From 966115c305c297cf4a1ec5ebbd0a55be46ff33ad Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 25 Dec 2014 13:22:55 -0500 Subject: Temporarily revert "Move pg_lzcompress.c to src/common." This reverts commit 60838df922345b26a616e49ac9fab808a35d1f85. That change needs a bit more thought to be workable. In view of the potentially machine-dependent stuff that went in today, we need all of the buildfarm to be testing those other changes. --- src/backend/access/heap/tuptoaster.c | 11 +- src/backend/utils/adt/Makefile | 4 +- src/backend/utils/adt/pg_lzcompress.c | 779 +++++++++++++++++++++++++++++++++ src/common/Makefile | 3 +- src/common/pg_lzcompress.c | 786 ---------------------------------- src/include/common/pg_lzcompress.h | 112 ----- src/include/utils/pg_lzcompress.h | 112 +++++ src/tools/msvc/Mkvcbuild.pm | 3 +- 8 files changed, 899 insertions(+), 911 deletions(-) create mode 100644 src/backend/utils/adt/pg_lzcompress.c delete mode 100644 src/common/pg_lzcompress.c delete mode 100644 src/include/common/pg_lzcompress.h create mode 100644 src/include/utils/pg_lzcompress.h diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c index c91bdc0d3f5..d230387c859 100644 --- a/src/backend/access/heap/tuptoaster.c +++ b/src/backend/access/heap/tuptoaster.c @@ -37,7 +37,7 @@ #include "catalog/catalog.h" #include "miscadmin.h" #include "utils/fmgroids.h" -#include "common/pg_lzcompress.h" +#include "utils/pg_lzcompress.h" #include "utils/rel.h" #include "utils/typcache.h" #include "utils/tqual.h" @@ -142,8 +142,7 @@ heap_tuple_untoast_attr(struct varlena * attr) attr = (struct varlena *) palloc(PGLZ_RAW_SIZE(tmp) + VARHDRSZ); SET_VARSIZE(attr, PGLZ_RAW_SIZE(tmp) + VARHDRSZ); - if (!pglz_decompress(tmp, VARDATA(attr))) - elog(ERROR, "compressed data is corrupted"); + pglz_decompress(tmp, VARDATA(attr)); pfree(tmp); } } @@ -168,8 +167,7 @@ heap_tuple_untoast_attr(struct varlena * attr) attr = (struct varlena *) palloc(PGLZ_RAW_SIZE(tmp) + VARHDRSZ); SET_VARSIZE(attr, PGLZ_RAW_SIZE(tmp) + VARHDRSZ); - if (!pglz_decompress(tmp, VARDATA(attr))) - elog(ERROR, "compressed data is corrupted"); + pglz_decompress(tmp, VARDATA(attr)); } else if (VARATT_IS_SHORT(attr)) { @@ -241,8 +239,7 @@ heap_tuple_untoast_attr_slice(struct varlena * attr, preslice = (struct varlena *) palloc(size); SET_VARSIZE(preslice, size); - if (!pglz_decompress(tmp, VARDATA(preslice))) - elog(ERROR, "compressed data is corrupted"); + pglz_decompress(tmp, VARDATA(preslice)); if (tmp != (PGLZ_Header *) attr) pfree(tmp); diff --git a/src/backend/utils/adt/Makefile b/src/backend/utils/adt/Makefile index 20e5ff10c7f..3ea9bf435a3 100644 --- a/src/backend/utils/adt/Makefile +++ b/src/backend/utils/adt/Makefile @@ -25,8 +25,8 @@ OBJS = acl.o arrayfuncs.o array_selfuncs.o array_typanalyze.o \ jsonfuncs.o like.o lockfuncs.o mac.o misc.o nabstime.o name.o \ network.o network_gist.o network_selfuncs.o \ numeric.o numutils.o oid.o oracle_compat.o \ - orderedsetaggs.o pg_locale.o pg_lsn.o pgstatfuncs.o \ - pseudotypes.o quote.o rangetypes.o rangetypes_gist.o \ + orderedsetaggs.o pg_lzcompress.o pg_locale.o pg_lsn.o \ + pgstatfuncs.o pseudotypes.o quote.o rangetypes.o rangetypes_gist.o \ rangetypes_selfuncs.o rangetypes_spgist.o rangetypes_typanalyze.o \ regexp.o regproc.o ri_triggers.o rowtypes.o ruleutils.o \ selfuncs.o tid.o timestamp.o trigfuncs.o \ diff --git a/src/backend/utils/adt/pg_lzcompress.c b/src/backend/utils/adt/pg_lzcompress.c new file mode 100644 index 00000000000..fe088901f03 --- /dev/null +++ b/src/backend/utils/adt/pg_lzcompress.c @@ -0,0 +1,779 @@ +/* ---------- + * pg_lzcompress.c - + * + * This is an implementation of LZ compression for PostgreSQL. + * It uses a simple history table and generates 2-3 byte tags + * capable of backward copy information for 3-273 bytes with + * a max offset of 4095. + * + * Entry routines: + * + * bool + * pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, + * const PGLZ_Strategy *strategy); + * + * source is the input data to be compressed. + * + * slen is the length of the input data. + * + * dest is the output area for the compressed result. + * It must be at least as big as PGLZ_MAX_OUTPUT(slen). + * + * strategy is a pointer to some information controlling + * the compression algorithm. If NULL, the compiled + * in default strategy is used. + * + * The return value is TRUE if compression succeeded, + * FALSE if not; in the latter case the contents of dest + * are undefined. + * + * void + * pglz_decompress(const PGLZ_Header *source, char *dest) + * + * source is the compressed input. + * + * dest is the area where the uncompressed data will be + * written to. It is the callers responsibility to + * provide enough space. The required amount can be + * obtained with the macro PGLZ_RAW_SIZE(source). + * + * The data is written to buff exactly as it was handed + * to pglz_compress(). No terminating zero byte is added. + * + * The decompression algorithm and internal data format: + * + * PGLZ_Header is defined as + * + * typedef struct PGLZ_Header { + * int32 vl_len_; + * int32 rawsize; + * } + * + * The header is followed by the compressed data itself. + * + * The data representation is easiest explained by