trunk/src/sorting.c

/***************************************
 $Header: /home/amb/CVS/routino/src/sorting.c,v 1.11 2010-09-25 13:54:18 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 "files.h"
#include "functions.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;

    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))
            {
             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;
         }
      }

    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	503	$Header: /home/amb/CVS/routino/src/sorting.c,v 1.11 2010-09-25 13:54:18 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	449	#include "files.h"
31	amb	269	#include "functions.h"
32
33
34			/* Variables */
35
36	amb	289	/+ The command line '--tmpdir' option or its default value. +/
37	amb	284	extern char *option_tmpdirname;
38	amb	269
39	amb	358	/+ The amount of RAM to use for filesorting. +/
40			extern size_t option_filesort_ramsize;
41	amb	269
42	amb	358
43	amb	269	/*++++++++++++++++++++++++++++++++++++++
44	amb	310	A function to sort the contents of a file of fixed length objects using a
45			limited amount of RAM.
46	amb	269
47			The data is sorted using a "Merge sort" http://en.wikipedia.org/wiki/Merge_sort
48			and in particular an "external sort" http://en.wikipedia.org/wiki/External_sorting.
49			The individual sort steps and the merge step both use a "Heap sort"
50			http://en.wikipedia.org/wiki/Heapsort. The combination of the two should work well
51			if the data is already partially sorted.
52
53			int fd_in The file descriptor of the input file (opened for reading and at the beginning).
54
55			int fd_out The file descriptor of the output file (opened for writing and empty).
56
57			size_t itemsize The size of each item in the file that needs sorting.
58
59			int (compare)(const void, const void*) The comparison function (identical to qsort if the
60			data to be sorted is an array of things not pointers).
61
62	amb	274	int (buildindex)(void ,index_t) If non-NULL then this function is called for each item, if it
63			returns 1 then it is written to the output file.
64	amb	269	++++++++++++++++++++++++++++++++++++++*/
65
66	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))
67	amb	269	{
68			int fds=NULL,heap=NULL;
69			int nfiles=0,ndata=0;
70			index_t count=0,total=0;
71	amb	358	size_t nitems=option_filesort_ramsize/(itemsize+sizeof(void*));
72	amb	283	void data=NULL,*datap=NULL;
73	amb	269	char *filename;
74			int i,more=1;
75
76			/* Allocate the RAM buffer and other bits */
77
78			data=malloc(nitems*itemsize);
79			datap=malloc(nitemssizeof(void));
80
81	amb	284	filename=(char*)malloc(strlen(option_tmpdirname)+24);
82	amb	269
83			/* Loop around, fill the buffer, sort the data and write a temporary file */
84
85			do
86			{
87			int fd,n=0;
88
89			/* Read in the data and create pointers */
90
91			for(i=0;i<nitems;i++)
92			{
93			datap[i]=data+i*itemsize;
94
95			if(ReadFile(fd_in,datap[i],itemsize))
96			{
97			more=0;
98			break;
99			}
100
101			total++;
102			}
103
104			n=i;
105
106			if(n==0)
107			break;
108
109			/* Sort the data pointers using a heap sort */
110
111	amb	503	filesort_heapsort(datap,n,compare);
112	amb	269
113			/* Shortcut if all read in and sorted at once */
114
115	amb	310	if(nfiles==0 && !more)
116	amb	269	{
117			for(i=0;i<n;i++)
118			{
119	amb	274	if(!buildindex \|\| buildindex(datap[i],count))
120			{
121			WriteFile(fd_out,datap[i],itemsize);
122			count++;
123			}
124	amb	269	}
125
126	amb	283	goto tidy_and_exit;
127	amb	269	}
128
