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buffering.h
1 typedef struct dblib_buffer_row {
3 TDSRESULTINFO *resinfo;
5 unsigned char *row_data;
7 DBINT row;
9 TDS_INT *sizes;
10 } DBLIB_BUFFER_ROW;
11
12 static void buffer_struct_print(const DBPROC_ROWBUF *buf);
13 static int buffer_save_row(DBPROCESS *dbproc);
14 static DBLIB_BUFFER_ROW* buffer_row_address(const DBPROC_ROWBUF * buf, int idx);
15
16 #if ENABLE_EXTRA_CHECKS
17 static void buffer_check(const DBPROC_ROWBUF *buf)
18 {
19 int i;
20
21 /* no buffering */
22 if (buf->capacity == 0 || buf->capacity == 1) {
23 assert(buf->head == 0);
24 assert(buf->tail == 0 || buf->tail == 1);
25 assert(buf->capacity == 1 || buf->rows == NULL);
26 return;
27 }
28
29 assert(buf->capacity > 0);
30 assert(buf->head >= 0);
31 assert(buf->tail >= 0);
32 assert(buf->head < buf->capacity);
33 assert(buf->tail <= buf->capacity);
34
35 /* check empty */
36 if (buf->tail == buf->capacity) {
37 assert(buf->head == 0);
38 for (i = 0; buf->rows && i < buf->capacity; ++i) {
39 assert(buf->rows[i].resinfo == NULL);
40 assert(buf->rows[i].row_data == NULL);
41 assert(buf->rows[i].sizes == NULL);
42 assert(buf->rows[i].row == 0);
43 }
44 return;
45 }
46
47 if (buf->rows == NULL)
48 return;
49
50 /* check filled part */
51 i = buf->tail;
52 do {
53 assert(i >= 0 && i < buf->capacity);
54 assert(buf->rows[i].resinfo != NULL);
55 assert(buf->rows[i].row > 0);
56 assert(buf->rows[i].row <= buf->received);
57 ++i;
58 if (i == buf->capacity)
59 i = 0;
60 } while (i != buf->head);
61
62 /* check empty part */
63 if (buf->head != buf->tail) {
64 i = buf->head;
65 do {
66 assert(i >= 0 && i < buf->capacity);
67 assert(buf->rows[i].resinfo == NULL);
68 assert(buf->rows[i].row_data == NULL);
69 assert(buf->rows[i].sizes == NULL);
70 assert(buf->rows[i].row == 0);
71 ++i;
72 if (i == buf->capacity)
73 i = 0;
74 } while (i != buf->tail);
75 }
76 }
77 #define BUFFER_CHECK(buf) buffer_check(buf)
78 #else
79 #define BUFFER_CHECK(buf) do {} while(0)
80 #endif
81
110 static int
111 buffer_count(const DBPROC_ROWBUF *buf)
112 {
113 BUFFER_CHECK(buf);
114 return (buf->head > buf->tail) ?
115 buf->head - buf->tail : /* |...TddddH....| */
116 buf->capacity - (buf->tail - buf->head); /* |ddddH....Tddd| */
117 }
118
122 static int
123 buffer_is_full(const DBPROC_ROWBUF *buf)
124 {
125 BUFFER_CHECK(buf);
126 return buf->capacity == buffer_count(buf) && buf->capacity > 1;
127 }
128
129 #ifndef NDEBUG
130 static int
131 buffer_index_valid(const DBPROC_ROWBUF *buf, int idx)
132 {
133 BUFFER_CHECK(buf);
134 if (buf->tail <= buf->head)
135 if (buf->head <= idx && idx <= buf->tail)
136 return 1;
137
138 if (0 <= idx && idx <= buf->head)
139 return 1;
140
141 if (buf->tail <= idx && idx < buf->capacity)
142 return 1;
143 #if 0
144 printf("buffer_index_valid: idx = %d\n", idx);
145 buffer_struct_print(buf);
146 #endif
147 return 0;
148 }
149 #endif
150
151 static void
152 buffer_free_row(DBLIB_BUFFER_ROW *row)
153 {
154 if (row->sizes)
155 TDS_ZERO_FREE(row->sizes);
156 if (row->row_data) {
157 tds_free_row(row->resinfo, row->row_data);
158 row->row_data = NULL;
159 }
160 tds_free_results(row->resinfo);
161 row->resinfo = NULL;
162 row->row = 0;
163 }
164
165 /*
166 * Buffer is freed at slightly odd points, whenever
167 * capacity changes:
168 *
169 * 1. When setting capacity, to release prior buffer.
