trunk/src/sorting.c

/***************************************
 $Header: /home/amb/CVS/routino/src/sorting.c,v 1.13 2010-12-18 19:12:03 amb Exp $

 Merge sort functions.

 Part of the Routino routing software.
 ******************/ /******************
 This file Copyright 2009-2010 Andrew M. Bishop

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU Affero General Public License as published by
 the Free Software Foundation, either version 3 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 Affero General Public License for more details.

 You should have received a copy of the GNU Affero General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ***************************************/


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include "types.h"

#include "files.h"
#include "sorting.h"


/* Variables */

/*+ The command line '--tmpdir' option or its default value. +*/
extern char *option_tmpdirname;

/*+ The amount of RAM to use for filesorting. +*/
extern size_t option_filesort_ramsize;


/*++++++++++++++++++++++++++++++++++++++
  A function to sort the contents of a file of fixed length objects using a
  limited amount of RAM.

  The data is sorted using a "Merge sort" http://en.wikipedia.org/wiki/Merge_sort
  and in particular an "external sort" http://en.wikipedia.org/wiki/External_sorting.
  The individual sort steps and the merge step both use a "Heap sort"
  http://en.wikipedia.org/wiki/Heapsort.  The combination of the two should work well
  if the data is already partially sorted.

  int fd_in The file descriptor of the input file (opened for reading and at the beginning).

  int fd_out The file descriptor of the output file (opened for writing and empty).

  size_t itemsize The size of each item in the file that needs sorting.

  int (*compare)(const void*, const void*) The comparison function (identical to qsort if the
                                           data to be sorted is an array of things not pointers).

  int (*buildindex)(void *,index_t) If non-NULL then this function is called for each item, if it
                                    returns 1 then it is written to the output file.
  ++++++++++++++++++++++++++++++++++++++*/

void filesort_fixed(int fd_in,int fd_out,size_t itemsize,int (*compare)(const void*,const void*),int (*buildindex)(void*,index_t))
{
 int *fds=NULL,*heap=NULL;
 int nfiles=0,ndata=0;
 index_t count=0,total=0;
 size_t nitems=option_filesort_ramsize/(itemsize+sizeof(void*));
 void *data=NULL,**datap=NULL;
 char *filename;
 int i,more=1;

 /* Allocate the RAM buffer and other bits */

 data=malloc(nitems*itemsize);
 datap=malloc(nitems*sizeof(void*));

 filename=(char*)malloc(strlen(option_tmpdirname)+24);

 /* Loop around, fill the buffer, sort the data and write a temporary file */

 do
   {
    int fd,n=0;

    /* Read in the data and create pointers */

    for(i=0;i<nitems;i++)
      {
       datap[i]=data+i*itemsize;

       if(ReadFile(fd_in,datap[i],itemsize))
         {
          more=0;
          break;
         }

       total++;
      }

    n=i;

    /* No new data read in this time round */

    if(n==0)
       break;

    /* Shortcut if there are no files (i.e. no data at all) */

    if(nfiles==0 && n==0)
       goto tidy_and_exit;

    /* Sort the data pointers using a heap sort */

    filesort_heapsort(datap,n,compare);

    /* Shortcut if all read in and sorted at once */

    if(nfiles==0 && !more)
      {
       for(i=0;i<n;i++)
         {
          if(!buildindex || buildindex(datap[i],count))
            {
             WriteFile(fd_out,datap[i],itemsize);
             count++;
            }
         }

       goto tidy_and_exit;
      }

    /* Create a temporary file and write the result */

    sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,nfiles);

    fd=OpenFileNew(filename);

    for(i=0;i<n;i++)
       WriteFile(fd,datap[i],itemsize);

    CloseFile(fd);

    nfiles++;
   }
 while(more);

 /* Shortcut if only one file (unlucky for us there must have been exactly
    nitems, lucky for us we still have the data in RAM) */

 if(nfiles==1)
   {
    for(i=0;i<nitems;i++)
      {
       if(!buildindex || buildindex(datap[i],count))
         {
          WriteFile(fd_out,datap[i],itemsize);
          count++;
         }
      }

    DeleteFile(filename);

    goto tidy_and_exit;
   }

 /* Check that number of files is less than file size */

 assert(nfiles<nitems);

 /* Open all of the temporary files */

 fds=(int*)malloc(nfiles*sizeof(int));

 for(i=0;i<nfiles;i++)
   {
    sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,i);

    fds[i]=ReOpenFile(filename);

    DeleteFile(filename);
   }

 /* Perform an n-way merge using a binary heap */

 heap=(int*)malloc(nfiles*sizeof(int));

 /* Fill the heap to start with */

 for(i=0;i<nfiles;i++)
   {
    int index;

    datap[i]=data+i*itemsize;

