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generation.c
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1 /*-------------------------------------------------------------------------
2  *
3  * generation.c
4  * Generational allocator definitions.
5  *
6  * Generation is a custom MemoryContext implementation designed for cases of
7  * chunks with similar lifespan.
8  *
9  * Portions Copyright (c) 2017-2021, PostgreSQL Global Development Group
10  *
11  * IDENTIFICATION
12  * src/backend/utils/mmgr/generation.c
13  *
14  *
15  * This memory context is based on the assumption that the chunks are freed
16  * roughly in the same order as they were allocated (FIFO), or in groups with
17  * similar lifespan (generations - hence the name of the context). This is
18  * typical for various queue-like use cases, i.e. when tuples are constructed,
19  * processed and then thrown away.
20  *
21  * The memory context uses a very simple approach to free space management.
22  * Instead of a complex global freelist, each block tracks a number
23  * of allocated and freed chunks. Freed chunks are not reused, and once all
24  * chunks in a block are freed, the whole block is thrown away. When the
25  * chunks allocated in the same block have similar lifespan, this works
26  * very well and is very cheap.
27  *
28  * The current implementation only uses a fixed block size - maybe it should
29  * adapt a min/max block size range, and grow the blocks automatically.
30  * It already uses dedicated blocks for oversized chunks.
31  *
32  * XXX It might be possible to improve this by keeping a small freelist for
33  * only a small number of recent blocks, but it's not clear it's worth the
34  * additional complexity.
35  *
36  *-------------------------------------------------------------------------
37  */
38 
39 #include "postgres.h"
40 
41 #include "lib/ilist.h"
42 #include "utils/memdebug.h"
43 #include "utils/memutils.h"
44 
45 
46 #define Generation_BLOCKHDRSZ MAXALIGN(sizeof(GenerationBlock))
47 #define Generation_CHUNKHDRSZ sizeof(GenerationChunk)
48 
49 typedef struct GenerationBlock GenerationBlock; /* forward reference */
51 
52 typedef void *GenerationPointer;
53 
54 /*
55  * GenerationContext is a simple memory context not reusing allocated chunks,
56  * and freeing blocks once all chunks are freed.
57  */
58 typedef struct GenerationContext
59 {
60  MemoryContextData header; /* Standard memory-context fields */
61 
62  /* Generational context parameters */
63  Size blockSize; /* standard block size */
64 
65  GenerationBlock *block; /* current (most recently allocated) block */
66  dlist_head blocks; /* list of blocks */
68 
69 /*
70  * GenerationBlock
71  * GenerationBlock is the unit of memory that is obtained by generation.c
72  * from malloc(). It contains one or more GenerationChunks, which are
73  * the units requested by palloc() and freed by pfree(). GenerationChunks
74  * cannot be returned to malloc() individually, instead pfree()
75  * updates the free counter of the block and when all chunks in a block
76  * are free the whole block is returned to malloc().
77  *
78  * GenerationBlock is the header data for a block --- the usable space
79  * within the block begins at the next alignment boundary.
80  */
82 {
83  dlist_node node; /* doubly-linked list of blocks */
84  Size blksize; /* allocated size of this block */
85  int nchunks; /* number of chunks in the block */
86  int nfree; /* number of free chunks */
87  char *freeptr; /* start of free space in this block */
88  char *endptr; /* end of space in this block */
89 };
90 
91 /*
92  * GenerationChunk
93  * The prefix of each piece of memory in a GenerationBlock
94  *
95  * Note: to meet the memory context APIs, the payload area of the chunk must
96  * be maxaligned, and the "context" link must be immediately adjacent to the
97  * payload area (cf. GetMemoryChunkContext). We simplify matters for this
98  * module by requiring sizeof(GenerationChunk) to be maxaligned, and then
99  * we can ensure things work by adding any required alignment padding before
100  * the pointer fields. There is a static assertion below that the alignment
101  * is done correctly.