129			/* Create a temporary file and write the result */
130
131	amb	284	sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,nfiles);
132	amb	269
133	amb	502	fd=OpenFileNew(filename);
134	amb	269
135			for(i=0;i<n;i++)
136			WriteFile(fd,datap[i],itemsize);
137
138			CloseFile(fd);
139
140			nfiles++;
141			}
142			while(more);
143
144			/* Shortcut if only one file (unlucky for us there must have been exactly
145			nitems, lucky for us we still have the data in RAM) */
146
147			if(nfiles==1)
148			{
149			for(i=0;i<nitems;i++)
150			{
151	amb	274	if(!buildindex \|\| buildindex(datap[i],count))
152			{
153			WriteFile(fd_out,datap[i],itemsize);
154			count++;
155			}
156	amb	269	}
157
158			DeleteFile(filename);
159
160	amb	283	goto tidy_and_exit;
161	amb	269	}
162
163			/* Check that number of files is less than file size */
164
165			assert(nfiles<nitems);
166
167			/* Open all of the temporary files */
168
169			fds=(int)malloc(nfilessizeof(int));
170
171			for(i=0;i<nfiles;i++)
172			{
173	amb	284	sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,i);
174	amb	269
175			fds[i]=ReOpenFile(filename);
176
177			DeleteFile(filename);
178			}
179
180			/* Perform an n-way merge using a binary heap */
181
182			heap=(int)malloc(nfilessizeof(int));
183
184			/* Fill the heap to start with */
185
186			for(i=0;i<nfiles;i++)
187			{
188			int index;
189
190			datap[i]=data+i*itemsize;
191
192			ReadFile(fds[i],datap[i],itemsize);
193
194			heap[i]=i;
195
196			index=i;
197
198			/* Bubble up the new value */
199
200			while(index>0 &&
201			compare(datap[heap[index]],datap[heap[(index-1)/2]])<0)
202			{
203			int newindex;
204			int temp;
205
206			newindex=(index-1)/2;
207
208			temp=heap[index];
209			heap[index]=heap[newindex];
210			heap[newindex]=temp;
211
212			index=newindex;
213			}
214			}
215
216			/* Repeatedly pull out the root of the heap and refill from the same file */
217
218			ndata=nfiles;
219
220			do
221			{
222			int index=0;
223
224	amb	274	if(!buildindex \|\| buildindex(datap[heap[0]],count))
225			{
226			WriteFile(fd_out,datap[heap[0]],itemsize);
227			count++;
228			}
229	amb	269
230			if(ReadFile(fds[heap[0]],datap[heap[0]],itemsize))
231			{
232			ndata--;
233			heap[0]=heap[ndata];
234			}
235
236			/* Bubble down the new value */
237
238			while((2*index+2)<ndata &&
239			(compare(datap[heap[index]],datap[heap[2*index+1]])>0 \|\|
240			compare(datap[heap[index]],datap[heap[2*index+2]])>0))
241			{
242			int newindex;
243			int temp;
244
245			if(compare(datap[heap[2index+1]],datap[heap[2index+2]])<0)
246			newindex=2*index+1;
247			else
248			newindex=2*index+2;
249
250			temp=heap[newindex];
251			heap[newindex]=heap[index];
252			heap[index]=temp;
253
254			index=newindex;
255			}
256
257			if((2*index+2)==ndata &&
258			compare(datap[heap[index]],datap[heap[2*index+1]])>0)
259			{
260			int newindex;
261			int temp;
262
263			newindex=2*index+1;
264
265			temp=heap[newindex];
266			heap[newindex]=heap[index];
267			heap[index]=temp;
268			}
269			}
270			while(ndata>0);
271
272			/* Tidy up */
273
274	amb	283	tidy_and_exit:
275	amb	269
276	amb	283	if(fds)
277			{
278			for(i=0;i<nfiles;i++)
279			CloseFile(fds[i]);
280			free(fds);
281			}
282
283			if(heap)
284			free(heap);
285
286	amb	269	free(data);
287			free(datap);
288			free(filename);
289			}
290
291
292			/*++++++++++++++++++++++++++++++++++++++
293	amb	310	A function to sort the contents of a file of variable length objects (each
294			preceded by its length in 2 bytes) using a limited amount of RAM.
