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3 (C) 2001, 2002, 2003, 2004, 2006, 2008, 2011, 2012 Christian Grothoff (and other contributing authors)
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21 * @file util/container_bloomfilter.c
22 * @brief data structure used to reduce disk accesses.
24 * The idea basically: Create a signature for each element in the
25 * database. Add those signatures to a bit array. When doing a lookup,
26 * check if the bit array matches the signature of the requested
27 * element. If yes, address the disk, otherwise return 'not found'.
29 * A property of the bloom filter is that sometimes we will have
30 * a match even if the element is not on the disk (then we do
31 * an unnecessary disk access), but what's most important is that
32 * we never get a single "false negative".
34 * To be able to delete entries from the bloom filter, we maintain
35 * a 4 bit counter in the file on the drive (we still use only one
38 * @author Igor Wronsky
39 * @author Christian Grothoff
43 #include "gnunet_common.h"
44 #include "gnunet_container_lib.h"
45 #include "gnunet_disk_lib.h"
47 #define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
49 #define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util", syscall)
51 #define LOG_STRERROR_FILE(kind,syscall,filename) GNUNET_log_from_strerror_file (kind, "util", syscall, filename)
53 struct GNUNET_CONTAINER_BloomFilter
57 * The actual bloomfilter bit array
62 * Filename of the filter
67 * The bit counter file on disk
69 struct GNUNET_DISK_FileHandle *fh;
72 * How many bits we set for each stored element
74 unsigned int addressesPerElement;
77 * Size of bitArray in bytes
86 * Get size of the bloom filter.
88 * @param bf the filter
89 * @return number of bytes used for the data of the bloom filter
92 GNUNET_CONTAINER_bloomfilter_get_size (const struct GNUNET_CONTAINER_BloomFilter
97 return bf->bitArraySize;
102 * Copy an existing memory. Any association with a file
103 * on-disk will be lost in the process.
104 * @param bf the filter to copy
105 * @return copy of the bf
107 struct GNUNET_CONTAINER_BloomFilter *
108 GNUNET_CONTAINER_bloomfilter_copy (const struct GNUNET_CONTAINER_BloomFilter
111 return GNUNET_CONTAINER_bloomfilter_init (bf->bitArray, bf->bitArraySize,
112 bf->addressesPerElement);
117 * Sets a bit active in the bitArray. Increment bit-specific
118 * usage counter on disk only if below 4bit max (==15).
120 * @param bitArray memory area to set the bit in
121 * @param bitIdx which bit to set
124 setBit (char *bitArray, unsigned int bitIdx)
127 unsigned int targetBit;
129 arraySlot = bitIdx / 8;
130 targetBit = (1L << (bitIdx % 8));
131 bitArray[arraySlot] |= targetBit;
135 * Clears a bit from bitArray. Bit is cleared from the array
136 * only if the respective usage counter on the disk hits/is zero.
138 * @param bitArray memory area to set the bit in
139 * @param bitIdx which bit to unset
142 clearBit (char *bitArray, unsigned int bitIdx)
145 unsigned int targetBit;
148 targetBit = (1L << (bitIdx % 8));
149 bitArray[slot] = bitArray[slot] & (~targetBit);
153 * Checks if a bit is active in the bitArray
155 * @param bitArray memory area to set the bit in
156 * @param bitIdx which bit to test
157 * @return GNUNET_YES if the bit is set, GNUNET_NO if not.
160 testBit (char *bitArray, unsigned int bitIdx)
163 unsigned int targetBit;
166 targetBit = (1L << (bitIdx % 8));
167 if (bitArray[slot] & targetBit)
174 * Sets a bit active in the bitArray and increments
175 * bit-specific usage counter on disk (but only if
176 * the counter was below 4 bit max (==15)).
