2 * Copyright (c) 1996-1998, Index Data.
3 * See the file LICENSE for details.
4 * Sebastian Hammer, Adam Dickmeiss
7 * Revision 1.7 1998-03-11 11:18:18 adam
8 * Changed the isc_merge to take into account the mfill (minimum-fill).
10 * Revision 1.6 1998/03/06 13:54:03 adam
11 * Fixed two nasty bugs in isc_merge.
13 * Revision 1.5 1997/02/12 20:42:43 adam
14 * Bug fix: during isc_merge operations, some pages weren't marked dirty
15 * even though they should be. At this point the merge operation marks
16 * a page dirty if the previous page changed at all. A better approach is
17 * to mark it dirty if the last key written changed in previous page.
19 * Revision 1.4 1996/11/08 11:15:31 adam
20 * Number of keys in chain are stored in first block and the function
21 * to retrieve this information, isc_pp_num is implemented.
23 * Revision 1.3 1996/11/04 14:08:59 adam
24 * Optimized free block usage.
26 * Revision 1.2 1996/11/01 13:36:46 adam
27 * New element, max_blocks_mem, that control how many blocks of max size
28 * to store in memory during isc_merge.
29 * Function isc_merge now ignores delete/update of identical keys and
30 * the proper blocks are then non-dirty and not written in flush_blocks.
32 * Revision 1.1 1996/11/01 08:59:15 adam
33 * First version of isc_merge that supports update/delete.
45 struct isc_merge_block {
46 int offset; /* offset in r_buf */
47 int block; /* block number of file (0 if none) */
48 int dirty; /* block is different from that on file */
51 static void flush_blocks (ISAMC is, struct isc_merge_block *mb, int ptr,
52 char *r_buf, int *firstpos, int cat, int last,
57 for (i = 0; i<ptr; i++)
62 /* consider this block number */
65 mb[i].block = isc_alloc_block (is, cat);
69 /* consider next block pointer */
70 if (last && i == ptr-1)
72 else if (!mb[i+1].block)
74 mb[i+1].block = isc_alloc_block (is, cat);
79 ssize = mb[i+1].offset - mb[i].offset;
82 /* skip rest if not dirty */
87 *firstpos = mb[i].block;
88 if (is->method->debug > 2)
89 logf (LOG_LOG, "isc: skip ptr=%d size=%d %d %d",
90 i, ssize, cat, mb[i].block);
91 ++(is->files[cat].no_skip_writes);
98 *firstpos = mb[i].block;
99 src = r_buf + mb[i].offset - ISAMC_BLOCK_OFFSET_1;
100 ssize += ISAMC_BLOCK_OFFSET_1;
102 memcpy (src+sizeof(int)+sizeof(ssize), numkeys,
104 if (is->method->debug > 2)
105 logf (LOG_LOG, "isc: flush ptr=%d numk=%d size=%d nextpos=%d",
106 i, *numkeys, (int) ssize, mb[i+1].block);
110 src = r_buf + mb[i].offset - ISAMC_BLOCK_OFFSET_N;
111 ssize += ISAMC_BLOCK_OFFSET_N;
112 if (is->method->debug > 2)
113 logf (LOG_LOG, "isc: flush ptr=%d size=%d nextpos=%d",
114 i, (int) ssize, mb[i+1].block);
116 memcpy (src, &mb[i+1].block, sizeof(int));
117 memcpy (src+sizeof(int), &ssize, sizeof(ssize));
118 isc_write_block (is, cat, mb[i].block, src);
122 static int get_border (ISAMC is, struct isc_merge_block *mb, int ptr,
123 int cat, int firstpos)
125 /* Border set to initial fill or block size depending on
126 whether we are creating a new one or updating and old one.