describing + * the process of decompression. + * + * If VARSIZE(x) == rawsize + sizeof(PGLZ_Header), then the data + * is stored uncompressed as plain bytes. Thus, the decompressor + * simply copies rawsize bytes from the location after the + * header to the destination. + * + * Otherwise the first byte after the header tells what to do + * the next 8 times. We call this the control byte. + * + * An unset bit in the control byte means, that one uncompressed + * byte follows, which is copied from input to output. + * + * A set bit in the control byte means, that a tag of 2-3 bytes + * follows. A tag contains information to copy some bytes, that + * are already in the output buffer, to the current location in + * the output. Let's call the three tag bytes T1, T2 and T3. The + * position of the data to copy is coded as an offset from the + * actual output position. + * + * The offset is in the upper nibble of T1 and in T2. + * The length is in the lower nibble of T1. + * + * So the 16 bits of a 2 byte tag are coded as + * + * 7---T1--0 7---T2--0 + * OOOO LLLL OOOO OOOO + * + * This limits the offset to 1-4095 (12 bits) and the length + * to 3-18 (4 bits) because 3 is always added to it. To emit + * a tag of 2 bytes with a length of 2 only saves one control + * bit. But we lose one byte in the possible length of a tag. + * + * In the actual implementation, the 2 byte tag's length is + * limited to 3-17, because the value 0xF in the length nibble + * has special meaning. It means, that the next following + * byte (T3) has to be added to the length value of 18. That + * makes total limits of 1-4095 for offset and 3-273 for length. + * + * Now that we have successfully decoded a tag. We simply copy + * the output that occurred bytes back to the current + * output location in the specified . Thus, a + * sequence of 200 spaces (think about bpchar fields) could be + * coded in 4 bytes. One literal space and a three byte tag to + * copy 199 bytes with a -1 offset. Whow - that's a compression + * rate of 98%! Well, the implementation needs to save the + * original data size too, so we need another 4 bytes for it + * and end up with a total compression rate of 96%, what's still + * worth a Whow. + * + * The compression algorithm + * + * The following uses numbers used in the default strategy. + * + * The compressor works best for attributes of a size between + * 1K and 1M. For smaller items there's not that much chance of + * redundancy in the character sequence (except for large areas + * of identical bytes like trailing spaces) and for bigger ones + * our 4K maximum look-back distance is too small. + * + * The compressor creates a table for lists of positions. + * For each input position (except the last 3), a hash key is + * built from the 4 next input bytes and the position remembered + * in the appropriate list. Thus, the table points to linked + * lists of likely to be at least in the first 4 characters + * matching strings. This is done on the fly while the input + * is compressed into the output area. Table entries are only + * kept for the last 4096 input positions, since we cannot use + * back-pointers larger than that anyway. The size of the hash + * table is chosen based on the size of the input - a larger table + * has a larger startup cost, as it needs to be initialized to + * zero, but reduces the number of hash collisions on long inputs. + * + * For each byte in the input, its hash key (built from this + * byte and the next 3) is used to find the appropriate list + * in the table. The lists remember the positions of all bytes + * that had the same hash key in the past in increasing backward + * offset order. Now for all entries in the used lists, the + * match length is computed by comparing the characters from the + * entries position with the characters from the actual input + * position. + * + * The compressor starts with a so called "good_match" of 128. + * It is a "prefer speed against compression ratio" optimizer. + * So if the first entry looked at already has 128 or more + * matching characters, the lookup stops and that position is + * used for the next tag in the output. + * + * For each subsequent entry in the history list, the "good_match" + * is lowered by 10%. So the compressor will be more happy with + * short matches the farer it has to go back in the history. + * Another "speed against ratio" preference characteristic of + * the algorithm. + * + * Thus there are 3 stop conditions for the lookup of matches: + * + * - a match >= good_match is found + * - there are no more history entries to look at + * - the next history entry is already too far back + * to be coded into a tag. + * + * Finally the match algorithm checks that at least a match + * of 3 or more bytes has been found, because thats the smallest + * amount of copy information to code into a tag. If so, a tag + * is omitted and all the input bytes covered by that are just + * scanned for the history add's, otherwise a literal character + * is omitted and only his history entry added. + * + * Acknowledgements: + * + * Many thanks to Adisak Pochanayon, who's article about SLZ + * inspired me to write the PostgreSQL compression this