    ReadFile(fds[i],datap[i],itemsize);

    heap[i]=i;

    index=i;

    /* Bubble up the new value */

    while(index>0 &&
          compare(datap[heap[index]],datap[heap[(index-1)/2]])<0)
      {
       int newindex;
       int temp;

       newindex=(index-1)/2;

       temp=heap[index];
       heap[index]=heap[newindex];
       heap[newindex]=temp;

       index=newindex;
      }
   }

 /* Repeatedly pull out the root of the heap and refill from the same file */

 ndata=nfiles;

 do
   {
    int index=0;

    if(!buildindex || buildindex(datap[heap[0]],count))
      {
       WriteFile(fd_out,datap[heap[0]],itemsize);
       count++;
      }

    if(ReadFile(fds[heap[0]],datap[heap[0]],itemsize))
      {
       ndata--;
       heap[0]=heap[ndata];
      }

    /* Bubble down the new value */

    while((2*index+2)<ndata &&
          (compare(datap[heap[index]],datap[heap[2*index+1]])>0 ||
           compare(datap[heap[index]],datap[heap[2*index+2]])>0))
      {
       int newindex;
       int temp;

       if(compare(datap[heap[2*index+1]],datap[heap[2*index+2]])<0)
          newindex=2*index+1;
       else
          newindex=2*index+2;

       temp=heap[newindex];
       heap[newindex]=heap[index];
       heap[index]=temp;

       index=newindex;
      }

    if((2*index+2)==ndata &&
       compare(datap[heap[index]],datap[heap[2*index+1]])>0)
      {
       int newindex;
       int temp;

       newindex=2*index+1;

       temp=heap[newindex];
       heap[newindex]=heap[index];
       heap[index]=temp;
      }
   }
 while(ndata>0);

 /* Tidy up */

 tidy_and_exit:

 if(fds)
   {
    for(i=0;i<nfiles;i++)
       CloseFile(fds[i]);
    free(fds);
   }

 if(heap)
    free(heap);

 free(data);
 free(datap);
 free(filename);
}


/*++++++++++++++++++++++++++++++++++++++
  A function to sort the contents of a file of variable length objects (each
  preceded by its length in 2 bytes) using a limited amount of RAM.

  The data is sorted using a "Merge sort" http://en.wikipedia.org/wiki/Merge_sort
  and in particular an "external sort" http://en.wikipedia.org/wiki/External_sorting.
  The individual sort steps and the merge step both use a "Heap sort"
  http://en.wikipedia.org/wiki/Heapsort.  The combination of the two should work well
  if the data is already partially sorted.

  int fd_in The file descriptor of the input file (opened for reading and at the beginning).

  int fd_out The file descriptor of the output file (opened for writing and empty).

  int (*compare)(const void*, const void*) The comparison function (identical to qsort if the
                                           data to be sorted is an array of things not pointers).

  int (*buildindex)(void *,index_t) If non-NULL then this function is called for each item, if it
                                    returns 1 then it is written to the output file.
  ++++++++++++++++++++++++++++++++++++++*/

void filesort_vary(int fd_in,int fd_out,int (*compare)(const void*,const void*),int (*buildindex)(void*,index_t))
{
 int *fds=NULL,*heap=NULL;
 int nfiles=0,ndata=0;
 index_t count=0,total=0;
 FILESORT_VARINT nextitemsize,largestitemsize=0;
 void *data=NULL,**datap=NULL;
 char *filename;
 int i,more=1;

 /* Allocate the RAM buffer and other bits */

 data=malloc(option_filesort_ramsize);

 filename=(char*)malloc(strlen(option_tmpdirname)+24);

 /* Loop around, fill the buffer, sort the data and write a temporary file */

 if(ReadFile(fd_in,&nextitemsize,FILESORT_VARSIZE))    /* Always have the next item size known in advance */
    goto tidy_and_exit;

 do
   {
    int fd,n=0;
    size_t ramused=FILESORT_VARALIGN-FILESORT_VARSIZE;

    datap=data+option_filesort_ramsize;

    /* Read in the data and create pointers */

    while((ramused+FILESORT_VARSIZE+nextitemsize)<=((void*)datap-sizeof(void*)-data))
      {
       FILESORT_VARINT itemsize=nextitemsize;

       if(itemsize>largestitemsize)
          largestitemsize=itemsize;

       *(FILESORT_VARINT*)(data+ramused)=itemsize;

       ramused+=FILESORT_VARSIZE;

       ReadFile(fd_in,data+ramused,itemsize);