178 * @param bitArray memory area to set the bit in
179 * @param bitIdx which bit to test
180 * @param fh A file to keep the 4 bit address usage counters in
183 incrementBit (char *bitArray, unsigned int bitIdx,
184 const struct GNUNET_DISK_FileHandle *fh)
190 unsigned int targetLoc;
192 setBit (bitArray, bitIdx);
193 if (GNUNET_DISK_handle_invalid (fh))
195 /* Update the counter file on disk */
196 fileSlot = bitIdx / 2;
197 targetLoc = bitIdx % 2;
199 GNUNET_assert (fileSlot ==
200 GNUNET_DISK_file_seek (fh, fileSlot, GNUNET_DISK_SEEK_SET));
201 if (1 != GNUNET_DISK_file_read (fh, &value, 1))
204 high = (value & (~0xF)) >> 4;
216 value = ((high << 4) | low);
217 GNUNET_assert (fileSlot ==
218 GNUNET_DISK_file_seek (fh, fileSlot, GNUNET_DISK_SEEK_SET));
219 GNUNET_assert (1 == GNUNET_DISK_file_write (fh, &value, 1));
223 * Clears a bit from bitArray if the respective usage
224 * counter on the disk hits/is zero.
226 * @param bitArray memory area to set the bit in
227 * @param bitIdx which bit to test
228 * @param fh A file to keep the 4bit address usage counters in
231 decrementBit (char *bitArray, unsigned int bitIdx,
232 const struct GNUNET_DISK_FileHandle *fh)
238 unsigned int targetLoc;
240 if (GNUNET_DISK_handle_invalid (fh))
241 return; /* cannot decrement! */
242 /* Each char slot in the counter file holds two 4 bit counters */
243 fileslot = bitIdx / 2;
244 targetLoc = bitIdx % 2;
245 if (GNUNET_SYSERR == GNUNET_DISK_file_seek (fh, fileslot, GNUNET_DISK_SEEK_SET))
247 GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "seek");
250 if (1 != GNUNET_DISK_file_read (fh, &value, 1))
253 high = (value & 0xF0) >> 4;
255 /* decrement, but once we have reached the max, never go back! */
258 if ((low > 0) && (low < 0xF))
262 clearBit (bitArray, bitIdx);
267 if ((high > 0) && (high < 0xF))
271 clearBit (bitArray, bitIdx);
274 value = ((high << 4) | low);
275 if (GNUNET_SYSERR == GNUNET_DISK_file_seek (fh, fileslot, GNUNET_DISK_SEEK_SET))
277 GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "seek");
280 GNUNET_assert (1 == GNUNET_DISK_file_write (fh, &value, 1));
283 #define BUFFSIZE 65536
286 * Creates a file filled with zeroes
288 * @param fh the file handle
289 * @param size the size of the file
290 * @return GNUNET_OK if created ok, GNUNET_SYSERR otherwise
293 make_empty_file (const struct GNUNET_DISK_FileHandle *fh, size_t size)
295 char buffer[BUFFSIZE];
296 size_t bytesleft = size;
299 if (GNUNET_DISK_handle_invalid (fh))
300 return GNUNET_SYSERR;
301 memset (buffer, 0, sizeof (buffer));
302 GNUNET_DISK_file_seek (fh, 0, GNUNET_DISK_SEEK_SET);
303 while (bytesleft > 0)
305 if (bytesleft > sizeof (buffer))
307 res = GNUNET_DISK_file_write (fh, buffer, sizeof (buffer));
313 res = GNUNET_DISK_file_write (fh, buffer, bytesleft);
317 if (GNUNET_SYSERR == res)
318 return GNUNET_SYSERR;
323 /* ************** GNUNET_CONTAINER_BloomFilter iterator ********* */
326 * Iterator (callback) method to be called by the
327 * bloomfilter iterator on each bit that is to be
328 * set or tested for the key.
331 * @param bf the filter to manipulate
332 * @param bit the current bit
333 * @return GNUNET_YES to continue, GNUNET_NO to stop early
335 typedef int (*BitIterator) (void *cls,
336 const struct GNUNET_CONTAINER_BloomFilter * bf,
341 * Call an iterator for each bit that the bloomfilter
342 * must test or set for this element.
