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aset.c
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1 /*-------------------------------------------------------------------------
2  *
3  * aset.c
4  * Allocation set definitions.
5  *
6  * AllocSet is our standard implementation of the abstract MemoryContext
7  * type.
8  *
9  *
10  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
11  * Portions Copyright (c) 1994, Regents of the University of California
12  *
13  * IDENTIFICATION
14  * src/backend/utils/mmgr/aset.c
15  *
16  * NOTE:
17  * This is a new (Feb. 05, 1999) implementation of the allocation set
18  * routines. AllocSet...() does not use OrderedSet...() any more.
19  * Instead it manages allocations in a block pool by itself, combining
20  * many small allocations in a few bigger blocks. AllocSetFree() normally
21  * doesn't free() memory really. It just add's the free'd area to some
22  * list for later reuse by AllocSetAlloc(). All memory blocks are free()'d
23  * at once on AllocSetReset(), which happens when the memory context gets
24  * destroyed.
25  * Jan Wieck
26  *
27  * Performance improvement from Tom Lane, 8/99: for extremely large request
28  * sizes, we do want to be able to give the memory back to free() as soon
29  * as it is pfree()'d. Otherwise we risk tying up a lot of memory in
30  * freelist entries that might never be usable. This is specially needed
31  * when the caller is repeatedly repalloc()'ing a block bigger and bigger;
32  * the previous instances of the block were guaranteed to be wasted until
33  * AllocSetReset() under the old way.
34  *
35  * Further improvement 12/00: as the code stood, request sizes in the
36  * midrange between "small" and "large" were handled very inefficiently,
37  * because any sufficiently large free chunk would be used to satisfy a
38  * request, even if it was much larger than necessary. This led to more
39  * and more wasted space in allocated chunks over time. To fix, get rid
40  * of the midrange behavior: we now handle only "small" power-of-2-size
41  * chunks as chunks. Anything "large" is passed off to malloc(). Change
42  * the number of freelists to change the small/large boundary.
43  *
44  *-------------------------------------------------------------------------
45  */
46 
47 #include "postgres.h"
48 
49 #include "port/pg_bitutils.h"
50 #include "utils/memdebug.h"
51 #include "utils/memutils.h"
52 
53 /*--------------------
54  * Chunk freelist k holds chunks of size 1 << (k + ALLOC_MINBITS),
55  * for k = 0 .. ALLOCSET_NUM_FREELISTS-1.
56  *
57  * Note that all chunks in the freelists have power-of-2 sizes. This
58  * improves recyclability: we may waste some space, but the wasted space
59  * should stay pretty constant as requests are made and released.
60  *
61  * A request too large for the last freelist is handled by allocating a
62  * dedicated block from malloc(). The block still has a block header and
63  * chunk header, but when the chunk is freed we'll return the whole block
64  * to malloc(), not put it on our freelists.
65  *
66  * CAUTION: ALLOC_MINBITS must be large enough so that
67  * 1<<ALLOC_MINBITS is at least MAXALIGN,
68  * or we may fail to align the smallest chunks adequately.
69  * 8-byte alignment is enough on all currently known machines.
70  *
71  * With the current parameters, request sizes up to 8K are treated as chunks,
72  * larger requests go into dedicated blocks. Change ALLOCSET_NUM_FREELISTS
73  * to adjust the boundary point; and adjust ALLOCSET_SEPARATE_THRESHOLD in
74  * memutils.h to agree. (Note: in contexts with small maxBlockSize, we may
75  * set the allocChunkLimit to less than 8K, so as to avoid space wastage.)
76  *--------------------
77  */
78 
79 #define ALLOC_MINBITS 3 /* smallest chunk size is 8 bytes */
80 #define ALLOCSET_NUM_FREELISTS 11
81 #define ALLOC_CHUNK_LIMIT (1 << (ALLOCSET_NUM_FREELISTS-1+ALLOC_MINBITS))
82 /* Size of largest chunk that we use a fixed size for */
83 #define ALLOC_CHUNK_FRACTION 4
84 /* We allow chunks to be at most 1/4 of maxBlockSize (less overhead) */
85 
86 /*--------------------
87  * The first block allocated for an allocset has size initBlockSize.
88  * Each time we have to allocate another block, we double the block size
89  * (if possible, and without exceeding maxBlockSize), so as to reduce
90  * the bookkeeping load on malloc().
91  *
92  * Blocks allocated to hold oversize chunks do not follow this rule, however;
93  * they are just however big they need to be to hold that single chunk.
94  *
95  * Also, if a minContextSize is specified, the first block has that size,
96  * and then initBlockSize is used for the next one.
97  *--------------------
98  */
99 
100 #define ALLOC_BLOCKHDRSZ MAXALIGN(sizeof(AllocBlockData))
101 #define ALLOC_CHUNKHDRSZ sizeof(struct AllocChunkData)
102 
103 typedef struct AllocBlockData *AllocBlock; /* forward reference */
104 typedef struct AllocChunkData *AllocChunk;
105 
106 /*
107  * AllocPointer
108  * Aligned pointer which may be a member of an allocation set.
109  */
110 typedef void *AllocPointer;
111 
112 /*
113  * AllocSetContext is our standard implementation of MemoryContext.
114  *
115  * Note: header.isReset means there is nothing for AllocSetReset to do.
116  * This is different from the aset being physically empty (empty blocks list)
117  * because we will still have a keeper block. It's also different from the set
118  * being logically empty, because we don't attempt to detect pfree'ing the
119  * last active chunk.
120  */
121 typedef struct AllocSetContext
122 {
123  MemoryContextData header; /* Standard memory-context fields */
124  /* Info about storage allocated in this context: */
125  AllocBlock blocks; /* head of list of blocks in this set */
126  AllocChunk freelist[ALLOCSET_NUM_FREELISTS]; /* free chunk lists */
127  /* Allocation parameters for this context: */
128  Size initBlockSize; /* initial block size */
129  Size maxBlockSize; /* maximum block size */
130  Size nextBlockSize; /* next block size to allocate */
131  Size allocChunkLimit; /* effective chunk size limit */
132  AllocBlock keeper; /* keep this block over resets */
133  /* freelist this context could be put in, or -1 if not a candidate: */
134  int freeListIndex; /* index in context_freelists[], or -1 */
136 
138 
139 /*
140  * AllocBlock
141  * An AllocBlock is the unit of memory that is obtained by aset.c
142  * from malloc(). It contains one or more AllocChunks, which are
143  * the units requested by palloc() and freed by pfree(). AllocChunks
144  * cannot be returned to malloc() individually, instead they are put
145  * on freelists by pfree() and re-used by the next palloc() that has
146  * a matching request size.
147  *
148  * AllocBlockData is the header data for a block --- the usable space
149  * within the block begins at the next alignment boundary.
150  */
151 typedef struct AllocBlockData
152 {
153  AllocSet aset; /* aset that owns this block */
154  AllocBlock prev; /* prev block in aset's blocks list, if any */
155  AllocBlock next; /* next block in aset's blocks list, if any */
156  char *freeptr; /* start of free space in this block */
157  char *endptr; /* end of space in this block */
159 
160 /*
161  * AllocChunk
162  * The prefix of each piece of memory in an AllocBlock
163  *
164  * Note: to meet the memory context APIs, the payload area of the chunk must
165  * be maxaligned, and the "aset" link must be immediately adjacent to the
166  * payload area (cf. GetMemoryChunkContext). We simplify matters for this
167  * module by requiring sizeof(AllocChunkData) to be maxaligned, and then
168  * we can ensure things work by adding any required alignment padding before
169  * the "aset" field. There is a static assertion below that the alignment
170  * is done correctly.
