root/sandbox/sigis/christian.gonzalez/trunk/core/src/dijkstra.c

/*
 * Shortest path algorithm for PostgreSQL
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

#include "postgres.h"
#include "executor/spi.h"
#include "funcapi.h"
#include "fmgr.h"

#include "dijkstra.h"

// The number of tuples to fetch from the SPI cursor at each iteration
#define TUPLIMIT 1000

#undef DEBUG
//#define DEBUG 1

#ifdef DEBUG
  #define DBG(format, arg...) ereport(NOTICE, (errmsg_internal(format, ## arg)));
#else
  #define DBG(format, arg...) do { ; } while (0)
#endif

/*
 * FUNCTIONS PROTOTYPES
 */
Datum shortest_path(PG_FUNCTION_ARGS);

static int finish(int code, int ret);

static int fetch_edge_columns(SPITupleTable *tuptable, edge_columns_t *edge_columns,
    bool bidirectional);

static void fetch_edge(HeapTuple *tuple, TupleDesc *tupdesc, edge_columns_t *edge_columns,
    edge_t *target_edge, int *minid);

static int compute_shortest_path(char* sql, int start_vertex,
    int end_vertex, bool directed, path_element_t **path, int *path_count);


#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

/*
 * Interface function to PostgreSQL
 */
PG_FUNCTION_INFO_V1(shortest_path);

Datum
shortest_path(PG_FUNCTION_ARGS)
{
  FuncCallContext     *funcctx;
  Datum               result;
  MemoryContext       oldcontext;

  int                 tuplen;
  int                 call_cntr;
  int                 max_calls;
  TupleDesc           tuple_desc;
  path_element_t      *path;
  int                 path_count;
  int                 ret;

  /* stuff done only on the first call of the function */
  if (SRF_IS_FIRSTCALL())
  {
      path_count = 0;

      /* create a function context for cross-call persistence */
      funcctx = SRF_FIRSTCALL_INIT();

      /* switch to memory context appropriate for multiple function calls */
      oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);


      ret = compute_shortest_path(DatumGetCString(DirectFunctionCall1(textout,PointerGetDatum(PG_GETARG_DATUM(0)))),
                                  PG_GETARG_INT32(1), //id
                                  PG_GETARG_INT32(2), //destination id
                                  PG_GETARG_BOOL(3), //if is directed
                                  //PG_GETARG_BOOL(4), //has reverse cost, not used
                                  &path,//for return the route
                                  &path_count //number of returned routes
                                  );

      /* total number of tuples to be returned */
      funcctx->max_calls = path_count;
      funcctx->user_fctx = path;

      /*Getting tuple_desc  from our type 'path_result'*/
      funcctx->tuple_desc = BlessTupleDesc(RelationNameGetTupleDesc("path_result"));

      MemoryContextSwitchTo(oldcontext);
  }

  /* stuff done on every call of the function */
  funcctx = SRF_PERCALL_SETUP();

  call_cntr = funcctx->call_cntr;
  max_calls = funcctx->max_calls;
  tuple_desc = funcctx->tuple_desc;
  path = (path_element_t*) funcctx->user_fctx;

  /*
   * do when there is more left to send
   */
  if (call_cntr < max_calls)
  {
    HeapTuple   tuple;
    Datum       *values;
    bool        *nulls;

    /*Number of attributes in the tuple */
    tuplen = tuple_desc->natts;

    values = SPI_palloc(tuplen * sizeof(Datum));
    nulls = SPI_palloc(tuplen * sizeof(bool));

    values[0] = Int32GetDatum(path[call_cntr].vertex_id);
    values[1] = Int32GetDatum(path[call_cntr].edge_id);
    values[2] = Float8GetDatum(path[call_cntr].cost);

    /* build tuple from datum array*/
    tuple = heap_form_tuple(tuple_desc,values,nulls);

    /* make the tuple into a datum */
    result = HeapTupleGetDatum(tuple);

    /* clean up (this is not really necessary) */
    SPI_pfree(values);
    SPI_pfree(nulls);

    SRF_RETURN_NEXT(funcctx, result);
  }
  else    /* do when there is no more left */
  {
    SRF_RETURN_DONE(funcctx);
  }