344 * @param bf the filter
345 * @param callback the method to call
346 * @param arg extra argument to callback
347 * @param key the key for which we iterate over the BF bits
350 iterateBits (const struct GNUNET_CONTAINER_BloomFilter *bf,
351 BitIterator callback, void *arg, const struct GNUNET_HashCode *key)
353 struct GNUNET_HashCode tmp[2];
356 unsigned int slot = 0;
358 bitCount = bf->addressesPerElement;
361 GNUNET_assert (bf->bitArraySize > 0);
362 GNUNET_assert (bf->bitArraySize * 8LL > bf->bitArraySize);
365 while (slot < (sizeof (struct GNUNET_HashCode) / sizeof (uint32_t)))
369 ntohl ((((uint32_t *) & tmp[round & 1])[slot])) %
370 ((bf->bitArraySize * 8LL))))
379 GNUNET_CRYPTO_hash (&tmp[round & 1], sizeof (struct GNUNET_HashCode),
380 &tmp[(round + 1) & 1]);
389 * Callback: increment bit
391 * @param cls pointer to writeable form of bf
392 * @param bf the filter to manipulate
393 * @param bit the bit to increment
397 incrementBitCallback (void *cls, const struct GNUNET_CONTAINER_BloomFilter *bf,
400 struct GNUNET_CONTAINER_BloomFilter *b = cls;
402 incrementBit (b->bitArray, bit, bf->fh);
408 * Callback: decrement bit
410 * @param cls pointer to writeable form of bf
411 * @param bf the filter to manipulate
412 * @param bit the bit to decrement
416 decrementBitCallback (void *cls, const struct GNUNET_CONTAINER_BloomFilter *bf,
419 struct GNUNET_CONTAINER_BloomFilter *b = cls;
421 decrementBit (b->bitArray, bit, bf->fh);
427 * Callback: test if all bits are set
429 * @param cls pointer set to GNUNET_NO if bit is not set
430 * @param bf the filter
431 * @param bit the bit to test
432 * @return YES if the bit is set, NO if not
435 testBitCallback (void *cls, const struct GNUNET_CONTAINER_BloomFilter *bf,
440 if (GNUNET_NO == testBit (bf->bitArray, bit))
448 /* *********************** INTERFACE **************** */
451 * Load a bloom-filter from a file.
453 * @param filename the name of the file (or the prefix)
454 * @param size the size of the bloom-filter (number of
455 * bytes of storage space to use); will be rounded up
457 * @param k the number of GNUNET_CRYPTO_hash-functions to apply per
458 * element (number of bits set per element in the set)
459 * @return the bloomfilter
461 struct GNUNET_CONTAINER_BloomFilter *
462 GNUNET_CONTAINER_bloomfilter_load (const char *filename, size_t size,
465 struct GNUNET_CONTAINER_BloomFilter *bf;
473 GNUNET_assert (NULL != filename);
474 if ((k == 0) || (size == 0))
479 while ( (ui < size) &&
482 size = ui; /* make sure it's a power of 2 */
484 bf = GNUNET_malloc (sizeof (struct GNUNET_CONTAINER_BloomFilter));
485 /* Try to open a bloomfilter file */
486 if (GNUNET_YES == GNUNET_DISK_file_test (filename))
488 GNUNET_DISK_file_open (filename,
489 GNUNET_DISK_OPEN_READWRITE,
490 GNUNET_DISK_PERM_USER_READ |
491 GNUNET_DISK_PERM_USER_WRITE);
494 /* file existed, try to read it! */
495 must_read = GNUNET_YES;
497 GNUNET_DISK_file_handle_size (bf->fh, &fsize))
499 GNUNET_DISK_file_close (bf->fh);
505 /* found existing empty file, just overwrite */
506 if (GNUNET_OK != make_empty_file (bf->fh, size * 4LL))
508 GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,
510 GNUNET_DISK_file_close (bf->fh);
515 else if (fsize != size * 4LL)
517 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
518 _("Size of file on disk is incorrect for this Bloom filter (want %llu, have %llu)\n"),
519 (unsigned long long) (size * 4LL),
520 (unsigned long long) fsize);
521 GNUNET_DISK_file_close (bf->fh);