171  */
172 typedef struct AllocChunkData
173 {
174  /* size is always the size of the usable space in the chunk */
176 #ifdef MEMORY_CONTEXT_CHECKING
177  /* when debugging memory usage, also store actual requested size */
178  /* this is zero in a free chunk */
179  Size requested_size;
180 
181 #define ALLOCCHUNK_RAWSIZE (SIZEOF_SIZE_T * 2 + SIZEOF_VOID_P)
182 #else
183 #define ALLOCCHUNK_RAWSIZE (SIZEOF_SIZE_T + SIZEOF_VOID_P)
184 #endif /* MEMORY_CONTEXT_CHECKING */
185 
186  /* ensure proper alignment by adding padding if needed */
187 #if (ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF) != 0
188  char padding[MAXIMUM_ALIGNOF - ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF];
189 #endif
190 
191  /* aset is the owning aset if allocated, or the freelist link if free */
192  void *aset;
193  /* there must not be any padding to reach a MAXALIGN boundary here! */
195 
196 /*
197  * Only the "aset" field should be accessed outside this module.
198  * We keep the rest of an allocated chunk's header marked NOACCESS when using
199  * valgrind. But note that chunk headers that are in a freelist are kept
200  * accessible, for simplicity.
201  */
202 #define ALLOCCHUNK_PRIVATE_LEN offsetof(AllocChunkData, aset)
203 
204 /*
205  * AllocPointerIsValid
206  * True iff pointer is valid allocation pointer.
207  */
208 #define AllocPointerIsValid(pointer) PointerIsValid(pointer)
209 
210 /*
211  * AllocSetIsValid
212  * True iff set is valid allocation set.
213  */
214 #define AllocSetIsValid(set) PointerIsValid(set)
215 
216 #define AllocPointerGetChunk(ptr) \
217  ((AllocChunk)(((char *)(ptr)) - ALLOC_CHUNKHDRSZ))
218 #define AllocChunkGetPointer(chk) \
219  ((AllocPointer)(((char *)(chk)) + ALLOC_CHUNKHDRSZ))
220 
221 /*
222  * Rather than repeatedly creating and deleting memory contexts, we keep some
223  * freed contexts in freelists so that we can hand them out again with little
224  * work. Before putting a context in a freelist, we reset it so that it has
225  * only its initial malloc chunk and no others. To be a candidate for a
226  * freelist, a context must have the same minContextSize/initBlockSize as
227  * other contexts in the list; but its maxBlockSize is irrelevant since that
228  * doesn't affect the size of the initial chunk.
229  *
230  * We currently provide one freelist for ALLOCSET_DEFAULT_SIZES contexts
231  * and one for ALLOCSET_SMALL_SIZES contexts; the latter works for
232  * ALLOCSET_START_SMALL_SIZES too, since only the maxBlockSize differs.
233  *
234  * Ordinarily, we re-use freelist contexts in last-in-first-out order, in
235  * hopes of improving locality of reference. But if there get to be too
236  * many contexts in the list, we'd prefer to drop the most-recently-created
237  * contexts in hopes of keeping the process memory map compact.
238  * We approximate that by simply deleting all existing entries when the list
239  * overflows, on the assumption that queries that allocate a lot of contexts
240  * will probably free them in more or less reverse order of allocation.
241  *
242  * Contexts in a freelist are chained via their nextchild pointers.
243  */
244 #define MAX_FREE_CONTEXTS 100 /* arbitrary limit on freelist length */
245 
246 typedef struct AllocSetFreeList
247 {
248  int num_free; /* current list length */
249  AllocSetContext *first_free; /* list header */
251 
252 /* context_freelists[0] is for default params, [1] for small params */
254 {
255  {
256  0, NULL
257  },
258  {
259  0, NULL
260  }
261 };
262 
263 /*
264  * These functions implement the MemoryContext API for AllocSet contexts.
265  */
266 static void *AllocSetAlloc(MemoryContext context, Size size);
267 static void AllocSetFree(MemoryContext context, void *pointer);
268 static void *AllocSetRealloc(MemoryContext context, void *pointer, Size size);
269 static void AllocSetReset(MemoryContext context);
270 static void AllocSetDelete(MemoryContext context);
271 static Size AllocSetGetChunkSpace(MemoryContext context, void *pointer);
272 static bool AllocSetIsEmpty(MemoryContext context);
273 static void AllocSetStats(MemoryContext context,
274  MemoryStatsPrintFunc printfunc, void *passthru,
275  MemoryContextCounters *totals,
276  bool print_to_stderr);
277 
278 #ifdef MEMORY_CONTEXT_CHECKING
279 static void AllocSetCheck(MemoryContext context);
280 #endif
281 
282 /*
283  * This is the virtual function table for AllocSet contexts.
284  */
287  AllocSetFree,
294 #ifdef MEMORY_CONTEXT_CHECKING
295  ,AllocSetCheck
296 #endif
297 };
298 
299 
300 /* ----------
301  * AllocSetFreeIndex -
302  *
303  * Depending on the size of an allocation compute which freechunk
304  * list of the alloc set it belongs to. Caller must have verified
305  * that size <= ALLOC_CHUNK_LIMIT.
306  * ----------
307  */
308 static inline int
310 {
311  int idx;
312 
313  if (size > (1 << ALLOC_MINBITS))
314  {
315  /*----------
316  * At this point we must compute ceil(log2(size >> ALLOC_MINBITS)).
317  * This is the same as
318  * pg_leftmost_one_pos32((size - 1) >> ALLOC_MINBITS) + 1
319  * or equivalently
320  * pg_leftmost_one_pos32(size - 1) - ALLOC_MINBITS + 1
321  *
322  * However, rather than just calling that function, we duplicate the
323  * logic here, allowing an additional optimization. It's reasonable
324  * to assume that ALLOC_CHUNK_LIMIT fits in 16 bits, so we can unroll
325  * the byte-at-a-time loop in pg_leftmost_one_pos32 and just handle
326  * the last two bytes.
327  *
328  * Yes, this function is enough of a hot-spot to make it worth this
329  * much trouble.
330  *----------
331  */
332 #ifdef HAVE__BUILTIN_CLZ
333  idx = 31 - __builtin_clz((uint32) size - 1) - ALLOC_MINBITS + 1;
334 #else
335  uint32 t,
336  tsize;
337 
338  /* Statically assert that we only have a 16-bit input value. */
340  "ALLOC_CHUNK_LIMIT must be less than 64kB");
341 
342  tsize = size - 1;
343  t = tsize >> 8;
344  idx = t ? pg_leftmost_one_pos[t] + 8 : pg_leftmost_one_pos[tsize];
345  idx -= ALLOC_MINBITS - 1;
346 #endif
347 
349  }
350  else
351  idx = 0;
352 
353  return idx;
354 }
355 
356 
357 /*
358  * Public routines
359  */
360 
361 
362 /*
363  * AllocSetContextCreateInternal
364  * Create a new AllocSet context.
365  *
366  * parent: parent context, or NULL if top-level context
367  * name: name of context (must be statically allocated)
368  * minContextSize: minimum context size
369  * initBlockSize: initial allocation block size
370  * maxBlockSize: maximum allocation block size
371  *
372  * Most callers should abstract the context size parameters using a macro
373  * such as ALLOCSET_DEFAULT_SIZES.
374  *
375  * Note: don't call this directly; go through the wrapper macro
376  * AllocSetContextCreate.