295
296			The data is sorted using a "Merge sort" http://en.wikipedia.org/wiki/Merge_sort
297			and in particular an "external sort" http://en.wikipedia.org/wiki/External_sorting.
298			The individual sort steps and the merge step both use a "Heap sort"
299			http://en.wikipedia.org/wiki/Heapsort. The combination of the two should work well
300			if the data is already partially sorted.
301
302			int fd_in The file descriptor of the input file (opened for reading and at the beginning).
303
304			int fd_out The file descriptor of the output file (opened for writing and empty).
305
306			int (compare)(const void, const void*) The comparison function (identical to qsort if the
307			data to be sorted is an array of things not pointers).
308
309			int (buildindex)(void ,index_t) If non-NULL then this function is called for each item, if it
310			returns 1 then it is written to the output file.
311			++++++++++++++++++++++++++++++++++++++*/
312
313	amb	311	void filesort_vary(int fd_in,int fd_out,int (compare)(const void,const void),int (buildindex)(void*,index_t))
314	amb	310	{
315			int fds=NULL,heap=NULL;
316			int nfiles=0,ndata=0;
317			index_t count=0,total=0;
318	amb	311	FILESORT_VARINT nextitemsize,largestitemsize=0;
319	amb	310	void data=NULL,*datap=NULL;
320			char *filename;
321			int i,more=1;
322
323			/* Allocate the RAM buffer and other bits */
324
325	amb	358	data=malloc(option_filesort_ramsize);
326	amb	310
327			filename=(char*)malloc(strlen(option_tmpdirname)+24);
328
329			/* Loop around, fill the buffer, sort the data and write a temporary file */
330
331	amb	311	if(ReadFile(fd_in,&nextitemsize,FILESORT_VARSIZE)) /* Always have the next item size known in advance */
332	amb	310	goto tidy_and_exit;
333
334			do
335			{
336			int fd,n=0;
337	amb	311	size_t ramused=FILESORT_VARALIGN-FILESORT_VARSIZE;
338	amb	310
339	amb	358	datap=data+option_filesort_ramsize;
340	amb	310
341			/* Read in the data and create pointers */
342
343	amb	311	while((ramused+FILESORT_VARSIZE+nextitemsize)<=((void)datap-sizeof(void)-data))
344	amb	310	{
345	amb	311	FILESORT_VARINT itemsize=nextitemsize;
346	amb	310
347			if(itemsize>largestitemsize)
348			largestitemsize=itemsize;
349
350	amb	311	(FILESORT_VARINT)(data+ramused)=itemsize;
351	amb	310
352	amb	311	ramused+=FILESORT_VARSIZE;
353	amb	310
354	amb	311	ReadFile(fd_in,data+ramused,itemsize);
355	amb	310
356	amb	311	--datap=data+ramused; / points to real data */
357	amb	310
358	amb	311	ramused+=itemsize;
359
360			ramused =FILESORT_VARALIGN*((ramused+FILESORT_VARSIZE-1)/FILESORT_VARALIGN);
361			ramused+=FILESORT_VARALIGN-FILESORT_VARSIZE;
362
363	amb	310	total++;
364			n++;
365
366	amb	311	if(ReadFile(fd_in,&nextitemsize,FILESORT_VARSIZE))
367	amb	310	{
368			more=0;
369			break;
370			}
371			}
372
373			if(n==0)
374			break;
375
376			/* Sort the data pointers using a heap sort */
377
378	amb	503	filesort_heapsort(datap,n,compare);
379	amb	310
380			/* Shortcut if all read in and sorted at once */
381
382			if(nfiles==0 && !more)
383			{
384			for(i=0;i<n;i++)
385			{
386			if(!buildindex \|\| buildindex(datap[i],count))
387			{
388	amb	311	FILESORT_VARINT itemsize=(FILESORT_VARINT)(datap[i]-FILESORT_VARSIZE);
389	amb	310