528 /* file did not exist, don't read, just create */
529 must_read = GNUNET_NO;
531 GNUNET_DISK_file_open (filename,
532 GNUNET_DISK_OPEN_CREATE |
533 GNUNET_DISK_OPEN_READWRITE,
534 GNUNET_DISK_PERM_USER_READ |
535 GNUNET_DISK_PERM_USER_WRITE);
541 if (GNUNET_OK != make_empty_file (bf->fh, size * 4LL))
543 GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,
545 GNUNET_DISK_file_close (bf->fh);
550 bf->filename = GNUNET_strdup (filename);
552 bf->bitArray = GNUNET_malloc_large (size);
553 if (bf->bitArray == NULL)
556 GNUNET_DISK_file_close (bf->fh);
557 GNUNET_free (bf->filename);
561 bf->bitArraySize = size;
562 bf->addressesPerElement = k;
563 if (GNUNET_YES != must_read)
564 return bf; /* already done! */
565 /* Read from the file what bits we can */
566 rbuff = GNUNET_malloc (BUFFSIZE);
568 while (pos < size * 8LL)
572 res = GNUNET_DISK_file_read (bf->fh, rbuff, BUFFSIZE);
575 LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "read", bf->filename);
577 GNUNET_free (bf->filename);
578 GNUNET_DISK_file_close (bf->fh);
583 break; /* is ok! we just did not use that many bits yet */
584 for (i = 0; i < res; i++)
586 if ((rbuff[i] & 0x0F) != 0)
587 setBit (bf->bitArray, pos + i * 2);
588 if ((rbuff[i] & 0xF0) != 0)
589 setBit (bf->bitArray, pos + i * 2 + 1);
593 pos += BUFFSIZE * 2; /* 2 bits per byte in the buffer */
601 * Create a bloom filter from raw bits.
603 * @param data the raw bits in memory (maybe NULL,
604 * in which case all bits should be considered
606 * @param size the size of the bloom-filter (number of
607 * bytes of storage space to use); also size of data
608 * -- unless data is NULL
609 * @param k the number of GNUNET_CRYPTO_hash-functions to apply per
610 * element (number of bits set per element in the set)
611 * @return the bloomfilter
613 struct GNUNET_CONTAINER_BloomFilter *
614 GNUNET_CONTAINER_bloomfilter_init (const char *data, size_t size,
617 struct GNUNET_CONTAINER_BloomFilter *bf;
619 if ((0 == k) || (0 == size))
621 bf = GNUNET_malloc (sizeof (struct GNUNET_CONTAINER_BloomFilter));
624 bf->bitArray = GNUNET_malloc_large (size);
625 if (NULL == bf->bitArray)
630 bf->bitArraySize = size;
631 bf->addressesPerElement = k;
633 memcpy (bf->bitArray, data, size);
639 * Copy the raw data of this bloomfilter into
640 * the given data array.
642 * @param bf bloomfilter to take the raw data from
643 * @param data where to write the data
644 * @param size the size of the given data array
645 * @return GNUNET_SYSERR if the data array is not big enough
648 GNUNET_CONTAINER_bloomfilter_get_raw_data (const struct
649 GNUNET_CONTAINER_BloomFilter *bf,
650 char *data, size_t size)
653 return GNUNET_SYSERR;
654 if (bf->bitArraySize != size)
655 return GNUNET_SYSERR;
656 memcpy (data, bf->bitArray, size);
662 * Free the space associated with a filter
663 * in memory, flush to drive if needed (do not
664 * free the space on the drive)
666 * @param bf the filter
669 GNUNET_CONTAINER_bloomfilter_free (struct GNUNET_CONTAINER_BloomFilter *bf)
674 GNUNET_DISK_file_close (bf->fh);
675 GNUNET_free_non_null (bf->filename);
676 GNUNET_free (bf->bitArray);
682 * Reset a bloom filter to empty. Clears the file on disk.
684 * @param bf the filter
687 GNUNET_CONTAINER_bloomfilter_clear (struct GNUNET_CONTAINER_BloomFilter *bf)
692 memset (bf->bitArray, 0, bf->bitArraySize);
693 if (bf->filename != NULL)
694 make_empty_file (bf->fh, bf->bitArraySize * 4LL);
699 * Test if an element is in the filter.