102  */
104 {
105  /* size is always the size of the usable space in the chunk */
107 #ifdef MEMORY_CONTEXT_CHECKING
108  /* when debugging memory usage, also store actual requested size */
109  /* this is zero in a free chunk */
110  Size requested_size;
111 
112 #define GENERATIONCHUNK_RAWSIZE (SIZEOF_SIZE_T * 2 + SIZEOF_VOID_P * 2)
113 #else
114 #define GENERATIONCHUNK_RAWSIZE (SIZEOF_SIZE_T + SIZEOF_VOID_P * 2)
115 #endif /* MEMORY_CONTEXT_CHECKING */
116 
117  /* ensure proper alignment by adding padding if needed */
118 #if (GENERATIONCHUNK_RAWSIZE % MAXIMUM_ALIGNOF) != 0
119  char padding[MAXIMUM_ALIGNOF - GENERATIONCHUNK_RAWSIZE % MAXIMUM_ALIGNOF];
120 #endif
121 
122  GenerationBlock *block; /* block owning this chunk */
123  GenerationContext *context; /* owning context, or NULL if freed chunk */
124  /* there must not be any padding to reach a MAXALIGN boundary here! */
125 };
126 
127 /*
128  * Only the "context" field should be accessed outside this module.
129  * We keep the rest of an allocated chunk's header marked NOACCESS when using
130  * valgrind. But note that freed chunk headers are kept accessible, for
131  * simplicity.
132  */
133 #define GENERATIONCHUNK_PRIVATE_LEN offsetof(GenerationChunk, context)
134 
135 /*
136  * GenerationIsValid
137  * True iff set is valid allocation set.
138  */
139 #define GenerationIsValid(set) PointerIsValid(set)
140 
141 #define GenerationPointerGetChunk(ptr) \
142  ((GenerationChunk *)(((char *)(ptr)) - Generation_CHUNKHDRSZ))
143 #define GenerationChunkGetPointer(chk) \
144  ((GenerationPointer *)(((char *)(chk)) + Generation_CHUNKHDRSZ))
145 
146 /*
147  * These functions implement the MemoryContext API for Generation contexts.
148  */
149 static void *GenerationAlloc(MemoryContext context, Size size);
150 static void GenerationFree(MemoryContext context, void *pointer);
151 static void *GenerationRealloc(MemoryContext context, void *pointer, Size size);
152 static void GenerationReset(MemoryContext context);
153 static void GenerationDelete(MemoryContext context);
154 static Size GenerationGetChunkSpace(MemoryContext context, void *pointer);
155 static bool GenerationIsEmpty(MemoryContext context);
156 static void GenerationStats(MemoryContext context,
157  MemoryStatsPrintFunc printfunc, void *passthru,
158  MemoryContextCounters *totals,
159  bool print_to_stderr);
160 
161 #ifdef MEMORY_CONTEXT_CHECKING
162 static void GenerationCheck(MemoryContext context);
163 #endif
164 
165 /*
166  * This is the virtual function table for Generation contexts.
167  */
177 #ifdef MEMORY_CONTEXT_CHECKING
178  ,GenerationCheck
179 #endif
180 };
181 
182 
183 /*
184  * Public routines
185  */
186 
187 
188 /*
189  * GenerationContextCreate
190  * Create a new Generation context.
191  *
192  * parent: parent context, or NULL if top-level context
193  * name: name of context (must be statically allocated)
194  * blockSize: generation block size
195  */
198  const char *name,
199  Size blockSize)
200 {
201  GenerationContext *set;
202 
203  /* Assert we padded GenerationChunk properly */
205  "sizeof(GenerationChunk) is not maxaligned");
208  "padding calculation in GenerationChunk is wrong");
209 
210  /*
211  * First, validate allocation parameters. (If we're going to throw an
212  * error, we should do so before the context is created, not after.) We
213  * somewhat arbitrarily enforce a minimum 1K block size, mostly because
214  * that's what AllocSet does.
215  */
216  if (blockSize != MAXALIGN(blockSize) ||
217  blockSize < 1024 ||
218  !AllocHugeSizeIsValid(blockSize))
219  elog(ERROR, "invalid blockSize for memory context: %zu",
220  blockSize);
221 
222  /*
223  * Allocate the context header. Unlike aset.c, we never try to combine
224  * this with the first regular block, since that would prevent us from
225  * freeing the first generation of allocations.