129 int fill = mb[ptr].block ? is->method->filecat[cat].bsize :
130 is->method->filecat[cat].ifill;
131 int off = (ptr||firstpos) ? ISAMC_BLOCK_OFFSET_N : ISAMC_BLOCK_OFFSET_1;
135 return mb[ptr].offset + fill - off;
138 ISAMC_P isc_merge (ISAMC is, ISAMC_P ipos, ISAMC_I data)
141 char i_item[128], *i_item_ptr;
142 int i_more, i_mode, i;
145 char f_item[128], *f_item_ptr;
148 struct isc_merge_block mb[200];
152 char r_item_buf[128]; /* temporary result output */
153 char *r_buf; /* block with resulting data */
154 int r_offset = 0; /* current offset in r_buf */
155 int ptr = 0; /* pointer */
156 void *r_clientData; /* encode client data */
160 r_clientData = (*is->method->code_start)(ISAMC_ENCODE);
161 r_buf = is->merge_buf + 128;
163 pp = isc_pp_open (is, ipos);
164 /* read first item from file. make sure f_more indicates no boundary */
166 f_more = isc_read_item (pp, &f_item_ptr);
171 if (is->method->debug > 1)
172 logf (LOG_LOG, "isc: isc_merge begin %d %d", cat, pp->pos);
174 /* read first item from i */
176 i_more = (*data->read_item)(data->clientData, &i_item_ptr, &i_mode);
178 mb[ptr].block = pp->pos; /* is zero if no block on disk */
182 border = get_border (is, mb, ptr, cat, firstpos);
183 while (i_more || f_more)
185 char *r_item = r_item_buf;
190 /* block to block boundary in the original file. */
194 /* the resulting output is of the same category as the
197 if (r_offset <= mb[ptr].offset +is->method->filecat[cat].mfill)
199 /* the resulting output block is too small/empty. Delete
200 the original (if any)
202 if (is->method->debug > 3)
203 logf (LOG_LOG, "isc: release A");
205 isc_release_block (is, pp->cat, mb[ptr].block);
206 mb[ptr].block = pp->pos;
213 /* indicate new boundary based on the original file */
214 mb[++ptr].block = pp->pos;
215 mb[ptr].dirty = (mb[ptr-1].dirty > 1) ? 1 : 0;
216 mb[ptr].offset = r_offset;
217 if (is->method->debug > 3)
218 logf (LOG_LOG, "isc: bound ptr=%d,offset=%d",
220 if (cat==is->max_cat && ptr >= is->method->max_blocks_mem)
222 /* We are dealing with block(s) of max size. Block(s)
223 except 1 will be flushed.
225 if (is->method->debug > 2)
226 logf (LOG_LOG, "isc: flush A %d sections", ptr);
227 flush_blocks (is, mb, ptr-1, r_buf, &firstpos, cat,
229 mb[0].block = mb[ptr-1].block;
230 mb[0].dirty = mb[ptr-1].dirty;
231 memcpy (r_buf, r_buf + mb[ptr-1].offset,
232 mb[ptr].offset - mb[ptr-1].offset);
235 mb[1].block = mb[ptr].block;
236 mb[1].dirty = mb[ptr].dirty;
237 mb[1].offset = mb[ptr].offset - mb[ptr-1].offset;
239 r_offset = mb[ptr].offset;
243 border = get_border (is, mb, ptr, cat, firstpos);
250 cmp = (*is->method->compare_item)(i_item, f_item);
251 if (cmp == 0) /* insert i=f */
253 if (!i_mode) /* delete item? */
257 i_more = (*data->read_item)(data->clientData, &i_item_ptr,
259 /* is next input item the same as current except
260 for the delete flag? */
261 cmp = (*is->method->compare_item)(i_item, f_item);
262 if (!cmp && i_mode) /* delete/insert nop? */
264 /* yes! insert as if it was an insert only */
265 memcpy (r_item, i_item, i_item_ptr - i_item);
267 i_more = (*data->read_item)(data->clientData, &i_item_ptr,
272 /* no! delete the item */
279 memcpy (r_item, f_item, f_item_ptr - f_item);
283 i_more = (*data->read_item)(data->clientData, &i_item_ptr,
288 f_more = isc_read_item (pp, &f_item_ptr);
290 else if (cmp > 0) /* insert f */
292 memcpy (r_item, f_item, f_item_ptr - f_item);
295 f_more = isc_read_item (pp, &f_item_ptr);
299 if (!i_mode) /* delete item which isn't there? */
301 logf (LOG_FATAL, "Inconsistent register at offset %d",
305 memcpy (r_item, i_item, i_item_ptr - i_item);
309 i_more = (*data->read_item)(data->clientData, &i_item_ptr,
312 if (r_item) /* insert resulting item? */
314 char *r_out_ptr = r_buf + r_offset;
317 (*is->method->code_item)(ISAMC_ENCODE, r_clientData,
318 &r_out_ptr, &r_item);
319 new_offset = r_out_ptr - r_buf;
323 if (border < new_offset && border >= r_offset)
325 if (is->method->debug > 2)
326 logf (LOG_LOG, "isc: border %d %d", ptr, border);
327 /* Max size of current block category reached ...