way. + * + * Jan Wieck + * + * Copyright (c) 1999-2014, PostgreSQL Global Development Group + * + * src/backend/utils/adt/pg_lzcompress.c + * ---------- + */ +#include "postgres.h" + +#include + +#include "utils/pg_lzcompress.h" + + +/* ---------- + * Local definitions + * ---------- + */ +#define PGLZ_MAX_HISTORY_LISTS 8192 /* must be power of 2 */ +#define PGLZ_HISTORY_SIZE 4096 +#define PGLZ_MAX_MATCH 273 + + +/* ---------- + * PGLZ_HistEntry - + * + * Linked list for the backward history lookup + * + * All the entries sharing a hash key are linked in a doubly linked list. + * This makes it easy to remove an entry when it's time to recycle it + * (because it's more than 4K positions old). + * ---------- + */ +typedef struct PGLZ_HistEntry +{ + struct PGLZ_HistEntry *next; /* links for my hash key's list */ + struct PGLZ_HistEntry *prev; + int hindex; /* my current hash key */ + const char *pos; /* my input position */ +} PGLZ_HistEntry; + + +/* ---------- + * The provided standard strategies + * ---------- + */ +static const PGLZ_Strategy strategy_default_data = { + 32, /* Data chunks less than 32 bytes are not + * compressed */ + INT_MAX, /* No upper limit on what we'll try to + * compress */ + 25, /* Require 25% compression rate, or not worth + * it */ + 1024, /* Give up if no compression in the first 1KB */ + 128, /* Stop history lookup if a match of 128 bytes + * is found */ + 10 /* Lower good match size by 10% at every loop + * iteration */ +}; +const PGLZ_Strategy *const PGLZ_strategy_default = &strategy_default_data; + + +static const PGLZ_Strategy strategy_always_data = { + 0, /* Chunks of any size are compressed */ + INT_MAX, + 0, /* It's enough to save one single byte */ + INT_MAX, /* Never give up early */ + 128, /* Stop history lookup if a match of 128 bytes + * is found */ + 6 /* Look harder for a good match */ +}; +const PGLZ_Strategy *const PGLZ_strategy_always = &strategy_always_data; + + +/* ---------- + * Statically allocated work arrays for history + * ---------- + */ +static int16 hist_start[PGLZ_MAX_HISTORY_LISTS]; +static PGLZ_HistEntry hist_entries[PGLZ_HISTORY_SIZE + 1]; + +/* + * Element 0 in hist_entries is unused, and means 'invalid'. Likewise, + * INVALID_ENTRY_PTR in next/prev pointers mean 'invalid'. + */ +#define INVALID_ENTRY 0 +#define INVALID_ENTRY_PTR (&hist_entries[INVALID_ENTRY]) + +/* ---------- + * pglz_hist_idx - + * + * Computes the history table slot for the lookup by the next 4 + * characters in the input. + * + * NB: because we use the next 4 characters, we are not guaranteed to + * find 3-character matches; they very possibly will be in the wrong + * hash list. This seems an acceptable tradeoff for spreading out the + * hash keys more. + * ---------- + */ +#define pglz_hist_idx(_s,_e, _mask) ( \ + ((((_e) - (_s)) < 4) ? (int) (_s)[0] : \ + (((_s)[0] << 6) ^ ((_s)[1] << 4) ^ \ + ((_s)[2] << 2) ^ (_s)[3])) & (_mask) \ + ) + + +/* ---------- + * pglz_hist_add - + * + * Adds a new entry to the history table. + * + * If _recycle is true, then we are recycling a previously used entry, + * and must first delink it from its old hashcode's linked list. + * + * NOTE: beware of multiple evaluations of macro's arguments, and note that + * _hn and _recycle are modified in the macro. + * ---------- + */ +#define pglz_hist_add(_hs,_he,_hn,_recycle,_s,_e, _mask) \ +do { \ + int __hindex = pglz_hist_idx((_s),(_e), (_mask)); \ + int16 *__myhsp = &(_hs)[__hindex]; \ + PGLZ_HistEntry *__myhe = &(_he)[_hn]; \ + if (_recycle) { \ + if (__myhe->prev == NULL) \ + (_hs)[__myhe->hindex] = __myhe->next - (_he); \ + else \ + __myhe->prev->next = __myhe->next; \ + if (__myhe->next != NULL) \ + __myhe->next->prev = __myhe->prev; \ + } \ + __myhe->next = &(_he)[*__myhsp]; \ + __myhe->prev = NULL; \ + __myhe->hindex = __hindex; \ + __myhe->pos = (_s); \ + /* If there was an existing entry in this hash slot, link */ \ + /* this new entry to it. However, the 0th entry in the */ \ + /* entries table is unused, so we can freely scribble on it. */ \ + /* So don't bother checking if the slot was used - we'll */ \ + /* scribble on the unused entry if it was not, but that's */ \ + /* harmless. Avoiding the branch in this critical path */ \ + /* speeds this up a little bit. */ \ + /* if (*__myhsp != INVALID_ENTRY) */ \ + (_he)[(*__myhsp)].prev = __myhe; \ + *__myhsp = _hn; \ + if (++(_hn) >= PGLZ_HISTORY_SIZE + 1) { \ + (_hn) = 1; \ + (_recycle) = true; \ + } \ +} while (0) + + +/* ---------- + * pglz_out_ctrl - + * + * Outputs the last and allocates a new control byte if needed. + * ---------- + */ +#define pglz_out_ctrl(__ctrlp,__ctrlb,__ctrl,__buf) \ +do { \ + if ((__ctrl & 0xff) == 0) \ + { \ + *(__ctrlp) = __ctrlb; \ + __ctrlp = (__buf)++; \ + __ctrlb = 0; \ + __ctrl = 1; \ + } \ +} while (0) + + +/* ---------- + * pglz_out_literal - + * + * Outputs a literal byte to the destination buffer including the + * appropriate control bit. + * ---------- + */ +#define pglz_out_literal(_ctrlp,_ctrlb,_ctrl,_buf,_byte) \ +do { \ + pglz_out_ctrl(_ctrlp,_ctrlb,_ctrl,_buf); \ + *(_buf)++ = (unsigned char)(_byte); \ + _ctrl <<= 1; \ +} while (0) + + +/* ---------- + * pglz_out_tag - + * + * Outputs a backward reference