226  */
227 
229  if (set == NULL)
230  {
232  ereport(ERROR,
233  (errcode(ERRCODE_OUT_OF_MEMORY),
234  errmsg("out of memory"),
235  errdetail("Failed while creating memory context \"%s\".",
236  name)));
237  }
238 
239  /*
240  * Avoid writing code that can fail between here and MemoryContextCreate;
241  * we'd leak the header if we ereport in this stretch.
242  */
243 
244  /* Fill in GenerationContext-specific header fields */
245  set->blockSize = blockSize;
246  set->block = NULL;
247  dlist_init(&set->blocks);
248 
249  /* Finally, do the type-independent part of context creation */
252  &GenerationMethods,
253  parent,
254  name);
255 
256  return (MemoryContext) set;
257 }
258 
259 /*
260  * GenerationReset
261  * Frees all memory which is allocated in the given set.
262  *
263  * The code simply frees all the blocks in the context - we don't keep any
264  * keeper blocks or anything like that.
265  */
266 static void
268 {
269  GenerationContext *set = (GenerationContext *) context;
270  dlist_mutable_iter miter;
271 
273 
274 #ifdef MEMORY_CONTEXT_CHECKING
275  /* Check for corruption and leaks before freeing */
276  GenerationCheck(context);
277 #endif
278 
279  dlist_foreach_modify(miter, &set->blocks)
280  {
282 
283  dlist_delete(miter.cur);
284 
285  context->mem_allocated -= block->blksize;
286 
287 #ifdef CLOBBER_FREED_MEMORY
288  wipe_mem(block, block->blksize);
289 #endif
290 
291  free(block);
292  }
293 
294  set->block = NULL;
295 
296  Assert(dlist_is_empty(&set->blocks));
297 }
298 
299 /*
300  * GenerationDelete
301  * Free all memory which is allocated in the given context.
302  */
303 static void
305 {
306  /* Reset to release all the GenerationBlocks */
307  GenerationReset(context);
308  /* And free the context header */
309  free(context);
310 }
311 
312 /*
313  * GenerationAlloc
314  * Returns pointer to allocated memory of given size or NULL if
315  * request could not be completed; memory is added to the set.
316  *
317  * No request may exceed:
318  * MAXALIGN_DOWN(SIZE_MAX) - Generation_BLOCKHDRSZ - Generation_CHUNKHDRSZ
319  * All callers use a much-lower limit.
320  *
321  * Note: when using valgrind, it doesn't matter how the returned allocation
322  * is marked, as mcxt.c will set it to UNDEFINED. In some paths we will
323  * return space that is marked NOACCESS - GenerationRealloc has to beware!
324  */
325 static void *
327 {
328  GenerationContext *set = (GenerationContext *) context;
330  GenerationChunk *chunk;
331  Size chunk_size = MAXALIGN(size);
332 
333  /* is it an over-sized chunk? if yes, allocate special block */
334  if (chunk_size > set->blockSize / 8)
335  {
336  Size blksize = chunk_size + Generation_BLOCKHDRSZ + Generation_CHUNKHDRSZ;
337 
338  block = (GenerationBlock *) malloc(blksize);
339  if (block == NULL)
340  return NULL;
341 
342  context->mem_allocated += blksize;
343 
344  /* block with a single (used) chunk */
345  block->blksize = blksize;
346  block->nchunks = 1;
347  block->nfree = 0;
348 
349  /* the block is completely full */
350  block->freeptr = block->endptr = ((char *) block) + blksize;
351 
352  chunk = (GenerationChunk *) (((char *) block) + Generation_BLOCKHDRSZ);
353  chunk->block = block;
354  chunk->context = set;
355  chunk->size = chunk_size;
356 
357 #ifdef MEMORY_CONTEXT_CHECKING
358  chunk->requested_size = size;
359  /* set mark to catch clobber of "unused" space */
360  if (size < chunk_size)
361  set_sentinel(GenerationChunkGetPointer(chunk), size);
362 #endif
363 #ifdef RANDOMIZE_ALLOCATED_MEMORY
364  /* fill the allocated space with junk */
365  randomize_mem((char *) GenerationChunkGetPointer(chunk), size);
366 #endif
367 
368  /* add the block to the list of allocated blocks */
369  dlist_push_head(&set->blocks, &block->node);
370 
371  /* Ensure any padding bytes are marked NOACCESS. */
373  chunk_size - size);
374 
375  /* Disallow external access to private part of chunk header. */
377 
378  return GenerationChunkGetPointer(chunk);
379  }
380 
381  /*
382  * Not an over-sized chunk. Is there enough space in the current block? If
383  * not, allocate a new "regular" block.