377  */
380  const char *name,
381  Size minContextSize,
384 {
385  int freeListIndex;
386  Size firstBlockSize;
387  AllocSet set;
388  AllocBlock block;
389 
390  /* Assert we padded AllocChunkData properly */
392  "sizeof(AllocChunkData) is not maxaligned");
395  "padding calculation in AllocChunkData is wrong");
396 
397  /*
398  * First, validate allocation parameters. Once these were regular runtime
399  * test and elog's, but in practice Asserts seem sufficient because nobody
400  * varies their parameters at runtime. We somewhat arbitrarily enforce a
401  * minimum 1K block size.
402  */
403  Assert(initBlockSize == MAXALIGN(initBlockSize) &&
404  initBlockSize >= 1024);
405  Assert(maxBlockSize == MAXALIGN(maxBlockSize) &&
406  maxBlockSize >= initBlockSize &&
407  AllocHugeSizeIsValid(maxBlockSize)); /* must be safe to double */
408  Assert(minContextSize == 0 ||
409  (minContextSize == MAXALIGN(minContextSize) &&
410  minContextSize >= 1024 &&
411  minContextSize <= maxBlockSize));
412 
413  /*
414  * Check whether the parameters match either available freelist. We do
415  * not need to demand a match of maxBlockSize.
416  */
417  if (minContextSize == ALLOCSET_DEFAULT_MINSIZE &&
418  initBlockSize == ALLOCSET_DEFAULT_INITSIZE)
419  freeListIndex = 0;
420  else if (minContextSize == ALLOCSET_SMALL_MINSIZE &&
421  initBlockSize == ALLOCSET_SMALL_INITSIZE)
422  freeListIndex = 1;
423  else
424  freeListIndex = -1;
425 
426  /*
427  * If a suitable freelist entry exists, just recycle that context.
428  */
429  if (freeListIndex >= 0)
430  {
431  AllocSetFreeList *freelist = &context_freelists[freeListIndex];
432 
433  if (freelist->first_free != NULL)
434  {
435  /* Remove entry from freelist */
436  set = freelist->first_free;
437  freelist->first_free = (AllocSet) set->header.nextchild;
438  freelist->num_free--;
439 
440  /* Update its maxBlockSize; everything else should be OK */
441  set->maxBlockSize = maxBlockSize;
442 
443  /* Reinitialize its header, installing correct name and parent */
447  parent,
448  name);
449 
450  ((MemoryContext) set)->mem_allocated =
451  set->keeper->endptr - ((char *) set);
452 
453  return (MemoryContext) set;
454  }
455  }
456 
457  /* Determine size of initial block */
458  firstBlockSize = MAXALIGN(sizeof(AllocSetContext)) +
460  if (minContextSize != 0)
461  firstBlockSize = Max(firstBlockSize, minContextSize);
462  else
463  firstBlockSize = Max(firstBlockSize, initBlockSize);
464 
465  /*
466  * Allocate the initial block. Unlike other aset.c blocks, it starts with
467  * the context header and its block header follows that.
468  */
469  set = (AllocSet) malloc(firstBlockSize);
470  if (set == NULL)
471  {
472  if (TopMemoryContext)
474  ereport(ERROR,
475  (errcode(ERRCODE_OUT_OF_MEMORY),
476  errmsg("out of memory"),
477  errdetail("Failed while creating memory context \"%s\".",
478  name)));
479  }
480 
481  /*
482  * Avoid writing code that can fail between here and MemoryContextCreate;
483  * we'd leak the header/initial block if we ereport in this stretch.
484  */
485 
486  /* Fill in the initial block's block header */
487  block = (AllocBlock) (((char *) set) + MAXALIGN(sizeof(AllocSetContext)));
488  block->aset = set;
489  block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
490  block->endptr = ((char *) set) + firstBlockSize;
491  block->prev = NULL;
492  block->next = NULL;
493 
494  /* Mark unallocated space NOACCESS; leave the block header alone. */
495  VALGRIND_MAKE_MEM_NOACCESS(block->freeptr, block->endptr - block->freeptr);
496 
497  /* Remember block as part of block list */
498  set->blocks = block;
499  /* Mark block as not to be released at reset time */
500  set->keeper = block;
501 
502  /* Finish filling in aset-specific parts of the context header */
503  MemSetAligned(set->freelist, 0, sizeof(set->freelist));
504 
505  set->initBlockSize = initBlockSize;
506  set->maxBlockSize = maxBlockSize;
507  set->nextBlockSize = initBlockSize;
508  set->freeListIndex = freeListIndex;
509 
510  /*
511  * Compute the allocation chunk size limit for this context. It can't be
512  * more than ALLOC_CHUNK_LIMIT because of the fixed number of freelists.
513  * If maxBlockSize is small then requests exceeding the maxBlockSize, or
514  * even a significant fraction of it, should be treated as large chunks
515  * too. For the typical case of maxBlockSize a power of 2, the chunk size
516  * limit will be at most 1/8th maxBlockSize, so that given a stream of
517  * requests that are all the maximum chunk size we will waste at most
518  * 1/8th of the allocated space.
519  *
520  * We have to have allocChunkLimit a power of two, because the requested
521  * and actually-allocated sizes of any chunk must be on the same side of
522  * the limit, else we get confused about whether the chunk is "big".
523  *
524  * Also, allocChunkLimit must not exceed ALLOCSET_SEPARATE_THRESHOLD.
525  */
527  "ALLOC_CHUNK_LIMIT != ALLOCSET_SEPARATE_THRESHOLD");
528 
529  set->allocChunkLimit = ALLOC_CHUNK_LIMIT;
530  while ((Size) (set->allocChunkLimit + ALLOC_CHUNKHDRSZ) >
531  (Size) ((maxBlockSize - ALLOC_BLOCKHDRSZ) / ALLOC_CHUNK_FRACTION))
532  set->allocChunkLimit >>= 1;
533 
534  /* Finally, do the type-independent part of context creation */
537  &AllocSetMethods,
538  parent,
539  name);
540 
541  ((MemoryContext) set)->mem_allocated = firstBlockSize;
542 
543  return (MemoryContext) set;
544 }
545 
546 /*
547  * AllocSetReset
548  * Frees all memory which is allocated in the given set.
549  *
550  * Actually, this routine has some discretion about what to do.
551  * It should mark all allocated chunks freed, but it need not necessarily
552  * give back all the resources the set owns. Our actual implementation is
553  * that we give back all but the "keeper" block (which we must keep, since
554  * it shares a malloc chunk with the context header). In this way, we don't
555  * thrash malloc() when a context is repeatedly reset after small allocations,
556  * which is typical behavior for per-tuple contexts.
557  */
558 static void
560 {
561  AllocSet set = (AllocSet) context;
562  AllocBlock block;
563  Size keepersize PG_USED_FOR_ASSERTS_ONLY
564  = set->keeper->endptr - ((char *) set);
565 
567 
568 #ifdef MEMORY_CONTEXT_CHECKING
569  /* Check for corruption and leaks before freeing */
570  AllocSetCheck(context);
571 #endif
572 
573  /* Clear chunk freelists */
574  MemSetAligned(set->freelist, 0, sizeof(set->freelist));
575 
576  block = set->blocks;
577 
578  /* New blocks list will be just the keeper block */
579  set->blocks = set->keeper;
580 
581  while (block != NULL)
582  {
583  AllocBlock next = block->next;
584 
585  if (block == set->keeper)
586  {
587  /* Reset the block, but don't return it to malloc */
588  char *datastart = ((char *) block) + ALLOC_BLOCKHDRSZ;
589 
590 #ifdef CLOBBER_FREED_MEMORY
591  wipe_mem(datastart, block->freeptr - datastart);
592 #else
593  /* wipe_mem() would have done this */
594  VALGRIND_MAKE_MEM_NOACCESS(datastart, block->freeptr - datastart);
595 #endif
596  block->freeptr = datastart;
597  block->prev = NULL;
598  block->next = NULL;
599  }
600  else
601  {
602  /* Normal case, release the block */
603  context->mem_allocated -= block->endptr - ((char *) block);
604 
605 #ifdef CLOBBER_FREED_MEMORY
606  wipe_mem(block, block->freeptr - ((char *) block));
607 #endif
608  free(block);
609  }
610  block = next;
611  }
612 
613  Assert(context->mem_allocated == keepersize);
614 
615  /* Reset block size allocation sequence, too */
616  set->nextBlockSize = set->initBlockSize;
617 }
618 
619 /*
620  * AllocSetDelete
621  * Frees all memory which is allocated in the given set,
622  * in preparation for deletion of the set.