  SPI_pfree(path);

}

/*
 *
 */
static int
compute_shortest_path(char* sql, int start_vertex, int end_vertex,
                                 bool directed, path_element_t **path, int *path_count)
{

  int             SPIcode;
  void            *SPIplan;
  Portal          SPIportal;
  bool            moredata = TRUE;
  int             ntuples;
  edge_t          *edges = NULL;
  int             total_tuples = 0;
  edge_columns_t  edge_columns = {id: PGR_COLUMN_NOTEXIST ,
                                 source: PGR_COLUMN_NOTEXIST,
                                 target: PGR_COLUMN_NOTEXIST,
                                 cost: PGR_COLUMN_NOTEXIST,
                                 bidirectional: PGR_COLUMN_NOTEXIST,
                                 reverse_cost: PGR_COLUMN_NOTEXIST};
  int             v_min_id = INT_MAX;
  int             *minid;
  int             s_count = 0;
  int             t_count = 0;
  char            *err_msg;
  int             ret = -1;
  register int    z;

  /*pointer for manipulating the 'minimum id' in fetch_edge function*/
  minid = &v_min_id;

  DBG("Minimum source and target id = %i", v_min_id);

  DBG("#---- executing function 'compute_shortest_path' ----#\n");

  if ((SPIcode = SPI_connect() ) != SPI_OK_CONNECT)
  {
    ereport(ERROR, (errmsg_internal("shortest_path: couldn't open a connection to SPI")));
    return -1;
  }

  if ( (SPIplan = SPI_prepare(sql, 0, NULL) )== NULL)
  {
    ereport(ERROR, (errmsg_internal("shortest_path: couldn't create query plan via SPI")));
    return -1;
  }

  if ((SPIportal = SPI_cursor_open(NULL, SPIplan, NULL, NULL, true)) == NULL)
  {
    ereport(ERROR, (errmsg_internal("shortest_path: SPI_cursor_open('%s') returns NULL", sql)));
    return -1;
  }

  while (moredata == TRUE)
  {
    SPI_cursor_fetch(SPIportal, TRUE, TUPLIMIT);

    if (edge_columns.id == PGR_COLUMN_NOTEXIST)
    {
      if (fetch_edge_columns(SPI_tuptable, &edge_columns, directed) == -1)
      {
        return finish(SPIcode, ret);
      }
    }

    ntuples = SPI_processed;
    total_tuples += ntuples;

    if (!edges)
    {
      edges = SPI_palloc(total_tuples * sizeof(edge_t));
    }
    else
    {
      edges = SPI_repalloc(edges, total_tuples * sizeof(edge_t));
    }

    if (edges == NULL)
    {
      ereport(ERROR, (errmsg_internal("Out of memory")));
      return finish(SPIcode, ret);
    }

    if (ntuples > 0)
    {
      int t;
      SPITupleTable *tuptable = SPI_tuptable;
      TupleDesc tupdesc = SPI_tuptable->tupdesc;

      for (t = 0; t < ntuples; t++)
      {
        HeapTuple tuple = tuptable->vals[t];
        fetch_edge(&tuple, &tupdesc, &edge_columns, &edges[total_tuples - ntuples + t], minid);

        /*
        DBG("Query columns values: id=%i source=%i target=%i cost=%f bidirectional=%i reverse_cost=%f",
              edges[total_tuples - ntuples + t].id,
              edges[total_tuples - ntuples + t].source,
              edges[total_tuples - ntuples + t].target,
              edges[total_tuples - ntuples + t].cost,
              edges[total_tuples - ntuples + t].bidirectional,
              edges[total_tuples - ntuples + t].reverse_cost);
         */
      }
      SPI_freetuptable(tuptable);
    }
    else
    {
        moredata = FALSE;
    }
  }

  DBG("Total %i tuples", total_tuples);
  DBG("'New' Minimum source and target id = %i", v_min_id);

  // reducing vertex id (renumbering)
  for(z=0; z<total_tuples; z++)
  {
    //check if edges[] contains source and target
    if(edges[z].source == start_vertex || edges[z].target == start_vertex)
    {
      ++s_count;
    }
    if(edges[z].source == end_vertex || edges[z].target == end_vertex)
    {
      ++t_count;
    }