701 * @param e the element
702 * @param bf the filter
703 * @return GNUNET_YES if the element is in the filter, GNUNET_NO if not
706 GNUNET_CONTAINER_bloomfilter_test (const struct GNUNET_CONTAINER_BloomFilter
707 *bf, const struct GNUNET_HashCode * e)
714 iterateBits (bf, &testBitCallback, &res, e);
720 * Add an element to the filter
722 * @param bf the filter
723 * @param e the element
726 GNUNET_CONTAINER_bloomfilter_add (struct GNUNET_CONTAINER_BloomFilter *bf,
727 const struct GNUNET_HashCode * e)
731 iterateBits (bf, &incrementBitCallback, bf, e);
736 * Or the entries of the given raw data array with the
737 * data of the given bloom filter. Assumes that
738 * the size of the data array and the current filter
741 * @param bf the filter
742 * @param data the data to or-in
743 * @param size number of bytes in data
746 GNUNET_CONTAINER_bloomfilter_or (struct GNUNET_CONTAINER_BloomFilter *bf,
747 const char *data, size_t size)
751 unsigned long long *fc;
752 const unsigned long long *dc;
756 if (bf->bitArraySize != size)
757 return GNUNET_SYSERR;
758 fc = (unsigned long long *) bf->bitArray;
759 dc = (const unsigned long long *) data;
760 n = size / sizeof (unsigned long long);
762 for (i = 0; i < n; i++)
764 for (i = n * sizeof (unsigned long long); i < size; i++)
765 bf->bitArray[i] |= data[i];
770 * Or the entries of the given raw data array with the
771 * data of the given bloom filter. Assumes that
772 * the size of the data array and the current filter
775 * @param bf the filter
776 * @param to_or the bloomfilter to or-in
777 * @param size number of bytes in data
780 GNUNET_CONTAINER_bloomfilter_or2 (struct GNUNET_CONTAINER_BloomFilter *bf,
781 const struct GNUNET_CONTAINER_BloomFilter
786 unsigned long long *fc;
787 const unsigned long long *dc;
791 if (bf->bitArraySize != size)
792 return GNUNET_SYSERR;
793 fc = (unsigned long long *) bf->bitArray;
794 dc = (const unsigned long long *) to_or->bitArray;
795 n = size / sizeof (unsigned long long);
797 for (i = 0; i < n; i++)
799 for (i = n * sizeof (unsigned long long); i < size; i++)
800 bf->bitArray[i] |= to_or->bitArray[i];
805 * Remove an element from the filter.
807 * @param bf the filter
808 * @param e the element to remove
811 GNUNET_CONTAINER_bloomfilter_remove (struct GNUNET_CONTAINER_BloomFilter *bf,
812 const struct GNUNET_HashCode * e)
816 if (bf->filename == NULL)
818 iterateBits (bf, &decrementBitCallback, bf, e);
822 * Resize a bloom filter. Note that this operation
823 * is pretty costly. Essentially, the bloom filter
824 * needs to be completely re-build.
826 * @param bf the filter
827 * @param iterator an iterator over all elements stored in the BF
828 * @param iterator_cls argument to the iterator function
829 * @param size the new size for the filter
830 * @param k the new number of GNUNET_CRYPTO_hash-function to apply per element
833 GNUNET_CONTAINER_bloomfilter_resize (struct GNUNET_CONTAINER_BloomFilter *bf,
834 GNUNET_HashCodeIterator iterator,
835 void *iterator_cls, size_t size,
838 struct GNUNET_HashCode hc;
841 GNUNET_free (bf->bitArray);
845 size = i; /* make sure it's a power of 2 */
847 bf->bitArraySize = size;
848 bf->bitArray = GNUNET_malloc (size);
849 if (bf->filename != NULL)
850 make_empty_file (bf->fh, bf->bitArraySize * 4LL);
851 while (GNUNET_YES == iterator (iterator_cls, &hc))
852 GNUNET_CONTAINER_bloomfilter_add (bf, &hc);
855 /* end of container_bloomfilter.c */