623  *
624  * Unlike AllocSetReset, this *must* free all resources of the set.
625  */
626 static void
628 {
629  AllocSet set = (AllocSet) context;
630  AllocBlock block = set->blocks;
631  Size keepersize PG_USED_FOR_ASSERTS_ONLY
632  = set->keeper->endptr - ((char *) set);
633 
635 
636 #ifdef MEMORY_CONTEXT_CHECKING
637  /* Check for corruption and leaks before freeing */
638  AllocSetCheck(context);
639 #endif
640 
641  /*
642  * If the context is a candidate for a freelist, put it into that freelist
643  * instead of destroying it.
644  */
645  if (set->freeListIndex >= 0)
646  {
647  AllocSetFreeList *freelist = &context_freelists[set->freeListIndex];
648 
649  /*
650  * Reset the context, if it needs it, so that we aren't hanging on to
651  * more than the initial malloc chunk.
652  */
653  if (!context->isReset)
654  MemoryContextResetOnly(context);
655 
656  /*
657  * If the freelist is full, just discard what's already in it. See
658  * comments with context_freelists[].
659  */
660  if (freelist->num_free >= MAX_FREE_CONTEXTS)
661  {
662  while (freelist->first_free != NULL)
663  {
664  AllocSetContext *oldset = freelist->first_free;
665 
666  freelist->first_free = (AllocSetContext *) oldset->header.nextchild;
667  freelist->num_free--;
668 
669  /* All that remains is to free the header/initial block */
670  free(oldset);
671  }
672  Assert(freelist->num_free == 0);
673  }
674 
675  /* Now add the just-deleted context to the freelist. */
676  set->header.nextchild = (MemoryContext) freelist->first_free;
677  freelist->first_free = set;
678  freelist->num_free++;
679 
680  return;
681  }
682 
683  /* Free all blocks, except the keeper which is part of context header */
684  while (block != NULL)
685  {
686  AllocBlock next = block->next;
687 
688  if (block != set->keeper)
689  context->mem_allocated -= block->endptr - ((char *) block);
690 
691 #ifdef CLOBBER_FREED_MEMORY
692  wipe_mem(block, block->freeptr - ((char *) block));
693 #endif
694 
695  if (block != set->keeper)
696  free(block);
697 
698  block = next;
699  }
700 
701  Assert(context->mem_allocated == keepersize);
702 
703  /* Finally, free the context header, including the keeper block */
704  free(set);
705 }
706 
707 /*
708  * AllocSetAlloc
709  * Returns pointer to allocated memory of given size or NULL if
710  * request could not be completed; memory is added to the set.
711  *
712  * No request may exceed:
713  * MAXALIGN_DOWN(SIZE_MAX) - ALLOC_BLOCKHDRSZ - ALLOC_CHUNKHDRSZ
714  * All callers use a much-lower limit.
715  *
716  * Note: when using valgrind, it doesn't matter how the returned allocation
717  * is marked, as mcxt.c will set it to UNDEFINED. In some paths we will
718  * return space that is marked NOACCESS - AllocSetRealloc has to beware!
719  */
720 static void *
722 {
723  AllocSet set = (AllocSet) context;
724  AllocBlock block;
725  AllocChunk chunk;
726  int fidx;
727  Size chunk_size;
728  Size blksize;
729 
731 
732  /*
733  * If requested size exceeds maximum for chunks, allocate an entire block
734  * for this request.
735  */
736  if (size > set->allocChunkLimit)
737  {
738  chunk_size = MAXALIGN(size);
739  blksize = chunk_size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
740  block = (AllocBlock) malloc(blksize);
741  if (block == NULL)
742  return NULL;
743 
744  context->mem_allocated += blksize;
745 
746  block->aset = set;
747  block->freeptr = block->endptr = ((char *) block) + blksize;
748 
749  chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
750  chunk->aset = set;
751  chunk->size = chunk_size;
752 #ifdef MEMORY_CONTEXT_CHECKING
753  chunk->requested_size = size;
754  /* set mark to catch clobber of "unused" space */
755  if (size < chunk_size)
756  set_sentinel(AllocChunkGetPointer(chunk), size);
757 #endif
758 #ifdef RANDOMIZE_ALLOCATED_MEMORY
759  /* fill the allocated space with junk */
760  randomize_mem((char *) AllocChunkGetPointer(chunk), size);
761 #endif
762 
763  /*
764  * Stick the new block underneath the active allocation block, if any,
765  * so that we don't lose the use of the space remaining therein.
766  */
767  if (set->blocks != NULL)
768  {
769  block->prev = set->blocks;
770  block->next = set->blocks->next;
771  if (block->next)
772  block->next->prev = block;
773  set->blocks->next = block;
774  }
775  else
776  {
777  block->prev = NULL;
778  block->next = NULL;
779  set->blocks = block;
780  }
781 
782  /* Ensure any padding bytes are marked NOACCESS. */
783  VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
784  chunk_size - size);
785 
786  /* Disallow external access to private part of chunk header. */
788 
789  return AllocChunkGetPointer(chunk);
790  }
791 
792  /*
793  * Request is small enough to be treated as a chunk. Look in the
794  * corresponding free list to see if there is a free chunk we could reuse.
795  * If one is found, remove it from the free list, make it again a member
796  * of the alloc set and return its data address.
797  */
798  fidx = AllocSetFreeIndex(size);
799  chunk = set->freelist[fidx];
800  if (chunk != NULL)
801  {
802  Assert(chunk->size >= size);
803 
804  set->freelist[fidx] = (AllocChunk) chunk->aset;
805 
806  chunk->aset = (void *) set;
807 
808 #ifdef MEMORY_CONTEXT_CHECKING
809  chunk->requested_size = size;
810  /* set mark to catch clobber of "unused" space */
811  if (size < chunk->size)
812  set_sentinel(AllocChunkGetPointer(chunk), size);
813 #endif
814 #ifdef RANDOMIZE_ALLOCATED_MEMORY
815  /* fill the allocated space with junk */
816  randomize_mem((char *) AllocChunkGetPointer(chunk), size);
817 #endif
818 
819  /* Ensure any padding bytes are marked NOACCESS. */
820  VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
821  chunk->size - size);
822 
823  /* Disallow external access to private part of chunk header. */
825 
826  return AllocChunkGetPointer(chunk);
827  }
828 
829  /*
830  * Choose the actual chunk size to allocate.
831  */
832  chunk_size = (1 << ALLOC_MINBITS) << fidx;
833  Assert(chunk_size >= size);
834 
835  /*
836  * If there is enough room in the active allocation block, we will put the
837  * chunk into that block. Else must start a new one.
838  */
839  if ((block = set->blocks) != NULL)
840  {
841  Size availspace = block->endptr - block->freeptr;
842 
843  if (availspace < (chunk_size + ALLOC_CHUNKHDRSZ))
844  {
845  /*
846  * The existing active (top) block does not have enough room for
847  * the requested allocation, but it might still have a useful
848  * amount of space in it. Once we push it down in the block list,
849  * we'll never try to allocate more space from it. So, before we
850  * do that, carve up its free space into chunks that we can put on
851  * the set's freelists.