384  */
385  block = set->block;
386 
387  if ((block == NULL) ||
388  (block->endptr - block->freeptr) < Generation_CHUNKHDRSZ + chunk_size)
389  {
390  Size blksize = set->blockSize;
391 
392  block = (GenerationBlock *) malloc(blksize);
393 
394  if (block == NULL)
395  return NULL;
396 
397  context->mem_allocated += blksize;
398 
399  block->blksize = blksize;
400  block->nchunks = 0;
401  block->nfree = 0;
402 
403  block->freeptr = ((char *) block) + Generation_BLOCKHDRSZ;
404  block->endptr = ((char *) block) + blksize;
405 
406  /* Mark unallocated space NOACCESS. */
408  blksize - Generation_BLOCKHDRSZ);
409 
410  /* add it to the doubly-linked list of blocks */
411  dlist_push_head(&set->blocks, &block->node);
412 
413  /* and also use it as the current allocation block */
414  set->block = block;
415  }
416 
417  /* we're supposed to have a block with enough free space now */
418  Assert(block != NULL);
419  Assert((block->endptr - block->freeptr) >= Generation_CHUNKHDRSZ + chunk_size);
420 
421  chunk = (GenerationChunk *) block->freeptr;
422 
423  /* Prepare to initialize the chunk header. */
425 
426  block->nchunks += 1;
427  block->freeptr += (Generation_CHUNKHDRSZ + chunk_size);
428 
429  Assert(block->freeptr <= block->endptr);
430 
431  chunk->block = block;
432  chunk->context = set;
433  chunk->size = chunk_size;
434 
435 #ifdef MEMORY_CONTEXT_CHECKING
436  chunk->requested_size = size;
437  /* set mark to catch clobber of "unused" space */
438  if (size < chunk->size)
439  set_sentinel(GenerationChunkGetPointer(chunk), size);
440 #endif
441 #ifdef RANDOMIZE_ALLOCATED_MEMORY
442  /* fill the allocated space with junk */
443  randomize_mem((char *) GenerationChunkGetPointer(chunk), size);
444 #endif
445 
446  /* Ensure any padding bytes are marked NOACCESS. */
448  chunk_size - size);
449 
450  /* Disallow external access to private part of chunk header. */
452 
453  return GenerationChunkGetPointer(chunk);
454 }
455 
456 /*
457  * GenerationFree
458  * Update number of chunks in the block, and if all chunks in the block
459  * are now free then discard the block.
460  */
461 static void
462 GenerationFree(MemoryContext context, void *pointer)
463 {
464  GenerationContext *set = (GenerationContext *) context;
465  GenerationChunk *chunk = GenerationPointerGetChunk(pointer);
467 
468  /* Allow access to private part of chunk header. */
470 
471  block = chunk->block;
472 
473 #ifdef MEMORY_CONTEXT_CHECKING
474  /* Test for someone scribbling on unused space in chunk */
475  if (chunk->requested_size < chunk->size)
476  if (!sentinel_ok(pointer, chunk->requested_size))
477  elog(WARNING, "detected write past chunk end in %s %p",
478  ((MemoryContext) set)->name, chunk);
479 #endif
480 
481 #ifdef CLOBBER_FREED_MEMORY
482  wipe_mem(pointer, chunk->size);
483 #endif
484 
485  /* Reset context to NULL in freed chunks */
486  chunk->context = NULL;
487 
488 #ifdef MEMORY_CONTEXT_CHECKING
489  /* Reset requested_size to 0 in freed chunks */
490  chunk->requested_size = 0;
491 #endif
492 
493  block->nfree += 1;
494 
495  Assert(block->nchunks > 0);
496  Assert(block->nfree <= block->nchunks);
497 
498  /* If there are still allocated chunks in the block, we're done. */
499  if (block->nfree < block->nchunks)
500  return;
501 
502  /*
503  * The block is empty, so let's get rid of it. First remove it from the
504  * list of blocks, then return it to malloc().
