to link nodes between them, each one must be assigned a label,
+ * consisting of l integers, l being the levels number of the tree. Each label
+ * is unique in the level, and the way it is generated allows the construction
+ * of a fat tree which fits the desired topology.
+ */
+ std::vector<unsigned int> label;
+
+ /** Links to the lower level, where the position in the vector corresponds to
+ * a port number.
+ */
+ std::vector<FatTreeLink*> children;
+ /** Links to the upper level, where the position in the vector corresponds to
+ * a port number.
+ */
+ std::vector<FatTreeLink*> parents;
+
+ /** Virtual link standing for the node global capacity.
+ */
+ Link* limiterLink;
+ /** If present, communications from this node to this node will pass through it
+ * instead of passing by an upper level switch.
+ */
+ Link* loopback;
+ FatTreeNode(sg_platf_cluster_cbarg_t cluster, int id, int level, int position);
+};
+
+
+
+/** \brief Link in a fat tree (@ref AsClusterFatTree).
+ *
+ * Represents a single, duplex link in a fat tree. This is necessary to have a tree.
+ * It is equivalent to a physical link.
+ */
+class FatTreeLink {
+public:
+ FatTreeLink(sg_platf_cluster_cbarg_t cluster, FatTreeNode *source, FatTreeNode *destination);
+ /** Link going up in the tree */
+ Link *upLink;
+ /** Link going down in the tree */
+ Link *downLink;
+ /** Upper end of the link */
+ FatTreeNode *upNode;
+ /** Lower end of the link */
+ FatTreeNode *downNode;
+};
+
+/**
+ * \class AsClusterFatTree
+ *
+ * \brief Fat tree representation and routing.
+ *
+ * Generate fat trees according to the topology asked for, according to:
+ * Eitan Zahavi, D-Mod-K Routing Providing Non-Blocking Traffic for Shift
+ * Permutations on Real Life Fat Trees (2010).
+ *
+ * RLFT are PGFT with some restrictions to address real world constraints,
+ * which are not currently enforced.
+ *
+ * The exact topology is described in the mandatory topo_parameters
+ * field, and follow the "h ; m_h, ..., m_1 ; w_h, ..., w_1 ; p_h, ..., p_1" format.
+ * h stands for the switches levels number, i.e. the fat tree is of height h,
+ * without the processing nodes. m_i stands for the number of lower level nodes
+ * connected to a node in level i. w_i stands for the number of upper levels
+ * nodes connected to a node in level i-1. p_i stands for the number of
+ * parallel links connecting two nodes between level i and i - 1. Level h is
+ * the topmost switch level, level 1 is the lowest switch level, and level 0
+ * represents the processing nodes. The number of provided nodes must be exactly
+ * the number of processing nodes required to fit the topology, which is the
+ * product of the m_i's.
+ *
+ * Routing is made using a destination-mod-k scheme.
+ */
+class XBT_PRIVATE AsClusterFatTree : public AsCluster {
+public:
+ explicit AsClusterFatTree(const char*name);
+ ~AsClusterFatTree() override;
+ void getRouteAndLatency(NetCard *src, NetCard *dst,
+ sg_platf_route_cbarg_t into,
+ double *latency) override;
+
+ /** \brief Generate the fat tree
+ *
+ * Once all processing nodes have been added, this will make sure the fat
+ * tree is generated by calling generateLabels(), generateSwitches() and
+ * then connection all nodes between them, using their label.
+ */
+ void seal() override;
+ /** \brief Read the parameters in topo_parameters field.
+ *
+ * It will also store the cluster for future use.
+ */
+ void parse_specific_arguments(sg_platf_cluster_cbarg_t cluster) override;
+ void addProcessingNode(int id);
+ void generateDotFile(const std::string& filename = "fatTree.dot") const;
+
+private:
+
+ //description of a PGFT (TODO : better doc)
+ unsigned int levels_ = 0;
+ std::vector<unsigned int> lowerLevelNodesNumber_; // number of children by node
+ std::vector<unsigned int> upperLevelNodesNumber_; // number of parents by node
+ std::vector<unsigned int> lowerLevelPortsNumber_; // ports between each level l and l-1
+
+ std::map<int, FatTreeNode*> computeNodes_;
+ std::vector<FatTreeNode*> nodes_;
+ std::vector<FatTreeLink*> links_;
+ std::vector<unsigned int> nodesByLevel_;
+
+ sg_platf_cluster_cbarg_t cluster_;
+
+ void addLink(FatTreeNode *parent, unsigned int parentPort,
+ FatTreeNode *child, unsigned int childPort);
+ int getLevelPosition(const unsigned int level);
+ void generateLabels();
+ void generateSwitches();
+ int connectNodeToParents(FatTreeNode *node);
+ bool areRelated(FatTreeNode *parent, FatTreeNode *child);
+ bool isInSubTree(FatTreeNode *root, FatTreeNode *node);
+};
+
+}
+}
+
+#endif