390	amb	311	WriteFile(fd_out,datap[i]-FILESORT_VARSIZE,itemsize+FILESORT_VARSIZE);
391	amb	310	count++;
392			}
393			}
394
395			goto tidy_and_exit;
396			}
397
398			/* Create a temporary file and write the result */
399
400			sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,nfiles);
401
402	amb	502	fd=OpenFileNew(filename);
403	amb	310
404			for(i=0;i<n;i++)
405			{
406	amb	311	FILESORT_VARINT itemsize=(FILESORT_VARINT)(datap[i]-FILESORT_VARSIZE);
407	amb	310
408	amb	311	WriteFile(fd,datap[i]-FILESORT_VARSIZE,itemsize+FILESORT_VARSIZE);
409	amb	310	}
410
411			CloseFile(fd);
412
413			nfiles++;
414			}
415			while(more);
416
417			/* Check that number of files is less than file size */
418
419	amb	311	largestitemsize=FILESORT_VARALIGN*(1+(largestitemsize+FILESORT_VARALIGN-FILESORT_VARSIZE)/FILESORT_VARALIGN);
420	amb	310
421	amb	358	assert(nfiles<((option_filesort_ramsize-nfilessizeof(void))/largestitemsize));
422	amb	310
423			/* Open all of the temporary files */
424
425			fds=(int)malloc(nfilessizeof(int));
426
427			for(i=0;i<nfiles;i++)
428			{
429			sprintf(filename,"%s/filesort.%d.tmp",option_tmpdirname,i);
430
431			fds[i]=ReOpenFile(filename);
432
433			DeleteFile(filename);
434			}
435
436			/* Perform an n-way merge using a binary heap */
437
438			heap=(int)malloc(nfilessizeof(int));
439
440	amb	358	datap=data+option_filesort_ramsize-nfilessizeof(void);
441	amb	310
442			/* Fill the heap to start with */
443
444			for(i=0;i<nfiles;i++)
445			{
446			int index;
447	amb	311	FILESORT_VARINT itemsize;
448	amb	310
449	amb	311	datap[i]=data+FILESORT_VARALIGN-FILESORT_VARSIZE+i*largestitemsize;
450	amb	310
451	amb	311	ReadFile(fds[i],&itemsize,FILESORT_VARSIZE);
452	amb	310
453	amb	311	(FILESORT_VARINT)(datap[i]-FILESORT_VARSIZE)=itemsize;
454	amb	310
455			ReadFile(fds[i],datap[i],itemsize);
456
457			heap[i]=i;
458
459			index=i;
460
461			/* Bubble up the new value */
462
463			while(index>0 &&
464			compare(datap[heap[index]],datap[heap[(index-1)/2]])<0)
465			{
466			int newindex;
467			int temp;
468
469			newindex=(index-1)/2;
470
471			temp=heap[index];
472			heap[index]=heap[newindex];
473			heap[newindex]=temp;
474
475			index=newindex;
476			}
477			}
478
479			/* Repeatedly pull out the root of the heap and refill from the same file */
480
481			ndata=nfiles;
482
483			do
484			{
485			int index=0;
486	amb	311	FILESORT_VARINT itemsize;
487	amb	310
488			if(!buildindex \|\| buildindex(datap[heap[0]],count))
489			{
490	amb	311	itemsize=(FILESORT_VARINT)(datap[heap[0]]-FILESORT_VARSIZE);
491	amb	310
492	amb	311	WriteFile(fd_out,datap[heap[0]]-FILESORT_VARSIZE,itemsize+FILESORT_VARSIZE);
493	amb	310	count++;
494			}
495
496	amb	311	if(ReadFile(fds[heap[0]],&itemsize,FILESORT_VARSIZE))
497	amb	310	{
498			ndata--;
499			heap[0]=heap[ndata];
500			}
501			else
502			{
503	amb	311	(FILESORT_VARINT)(datap[heap[0]]-FILESORT_VARSIZE)=itemsize;
504	amb	310
505			ReadFile(fds[heap[0]],datap[heap[0]],itemsize);
506			}
507
508			/* Bubble down the new value */
509
510			while((2*index+2)<ndata &&
511			(compare(datap[heap[index]],datap[heap[2*index+1]])>0 \|\|
512			compare(datap[heap[index]],datap[heap[2*index+2]])>0))
513			{
514			int newindex;
515			int temp;
516
517			if(compare(datap[heap[2index+1]],datap[heap[2index+2]])<0)