       *--datap=data+ramused; /* points to real data */

       ramused+=itemsize;

       ramused =FILESORT_VARALIGN*((ramused+FILESORT_VARSIZE-1)/FILESORT_VARALIGN);
       ramused+=FILESORT_VARALIGN-FILESORT_VARSIZE;

       total++;
       n++;

       if(ReadFile(fd_in,&nextitemsize,FILESORT_VARSIZE))
         {
          more=0;
          break;
         }
      }

    /* No new data read in this time round */

    if(n==0)
       break;

    /* Sort the data pointers using a heap sort */

    filesort_heapsort(datap,n,compare);

    /* Shortcut if all read in and sorted at once */

    if(nfiles==0 && !more)
      {
       for(i=0;i<n;i++)
         {
          if(!buildindex || buildindex(datap[i],count))
            {
             FILESORT_VARINT itemsize=*(FILESORT_VARINT*)(datap[i]-FILESORT_VARSIZE);

             WriteFile(fd_out,datap[i]-FILESORT_VARSIZE,itemsize+FILESORT_VARSIZE);
             count++;
            }
         }

       goto tidy_and_exit;
      }

    /* Create a temporary file and write the result */

    sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,nfiles);

    fd=OpenFileNew(filename);

    for(i=0;i<n;i++)
      {
       FILESORT_VARINT itemsize=*(FILESORT_VARINT*)(datap[i]-FILESORT_VARSIZE);

       WriteFile(fd,datap[i]-FILESORT_VARSIZE,itemsize+FILESORT_VARSIZE);
      }

    CloseFile(fd);

    nfiles++;
   }
 while(more);

 /* Check that number of files is less than file size */

 largestitemsize=FILESORT_VARALIGN*(1+(largestitemsize+FILESORT_VARALIGN-FILESORT_VARSIZE)/FILESORT_VARALIGN);

 assert(nfiles<((option_filesort_ramsize-nfiles*sizeof(void*))/largestitemsize));

 /* Open all of the temporary files */

 fds=(int*)malloc(nfiles*sizeof(int));

 for(i=0;i<nfiles;i++)
   {
    sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,i);

    fds[i]=ReOpenFile(filename);

    DeleteFile(filename);
   }

 /* Perform an n-way merge using a binary heap */

 heap=(int*)malloc(nfiles*sizeof(int));

 datap=data+option_filesort_ramsize-nfiles*sizeof(void*);

 /* Fill the heap to start with */

 for(i=0;i<nfiles;i++)
   {
    int index;
    FILESORT_VARINT itemsize;

    datap[i]=data+FILESORT_VARALIGN-FILESORT_VARSIZE+i*largestitemsize;

    ReadFile(fds[i],&itemsize,FILESORT_VARSIZE);

    *(FILESORT_VARINT*)(datap[i]-FILESORT_VARSIZE)=itemsize;

    ReadFile(fds[i],datap[i],itemsize);

    heap[i]=i;

    index=i;

    /* Bubble up the new value */

    while(index>0 &&
          compare(datap[heap[index]],datap[heap[(index-1)/2]])<0)
      {
       int newindex;
       int temp;

       newindex=(index-1)/2;

       temp=heap[index];
       heap[index]=heap[newindex];
       heap[newindex]=temp;

       index=newindex;
      }
   }

 /* Repeatedly pull out the root of the heap and refill from the same file */

 ndata=nfiles;

 do
   {
    int index=0;
    FILESORT_VARINT itemsize;

    if(!buildindex || buildindex(datap[heap[0]],count))
      {
       itemsize=*(FILESORT_VARINT*)(datap[heap[0]]-FILESORT_VARSIZE);

       WriteFile(fd_out,datap[heap[0]]-FILESORT_VARSIZE,itemsize+FILESORT_VARSIZE);
       count++;
      }

    if(ReadFile(fds[heap[0]],&itemsize,FILESORT_VARSIZE))
      {
       ndata--;
       heap[0]=heap[ndata];
      }
    else
      {
       *(FILESORT_VARINT*)(datap[heap[0]]-FILESORT_VARSIZE)=itemsize;

       ReadFile(fds[heap[0]],datap[heap[0]],itemsize);
      }

    /* Bubble down the new value */

    while((2*index+2)<ndata &&
          (compare(datap[heap[index]],datap[heap[2*index+1]])>0 ||
           compare(datap[heap[index]],datap[heap[2*index+2]])>0))
      {
       int newindex;
       int temp;

       if(compare(datap[heap[2*index+1]],datap[heap[2*index+2]])<0)
          newindex=2*index+1;
       else
          newindex=2*index+2;

       temp=heap[newindex];
       heap[newindex]=heap[index];
       heap[index]=temp;

       index=newindex;
      }

    if((2*index+2)==ndata &&
       compare(datap[heap[index]],datap[heap[2*index+1]])>0)
      {
       int newindex;
       int temp;

       newindex=2*index+1;

       temp=heap[newindex];
       heap[newindex]=heap[index];
       heap[index]=temp;
      }
   }
 while(ndata>0);

 /* Tidy up */

 tidy_and_exit:

 if(fds)
   {
    for(i=0;i<nfiles;i++)
       CloseFile(fds[i]);
    free(fds);
   }

 if(heap)
    free(heap);

 free(data);
 free(filename);
}


/*++++++++++++++++++++++++++++++++++++++
  A function to sort an array of pointers efficiently.