852  *
853  * Because we can only get here when there's less than
854  * ALLOC_CHUNK_LIMIT left in the block, this loop cannot iterate
855  * more than ALLOCSET_NUM_FREELISTS-1 times.
856  */
857  while (availspace >= ((1 << ALLOC_MINBITS) + ALLOC_CHUNKHDRSZ))
858  {
859  Size availchunk = availspace - ALLOC_CHUNKHDRSZ;
860  int a_fidx = AllocSetFreeIndex(availchunk);
861 
862  /*
863  * In most cases, we'll get back the index of the next larger
864  * freelist than the one we need to put this chunk on. The
865  * exception is when availchunk is exactly a power of 2.
866  */
867  if (availchunk != ((Size) 1 << (a_fidx + ALLOC_MINBITS)))
868  {
869  a_fidx--;
870  Assert(a_fidx >= 0);
871  availchunk = ((Size) 1 << (a_fidx + ALLOC_MINBITS));
872  }
873 
874  chunk = (AllocChunk) (block->freeptr);
875 
876  /* Prepare to initialize the chunk header. */
877  VALGRIND_MAKE_MEM_UNDEFINED(chunk, ALLOC_CHUNKHDRSZ);
878 
879  block->freeptr += (availchunk + ALLOC_CHUNKHDRSZ);
880  availspace -= (availchunk + ALLOC_CHUNKHDRSZ);
881 
882  chunk->size = availchunk;
883 #ifdef MEMORY_CONTEXT_CHECKING
884  chunk->requested_size = 0; /* mark it free */
885 #endif
886  chunk->aset = (void *) set->freelist[a_fidx];
887  set->freelist[a_fidx] = chunk;
888  }
889 
890  /* Mark that we need to create a new block */
891  block = NULL;
892  }
893  }
894 
895  /*
896  * Time to create a new regular (multi-chunk) block?
897  */
898  if (block == NULL)
899  {
900  Size required_size;
901 
902  /*
903  * The first such block has size initBlockSize, and we double the
904  * space in each succeeding block, but not more than maxBlockSize.
905  */
906  blksize = set->nextBlockSize;
907  set->nextBlockSize <<= 1;
908  if (set->nextBlockSize > set->maxBlockSize)
909  set->nextBlockSize = set->maxBlockSize;
910 
911  /*
912  * If initBlockSize is less than ALLOC_CHUNK_LIMIT, we could need more
913  * space... but try to keep it a power of 2.
914  */
915  required_size = chunk_size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
916  while (blksize < required_size)
917  blksize <<= 1;
918 
919  /* Try to allocate it */
920  block = (AllocBlock) malloc(blksize);
921 
922  /*
923  * We could be asking for pretty big blocks here, so cope if malloc
924  * fails. But give up if there's less than 1 MB or so available...
925  */
926  while (block == NULL && blksize > 1024 * 1024)
927  {
928  blksize >>= 1;
929  if (blksize < required_size)
930  break;
931  block = (AllocBlock) malloc(blksize);
932  }
933 
934  if (block == NULL)
935  return NULL;
936 
937  context->mem_allocated += blksize;
938 
939  block->aset = set;
940  block->freeptr = ((char *) block) + ALLOC_BLOCKHDRSZ;
941  block->endptr = ((char *) block) + blksize;
942 
943  /* Mark unallocated space NOACCESS. */
945  blksize - ALLOC_BLOCKHDRSZ);
946 
947  block->prev = NULL;
948  block->next = set->blocks;
949  if (block->next)
950  block->next->prev = block;
951  set->blocks = block;
952  }
953 
954  /*
955  * OK, do the allocation
956  */
957  chunk = (AllocChunk) (block->freeptr);
958 
959  /* Prepare to initialize the chunk header. */
961 
962  block->freeptr += (chunk_size + ALLOC_CHUNKHDRSZ);
963  Assert(block->freeptr <= block->endptr);
964 
965  chunk->aset = (void *) set;
966  chunk->size = chunk_size;
967 #ifdef MEMORY_CONTEXT_CHECKING
968  chunk->requested_size = size;
969  /* set mark to catch clobber of "unused" space */
970  if (size < chunk->size)
971  set_sentinel(AllocChunkGetPointer(chunk), size);
972 #endif
973 #ifdef RANDOMIZE_ALLOCATED_MEMORY
974  /* fill the allocated space with junk */
975  randomize_mem((char *) AllocChunkGetPointer(chunk), size);
976 #endif
977 
978  /* Ensure any padding bytes are marked NOACCESS. */
979  VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
980  chunk_size - size);
981 
982  /* Disallow external access to private part of chunk header. */
984 
985  return AllocChunkGetPointer(chunk);
986 }
987 
988 /*
989  * AllocSetFree
990  * Frees allocated memory; memory is removed from the set.
991  */
992 static void
993 AllocSetFree(MemoryContext context, void *pointer)
994 {
995  AllocSet set = (AllocSet) context;
996  AllocChunk chunk = AllocPointerGetChunk(pointer);
997 
998  /* Allow access to private part of chunk header. */
1000 
1001 #ifdef MEMORY_CONTEXT_CHECKING
1002  /* Test for someone scribbling on unused space in chunk */
1003  if (chunk->requested_size < chunk->size)
1004  if (!sentinel_ok(pointer, chunk->requested_size))
1005  elog(WARNING, "detected write past chunk end in %s %p",
1006  set->header.name, chunk);
1007 #endif
1008 
1009  if (chunk->size > set->allocChunkLimit)
1010  {
1011  /*
1012  * Big chunks are certain to have been allocated as single-chunk
1013  * blocks. Just unlink that block and return it to malloc().
1014  */
1015  AllocBlock block = (AllocBlock) (((char *) chunk) - ALLOC_BLOCKHDRSZ);
1016 
1017  /*
1018  * Try to verify that we have a sane block pointer: it should
1019  * reference the correct aset, and freeptr and endptr should point
1020  * just past the chunk.
1021  */
1022  if (block->aset != set ||
1023  block->freeptr != block->endptr ||
1024  block->freeptr != ((char *) block) +
1025  (chunk->size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
1026  elog(ERROR, "could not find block containing chunk %p", chunk);
1027 
1028  /* OK, remove block from aset's list and free it */
1029  if (block->prev)
1030  block->prev->next = block->next;
1031  else
1032  set->blocks = block->next;
1033  if (block->next)
1034  block->next->prev = block->prev;
1035 
1036  context->mem_allocated -= block->endptr - ((char *) block);
1037 
1038 #ifdef CLOBBER_FREED_MEMORY
1039  wipe_mem(block, block->freeptr - ((char *) block));
1040 #endif
1041  free(block);
1042  }
1043  else
1044  {
1045  /* Normal case, put the chunk into appropriate freelist */
1046  int fidx = AllocSetFreeIndex(chunk->size);
1047 
1048  chunk->aset = (void *) set->freelist[fidx];
1049 
1050 #ifdef CLOBBER_FREED_MEMORY
1051  wipe_mem(pointer, chunk->size);
1052 #endif
1053 
1054 #ifdef MEMORY_CONTEXT_CHECKING
1055  /* Reset requested_size to 0 in chunks that are on freelist */
1056  chunk->requested_size = 0;
1057 #endif
1058  set->freelist[fidx] = chunk;
1059  }
1060 }
1061 
1062 /*
1063  * AllocSetRealloc
1064  * Returns new pointer to allocated memory of given size or NULL if
1065  * request could not be completed; this memory is added to the set.