505  */
506  dlist_delete(&block->node);
507 
508  /* Also make sure the block is not marked as the current block. */
509  if (set->block == block)
510  set->block = NULL;
511 
512  context->mem_allocated -= block->blksize;
513  free(block);
514 }
515 
516 /*
517  * GenerationRealloc
518  * When handling repalloc, we simply allocate a new chunk, copy the data
519  * and discard the old one. The only exception is when the new size fits
520  * into the old chunk - in that case we just update chunk header.
521  */
522 static void *
523 GenerationRealloc(MemoryContext context, void *pointer, Size size)
524 {
525  GenerationContext *set = (GenerationContext *) context;
526  GenerationChunk *chunk = GenerationPointerGetChunk(pointer);
527  GenerationPointer newPointer;
528  Size oldsize;
529 
530  /* Allow access to private part of chunk header. */
532 
533  oldsize = chunk->size;
534 
535 #ifdef MEMORY_CONTEXT_CHECKING
536  /* Test for someone scribbling on unused space in chunk */
537  if (chunk->requested_size < oldsize)
538  if (!sentinel_ok(pointer, chunk->requested_size))
539  elog(WARNING, "detected write past chunk end in %s %p",
540  ((MemoryContext) set)->name, chunk);
541 #endif
542 
543  /*
544  * Maybe the allocated area already is >= the new size. (In particular,
545  * we always fall out here if the requested size is a decrease.)
546  *
547  * This memory context does not use power-of-2 chunk sizing and instead
548  * carves the chunks to be as small as possible, so most repalloc() calls
549  * will end up in the palloc/memcpy/pfree branch.
550  *
551  * XXX Perhaps we should annotate this condition with unlikely()?
552  */
553  if (oldsize >= size)
554  {
555 #ifdef MEMORY_CONTEXT_CHECKING
556  Size oldrequest = chunk->requested_size;
557 
558 #ifdef RANDOMIZE_ALLOCATED_MEMORY
559  /* We can only fill the extra space if we know the prior request */
560  if (size > oldrequest)
561  randomize_mem((char *) pointer + oldrequest,
562  size - oldrequest);
563 #endif
564 
565  chunk->requested_size = size;
566 
567  /*
568  * If this is an increase, mark any newly-available part UNDEFINED.
569  * Otherwise, mark the obsolete part NOACCESS.
570  */
571  if (size > oldrequest)
572  VALGRIND_MAKE_MEM_UNDEFINED((char *) pointer + oldrequest,
573  size - oldrequest);
574  else
575  VALGRIND_MAKE_MEM_NOACCESS((char *) pointer + size,
576  oldsize - size);
577 
578  /* set mark to catch clobber of "unused" space */
579  if (size < oldsize)
580  set_sentinel(pointer, size);
581 #else /* !MEMORY_CONTEXT_CHECKING */
582 
583  /*
584  * We don't have the information to determine whether we're growing
585  * the old request or shrinking it, so we conservatively mark the
586  * entire new allocation DEFINED.
587  */
588  VALGRIND_MAKE_MEM_NOACCESS(pointer, oldsize);
589  VALGRIND_MAKE_MEM_DEFINED(pointer, size);
590 #endif
591 
592  /* Disallow external access to private part of chunk header. */
594 
595  return pointer;
596  }
597 
598  /* allocate new chunk */
599  newPointer = GenerationAlloc((MemoryContext) set, size);
600 
601  /* leave immediately if request was not completed */
602  if (newPointer == NULL)
603  {
604  /* Disallow external access to private part of chunk header. */
606  return NULL;
607  }
608 
609  /*
610  * GenerationAlloc() may have returned a region that is still NOACCESS.