  The data is sorted using a "Heap sort" http://en.wikipedia.org/wiki/Heapsort,
  in particular an this good because it can operate in-place and doesn't
  allocate more memory like using qsort() does.

  void **datap A pointer to the array of pointers to sort.

  size_t nitems The number of items of data to sort.

  int(*compare)(const void *, const void *) The comparison function (identical to qsort if the
                                            data to be sorted was an array of things not pointers).
  ++++++++++++++++++++++++++++++++++++++*/

void filesort_heapsort(void **datap,size_t nitems,int(*compare)(const void*, const void*))
{
 int i;

 /* Fill the heap by pretending to insert the data that is already there */

 for(i=1;i<nitems;i++)
   {
    int index=i;

    /* Bubble up the new value (upside-down, put largest at top) */

    while(index>0 &&
          compare(datap[index],datap[(index-1)/2])>0) /* reversed compared to filesort() above */
      {
       int newindex;
       void *temp;

       newindex=(index-1)/2;

       temp=datap[index];
       datap[index]=datap[newindex];
       datap[newindex]=temp;

       index=newindex;
      }
   }

 /* Repeatedly pull out the root of the heap and swap with the bottom item */

 for(i=nitems-1;i>0;i--)
   {
    int index=0;
    void *temp;

    temp=datap[index];
    datap[index]=datap[i];
    datap[i]=temp;

    /* Bubble down the new value (upside-down, put largest at top) */

    while((2*index+2)<i &&
          (compare(datap[index],datap[2*index+1])<0 || /* reversed compared to filesort() above */
           compare(datap[index],datap[2*index+2])<0))  /* reversed compared to filesort() above */
      {
       int newindex;
       void *temp;

       if(compare(datap[2*index+1],datap[2*index+2])>0) /* reversed compared to filesort() above */
          newindex=2*index+1;
       else
          newindex=2*index+2;

       temp=datap[newindex];
       datap[newindex]=datap[index];
       datap[index]=temp;

       index=newindex;
      }

    if((2*index+2)==i &&
       compare(datap[index],datap[2*index+1])<0) /* reversed compared to filesort() above */
      {
       int newindex;
       void *temp;

       newindex=2*index+1;