1066  * Memory associated with given pointer is copied into the new memory,
1067  * and the old memory is freed.
1068  *
1069  * Without MEMORY_CONTEXT_CHECKING, we don't know the old request size. This
1070  * makes our Valgrind client requests less-precise, hazarding false negatives.
1071  * (In principle, we could use VALGRIND_GET_VBITS() to rediscover the old
1072  * request size.)
1073  */
1074 static void *
1075 AllocSetRealloc(MemoryContext context, void *pointer, Size size)
1076 {
1077  AllocSet set = (AllocSet) context;
1078  AllocChunk chunk = AllocPointerGetChunk(pointer);
1079  Size oldsize;
1080 
1081  /* Allow access to private part of chunk header. */
1083 
1084  oldsize = chunk->size;
1085 
1086 #ifdef MEMORY_CONTEXT_CHECKING
1087  /* Test for someone scribbling on unused space in chunk */
1088  if (chunk->requested_size < oldsize)
1089  if (!sentinel_ok(pointer, chunk->requested_size))
1090  elog(WARNING, "detected write past chunk end in %s %p",
1091  set->header.name, chunk);
1092 #endif
1093 
1094  if (oldsize > set->allocChunkLimit)
1095  {
1096  /*
1097  * The chunk must have been allocated as a single-chunk block. Use
1098  * realloc() to make the containing block bigger, or smaller, with
1099  * minimum space wastage.
1100  */
1101  AllocBlock block = (AllocBlock) (((char *) chunk) - ALLOC_BLOCKHDRSZ);
1102  Size chksize;
1103  Size blksize;
1104  Size oldblksize;
1105 
1106  /*
1107  * Try to verify that we have a sane block pointer: it should
1108  * reference the correct aset, and freeptr and endptr should point
1109  * just past the chunk.
1110  */
1111  if (block->aset != set ||
1112  block->freeptr != block->endptr ||
1113  block->freeptr != ((char *) block) +
1114  (oldsize + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
1115  elog(ERROR, "could not find block containing chunk %p", chunk);
1116 
1117  /*
1118  * Even if the new request is less than set->allocChunkLimit, we stick
1119  * with the single-chunk block approach. Therefore we need
1120  * chunk->size to be bigger than set->allocChunkLimit, so we don't get
1121  * confused about the chunk's status in future calls.
1122  */
1123  chksize = Max(size, set->allocChunkLimit + 1);
1124  chksize = MAXALIGN(chksize);
1125 
1126  /* Do the realloc */
1127  blksize = chksize + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
1128  oldblksize = block->endptr - ((char *) block);
1129 
1130  block = (AllocBlock) realloc(block, blksize);
1131  if (block == NULL)
1132  {
1133  /* Disallow external access to private part of chunk header. */
1135  return NULL;
1136  }
1137 
1138  /* updated separately, not to underflow when (oldblksize > blksize) */
1139  context->mem_allocated -= oldblksize;
1140  context->mem_allocated += blksize;
1141 
1142  block->freeptr = block->endptr = ((char *) block) + blksize;
1143 
1144  /* Update pointers since block has likely been moved */
1145  chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
1146  pointer = AllocChunkGetPointer(chunk);
1147  if (block->prev)
1148  block->prev->next = block;
1149  else
1150  set->blocks = block;
1151  if (block->next)
1152  block->next->prev = block;
1153  chunk->size = chksize;
1154 
1155 #ifdef MEMORY_CONTEXT_CHECKING
1156 #ifdef RANDOMIZE_ALLOCATED_MEMORY
1157  /* We can only fill the extra space if we know the prior request */
1158  if (size > chunk->requested_size)
1159  randomize_mem((char *) pointer + chunk->requested_size,
1160  size - chunk->requested_size);
1161 #endif
1162 
1163  /*
1164  * realloc() (or randomize_mem()) will have left any newly-allocated
1165  * part UNDEFINED, but we may need to adjust trailing bytes from the
1166  * old allocation.
1167  */
1168 #ifdef USE_VALGRIND
1169  if (oldsize > chunk->requested_size)
1170  VALGRIND_MAKE_MEM_UNDEFINED((char *) pointer + chunk->requested_size,
1171  oldsize - chunk->requested_size);
1172 #endif
1173 
1174  chunk->requested_size = size;
1175 
1176  /* set mark to catch clobber of "unused" space */
1177  if (size < chunk->size)
1178  set_sentinel(pointer, size);
1179 #else /* !MEMORY_CONTEXT_CHECKING */
1180 
1181  /*
1182  * We don't know how much of the old chunk size was the actual
1183  * allocation; it could have been as small as one byte. We have to be
1184  * conservative and just mark the entire old portion DEFINED.
1185  */
1186  VALGRIND_MAKE_MEM_DEFINED(pointer, oldsize);
1187 #endif
1188 
1189  /* Ensure any padding bytes are marked NOACCESS. */
1190  VALGRIND_MAKE_MEM_NOACCESS((char *) pointer + size, chksize - size);
1191 
1192  /* Disallow external access to private part of chunk header. */
1194 
1195  return pointer;
1196  }
1197 
1198  /*
1199  * Chunk sizes are aligned to power of 2 in AllocSetAlloc(). Maybe the
1200  * allocated area already is >= the new size. (In particular, we will
1201  * fall out here if the requested size is a decrease.)
1202  */
1203  else if (oldsize >= size)
1204  {
1205 #ifdef MEMORY_CONTEXT_CHECKING
1206  Size oldrequest = chunk->requested_size;
1207 
1208 #ifdef RANDOMIZE_ALLOCATED_MEMORY
1209  /* We can only fill the extra space if we know the prior request */
1210  if (size > oldrequest)
1211  randomize_mem((char *) pointer + oldrequest,
1212  size - oldrequest);
1213 #endif
1214 
1215  chunk->requested_size = size;
1216 
1217  /*
1218  * If this is an increase, mark any newly-available part UNDEFINED.
1219  * Otherwise, mark the obsolete part NOACCESS.
1220  */
1221  if (size > oldrequest)
1222  VALGRIND_MAKE_MEM_UNDEFINED((char *) pointer + oldrequest,
1223  size - oldrequest);
1224  else
1225  VALGRIND_MAKE_MEM_NOACCESS((char *) pointer + size,
1226  oldsize - size);
1227 
1228  /* set mark to catch clobber of "unused" space */
1229  if (size < oldsize)
1230  set_sentinel(pointer, size);
1231 #else /* !MEMORY_CONTEXT_CHECKING */
1232 
1233  /*
1234  * We don't have the information to determine whether we're growing
1235  * the old request or shrinking it, so we conservatively mark the
1236  * entire new allocation DEFINED.
1237  */
1238  VALGRIND_MAKE_MEM_NOACCESS(pointer, oldsize);
1239  VALGRIND_MAKE_MEM_DEFINED(pointer, size);
1240 #endif
1241 
1242  /* Disallow external access to private part of chunk header. */
1244 
1245  return pointer;
1246  }
1247  else
1248  {
1249  /*
1250  * Enlarge-a-small-chunk case. We just do this by brute force, ie,
1251  * allocate a new chunk and copy the data. Since we know the existing
1252  * data isn't huge, this won't involve any great memcpy expense, so
1253  * it's not worth being smarter. (At one time we tried to avoid
1254  * memcpy when it was possible to enlarge the chunk in-place, but that
1255  * turns out to misbehave unpleasantly for repeated cycles of
1256  * palloc/repalloc/pfree: the eventually freed chunks go into the
1257  * wrong freelist for the next initial palloc request, and so we leak
1258  * memory indefinitely. See pgsql-hackers archives for 2007-08-11.)