170 * 2. By dbresults. When called the second time, it has to
171 * release prior storage because the new resultset will have
172 * a different width.
173 * 3. By dbclose(), else open/close/open would leak.
174 */
175 static void
176 buffer_free(DBPROC_ROWBUF *buf)
177 {
178 BUFFER_CHECK(buf);
179 if (buf->rows != NULL) {
180 int i;
181 for (i = 0; i < buf->capacity; ++i)
182 buffer_free_row(&buf->rows[i]);
183 TDS_ZERO_FREE(buf->rows);
184 }
185 BUFFER_CHECK(buf);
186 }
187
188 /*
189 * When no rows are currently buffered (and the buffer is allocated)
190 * set the indices to their initial positions.
191 */
192 static void
193 buffer_reset(DBPROC_ROWBUF *buf)
194 {
195 buf->head = 0;
196 buf->current = buf->tail = buf->capacity;
197 BUFFER_CHECK(buf);
198 }
199
200 static int
201 buffer_idx_increment(const DBPROC_ROWBUF *buf, int idx)
202 {
203 if (++idx >= buf->capacity) {
204 idx = 0;
205 }
206 return idx;
207 }
208
213 static DBLIB_BUFFER_ROW*
214 buffer_row_address(const DBPROC_ROWBUF * buf, int idx)
215 {
216 BUFFER_CHECK(buf);
217 if (idx < 0 || idx >= buf->capacity) {
218 printf("idx is %d:\n", idx);
219 buffer_struct_print(buf);
220 return NULL;
221 }
222
223 return &(buf->rows[idx]);
224 }
225
229 static DBINT
230 buffer_idx2row(const DBPROC_ROWBUF *buf, int idx)
231 {
232 BUFFER_CHECK(buf);
233 return buffer_row_address(buf, idx)->row;
234 }
235
239 static int
240 buffer_row2idx(const DBPROC_ROWBUF *buf, int row_number)
241 {
242 int i, ii, idx = -1;
243
244 BUFFER_CHECK(buf);
245 if (buf->tail == buf->capacity) {
246 assert (buf->head == 0);
247 return -1; /* no rows buffered */
248 }
249
250 /*
251 * March through the buffers from tail to head, stop if we find our row.
252 * A full queue is indicated by tail == head (which means we can't write).
253 */
254 for (ii=0, i = buf->tail; i != buf->head || ii == 0; i = buffer_idx_increment(buf, i)) {
255 if( buffer_idx2row(buf, i) == row_number) {
256 idx = i;
257 break;
258 }
259 assert(ii++ < buf->capacity); /* prevent infinite loop */
260 }
261
262 return idx;
263 }
264
269 static void
270 buffer_delete_rows(DBPROC_ROWBUF * buf, int count)
271 {
272 int i;
273
274 BUFFER_CHECK(buf);
275 if (count < 0 || count > buffer_count(buf)) {
276 count = buffer_count(buf);
277 }
278
279 for (i=0; i < count; i++) {
280 if (buf->tail < buf->capacity)
281 buffer_free_row(&buf->rows[buf->tail]);
282 buf->tail = buffer_idx_increment(buf, buf->tail);
283 /*
284 * If deleting rows from the buffer catches the tail to the head,
285 * return to the initial position. Otherwise, it will look full.