       temp=datap[newindex];
       datap[newindex]=datap[index];
       datap[index]=temp;
      }
   }
}
1	amb	269	/***************************************
2	amb	543	$Header: /home/amb/CVS/routino/src/sorting.c,v 1.13 2010-12-18 19:12:03 amb Exp $
3	amb	269
4			Merge sort functions.
5
6			Part of the Routino routing software.
7			****************/ /****************
8	amb	449	This file Copyright 2009-2010 Andrew M. Bishop
9	amb	269
10			This program is free software: you can redistribute it and/or modify
11			it under the terms of the GNU Affero General Public License as published by
12			the Free Software Foundation, either version 3 of the License, or
13			(at your option) any later version.
14
15			This program is distributed in the hope that it will be useful,
16			but WITHOUT ANY WARRANTY; without even the implied warranty of
17			MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18			GNU Affero General Public License for more details.
19
20			You should have received a copy of the GNU Affero General Public License
21			along with this program. If not, see <http://www.gnu.org/licenses/>.
22			***************************************/
23
24
25			#include <stdio.h>
26			#include <stdlib.h>
27			#include <string.h>
28			#include <assert.h>
29
30	amb	532	#include "types.h"
31
32	amb	449	#include "files.h"
33	amb	532	#include "sorting.h"
34	amb	269
35
36			/* Variables */
37
38	amb	289	/+ The command line '--tmpdir' option or its default value. +/
39	amb	284	extern char *option_tmpdirname;
40	amb	269
41	amb	358	/+ The amount of RAM to use for filesorting. +/
42			extern size_t option_filesort_ramsize;
43	amb	269
44	amb	358
45	amb	269	/*++++++++++++++++++++++++++++++++++++++
46	amb	310	A function to sort the contents of a file of fixed length objects using a
47			limited amount of RAM.
48	amb	269
49			The data is sorted using a "Merge sort" http://en.wikipedia.org/wiki/Merge_sort
50			and in particular an "external sort" http://en.wikipedia.org/wiki/External_sorting.
51			The individual sort steps and the merge step both use a "Heap sort"
52			http://en.wikipedia.org/wiki/Heapsort. The combination of the two should work well
53			if the data is already partially sorted.
54
55			int fd_in The file descriptor of the input file (opened for reading and at the beginning).
56
57			int fd_out The file descriptor of the output file (opened for writing and empty).
58
59			size_t itemsize The size of each item in the file that needs sorting.
60
61			int (compare)(const void, const void*) The comparison function (identical to qsort if the
62			data to be sorted is an array of things not pointers).
63
64	amb	274	int (buildindex)(void ,index_t) If non-NULL then this function is called for each item, if it
65			returns 1 then it is written to the output file.
66	amb	269	++++++++++++++++++++++++++++++++++++++*/
67
68	amb	311	void filesort_fixed(int fd_in,int fd_out,size_t itemsize,int (compare)(const void,const void),int (buildindex)(void*,index_t))
69	amb	269	{
70			int fds=NULL,heap=NULL;
71			int nfiles=0,ndata=0;
72			index_t count=0,total=0;
73	amb	358	size_t nitems=option_filesort_ramsize/(itemsize+sizeof(void*));
74	amb	283	void data=NULL,*datap=NULL;
75	amb	269	char *filename;
76			int i,more=1;
77
78			/* Allocate the RAM buffer and other bits */
79
80			data=malloc(nitems*itemsize);
81			datap=malloc(nitemssizeof(void));
82
83	amb	284	filename=(char*)malloc(strlen(option_tmpdirname)+24);
84	amb	269
85			/* Loop around, fill the buffer, sort the data and write a temporary file */
86
87			do
88			{
89			int fd,n=0;
90
91			/* Read in the data and create pointers */
92
93			for(i=0;i<nitems;i++)
94			{
95			datap[i]=data+i*itemsize;
96
97			if(ReadFile(fd_in,datap[i],itemsize))
98			{
99			more=0;
100			break;
101			}
102
103			total++;
104			}
105
106			n=i;
107
108	amb	543	/* No new data read in this time round */
109
110	amb	269	if(n==0)
111			break;
112
113	amb	543	/* Shortcut if there are no files (i.e. no data at all) */
114
115			if(nfiles==0 && n==0)
116			goto tidy_and_exit;
117
118	amb	269	/* Sort the data pointers using a heap sort */
119
120	amb	503	filesort_heapsort(datap,n,compare);
121	amb	269
122			/* Shortcut if all read in and sorted at once */
123
124	amb	310	if(nfiles==0 && !more)
125	amb	269	{
126			for(i=0;i<n;i++)
127			{
128	amb	274	if(!buildindex \|\| buildindex(datap[i],count))
129			{
130			WriteFile(fd_out,datap[i],itemsize);
131			count++;
132			}
133	amb	269	}
134