1259  */
1260  AllocPointer newPointer;
1261 
1262  /* allocate new chunk */
1263  newPointer = AllocSetAlloc((MemoryContext) set, size);
1264 
1265  /* leave immediately if request was not completed */
1266  if (newPointer == NULL)
1267  {
1268  /* Disallow external access to private part of chunk header. */
1270  return NULL;
1271  }
1272 
1273  /*
1274  * AllocSetAlloc() may have returned a region that is still NOACCESS.
1275  * Change it to UNDEFINED for the moment; memcpy() will then transfer
1276  * definedness from the old allocation to the new. If we know the old
1277  * allocation, copy just that much. Otherwise, make the entire old
1278  * chunk defined to avoid errors as we copy the currently-NOACCESS
1279  * trailing bytes.
1280  */
1281  VALGRIND_MAKE_MEM_UNDEFINED(newPointer, size);
1282 #ifdef MEMORY_CONTEXT_CHECKING
1283  oldsize = chunk->requested_size;
1284 #else
1285  VALGRIND_MAKE_MEM_DEFINED(pointer, oldsize);
1286 #endif
1287 
1288  /* transfer existing data (certain to fit) */
1289  memcpy(newPointer, pointer, oldsize);
1290 
1291  /* free old chunk */
1292  AllocSetFree((MemoryContext) set, pointer);
1293 
1294  return newPointer;
1295  }
1296 }
1297 
1298 /*
1299  * AllocSetGetChunkSpace
1300  * Given a currently-allocated chunk, determine the total space
1301  * it occupies (including all memory-allocation overhead).
1302  */
1303 static Size
1304 AllocSetGetChunkSpace(MemoryContext context, void *pointer)
1305 {
1306  AllocChunk chunk = AllocPointerGetChunk(pointer);
1307  Size result;
1308 
1310  result = chunk->size + ALLOC_CHUNKHDRSZ;
1312  return result;
1313 }
1314 
1315 /*
1316  * AllocSetIsEmpty
1317  * Is an allocset empty of any allocated space?
1318  */
1319 static bool
1321 {
1322  /*
1323  * For now, we say "empty" only if the context is new or just reset. We
1324  * could examine the freelists to determine if all space has been freed,
1325  * but it's not really worth the trouble for present uses of this
1326  * functionality.
1327  */
1328  if (context->isReset)
1329  return true;
1330  return false;
1331 }
1332 
1333 /*
1334  * AllocSetStats
1335  * Compute stats about memory consumption of an allocset.
1336  *
1337  * printfunc: if not NULL, pass a human-readable stats string to this.
1338  * passthru: pass this pointer through to printfunc.
1339  * totals: if not NULL, add stats about this context into *totals.
1340  * print_to_stderr: print stats to stderr if true, elog otherwise.
1341  */
1342 static void
1344  MemoryStatsPrintFunc printfunc, void *passthru,
1345  MemoryContextCounters *totals, bool print_to_stderr)
1346 {
1347  AllocSet set = (AllocSet) context;
1348  Size nblocks = 0;
1349  Size freechunks = 0;
1350  Size totalspace;
1351  Size freespace = 0;
1352  AllocBlock block;
1353  int fidx;
1354 
1355  /* Include context header in totalspace */
1356  totalspace = MAXALIGN(sizeof(AllocSetContext));
1357 
1358  for (block = set->blocks; block != NULL; block = block->next)
1359  {
1360  nblocks++;
1361  totalspace += block->endptr - ((char *) block);
1362  freespace += block->endptr - block->freeptr;
1363  }
1364  for (fidx = 0; fidx < ALLOCSET_NUM_FREELISTS; fidx++)
1365  {
1366  AllocChunk chunk;
1367 
1368  for (chunk = set->freelist[fidx]; chunk != NULL;
1369  chunk = (AllocChunk) chunk->aset)
1370  {
1371  freechunks++;
1372  freespace += chunk->size + ALLOC_CHUNKHDRSZ;
1373  }
1374  }
1375 
1376  if (printfunc)
1377  {
1378  char stats_string[200];
1379 
1380  snprintf(stats_string, sizeof(stats_string),
1381  "%zu total in %zd blocks; %zu free (%zd chunks); %zu used",
1382  totalspace, nblocks, freespace, freechunks,
1383  totalspace - freespace);
1384  printfunc(context, passthru, stats_string, print_to_stderr);
1385  }
1386 
1387  if (totals)
1388  {
1389  totals->nblocks += nblocks;
1390  totals->freechunks += freechunks;
1391  totals->totalspace += totalspace;
1392  totals->freespace += freespace;
1393  }
1394 }
1395 
1396 
1397 #ifdef MEMORY_CONTEXT_CHECKING
1398 
1399 /*
1400  * AllocSetCheck
1401  * Walk through chunks and check consistency of memory.
1402  *
1403  * NOTE: report errors as WARNING, *not* ERROR or FATAL. Otherwise you'll
1404  * find yourself in an infinite loop when trouble occurs, because this
1405  * routine will be entered again when elog cleanup tries to release memory!
1406  */
1407 static void
1408 AllocSetCheck(MemoryContext context)
1409 {
1410  AllocSet set = (AllocSet) context;
1411  const char *name = set->header.name;
1412  AllocBlock prevblock;
1413  AllocBlock block;
1414  Size total_allocated = 0;
1415 
1416  for (prevblock = NULL, block = set->blocks;
1417  block != NULL;
1418  prevblock = block, block = block->next)
1419  {
1420  char *bpoz = ((char *) block) + ALLOC_BLOCKHDRSZ;
1421  long blk_used = block->freeptr - bpoz;
1422  long blk_data = 0;
1423  long nchunks = 0;
1424 
1425  if (set->keeper == block)
1426  total_allocated += block->endptr - ((char *) set);
1427  else
1428  total_allocated += block->endptr - ((char *) block);
1429 
1430  /*
1431  * Empty block - empty can be keeper-block only
1432  */
1433  if (!blk_used)
1434  {
1435  if (set->keeper != block)
1436  elog(WARNING, "problem in alloc set %s: empty block %p",
1437  name, block);
1438  }
1439 
1440  /*
1441  * Check block header fields
1442  */
1443  if (block->aset != set ||
1444  block->prev != prevblock ||
1445  block->freeptr < bpoz ||
1446  block->freeptr > block->endptr)
1447  elog(WARNING, "problem in alloc set %s: corrupt header in block %p",
1448  name, block);
1449 
1450  /*
1451  * Chunk walker
1452  */
1453  while (bpoz < block->freeptr)
1454  {
1455  AllocChunk chunk = (AllocChunk) bpoz;
1456  Size chsize,
1457  dsize;
1458 
1459  /* Allow access to private part of chunk header. */
1461 
1462  chsize = chunk->size; /* aligned chunk size */
1463  dsize = chunk->requested_size; /* real data */
1464 
1465  /*
1466  * Check chunk size
1467  */
1468  if (dsize > chsize)
1469  elog(WARNING, "problem in alloc set %s: req size > alloc size for chunk %p in block %p",
1470  name, chunk, block);
1471  if (chsize < (1 << ALLOC_MINBITS))
1472  elog(WARNING, "problem in alloc set %s: bad size %zu for chunk %p in block %p",
1473  name, chsize, chunk, block);
1474 
1475  /* single-chunk block? */
1476  if (chsize > set->allocChunkLimit &&
1477  chsize + ALLOC_CHUNKHDRSZ != blk_used)
1478  elog(WARNING, "problem in alloc set %s: bad single-chunk %p in block %p",
1479  name, chunk, block);
1480 
1481  /*
1482  * If chunk is allocated, check for correct aset pointer. (If it's
1483  * free, the aset is the freelist pointer, which we can't check as
1484  * easily...) Note this is an incomplete test, since palloc(0)
1485  * produces an allocated chunk with requested_size == 0.