286 */
287 if (buf->tail == buf->head) {
288 buffer_reset(buf);
289 break;
290 }
291 }
292 #if 0
293 buffer_struct_print(buf);
294 #endif
295 BUFFER_CHECK(buf);
296 }
297
298 static void
299 buffer_transfer_bound_data(DBPROC_ROWBUF *buf, TDS_INT res_type, TDS_INT compute_id, DBPROCESS * dbproc, int idx)
300 {
301 int i;
302 int srctype, desttype;
303 BYTE *src;
304 const DBLIB_BUFFER_ROW *row;
305
306 tdsdump_log(TDS_DBG_FUNC, "buffer_transfer_bound_data(%p %d %d %p %d)\n", buf, res_type, compute_id, dbproc, idx);
307 BUFFER_CHECK(buf);
308 assert(buffer_index_valid(buf, idx));
309
310 row = buffer_row_address(buf, idx);
311 assert(row->resinfo);
312
313 for (i = 0; i < row->resinfo->num_cols; i++) {
314 DBINT srclen;
315 TDSCOLUMN *curcol = row->resinfo->columns[i];
316
317 if (row->sizes)
318 curcol->column_cur_size = row->sizes[i];
319
320 if (curcol->column_nullbind) {
321 if (curcol->column_cur_size < 0) {
322 *(DBINT *)(curcol->column_nullbind) = -1;
323 } else {
324 *(DBINT *)(curcol->column_nullbind) = 0;
325 }
326 }
327 if (!curcol->column_varaddr)
328 continue;
329
330 if (row->row_data)
331 src = &row->row_data[curcol->column_data - row->resinfo->current_row];
332 else
333 src = curcol->column_data;
334 srclen = curcol->column_cur_size;
335 if (is_blob_col(curcol))
336 src = (BYTE *) ((TDSBLOB *) src)->textvalue;
337 desttype = _db_get_server_type(curcol->column_bindtype);
338 srctype = tds_get_conversion_type(curcol->column_type, curcol->column_size);
339
340 if (srclen <= 0) {
341 if (srclen == 0 || !curcol->column_nullbind)
342 dbgetnull(dbproc, curcol->column_bindtype, curcol->column_bindlen,
343 (BYTE *) curcol->column_varaddr);
344 } else {
345 copy_data_to_host_var(dbproc, srctype, src, srclen, desttype,
346 (BYTE *) curcol->column_varaddr, curcol->column_bindlen,
347 curcol->column_bindtype, (DBINT*) curcol->column_nullbind);
348 }
349 }
350
351 /*
352 * This function always bumps current. Usually, it's called
353 * by dbnextrow(), so bumping current is a pretty obvious choice.
354 * It can also be called by dbgetrow(), but that function also
355 * causes the bump. If you call dbgetrow() for row N, a subsequent
356 * call to dbnextrow() yields N+1.
357 */
358 buf->current = buffer_idx_increment(buf, buf->current);
359
360 } /* end buffer_transfer_bound_data() */
361
362 static void
363 buffer_struct_print(const DBPROC_ROWBUF *buf)
364 {
365 assert(buf);
366
367 printf("\t%d rows in buffer\n", buffer_count(buf));
368
369 printf("\thead = %d\t", buf->head);
370 printf("\ttail = %d\t", buf->tail);
371 printf("\tcurrent = %d\n", buf->current);
372 printf("\tcapacity = %d\t", buf->capacity);
373 printf("\thead row number = %d\n", buf->received);
374 }
375
376 /* * * Functions called only by public db-lib API take DBPROCESS* * */
377
394 static int
395 buffer_current_index(const DBPROCESS *dbproc)
396 {
397 const DBPROC_ROWBUF *buf = &dbproc->row_buf;
398 #if 0
399 buffer_struct_print(buf);
400 #endif
401 if (buf->capacity <= 1) /* no buffering */
402 return -1;
403 if (buf->current == buf->head || buf->current == buf->capacity)
404 return -1;
405
406 assert(buf->current >= 0);
407 assert(buf->current < buf->capacity);
408
409 if( buf->tail < buf->head) {
410 assert(buf->tail < buf->current);
411 assert(buf->current < buf->head);
412 } else {
413 if (buf->current > buf->head)
414 assert(buf->current > buf->tail);
415 }
416 return buf->current;
417 }
418
419 /*
420 * Normally called by dbsetopt() to prepare for buffering
421 * Called with nrows == 0 by dbopen to safely set buf->rows to NULL.