135	amb	283	goto tidy_and_exit;
136	amb	269	}
137
138			/* Create a temporary file and write the result */
139
140	amb	284	sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,nfiles);
141	amb	269
142	amb	502	fd=OpenFileNew(filename);
143	amb	269
144			for(i=0;i<n;i++)
145			WriteFile(fd,datap[i],itemsize);
146
147			CloseFile(fd);
148
149			nfiles++;
150			}
151			while(more);
152
153			/* Shortcut if only one file (unlucky for us there must have been exactly
154			nitems, lucky for us we still have the data in RAM) */
155
156			if(nfiles==1)
157			{
158			for(i=0;i<nitems;i++)
159			{
160	amb	274	if(!buildindex \|\| buildindex(datap[i],count))
161			{
162			WriteFile(fd_out,datap[i],itemsize);
163			count++;
164			}
165	amb	269	}
166
167			DeleteFile(filename);
168
169	amb	283	goto tidy_and_exit;
170	amb	269	}
171
172			/* Check that number of files is less than file size */
173
174			assert(nfiles<nitems);
175
176			/* Open all of the temporary files */
177
178			fds=(int)malloc(nfilessizeof(int));
179
180			for(i=0;i<nfiles;i++)
181			{
182	amb	284	sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,i);
183	amb	269
184			fds[i]=ReOpenFile(filename);
185
186			DeleteFile(filename);
187			}
188
189			/* Perform an n-way merge using a binary heap */
190
191			heap=(int)malloc(nfilessizeof(int));
192
193			/* Fill the heap to start with */
194
195			for(i=0;i<nfiles;i++)
196			{
197			int index;
198
199			datap[i]=data+i*itemsize;
200
201			ReadFile(fds[i],datap[i],itemsize);
202
203			heap[i]=i;
204
205			index=i;
206
207			/* Bubble up the new value */
208
209			while(index>0 &&
210			compare(datap[heap[index]],datap[heap[(index-1)/2]])<0)
211			{
212			int newindex;
213			int temp;
214
215			newindex=(index-1)/2;
216
217			temp=heap[index];
218			heap[index]=heap[newindex];
219			heap[newindex]=temp;
220
221			index=newindex;
222			}
223			}
224
225			/* Repeatedly pull out the root of the heap and refill from the same file */
226
227			ndata=nfiles;
228
229			do
230			{
231			int index=0;
232
233	amb	274	if(!buildindex \|\| buildindex(datap[heap[0]],count))
234			{
235			WriteFile(fd_out,datap[heap[0]],itemsize);
236			count++;
237			}
238	amb	269
239			if(ReadFile(fds[heap[0]],datap[heap[0]],itemsize))
240			{
241			ndata--;
242			heap[0]=heap[ndata];
243			}
244
245			/* Bubble down the new value */
246
247			while((2*index+2)<ndata &&
248			(compare(datap[heap[index]],datap[heap[2*index+1]])>0 \|\|
249			compare(datap[heap[index]],datap[heap[2*index+2]])>0))
250			{
251			int newindex;
252			int temp;
253
254			if(compare(datap[heap[2index+1]],datap[heap[2index+2]])<0)
255			newindex=2*index+1;
256			else
257			newindex=2*index+2;
258
259			temp=heap[newindex];
260			heap[newindex]=heap[index];
261			heap[index]=temp;
262
263			index=newindex;
264			}
265
266			if((2*index+2)==ndata &&
267			compare(datap[heap[index]],datap[heap[2*index+1]])>0)
268			{
269			int newindex;
270			int temp;
271
272			newindex=2*index+1;
273
274			temp=heap[newindex];
275			heap[newindex]=heap[index];
276			heap[index]=temp;
277			}
278			}
279			while(ndata>0);
280
281			/* Tidy up */
282
283	amb	283	tidy_and_exit:
284	amb	269
285	amb	283	if(fds)
286			{
287			for(i=0;i<nfiles;i++)
288			CloseFile(fds[i]);
289			free(fds);
290			}
291
292			if(heap)
293			free(heap);
294
295	amb	269	free(data);
296			free(datap);
297			free(filename);
298			}
299
300
301			/*++++++++++++++++++++++++++++++++++++++
302	amb	310	A function to sort the contents of a file of variable length objects (each
303			preceded by its length in 2 bytes) using a limited amount of RAM.
304
305			The data is sorted using a "Merge sort" http://en.wikipedia.org/wiki/Merge_sort
306			and in particular an "external sort" http://en.wikipedia.org/wiki/External_sorting.
307			The individual sort steps and the merge step both use a "Heap sort"
308			http://en.wikipedia.org/wiki/Heapsort. The combination of the two should work well
309			if the data is already partially sorted.
310
311			int fd_in The file descriptor of the input file (opened for reading and at the beginning).
312
313			int fd_out The file descriptor of the output file (opened for writing and empty).
314
315			int (compare)(const void, const void*) The comparison function (identical to qsort if the
316			data to be sorted is an array of things not pointers).
317
318			int (buildindex)(void ,index_t) If non-NULL then this function is called for each item, if it
319			returns 1 then it is written to the output file.