1486  */
1487  if (dsize > 0 && chunk->aset != (void *) set)
1488  elog(WARNING, "problem in alloc set %s: bogus aset link in block %p, chunk %p",
1489  name, block, chunk);
1490 
1491  /*
1492  * Check for overwrite of padding space in an allocated chunk.
1493  */
1494  if (chunk->aset == (void *) set && dsize < chsize &&
1495  !sentinel_ok(chunk, ALLOC_CHUNKHDRSZ + dsize))
1496  elog(WARNING, "problem in alloc set %s: detected write past chunk end in block %p, chunk %p",
1497  name, block, chunk);
1498 
1499  /*
1500  * If chunk is allocated, disallow external access to private part
1501  * of chunk header.
1502  */
1503  if (chunk->aset == (void *) set)
1505 
1506  blk_data += chsize;
1507  nchunks++;
1508 
1509  bpoz += ALLOC_CHUNKHDRSZ + chsize;
1510  }
1511 
1512  if ((blk_data + (nchunks * ALLOC_CHUNKHDRSZ)) != blk_used)
1513  elog(WARNING, "problem in alloc set %s: found inconsistent memory block %p",
1514  name, block);
1515  }
1516 
1517  Assert(total_allocated == context->mem_allocated);
1518 }
1519 
1520 #endif /* MEMORY_CONTEXT_CHECKING */
#define MemSetAligned(start, val, len)
Definition: c.h:1041
Size initBlockSize
Definition: aset.c:128
#define VALGRIND_MAKE_MEM_DEFINED(addr, size)
Definition: memdebug.h:26
AllocBlock blocks
Definition: aset.c:125
static int32 next
Definition: blutils.c:219
struct AllocBlockData AllocBlockData
static Size AllocSetGetChunkSpace(MemoryContext context, void *pointer)
Definition: aset.c:1304
MemoryContextData header
Definition: aset.c:123
void * AllocPointer
Definition: aset.c:110
#define AllocSetIsValid(set)
Definition: aset.c:214
#define VALGRIND_MAKE_MEM_UNDEFINED(addr, size)
Definition: memdebug.h:28
struct AllocSetFreeList AllocSetFreeList
#define VALGRIND_MAKE_MEM_NOACCESS(addr, size)
Definition: memdebug.h:27
static int AllocSetFreeIndex(Size size)
Definition: aset.c:309
static void AllocSetReset(MemoryContext context)
Definition: aset.c:559
int num_free
Definition: aset.c:248
#define AllocChunkGetPointer(chk)
Definition: aset.c:218
#define ALLOCCHUNK_PRIVATE_LEN
Definition: aset.c:202
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
Datum idx(PG_FUNCTION_ARGS)
Definition: _int_op.c:259
#define ALLOC_BLOCKHDRSZ
Definition: aset.c:100
AllocBlock keeper
Definition: aset.c:132
AllocSet aset
Definition: aset.c:153
void MemoryContextResetOnly(MemoryContext context)
Definition: mcxt.c:162
char * freeptr
Definition: aset.c:156
static void AllocSetStats(MemoryContext context, MemoryStatsPrintFunc printfunc, void *passthru, MemoryContextCounters *totals, bool print_to_stderr)
Definition: aset.c:1343
#define ALLOCSET_DEFAULT_MINSIZE
Definition: memutils.h:192
#define ALLOCSET_SMALL_MINSIZE
Definition: memutils.h:202
AllocSetContext * first_free
Definition: aset.c:249
#define malloc(a)
Definition: header.h:50
#define StaticAssertStmt(condition, errmessage)
Definition: c.h:918
static AllocSetFreeList context_freelists[2]
Definition: aset.c:253
#define ERROR
Definition: elog.h:46
#define ALLOC_CHUNK_LIMIT
Definition: aset.c:81
void MemoryContextStats(MemoryContext context)
Definition: mcxt.c:505
PGDLLIMPORT const uint8 pg_leftmost_one_pos[256]
Definition: pg_bitutils.c:34
char * endptr
Definition: aset.c:157
#define ALLOCSET_NUM_FREELISTS
Definition: aset.c:80
static void * AllocSetRealloc(MemoryContext context, void *pointer, Size size)
Definition: aset.c:1075
#define ALLOCSET_SEPARATE_THRESHOLD
Definition: memutils.h:222
int errdetail(const char *fmt,...)
Definition: elog.c:1042
#define ALLOC_CHUNKHDRSZ
Definition: aset.c:101
unsigned int uint32
Definition: c.h:441
AllocBlock next
Definition: aset.c:155
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
struct MemoryContextData * MemoryContext
Definition: palloc.h:36
MemoryContext AllocSetContextCreateInternal(MemoryContext parent, const char *name, Size minContextSize, Size initBlockSize, Size maxBlockSize)
Definition: aset.c:379
static bool AllocSetIsEmpty(MemoryContext context)
Definition: aset.c:1320
#define WARNING
Definition: elog.h:40
#define ALLOCSET_SMALL_INITSIZE
Definition: memutils.h:203
int freeListIndex
Definition: aset.c:134
#define ALLOCCHUNK_RAWSIZE
Definition: aset.c:183
#define ALLOC_CHUNK_FRACTION
Definition: aset.c:83
struct AllocBlockData * AllocBlock
Definition: aset.c:103
#define MAX_FREE_CONTEXTS
Definition: aset.c:244
AllocChunk freelist[ALLOCSET_NUM_FREELISTS]
Definition: aset.c:126
Size nextBlockSize
Definition: aset.c:130
#define ereport(elevel,...)
Definition: elog.h:157
AllocBlock prev
Definition: aset.c:154
#define free(a)
Definition: header.h:65
Size allocChunkLimit
Definition: aset.c:131
#define Max(x, y)
Definition: c.h:980
struct AllocChunkData * AllocChunk
Definition: aset.c:104
#define Assert(condition)
Definition: c.h:804
static void AllocSetFree(MemoryContext context, void *pointer)
Definition: aset.c:993
size_t Size
Definition: c.h:540
#define MAXALIGN(LEN)
Definition: c.h:757
struct AllocChunkData AllocChunkData
static void AllocSetDelete(MemoryContext context)
Definition: aset.c:627
#define realloc(a, b)
Definition: header.h:60
const char * name
Definition: encode.c:515
Size mem_allocated
Definition: memnodes.h:84
#define AllocHugeSizeIsValid(size)
Definition: memutils.h:46
void * aset
Definition: aset.c:192
int errmsg(const char *fmt,...)
Definition: elog.c:909
#define elog(elevel,...)
Definition: elog.h:232
#define ALLOCSET_DEFAULT_INITSIZE
Definition: memutils.h:193
static void * AllocSetAlloc(MemoryContext context, Size size)
Definition: aset.c:721
static const MemoryContextMethods AllocSetMethods
Definition: aset.c:285
AllocSetContext * AllocSet
Definition: aset.c:137
struct AllocSetContext AllocSetContext
#define ALLOC_MINBITS
Definition: aset.c:79
Size maxBlockSize
Definition: aset.c:129
#define snprintf
Definition: port.h:216
#define offsetof(type, field)
Definition: c.h:727
MemoryContext nextchild
Definition: memnodes.h:89
Size size
Definition: aset.c:175
#define PG_USED_FOR_ASSERTS_ONLY
Definition: c.h:155
#define AllocPointerGetChunk(ptr)
Definition: aset.c:216