    /*re-assign the news id to source and target*/
    DBG("Original source id -> %i -- Original target id ->%i", edges[z].source, edges[z].target);

    edges[z].source-=v_min_id;
    edges[z].target-=v_min_id;

    DBG("New source id -> %i -- New target id ->%i \n", edges[z].source, edges[z].target);

  }

  if(s_count == 0)
  {
    ereport(ERROR, (errmsg_internal("Start vertex was not found.")));
    return -1;
  }

  if(t_count == 0)
  {
    ereport(ERROR, (errmsg_internal("Target vertex was not found.")));
    return -1;
  }

  start_vertex -= v_min_id;
  end_vertex   -= v_min_id;

  DBG("#---- executing function 'boost_dijkstra' ----#\n");

  ret = boost_dijkstra(edges, total_tuples, start_vertex, end_vertex,
                       directed, path, path_count, &err_msg);

  DBG("SIZE %i\n",*path_count);


  //restoring original vertex id
  for(z=0;z<*path_count;z++)
  {
    //DBG("vetex %i\n",(*path)[z].vertex_id);
    (*path)[z].vertex_id+=v_min_id;
  }

  DBG("ret = %i\n", ret);
  DBG("*path_count = %i\n", *path_count);

  if (ret < 0)
  {
    ereport(ERROR, (errcode(ERRCODE_E_R_E_CONTAINING_SQL_NOT_PERMITTED),
            errmsg("Error computing path: %s", err_msg)));
  }

  return finish(SPIcode, ret);
}

/*
 *
 */
static int
finish(int code, int ret)
{
  DBG("#---- executing function 'finish' ----#\n");

  code = SPI_finish();
  if (code  != SPI_OK_FINISH )
  {
    ereport(ERROR, (errmsg_internal("couldn't disconnect from SPI")));
    return -1 ;
  }
  return ret;
}

 /*
  * verify if the "mandatory and additional columns" were passed to query
  */
static int
fetch_edge_columns(SPITupleTable *tuptable, edge_columns_t *edge_columns, bool directed)
{

  DBG("#---- executing function 'fetch_edge_columns' ----#\n");
  /*
   * Getting the column number from the query
   */
  edge_columns->id = SPI_fnumber(tuptable->tupdesc, "id");
  edge_columns->source = SPI_fnumber(tuptable->tupdesc, "source");
  edge_columns->target = SPI_fnumber(tuptable->tupdesc, "target");
  edge_columns->cost = SPI_fnumber(tuptable->tupdesc, "cost");

  /*
   *Additional columns
   */
  edge_columns->bidirectional = SPI_fnumber(tuptable->tupdesc, "bidirectional");
  edge_columns->reverse_cost = SPI_fnumber(tuptable->tupdesc, "reverse_cost");

  /*
   * verify if the "mandatory columns" were passed to query string really exists
   */
  if (edge_columns->id == SPI_ERROR_NOATTRIBUTE || edge_columns->source == SPI_ERROR_NOATTRIBUTE ||
      edge_columns->target == SPI_ERROR_NOATTRIBUTE || edge_columns->cost == SPI_ERROR_NOATTRIBUTE)
  {
    ereport(ERROR, (errmsg_internal("Error!: Query must return columns 'id', 'source', 'target' and 'cost'")));
    return -1;
  }

  /*
   * verify if the "mandatory columns" data type are corrects
   */
  if (SPI_gettypeid(tuptable->tupdesc, edge_columns->id) != INT4OID ||
      SPI_gettypeid(tuptable->tupdesc, edge_columns->source) != INT4OID ||
      SPI_gettypeid(tuptable->tupdesc, edge_columns->target) != INT4OID ||
      SPI_gettypeid(tuptable->tupdesc, edge_columns->cost) != FLOAT8OID)
  {
    ereport(ERROR, (errmsg_internal("Error, columns 'source', 'target' must be of type int4 and 'cost' must be of type float8")));
    return -1;
  }