320			++++++++++++++++++++++++++++++++++++++*/
321
322	amb	311	void filesort_vary(int fd_in,int fd_out,int (compare)(const void,const void),int (buildindex)(void*,index_t))
323	amb	310	{
324			int fds=NULL,heap=NULL;
325			int nfiles=0,ndata=0;
326			index_t count=0,total=0;
327	amb	311	FILESORT_VARINT nextitemsize,largestitemsize=0;
328	amb	310	void data=NULL,*datap=NULL;
329			char *filename;
330			int i,more=1;
331
332			/* Allocate the RAM buffer and other bits */
333
334	amb	358	data=malloc(option_filesort_ramsize);
335	amb	310
336			filename=(char*)malloc(strlen(option_tmpdirname)+24);
337
338			/* Loop around, fill the buffer, sort the data and write a temporary file */
339
340	amb	311	if(ReadFile(fd_in,&nextitemsize,FILESORT_VARSIZE)) /* Always have the next item size known in advance */
341	amb	310	goto tidy_and_exit;
342
343			do
344			{
345			int fd,n=0;
346	amb	311	size_t ramused=FILESORT_VARALIGN-FILESORT_VARSIZE;
347	amb	310
348	amb	358	datap=data+option_filesort_ramsize;
349	amb	310
350			/* Read in the data and create pointers */
351
352	amb	311	while((ramused+FILESORT_VARSIZE+nextitemsize)<=((void)datap-sizeof(void)-data))
353	amb	310	{
354	amb	311	FILESORT_VARINT itemsize=nextitemsize;
355	amb	310
356			if(itemsize>largestitemsize)
357			largestitemsize=itemsize;
358
359	amb	311	(FILESORT_VARINT)(data+ramused)=itemsize;
360	amb	310
361	amb	311	ramused+=FILESORT_VARSIZE;
362	amb	310
363	amb	311	ReadFile(fd_in,data+ramused,itemsize);
364	amb	310
365	amb	311	--datap=data+ramused; / points to real data */
366	amb	310
367	amb	311	ramused+=itemsize;
368
369			ramused =FILESORT_VARALIGN*((ramused+FILESORT_VARSIZE-1)/FILESORT_VARALIGN);
370			ramused+=FILESORT_VARALIGN-FILESORT_VARSIZE;
371
372	amb	310	total++;
373			n++;
374
375	amb	311	if(ReadFile(fd_in,&nextitemsize,FILESORT_VARSIZE))
376	amb	310	{
377			more=0;
378			break;
379			}
380			}
381
382	amb	543	/* No new data read in this time round */
383
384	amb	310	if(n==0)
385			break;
386
387			/* Sort the data pointers using a heap sort */
388
389	amb	503	filesort_heapsort(datap,n,compare);
390	amb	310
391			/* Shortcut if all read in and sorted at once */
392
393			if(nfiles==0 && !more)
394			{
395			for(i=0;i<n;i++)
396			{
397			if(!buildindex \|\| buildindex(datap[i],count))
398			{
399	amb	311	FILESORT_VARINT itemsize=(FILESORT_VARINT)(datap[i]-FILESORT_VARSIZE);
400	amb	310
401	amb	311	WriteFile(fd_out,datap[i]-FILESORT_VARSIZE,itemsize+FILESORT_VARSIZE);
402	amb	310	count++;
403			}
404			}
405
406			goto tidy_and_exit;
407			}
408
409			/* Create a temporary file and write the result */
410
411			sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,nfiles);
412
413	amb	502	fd=OpenFileNew(filename);
414	amb	310
415			for(i=0;i<n;i++)
416			{
417	amb	311	FILESORT_VARINT itemsize=(FILESORT_VARINT)(datap[i]-FILESORT_VARSIZE);
418	amb	310
419	amb	311	WriteFile(fd,datap[i]-FILESORT_VARSIZE,itemsize+FILESORT_VARSIZE);
420	amb	310	}
421
422			CloseFile(fd);
423
424			nfiles++;
425			}
426			while(more);
427
428			/* Check that number of files is less than file size */
429
430	amb	311	largestitemsize=FILESORT_VARALIGN*(1+(largestitemsize+FILESORT_VARALIGN-FILESORT_VARSIZE)/FILESORT_VARALIGN);
431	amb	310
432	amb	358	assert(nfiles<((option_filesort_ramsize-nfilessizeof(void))/largestitemsize));
433	amb	310
434			/* Open all of the temporary files */
435
436			fds=(int)malloc(nfilessizeof(int));
437
438			for(i=0;i<nfiles;i++)
439			{
440			sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,i);
441
442			fds[i]=ReOpenFile(filename);
443
444			DeleteFile(filename);
445			}
446
447			/* Perform an n-way merge using a binary heap */
448
449			heap=(int)malloc(nfilessizeof(int));
450
451	amb	358	datap=data+option_filesort_ramsize-nfilessizeof(void);
452	amb	310
453			/* Fill the heap to start with */
454
455			for(i=0;i<nfiles;i++)
456			{
457			int index;
458	amb	311	FILESORT_VARINT itemsize;
459	amb	310
460	amb	311	datap[i]=data+FILESORT_VARALIGN-FILESORT_VARSIZE+i*largestitemsize;
461	amb	310
462	amb	311	ReadFile(fds[i],&itemsize,FILESORT_VARSIZE);
463	amb	310
464	amb	311	(FILESORT_VARINT)(datap[i]-FILESORT_VARSIZE)=itemsize;
465	amb	310
466			ReadFile(fds[i],datap[i],itemsize);
467
468			heap[i]=i;
469
470			index=i;
471
472			/* Bubble up the new value */
473
474			while(index>0 &&
475			compare(datap[heap[index]],datap[heap[(index-1)/2]])<0)
476			{
477			int newindex;
478			int temp;
479
480			newindex=(index-1)/2;
481