tag of 2-4 bytes (depending on + * offset and length) to the destination buffer including the + * appropriate control bit. + * ---------- + */ +#define pglz_out_tag(_ctrlp,_ctrlb,_ctrl,_buf,_len,_off) \ +do { \ + pglz_out_ctrl(_ctrlp,_ctrlb,_ctrl,_buf); \ + _ctrlb |= _ctrl; \ + _ctrl <<= 1; \ + if (_len > 17) \ + { \ + (_buf)[0] = (unsigned char)((((_off) & 0xf00) >> 4) | 0x0f); \ + (_buf)[1] = (unsigned char)(((_off) & 0xff)); \ + (_buf)[2] = (unsigned char)((_len) - 18); \ + (_buf) += 3; \ + } else { \ + (_buf)[0] = (unsigned char)((((_off) & 0xf00) >> 4) | ((_len) - 3)); \ + (_buf)[1] = (unsigned char)((_off) & 0xff); \ + (_buf) += 2; \ + } \ +} while (0) + + +/* ---------- + * pglz_find_match - + * + * Lookup the history table if the actual input stream matches + * another sequence of characters, starting somewhere earlier + * in the input buffer. + * ---------- + */ +static inline int +pglz_find_match(int16 *hstart, const char *input, const char *end, + int *lenp, int *offp, int good_match, int good_drop, int mask) +{ + PGLZ_HistEntry *hent; + int16 hentno; + int32 len = 0; + int32 off = 0; + + /* + * Traverse the linked history list until a good enough match is found. + */ + hentno = hstart[pglz_hist_idx(input, end, mask)]; + hent = &hist_entries[hentno]; + while (hent != INVALID_ENTRY_PTR) + { + const char *ip = input; + const char *hp = hent->pos; + int32 thisoff; + int32 thislen; + + /* + * Stop if the offset does not fit into our tag anymore. + */ + thisoff = ip - hp; + if (thisoff >= 0x0fff) + break; + + /* + * Determine length of match. A better match must be larger than the + * best so far. And if we already have a match of 16 or more bytes, + * it's worth the call overhead to use memcmp() to check if this match + * is equal for the same size. After that we must fallback to + * character by character comparison to know the exact position where + * the diff occurred. + */ + thislen = 0; + if (len >= 16) + { + if (memcmp(ip, hp, len) == 0) + { + thislen = len; + ip += len; + hp += len; + while (ip < end && *ip == *hp && thislen < PGLZ_MAX_MATCH) + { + thislen++; + ip++; + hp++; + } + } + } + else + { + while (ip < end && *ip == *hp && thislen < PGLZ_MAX_MATCH) + { + thislen++; + ip++; + hp++; + } + } + + /* + * Remember this match as the best (if it is) + */ + if (thislen > len) + { + len = thislen; + off = thisoff; + } + + /* + * Advance to the next history entry + */ + hent = hent->next; + + /* + * Be happy with lesser good matches the more entries we visited. But + * no point in doing calculation if we're at end of list. + */ + if (hent != INVALID_ENTRY_PTR) + { + if (len >= good_match) + break; + good_match -= (good_match * good_drop) / 100; + } + } + + /* + * Return match information only if it results at least in one byte + * reduction. + */ + if (len > 2) + { + *lenp = len; + *offp = off; + return 1; + } + + return 0; +} + + +/* ---------- + * pglz_compress - + * + * Compresses source into dest using strategy. + * ---------- + */ +bool +pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, + const PGLZ_Strategy *strategy) +{ + unsigned char *bp = ((unsigned char *) dest) + sizeof(PGLZ_Header); + unsigned char *bstart = bp; + int hist_next = 1; + bool hist_recycle = false; + const char *dp = source; + const char *dend = source + slen; + unsigned char ctrl_dummy = 0; + unsigned char *ctrlp = &ctrl_dummy; + unsigned char ctrlb = 0; + unsigned char ctrl = 0; + bool found_match = false; + int32 match_len; + int32 match_off; + int32 good_match; + int32 good_drop; + int32 result_size; + int32 result_max; + int32 need_rate; + int hashsz; + int mask; + + /* + * Our fallback strategy is the default. + */ + if (strategy == NULL) + strategy = PGLZ_strategy_default; + + /* + * If the strategy forbids compression (at all or if source chunk size out + * of range), fail. + */ + if (strategy->match_size_good <= 0 || + slen < strategy->min_input_size || + slen > strategy->max_input_size) + return false; + + /* + * Save the original source size in the header. + */ + dest->rawsize = slen; + + /* + * Limit the match parameters to the supported range. + */ + good_match = strategy->match_size_good; + if (good_match > PGLZ_MAX_MATCH) + good_match = PGLZ_MAX_MATCH; + else if (good_match < 17) + good_match = 17; + + good_drop = strategy->match_size_drop; + if (good_drop < 0) + good_drop = 0; + else if (good_drop > 100) + good_drop = 100; + + need_rate = strategy->min_comp_rate; + if (need_rate < 0) + need_rate = 0; + else if (need_rate > 99) + need_rate = 99; + + /* + * Compute the maximum result size allowed by the strategy, namely the + * input size minus the minimum wanted compression rate. This had better + * be <= slen, else we might overrun the provided output buffer. + */ + if (slen > (INT_MAX / 100)) + { + /* Approximate to avoid overflow */ + result_max = (slen / 100) * (100 - need_rate); + } + else + result_max = (slen * (100 - need_rate)) / 100; + + /* + * Experiments suggest that these hash sizes work pretty well. A large + * hash table minimizes collision, but has a higher startup cost. For a + * small input, the startup cost dominates. The table size must be a power + * of two. + */ + if (slen < 