  DBG("Query columns numbers: id=%i source=%i target=%i cost=%i",
      edge_columns->id, edge_columns->source, edge_columns->target, edge_columns->cost);

  /*
   * verify if the "additional column bidirectional" were passed to query string
   */

  if (edge_columns->bidirectional == SPI_ERROR_NOATTRIBUTE)
  {
    edge_columns->bidirectional = PGR_COLUMN_NOTEXIST;
  }
  else
  {
    DBG("Additional column number: bidirectional=%i", edge_columns->bidirectional);

    if (directed)
    {
      if (SPI_gettypeid(tuptable->tupdesc, edge_columns->bidirectional) != BOOLOID)
      {
        ereport(ERROR, (errmsg_internal("Error, columns 'bidirectional' must be of type bool")));
        return -1;
      }
    }
    else
    {
     DBG("Additional column 'bidirectional' exists in the query, but it is not used because the 'directed' parameter is false");
    }
  }

  /*
   * verify if the "additional column reverse_cost" were passed to query
   */
  if (edge_columns->reverse_cost == SPI_ERROR_NOATTRIBUTE)
  {
    edge_columns->reverse_cost = PGR_COLUMN_NOTEXIST;
  }
  else
  {
    DBG("Additional column number: reverse_cost=%i", edge_columns->reverse_cost);

    if(directed)
    {
      if (SPI_gettypeid(tuptable->tupdesc, edge_columns->reverse_cost) != FLOAT8OID)
      {
        ereport(ERROR, (errmsg_internal("Error, columns 'reverse_cost' must be of type float8")));
        return -1;
      }
    }
    else
    {
      DBG("Additional column 'reverse_cost' exists in the query, but it is not used because the 'directed' parameter is false");
    }
  }

  return 0;
}

/*
 *
 */
static void
fetch_edge(HeapTuple *tuple, TupleDesc *tupdesc, edge_columns_t *edge_columns, edge_t *target_edge,int *minid)
{
  Datum binval;
  bool isnull;

  DBG("#---- Executing function 'fetch_edge' ----#\n");

  /*
   * Getting values in the columns
   */
  binval = SPI_getbinval(*tuple, *tupdesc, edge_columns->id, &isnull);
  if (isnull)
  {
    ereport(ERROR, (errmsg_internal("id contains a null value")));
  }
  target_edge->id = DatumGetInt32(binval);

  binval = SPI_getbinval(*tuple, *tupdesc, edge_columns->source, &isnull);
  if (isnull)
  {
    ereport(ERROR, (errmsg_internal("source contains a null value")));
  }
  target_edge->source = DatumGetInt32(binval);

  //getting the min vertex id
  *minid = PGR_FUNC_MIN(target_edge->source,*minid);

  binval = SPI_getbinval(*tuple, *tupdesc, edge_columns->target, &isnull);
  if (isnull)
  {
    ereport(ERROR, (errmsg_internal("target contains a null value")));
  }
  target_edge->target = DatumGetInt32(binval);

  //getting the min vertex id
  *minid = PGR_FUNC_MIN(target_edge->target,*minid);

  binval = SPI_getbinval(*tuple, *tupdesc, edge_columns->cost, &isnull);
  if (isnull)
  {
    ereport(ERROR, (errmsg_internal("cost contains a null value")));
  }
  target_edge->cost = DatumGetFloat8(binval);

  /*
   * Get values from additional columns
   */
  if (edge_columns->bidirectional != PGR_COLUMN_NOTEXIST)
  {
    binval = SPI_getbinval(*tuple, *tupdesc, edge_columns->bidirectional, &isnull);
    if (isnull)
    {
      ereport(ERROR, (errmsg_internal("bidirectional contains a null value")));
    }
    target_edge->bidirectional =  DatumGetBool(binval);
  }

  if (edge_columns->reverse_cost != PGR_COLUMN_NOTEXIST)
  {
    binval = SPI_getbinval(*tuple, *tupdesc, edge_columns->reverse_cost, &isnull);
    if (isnull)
    {
      ereport(ERROR, (errmsg_internal("reverse_cost contains a null value")));
    }
    target_edge->reverse_cost =  DatumGetFloat8(binval);
  }
}