482			temp=heap[index];
483			heap[index]=heap[newindex];
484			heap[newindex]=temp;
485
486			index=newindex;
487			}
488			}
489
490			/* Repeatedly pull out the root of the heap and refill from the same file */
491
492			ndata=nfiles;
493
494			do
495			{
496			int index=0;
497	amb	311	FILESORT_VARINT itemsize;
498	amb	310
499			if(!buildindex \|\| buildindex(datap[heap[0]],count))
500			{
501	amb	311	itemsize=(FILESORT_VARINT)(datap[heap[0]]-FILESORT_VARSIZE);
502	amb	310
503	amb	311	WriteFile(fd_out,datap[heap[0]]-FILESORT_VARSIZE,itemsize+FILESORT_VARSIZE);
504	amb	310	count++;
505			}
506
507	amb	311	if(ReadFile(fds[heap[0]],&itemsize,FILESORT_VARSIZE))
508	amb	310	{
509			ndata--;
510			heap[0]=heap[ndata];
511			}
512			else
513			{
514	amb	311	(FILESORT_VARINT)(datap[heap[0]]-FILESORT_VARSIZE)=itemsize;
515	amb	310
516			ReadFile(fds[heap[0]],datap[heap[0]],itemsize);
517			}
518
519			/* Bubble down the new value */
520
521			while((2*index+2)<ndata &&
522			(compare(datap[heap[index]],datap[heap[2*index+1]])>0 \|\|
523			compare(datap[heap[index]],datap[heap[2*index+2]])>0))
524			{
525			int newindex;
526			int temp;
527
528			if(compare(datap[heap[2index+1]],datap[heap[2index+2]])<0)
529			newindex=2*index+1;
530			else
531			newindex=2*index+2;
532
533			temp=heap[newindex];
534			heap[newindex]=heap[index];
535			heap[index]=temp;
536
537			index=newindex;
538			}
539
540			if((2*index+2)==ndata &&
541			compare(datap[heap[index]],datap[heap[2*index+1]])>0)
542			{
543			int newindex;
544			int temp;
545
546			newindex=2*index+1;
547
548			temp=heap[newindex];
549			heap[newindex]=heap[index];
550			heap[index]=temp;
551			}
552			}
553			while(ndata>0);
554
555			/* Tidy up */
556
557			tidy_and_exit:
558
559			if(fds)
560			{
561			for(i=0;i<nfiles;i++)
562			CloseFile(fds[i]);
563			free(fds);
564			}
565
566			if(heap)
567			free(heap);
568
569			free(data);
570			free(filename);
571			}
572
573
574			/*++++++++++++++++++++++++++++++++++++++
575	amb	269	A function to sort an array of pointers efficiently.
576
577			The data is sorted using a "Heap sort" http://en.wikipedia.org/wiki/Heapsort,
578			in particular an this good because it can operate in-place and doesn't
579			allocate more memory like using qsort() does.
580
581			void **datap A pointer to the array of pointers to sort.
582
583			size_t nitems The number of items of data to sort.
584
585			int(compare)(const void , const void *) The comparison function (identical to qsort if the
586			data to be sorted was an array of things not pointers).
587			++++++++++++++++++++++++++++++++++++++*/
588
589	amb	503	void filesort_heapsort(void *datap,size_t nitems,int(compare)(const void, const void))
590	amb	269	{
591			int i;
592
593			/* Fill the heap by pretending to insert the data that is already there */
594
595			for(i=1;i<nitems;i++)
596			{
597			int index=i;
598
599			/* Bubble up the new value (upside-down, put largest at top) */
600
601			while(index>0 &&
602			compare(datap[index],datap[(index-1)/2])>0) /* reversed compared to filesort() above */
603			{
604			int newindex;
605			void *temp;
606
607			newindex=(index-1)/2;
608
609			temp=datap[index];
610			datap[index]=datap[newindex];
611			datap[newindex]=temp;
612
613			index=newindex;
614			}
615			}
616
617			/* Repeatedly pull out the root of the heap and swap with the bottom item */
618
619			for(i=nitems-1;i>0;i--)
620			{
621			int index=0;
622			void *temp;
623
624			temp=datap[index];
625			datap[index]=datap[i];
626			datap[i]=temp;
627
628			/* Bubble down the new value (upside-down, put largest at top) */
629
630			while((2*index+2)<i &&
631			(compare(datap[index],datap[2index+1])<0 \|\| / reversed compared to filesort() above */
632			compare(datap[index],datap[2index+2])<0)) / reversed compared to filesort() above */
633			{
634			int newindex;
635			void *temp;
636
637			if(compare(datap[2index+1],datap[2index+2])>0) /* reversed compared to filesort() above */
638			newindex=2*index+1;
639			else
640			newindex=2*index+2;
641
642			temp=datap[newindex];
643			datap[newindex]=datap[index];
644			datap[index]=temp;
645
646			index=newindex;
647			}
648
649			if((2*index+2)==i &&
650			compare(datap[index],datap[2index+1])<0) / reversed compared to filesort() above */
651			{
652			int newindex;
653			void *temp;
654
655			newindex=2*index+1;
656
657			temp=datap[newindex];
658			datap[newindex]=datap[index];
659			datap[index]=temp;
660			}
661			}
662			}