422 */
423 static void
424 buffer_set_capacity(DBPROCESS *dbproc, int nrows)
425 {
426 DBPROC_ROWBUF *buf = &dbproc->row_buf;
427
428 buffer_free(buf);
429
430 memset(buf, 0, sizeof(DBPROC_ROWBUF));
431
432 if (0 == nrows) {
433 buf->capacity = 1;
434 BUFFER_CHECK(buf);
435 return;
436 }
437
438 assert(0 < nrows);
439
440 buf->capacity = nrows;
441 BUFFER_CHECK(buf);
442 }
443
444 /*
445 * Called only by dbresults(); capacity must be >= 1.
446 * Sybase's documents say dbresults() cannot return FAIL if the prior calls worked,
447 * which is a little strange, because (for FreeTDS, at least), dbresults
448 * is when we learn about the result set's width. Without that information, we
449 * can't allocate memory for the buffer. But if we *fail* to allocate memory,
450 * we're not to communicate it back to the caller?
451 */
452 static void
453 buffer_alloc(DBPROCESS *dbproc)
454 {
455 DBPROC_ROWBUF *buf = &dbproc->row_buf;
456
457 /* Call this function only after setting capacity. */
458
459 assert(buf);
460 assert(buf->capacity > 0);
461 assert(buf->rows == NULL);
462
463 buf->rows = (DBLIB_BUFFER_ROW *) calloc(buf->capacity, sizeof(DBLIB_BUFFER_ROW));
464
465 assert(buf->rows);
466
467 buffer_reset(buf);
468
469 buf->received = 0;
470 }
471
476 static int
477 buffer_add_row(DBPROCESS *dbproc, TDSRESULTINFO *resinfo)
478 {
479 DBPROC_ROWBUF *buf = &dbproc->row_buf;
480 DBLIB_BUFFER_ROW *row;
481 int i;
482
483 assert(buf->capacity >= 0);
484
485 if (buffer_is_full(buf))
486 return -1;
487
488 row = buffer_row_address(buf, buf->head);
489
490 /* bump the row number, write it, and move the data to head */
491 if (row->resinfo) {
492 tds_free_row(row->resinfo, row->row_data);
493 tds_free_results(row->resinfo);
494 }
495 row->row = ++buf->received;
496 ++resinfo->ref_count;
497 row->resinfo = resinfo;
498 row->row_data = NULL;
499 if (row->sizes)
500 free(row->sizes);
501 row->sizes = (TDS_INT *) calloc(resinfo->num_cols, sizeof(TDS_INT));
502 for (i = 0; i < resinfo->num_cols; ++i)
503 row->sizes[i] = resinfo->columns[i]->column_cur_size;
504
505 /* initial condition is head == 0 and tail == capacity */
506 if (buf->tail == buf->capacity) {
507 /* bumping this tail will set it to zero */
508 assert(buf->head == 0);
509 buf->tail = 0;
510 }
511
512 /* update current, bump the head */
513 buf->current = buf->head;
514 buf->head = buffer_idx_increment(buf, buf->head);
515
516 return buf->current;
517 }
518
519 static int
520 buffer_save_row(DBPROCESS *dbproc)
521 {
522 DBPROC_ROWBUF *buf = &dbproc->row_buf;
523 DBLIB_BUFFER_ROW *row;
524 int idx = buf->head - 1;
525
526 if (buf->capacity <= 1)
527 return SUCCEED;
528
529 if (idx < 0)
530 idx = buf->capacity - 1;
531 if (idx >= 0 && idx < buf->capacity) {
532 row = &buf->rows[idx];
533
534 if (row->resinfo && !row->row_data) {
535 row->row_data = row->resinfo->current_row;
536 tds_alloc_row(row->resinfo);
537 }
538 }
539
540 return SUCCEED;
541 }
542