128) + hashsz = 512; + else if (slen < 256) + hashsz = 1024; + else if (slen < 512) + hashsz = 2048; + else if (slen < 1024) + hashsz = 4096; + else + hashsz = 8192; + mask = hashsz - 1; + + /* + * Initialize the history lists to empty. We do not need to zero the + * hist_entries[] array; its entries are initialized as they are used. + */ + memset(hist_start, 0, hashsz * sizeof(int16)); + + /* + * Compress the source directly into the output buffer. + */ + while (dp < dend) + { + /* + * If we already exceeded the maximum result size, fail. + * + * We check once per loop; since the loop body could emit as many as 4 + * bytes (a control byte and 3-byte tag), PGLZ_MAX_OUTPUT() had better + * allow 4 slop bytes. + */ + if (bp - bstart >= result_max) + return false; + + /* + * If we've emitted more than first_success_by bytes without finding + * anything compressible at all, fail. This lets us fall out + * reasonably quickly when looking at incompressible input (such as + * pre-compressed data). + */ + if (!found_match && bp - bstart >= strategy->first_success_by) + return false; + + /* + * Try to find a match in the history + */ + if (pglz_find_match(hist_start, dp, dend, &match_len, + &match_off, good_match, good_drop, mask)) + { + /* + * Create the tag and add history entries for all matched + * characters. + */ + pglz_out_tag(ctrlp, ctrlb, ctrl, bp, match_len, match_off); + while (match_len--) + { + pglz_hist_add(hist_start, hist_entries, + hist_next, hist_recycle, + dp, dend, mask); + dp++; /* Do not do this ++ in the line above! */ + /* The macro would do it four times - Jan. */ + } + found_match = true; + } + else + { + /* + * No match found. Copy one literal byte. + */ + pglz_out_literal(ctrlp, ctrlb, ctrl, bp, *dp); + pglz_hist_add(hist_start, hist_entries, + hist_next, hist_recycle, + dp, dend, mask); + dp++; /* Do not do this ++ in the line above! */ + /* The macro would do it four times - Jan. */ + } + } + + /* + * Write out the last control byte and check that we haven't overrun the + * output size allowed by the strategy. + */ + *ctrlp = ctrlb; + result_size = bp - bstart; + if (result_size >= result_max) + return false; + + /* + * Success - need only fill in the actual length of the compressed datum. + */ + SET_VARSIZE_COMPRESSED(dest, result_size + sizeof(PGLZ_Header)); + + return true; +} + + +/* ---------- + * pglz_decompress - + * + * Decompresses source into dest. + * ---------- + */ +void +pglz_decompress(const PGLZ_Header *source, char *dest) +{ + const unsigned char *sp; + const unsigned char *srcend; + unsigned char *dp; + unsigned char *destend; + + sp = ((const unsigned char *) source) + sizeof(PGLZ_Header); + srcend = ((const unsigned char *) source) + VARSIZE(source); + dp = (unsigned char *) dest; + destend = dp + source->rawsize; + + while (sp < srcend && dp < destend) + { + /* + * Read one control byte and process the next 8 items (or as many as + * remain in the compressed input). + */ + unsigned char ctrl = *sp++; + int ctrlc; + + for (ctrlc = 0; ctrlc < 8 && sp < srcend; ctrlc++) + { + if (ctrl & 1) + { + /* + * Otherwise it contains the match length minus 3 and the + * upper 4 bits of the offset. The next following byte + * contains the lower 8 bits of the offset. If the length is + * coded as 18, another extension tag byte tells how much + * longer the match really was (0-255). + */ + int32 len; + int32 off; + + len = (sp[0] & 0x0f) + 3; + off = ((sp[0] & 0xf0) << 4) | sp[1]; + sp += 2; + if (len == 18) + len += *sp++; + + /* + * Check for output buffer overrun, to ensure we don't clobber + * memory in case of corrupt input. Note: we must advance dp + * here to ensure the error is detected below the loop. We + * don't simply put the elog inside the loop since that will + * probably interfere with optimization. + */ + if (dp + len > destend) + { + dp += len; + break; + } + + /* + * Now we copy the bytes specified by the tag from OUTPUT to + * OUTPUT. It is dangerous and platform dependent to use + * memcpy() here, because the copied areas could overlap + * extremely! + */ + while (len--) + { + *dp = dp[-off]; + dp++; + } + } + else + { + /* + * An unset control bit means LITERAL BYTE. So we just copy + * one from INPUT to OUTPUT. + */ + if (dp >= destend) /* check for buffer overrun */ + break; /* do not clobber memory */ + + *dp++ = *sp++; + } + + /* + * Advance the control bit + */ + ctrl >>= 1; + } + } + + /* + * Check we decompressed the right amount. + */ + if (dp != destend || sp != srcend) + elog(ERROR, "compressed data is corrupt"); + + /* + * That's it. + */ +} diff --git a/src/common/Makefile b/src/common/Makefile index bd77c1da8c3..7edbaaa2c1a 100644 --- a/src/common/Makefile +++ b/src/common/Makefile @@ -23,8 +23,7 @@ include $(top_builddir)/src/Makefile.global override CPPFLAGS := -DFRONTEND $(CPPFLAGS) LIBS += $(PTHREAD_LIBS) -OBJS_COMMON = exec.o pg_lzcompress.o pgfnames.o psprintf.o relpath.o \ - rmtree.o username.o wait_error.o +OBJS_COMMON = exec.o pgfnames.o psprintf.o relpath.o rmtree.o username.o wait_error.o OBJS_FRONTEND = $(OBJS_COMMON) fe_memutils.o diff --git a/src/common/pg_lzcompress.c b/src/common/pg_lzcompress.c deleted file mode 100644 index 9f97c362d18..00000000000 --- a/src/common/pg_lzcompress.c +++ /dev/null @@ -1,786 +0,0 @@ -/* ---------- - * pg_lzcompress.c - - * - * This is an implementation of LZ compression for PostgreSQL. - * It uses a simple history table and generates 2-3 byte tags - * capable of backward copy information for 3-273 bytes with - * a max offset of 4095. - * - * Entry routines: - * - * bool - * pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, - * const PGLZ_Strategy *strategy); - * - * source is the input data to be compressed. - * - * slen is the length of the input data. - * - * dest is the output area for the compressed result. - * It must be at least as big as PGLZ_MAX_OUTPUT(slen). - * - * strategy is a pointer to some information controlling - * the compression algorithm. If NULL, the compiled - * in default strategy is used. - * - * The return value is TRUE if compression succeeded, - * FALSE if not; in the latter case the contents of dest - * are undefined. - * - * bool - * pglz_decompress(const PGLZ_Header *source, char *dest) - * - * source is the compressed input. - * - * dest is the area where the uncompressed data will be - * written to. It is the callers responsibility to - * provide enough space. The required amount can be - * obtained with the macro PGLZ_RAW_SIZE(source). - * - * The data is written to buff exactly as it was handed - * to pglz_compress(). No terminating zero byte is added. - * - * The return value is TRUE if decompression succeeded, - * FALSE if not; in the latter case the contents of dest - * are undefined. - * - * The decompression algorithm and internal data format: - * - * PGLZ_Header is defined as - * - * typedef struct PGLZ_Header { - * int32 vl_len_; - * int32 rawsize; - * } - * - * The header is followed by the compressed data itself. - * - * The data representation is easiest explained by describing - * the process of decompression. - * - * If VARSIZE(x) == rawsize + sizeof(PGLZ_Header), then the data - * is stored uncompressed as plain bytes. Thus, the decompressor - * simply copies rawsize bytes from the location after the - * header to the destination. - * - * Otherwise the first byte after the header tells what to do - * the next 8 times. We call this the control byte. - * - * An unset bit in the control byte means, that one uncompressed - * byte follows, which is copied from input to output. - * - * A set bit in the control byte means, that a tag of 2-3 bytes - * follows. A tag contains information to copy some bytes, that - * are already in the output buffer, to the current location in - * the output. Let's call the three tag bytes T1, T2 and T3. The - * position of the data to copy is coded as an offset from the - * actual output position. - * - * The offset is in the upper nibble of T1 and in T2. - * The length is in the lower nibble of T1. - * - * So the 16 bits of a 2 byte tag are coded as - * - * 7---T1--0 7---T2--0 - * OOOO LLLL OOOO OOOO - * - * This limits the offset to 1-4095 (12 bits) and the length - * to 3-18 (4 bits) because 3 is always added to it. To emit - * a tag of 2 bytes with a length of 2 only saves one control - * bit. But we lose one byte in the possible length of a tag. - * - * In the actual implementation, the 2 byte tag's length is - * limited to 3-17, because the value 0xF in the length nibble - * has special meaning. It means, that the next following - * byte (T3) has to be added to the length value of 18. That - * makes total limits of 1-4095 for offset and 3-273 for length. - * - * Now that we have successfully decoded a tag. We simply copy - * the output that occurred bytes back to the current - * output location in the specified . Thus, a - * sequence of 200 spaces (think about bpchar fields) could be - * coded in 4 bytes. One literal space and a three byte tag to - * copy 199 bytes with a -1 offset. Whow - that's a compression - * rate of 98%! Well, the implementation needs to save the - * original data size too, so we need another 4 bytes for it - * and end up with a total compression rate of 96%, what's still - * worth a Whow. - * - * The compression algorithm - * - * The following uses numbers used in the default strategy. - * - * The compressor works best for attributes of a size between - * 1K and 1M. For smaller items there's not that much chance of - * redundancy in the character sequence (except for large areas - * of identical bytes like trailing spaces) and for bigger ones - * our 4K maximum look-back distance is too small. - * - * The compressor creates a table for lists of positions. - * For each input position (except the last 3), a hash key is - * built from the 4 next input bytes and the position remembered - * in the appropriate list. Thus, the table points to linked - * lists of likely to be at least in the first 4 characters - * matching strings. This is done on the fly while the input - * is compressed into the output area. Table entries are only - * kept for the last 4096 input positions, since we cannot use - * back-pointers larger than that anyway. The size of the hash - * table is chosen based on the size of the input - a larger table - * has a larger startup cost, as it needs to be initialized to - * zero, but reduces the number