611  * Change it to UNDEFINED for the moment; memcpy() will then transfer
612  * definedness from the old allocation to the new. If we know the old
613  * allocation, copy just that much. Otherwise, make the entire old chunk
614  * defined to avoid errors as we copy the currently-NOACCESS trailing
615  * bytes.
616  */
617  VALGRIND_MAKE_MEM_UNDEFINED(newPointer, size);
618 #ifdef MEMORY_CONTEXT_CHECKING
619  oldsize = chunk->requested_size;
620 #else
621  VALGRIND_MAKE_MEM_DEFINED(pointer, oldsize);
622 #endif
623 
624  /* transfer existing data (certain to fit) */
625  memcpy(newPointer, pointer, oldsize);
626 
627  /* free old chunk */
628  GenerationFree((MemoryContext) set, pointer);
629 
630  return newPointer;
631 }
632 
633 /*
634  * GenerationGetChunkSpace
635  * Given a currently-allocated chunk, determine the total space
636  * it occupies (including all memory-allocation overhead).
637  */
638 static Size
639 GenerationGetChunkSpace(MemoryContext context, void *pointer)
640 {
641  GenerationChunk *chunk = GenerationPointerGetChunk(pointer);
642  Size result;
643 
645  result = chunk->size + Generation_CHUNKHDRSZ;
647  return result;
648 }
649 
650 /*
651  * GenerationIsEmpty
652  * Is a GenerationContext empty of any allocated space?
653  */
654 static bool
656 {
657  GenerationContext *set = (GenerationContext *) context;
658 
659  return dlist_is_empty(&set->blocks);
660 }
661 
662 /*
663  * GenerationStats
664  * Compute stats about memory consumption of a Generation context.
665  *
666  * printfunc: if not NULL, pass a human-readable stats string to this.
667  * passthru: pass this pointer through to printfunc.
668  * totals: if not NULL, add stats about this context into *totals.
669  * print_to_stderr: print stats to stderr if true, elog otherwise.
670  *
671  * XXX freespace only accounts for empty space at the end of the block, not
672  * space of freed chunks (which is unknown).
673  */
674 static void
676  MemoryStatsPrintFunc printfunc, void *passthru,
677  MemoryContextCounters *totals, bool print_to_stderr)
678 {
679  GenerationContext *set = (GenerationContext *) context;
680  Size nblocks = 0;
681  Size nchunks = 0;
682  Size nfreechunks = 0;
683  Size totalspace;
684  Size freespace = 0;
685  dlist_iter iter;
686 
687  /* Include context header in totalspace */
688  totalspace = MAXALIGN(sizeof(GenerationContext));
689 
690  dlist_foreach(iter, &set->blocks)
691  {
693 
694  nblocks++;
695  nchunks += block->nchunks;
696  nfreechunks += block->nfree;
697  totalspace += block->blksize;
698  freespace += (block->endptr - block->freeptr);
699  }
700 
701  if (printfunc)
702  {
703  char stats_string[200];
704 
705  snprintf(stats_string, sizeof(stats_string),
706  "%zu total in %zd blocks (%zd chunks); %zu free (%zd chunks); %zu used",
707  totalspace, nblocks, nchunks, freespace,
708  nfreechunks, totalspace - freespace);
709  printfunc(context, passthru, stats_string, print_to_stderr);
710  }
711 
712  if (totals)
713  {
714  totals->nblocks += nblocks;
715  totals->freechunks += nfreechunks;
716  totals->totalspace += totalspace;
717  totals->freespace += freespace;
718  }
719 }
720 
721 
722 #ifdef MEMORY_CONTEXT_CHECKING
723 
724 /*
725  * GenerationCheck
726  * Walk through chunks and check consistency of memory.
727  *
728  * NOTE: report errors as WARNING, *not* ERROR or FATAL. Otherwise you'll
729  * find yourself in an infinite loop when trouble occurs, because this
730  * routine will be entered again when elog cleanup tries to release memory!