518			newindex=2*index+1;
519			else
520			newindex=2*index+2;
521
522			temp=heap[newindex];
523			heap[newindex]=heap[index];
524			heap[index]=temp;
525
526			index=newindex;
527			}
528
529			if((2*index+2)==ndata &&
530			compare(datap[heap[index]],datap[heap[2*index+1]])>0)
531			{
532			int newindex;
533			int temp;
534
535			newindex=2*index+1;
536
537			temp=heap[newindex];
538			heap[newindex]=heap[index];
539			heap[index]=temp;
540			}
541			}
542			while(ndata>0);
543
544			/* Tidy up */
545
546			tidy_and_exit:
547
548			if(fds)
549			{
550			for(i=0;i<nfiles;i++)
551			CloseFile(fds[i]);
552			free(fds);
553			}
554
555			if(heap)
556			free(heap);
557
558			free(data);
559			free(filename);
560			}
561
562
563			/*++++++++++++++++++++++++++++++++++++++
564	amb	269	A function to sort an array of pointers efficiently.
565
566			The data is sorted using a "Heap sort" http://en.wikipedia.org/wiki/Heapsort,
567			in particular an this good because it can operate in-place and doesn't
568			allocate more memory like using qsort() does.
569
570			void **datap A pointer to the array of pointers to sort.
571
572			size_t nitems The number of items of data to sort.
573
574			int(compare)(const void , const void *) The comparison function (identical to qsort if the
575			data to be sorted was an array of things not pointers).
576			++++++++++++++++++++++++++++++++++++++*/
577
578	amb	503	void filesort_heapsort(void *datap,size_t nitems,int(compare)(const void, const void))
579	amb	269	{
580			int i;
581
582			/* Fill the heap by pretending to insert the data that is already there */
583
584			for(i=1;i<nitems;i++)
585			{
586			int index=i;
587
588			/* Bubble up the new value (upside-down, put largest at top) */
589
590			while(index>0 &&
591			compare(datap[index],datap[(index-1)/2])>0) /* reversed compared to filesort() above */
592			{
593			int newindex;
594			void *temp;
595
596			newindex=(index-1)/2;
597
598			temp=datap[index];
599			datap[index]=datap[newindex];
600			datap[newindex]=temp;
601
602			index=newindex;
603			}
604			}
605
606			/* Repeatedly pull out the root of the heap and swap with the bottom item */
607
608			for(i=nitems-1;i>0;i--)
609			{
610			int index=0;
611			void *temp;
612
613			temp=datap[index];
614			datap[index]=datap[i];
615			datap[i]=temp;
616
617			/* Bubble down the new value (upside-down, put largest at top) */
618
619			while((2*index+2)<i &&
620			(compare(datap[index],datap[2index+1])<0 \|\| / reversed compared to filesort() above */
621			compare(datap[index],datap[2index+2])<0)) / reversed compared to filesort() above */
622			{
623			int newindex;
624			void *temp;
625
626			if(compare(datap[2index+1],datap[2index+2])>0) /* reversed compared to filesort() above */
627			newindex=2*index+1;
628			else
629			newindex=2*index+2;
630
631			temp=datap[newindex];
632			datap[newindex]=datap[index];
633			datap[index]=temp;
634
635			index=newindex;
636			}
637
638			if((2*index+2)==i &&
639			compare(datap[index],datap[2index+1])<0) / reversed compared to filesort() above */
640			{
641			int newindex;
642			void *temp;
643
644			newindex=2*index+1;
645
646			temp=datap[newindex];
647			datap[newindex]=datap[index];
648			datap[index]=temp;
649			}
650			}
651			}