328 make new virtual block entry */
331 mb[ptr].offset = r_offset;
332 if (cat == is->max_cat && ptr >= is->method->max_blocks_mem)
334 /* We are dealing with block(s) of max size. Block(s)
335 except one will be flushed. Note: the block(s) are
336 surely not the last one(s).
338 if (is->method->debug > 2)
339 logf (LOG_LOG, "isc: flush B %d sections", ptr-1);
340 flush_blocks (is, mb, ptr-1, r_buf, &firstpos, cat,
342 mb[0].block = mb[ptr-1].block;
343 mb[0].dirty = mb[ptr-1].dirty;
344 memcpy (r_buf, r_buf + mb[ptr-1].offset,
345 mb[ptr].offset - mb[ptr-1].offset);
348 mb[1].block = mb[ptr].block;
349 mb[1].dirty = mb[0].dirty;
350 mb[1].offset = mb[ptr].offset - mb[ptr-1].offset;
351 memcpy (r_buf + mb[1].offset, r_buf + r_offset,
352 new_offset - r_offset);
353 new_offset = (new_offset - r_offset) + mb[1].offset;
356 border = get_border (is, mb, ptr, cat, firstpos);
358 r_offset = new_offset;
360 if (cat < is->max_cat && ptr >= is->method->filecat[cat].mblocks)
362 /* Max number blocks in current category reached ->
363 must switch to next category (with larger block size)
367 (is->files[cat].no_remap)++;
368 /* delete all original block(s) read so far */
369 for (i = 0; i < ptr; i++)
371 isc_release_block (is, pp->cat, mb[i].block);
372 /* also delete all block to be read in the future */
375 /* remap block offsets */
376 assert (mb[j].offset == 0);
380 for (i = 1; i < ptr; i++)
382 int border = is->method->filecat[cat].ifill -
383 ISAMC_BLOCK_OFFSET_1 + mb[j].offset;
384 if (is->method->debug > 3)
385 logf (LOG_LOG, "isc: remap %d border=%d", i, border);
386 if (mb[i+1].offset > border && mb[i].offset <= border)
388 if (is->method->debug > 3)
389 logf (LOG_LOG, "isc: to %d %d", j, mb[i].offset);
392 mb[j].offset = mb[i].offset;
395 if (is->method->debug > 2)
396 logf (LOG_LOG, "isc: remap from %d to %d sections to cat %d",
399 border = get_border (is, mb, ptr, cat, firstpos);
402 if (mb[ptr].offset < r_offset)
403 { /* make the final boundary offset */
406 mb[ptr].offset = r_offset;
409 { /* empty output. Release last block if any */
410 if (cat == pp->cat && mb[ptr].block)
412 if (is->method->debug > 3)
413 logf (LOG_LOG, "isc: release C");
414 isc_release_block (is, pp->cat, mb[ptr].block);
421 if (is->method->debug > 2)
422 logf (LOG_LOG, "isc: flush C, %d sections", ptr);
426 /* we have to patch initial block with num keys if that
428 if (numKeys != isc_pp_num (pp))
430 if (is->method->debug > 2)
431 logf (LOG_LOG, "isc: patch num keys firstpos=%d num=%d",
433 bf_write (is->files[cat].bf, firstpos, ISAMC_BLOCK_OFFSET_N,
434 sizeof(numKeys), &numKeys);
438 { /* we haven't flushed initial block yet and there surely are some
439 blocks to flush. Make first block dirty if numKeys differ */
440 if (numKeys != isc_pp_num (pp))
443 /* flush rest of block(s) in r_buf */
444 flush_blocks (is, mb, ptr, r_buf, &firstpos, cat, 1, &numKeys);
446 (*is->method->code_stop)(ISAMC_ENCODE, r_clientData);
449 if (is->method->debug > 1)
450 logf (LOG_LOG, "isc: isc_merge return %d %d", cat, firstpos);
452 return cat + firstpos * 8;