731  */
732 static void
733 GenerationCheck(MemoryContext context)
734 {
735  GenerationContext *gen = (GenerationContext *) context;
736  const char *name = context->name;
737  dlist_iter iter;
738  Size total_allocated = 0;
739 
740  /* walk all blocks in this context */
741  dlist_foreach(iter, &gen->blocks)
742  {
744  int nfree,
745  nchunks;
746  char *ptr;
747 
748  total_allocated += block->blksize;
749 
750  /*
751  * nfree > nchunks is surely wrong, and we don't expect to see
752  * equality either, because such a block should have gotten freed.
753  */
754  if (block->nfree >= block->nchunks)
755  elog(WARNING, "problem in Generation %s: number of free chunks %d in block %p exceeds %d allocated",
756  name, block->nfree, block, block->nchunks);
757 
758  /* Now walk through the chunks and count them. */
759  nfree = 0;
760  nchunks = 0;
761  ptr = ((char *) block) + Generation_BLOCKHDRSZ;
762 
763  while (ptr < block->freeptr)
764  {
765  GenerationChunk *chunk = (GenerationChunk *) ptr;
766 
767  /* Allow access to private part of chunk header. */
769 
770  /* move to the next chunk */
771  ptr += (chunk->size + Generation_CHUNKHDRSZ);
772 
773  nchunks += 1;
774 
775  /* chunks have both block and context pointers, so check both */
776  if (chunk->block != block)
777  elog(WARNING, "problem in Generation %s: bogus block link in block %p, chunk %p",
778  name, block, chunk);
779 
780  /*
781  * Check for valid context pointer. Note this is an incomplete
782  * test, since palloc(0) produces an allocated chunk with
783  * requested_size == 0.
784  */
785  if ((chunk->requested_size > 0 && chunk->context != gen) ||
786  (chunk->context != gen && chunk->context != NULL))
787  elog(WARNING, "problem in Generation %s: bogus context link in block %p, chunk %p",
788  name, block, chunk);
789 
790  /* now make sure the chunk size is correct */
791  if (chunk->size < chunk->requested_size ||
792  chunk->size != MAXALIGN(chunk->size))
793  elog(WARNING, "problem in Generation %s: bogus chunk size in block %p, chunk %p",
794  name, block, chunk);
795 
796  /* is chunk allocated? */
797  if (chunk->context != NULL)
798  {
799  /* check sentinel, but only in allocated blocks */
800  if (chunk->requested_size < chunk->size &&
801  !sentinel_ok(chunk, Generation_CHUNKHDRSZ + chunk->requested_size))
802  elog(WARNING, "problem in Generation %s: detected write past chunk end in block %p, chunk %p",
803  name, block, chunk);
804  }
805  else
806  nfree += 1;
807 
808  /*
809  * If chunk is allocated, disallow external access to private part
810  * of chunk header.
811  */
812  if (chunk->context != NULL)
814  }
815 
816  /*
817  * Make sure we got the expected number of allocated and free chunks
818  * (as tracked in the block header).
819  */
820  if (nchunks != block->nchunks)
821  elog(WARNING, "problem in Generation %s: number of allocated chunks %d in block %p does not match header %d",
822  name, nchunks, block, block->nchunks);
823 
824  if (nfree != block->nfree)
825  elog(WARNING, "problem in Generation %s: number of free chunks %d in block %p does not match header %d",
826  name, nfree, block, block->nfree);
827  }
828 
829  Assert(total_allocated == context->mem_allocated);
830 }
831 
832 #endif /* MEMORY_CONTEXT_CHECKING */
static void GenerationDelete(MemoryContext context)
Definition: generation.c:304
#define GenerationPointerGetChunk(ptr)
Definition: generation.c:141
#define VALGRIND_MAKE_MEM_DEFINED(addr, size)
Definition: memdebug.h:26
dlist_node * cur
Definition: ilist.h:180
#define dlist_foreach_modify(iter, lhead)
Definition: ilist.h:543
static void dlist_push_head(dlist_head *head, dlist_node *node)
Definition: ilist.h:300
#define VALGRIND_MAKE_MEM_UNDEFINED(addr, size)
Definition: memdebug.h:28
#define dlist_foreach(iter, lhead)
Definition: ilist.h:526
#define VALGRIND_MAKE_MEM_NOACCESS(addr, size)
Definition: memdebug.h:27
static void GenerationReset(MemoryContext context)
Definition: generation.c:267
#define GENERATIONCHUNK_RAWSIZE
Definition: generation.c:114
GenerationBlock * block
Definition: generation.c:122
int errcode(int sqlerrcode)
Definition: elog.c:698
void(* MemoryStatsPrintFunc)(MemoryContext context, void *passthru, const char *stats_string, bool print_to_stderr)
Definition: memnodes.h:54
void * GenerationPointer
Definition: generation.c:52
static void GenerationStats(MemoryContext context, MemoryStatsPrintFunc printfunc, void *passthru, MemoryContextCounters *totals, bool print_to_stderr)
Definition: generation.c:675
MemoryContextData header
Definition: generation.c:60
#define GENERATIONCHUNK_PRIVATE_LEN
Definition: generation.c:133
#define malloc(a)
Definition: header.h:50
#define StaticAssertStmt(condition, errmessage)
Definition: c.h:918
#define dlist_container(type, membername, ptr)
Definition: ilist.h:496
#define GenerationIsValid(set)
Definition: generation.c:139
#define ERROR
Definition: elog.h:46
dlist_head blocks
Definition: generation.c:66
void MemoryContextStats(MemoryContext context)
Definition: mcxt.c:505
GenerationContext * context
Definition: generation.c:123
int errdetail(const char *fmt,...)
Definition: elog.c:1042
dlist_node node
Definition: generation.c:83
static Size GenerationGetChunkSpace(MemoryContext context, void *pointer)
Definition: generation.c:639
static const MemoryContextMethods GenerationMethods
Definition: generation.c:168
static void dlist_delete(dlist_node *node)
Definition: ilist.h:358
static void GenerationFree(MemoryContext context, void *pointer)
Definition: generation.c:462
void MemoryContextCreate(MemoryContext node, NodeTag tag, const MemoryContextMethods *methods, MemoryContext parent, const char *name)
Definition: mcxt.c:815
#define AssertArg(condition)
Definition: c.h:806
MemoryContext TopMemoryContext
Definition: mcxt.c:48
#define GenerationChunkGetPointer(chk)
Definition: generation.c:143
#define WARNING
Definition: elog.h:40
MemoryContext GenerationContextCreate(MemoryContext parent, const char *name, Size blockSize)
Definition: generation.c:197
struct GenerationContext GenerationContext
dlist_node * cur
Definition: ilist.h:161
char * freeptr
Definition: generation.c:87
static void dlist_init(dlist_head *head)
Definition: ilist.h:278
#define ereport(elevel,...)
Definition: elog.h:157
#define free(a)
Definition: header.h:65
#define Assert(condition)
Definition: c.h:804
static bool dlist_is_empty(dlist_head *head)
Definition: ilist.h:289
size_t Size
Definition: c.h:540
#define MAXALIGN(LEN)
Definition: c.h:757
static void * GenerationRealloc(MemoryContext context, void *pointer, Size size)
Definition: generation.c:523
const char * name
Definition: encode.c:561
Size mem_allocated
Definition: memnodes.h:84
#define AllocHugeSizeIsValid(size)
Definition: memutils.h:46
int errmsg(const char *fmt,...)
Definition: elog.c:909
GenerationBlock * block
Definition: generation.c:65
static bool GenerationIsEmpty(MemoryContext context)
Definition: generation.c:655
#define elog(elevel,...)
Definition: elog.h:232
#define Generation_CHUNKHDRSZ
Definition: generation.c:47
static void * GenerationAlloc(MemoryContext context, Size size)
Definition: generation.c:326
#define Generation_BLOCKHDRSZ
Definition: generation.c:46
#define snprintf
Definition: port.h:216
const char * name
Definition: memnodes.h:90
#define offsetof(type, field)
Definition: c.h:727