of hash collisions on long inputs. - * - * For each byte in the input, its hash key (built from this - * byte and the next 3) is used to find the appropriate list - * in the table. The lists remember the positions of all bytes - * that had the same hash key in the past in increasing backward - * offset order. Now for all entries in the used lists, the - * match length is computed by comparing the characters from the - * entries position with the characters from the actual input - * position. - * - * The compressor starts with a so called "good_match" of 128. - * It is a "prefer speed against compression ratio" optimizer. - * So if the first entry looked at already has 128 or more - * matching characters, the lookup stops and that position is - * used for the next tag in the output. - * - * For each subsequent entry in the history list, the "good_match" - * is lowered by 10%. So the compressor will be more happy with - * short matches the farer it has to go back in the history. - * Another "speed against ratio" preference characteristic of - * the algorithm. - * - * Thus there are 3 stop conditions for the lookup of matches: - * - * - a match >= good_match is found - * - there are no more history entries to look at - * - the next history entry is already too far back - * to be coded into a tag. - * - * Finally the match algorithm checks that at least a match - * of 3 or more bytes has been found, because thats the smallest - * amount of copy information to code into a tag. If so, a tag - * is omitted and all the input bytes covered by that are just - * scanned for the history add's, otherwise a literal character - * is omitted and only his history entry added. - * - * Acknowledgements: - * - * Many thanks to Adisak Pochanayon, who's article about SLZ - * inspired me to write the PostgreSQL compression this way. - * - * Jan Wieck - * - * Copyright (c) 1999-2014, PostgreSQL Global Development Group - * - * src/common/pg_lzcompress.c - * ---------- - */ -#include "postgres.h" - -#include - -#include "common/pg_lzcompress.h" - - -/* ---------- - * Local definitions - * ---------- - */ -#define PGLZ_MAX_HISTORY_LISTS 8192 /* must be power of 2 */ -#define PGLZ_HISTORY_SIZE 4096 -#define PGLZ_MAX_MATCH 273 - - -/* ---------- - * PGLZ_HistEntry - - * - * Linked list for the backward history lookup - * - * All the entries sharing a hash key are linked in a doubly linked list. - * This makes it easy to remove an entry when it's time to recycle it - * (because it's more than 4K positions old). - * ---------- - */ -typedef struct PGLZ_HistEntry -{ - struct PGLZ_HistEntry *next; /* links for my hash key's list */ - struct PGLZ_HistEntry *prev; - int hindex; /* my current hash key */ - const char *pos; /* my input position */ -} PGLZ_HistEntry; - - -/* ---------- - * The provided standard strategies - * ---------- - */ -static const PGLZ_Strategy strategy_default_data = { - 32, /* Data chunks less than 32 bytes are not - * compressed */ - INT_MAX, /* No upper limit on what we'll try to - * compress */ - 25, /* Require 25% compression rate, or not worth - * it */ - 1024, /* Give up if no compression in the first 1KB */ - 128, /* Stop history lookup if a match of 128 bytes - * is found */ - 10 /* Lower good match size by 10% at every loop - * iteration */ -}; -const PGLZ_Strategy *const PGLZ_strategy_default = &strategy_default_data; - - -static const PGLZ_Strategy strategy_always_data = { - 0, /* Chunks of any size are compressed */ - INT_MAX, - 0, /* It's enough to save one single byte */ - INT_MAX, /* Never give up early */ - 128, /* Stop history lookup if a match of 128 bytes - * is found */ - 6 /* Look harder for a good match */ -}; -const PGLZ_Strategy *const PGLZ_strategy_always = &strategy_always_data; - - -/* ---------- - * Statically allocated work arrays for history - * ---------- - */ -static int16 hist_start[PGLZ_MAX_HISTORY_LISTS]; -static PGLZ_HistEntry hist_entries[PGLZ_HISTORY_SIZE + 1]; - -/* - * Element 0 in hist_entries is unused, and means 'invalid'. Likewise, - * INVALID_ENTRY_PTR in next/prev pointers mean 'invalid'. - */ -#define INVALID_ENTRY 0 -#define INVALID_ENTRY_PTR (&hist_entries[INVALID_ENTRY]) - -/* ---------- - * pglz_hist_idx - - * - * Computes the history table slot for the lookup by the next 4 - * characters in the input. - * - * NB: because we use the next 4 characters, we are not guaranteed to - * find 3-character matches; they very possibly will be in the wrong - * hash list. This seems an acceptable tradeoff for spreading out the - * hash keys more. - * ---------- - */ -#define pglz_hist_idx(_s,_e, _mask) ( \ - ((((_e) - (_s)) < 4) ? (int) (_s)[0] : \ - (((_s)[0] << 6) ^ ((_s)[1] << 4) ^ \ - ((_s)[2] << 2) ^ (_s)[3])) & (_mask) \ - ) - - -/* ---------- - * pglz_hist_add - - * - * Adds a new entry to the history table. - * - * If _recycle is true, then we are recycling a previously used entry, - * and must first delink it from its old hashcode's linked list. - * - * NOTE: beware of multiple evaluations of macro's arguments, and note that - * _hn and _recycle are modified in the macro. - * ---------- - */ -#define pglz_hist_add(_hs,_he,_hn,_recycle,_s,_e, _mask) \ -do { \ - int __hindex = pglz_hist_idx((_s),(_e), (_mask)); \ - int16 *__myhsp = &(_hs)[__hindex]; \ - PGLZ_HistEntry *__myhe = &(_he)[_hn]; \ - if (_recycle) { \ - if (__myhe->prev == NULL) \ - (_hs)[__myhe->hindex] = __myhe->next - (_he); \ - else \ - __myhe->prev->next = __myhe->next; \ - if (__myhe->next != NULL) \ - __myhe->next->prev = __myhe->prev; \ - } \ - __myhe->next = &(_he)[*__myhsp]; \ - __myhe->prev = NULL; \ - __myhe->hindex = __hindex; \ - __myhe->pos = (_s); \ - /* If there was an existing entry in this hash slot, link */ \ - /* this new entry to it. However, the 0th entry in the */ \ - /* entries table is unused, so we can freely scribble on it. */ \ - /* So don't bother checking if the slot was used - we'll */ \ - /* scribble on the unused entry if it was not, but that's */ \ - /* harmless. Avoiding the branch in this critical path */ \ - /* speeds this up a little bit. */ \ - /* if (*__myhsp != INVALID_ENTRY) */ \ - (_he)[(*__myhsp)].prev = __myhe; \ - *__myhsp = _hn; \ - if (++(_hn) >= PGLZ_HISTORY_SIZE + 1) { \ - (_hn) = 1; \ - (_recycle) = true; \ - } \ -} while (0) - - -/* ---------- - * pglz_out_ctrl - - * - * Outputs the last and allocates a new control byte if needed. - * ---------- - */ -#define pglz_out_ctrl(__ctrlp,__ctrlb,__ctrl,__buf) \ -do { \ - if ((__ctrl & 0xff) == 0) \ - { \ - *(__ctrlp) = __ctrlb; \ - __ctrlp = (__buf)++; \ - __ctrlb = 0; \ - __ctrl = 1; \ - } \ -} while (0) - - -/* ---------- - * pglz_out_literal - - * - * Outputs a literal byte to the destination buffer including the - * appropriate control bit. - * ---------- - */ -#define pglz_out_literal(_ctrlp,_ctrlb,_ctrl,_buf,_byte) \ -do { \ - pglz_out_ctrl(_ctrlp,_ctrlb,_ctrl,_buf); \ - *(_buf)++ = (unsigned char)(_byte); \ - _ctrl <<= 1; \ -} while (0) - - -/* ---------- - * pglz_out_tag - - * - * Outputs a backward reference tag of 2-4 bytes (depending on - * offset and length) to the destination buffer including the - * appropriate control bit. - * ---------- - */ -#define pglz_out_tag(_ctrlp,_ctrlb,_ctrl,_buf,_len,_off) \ -do { \ - pglz_out_ctrl(_ctrlp,_ctrlb,_ctrl,_buf); \ - _ctrlb |= _ctrl; \ - _ctrl <<= 1; \ - if (_len > 17) \ - { \ - (_buf)[0] = (unsigned char)((((_off) & 0xf00) >> 4) | 0x0f); \ - (_buf)[1] = (unsigned char)(((_off) & 0xff)); \ - (_buf)[2] = (unsigned char)((_len) - 18); \ - (_buf) += 3; \ - } else { \ - (_buf)[0] = (unsigned char)((((_off) & 0xf00) >> 4) | ((_len) - 3)); \ - (_buf)[1] = (unsigned char)((_off) & 0xff); \ - (_buf) += 2; \ - } \ -} while (0) - - -/* ---------- - * pglz_find_match - - * - * Lookup the history table if the actual input stream matches - * another sequence of characters, starting somewhere earlier - * in the input buffer. - * ---------- - */ -static inline int -pglz_find_match(int16 *hstart, const char *input, const char *end, - int *lenp, int *offp, int good_match, int good_drop, int mask) -{ - PGLZ_HistEntry *hent; - int16 hentno; - int32 len = 0; - int32 off = 0; - - /* - * Traverse the linked history list until a good enough match is found. - */ - hentno = hstart[pglz_hist_idx(input, end, mask)]; - hent = &hist_entries[hentno]; - while (hent != INVALID_ENTRY_PTR) - { - const char *ip = input; - const char *hp = hent->pos; - int32 thisoff; - int32 thislen; - - /* - * Stop if the offset does not fit into our tag anymore. - */ - thisoff = ip - hp; - if (thisoff >= 0x0fff) - break; - - /* - * Determine length of match. A better match must be larger than the - * best so far. And if we already have a match of 16 or more bytes, - * it's worth the call overhead to use memcmp() to check if this match - * is equal for the same size. After that we must fallback to - * character by character comparison to know the exact position where - * the diff occurred. - */ - thislen = 0; - if (len >= 16) - { - if (memcmp(ip, hp, len) == 0) - { - thislen = len; - ip += len; - hp += len; - while (ip < end && *ip == *hp && thislen < PGLZ_MAX_MATCH) - { - thislen++; - ip++; - hp++; - } - } - } - else - { - while (ip < end && *ip == *hp && thislen < PGLZ_MAX_MATCH) - { - thislen++; - ip++; - hp++; - } - } - - /* - * Remember this match as the best (if it is) - */ - if (thislen > len) - { - len = thislen; - off = thisoff; - } - - /* - * Advance to the next history entry - */ - hent = hent->next; - - /* - * Be happy with lesser good matches the more entries we visited. But - * no point in doing calculation if we're at end of list. - */ - if (hent != INVALID_ENTRY_PTR) - { - if (len >= good_match) - break; - good_match -= (good_match * good_drop) / 100; - } - } - - /* - * Return match information only if it results at least in one byte - * reduction. - */ - if (len > 2) - { - *lenp = len; - *offp = off; - return 1; - } - - return 0; -} - - -/* ---------- - * pglz_compress - - * - * Compresses source into dest using strategy. Returns false if a failure - * occurred, true in case of success. - * ---------- - */ -bool -pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, - const PGLZ_Strategy *strategy) -{ - unsigned char *bp = ((unsigned char *) dest) + sizeof(PGLZ_Header); - unsigned char *bstart = bp; - int hist_next = 1; - bool hist_recycle = false; - const char *dp = source; - const char *dend = source + slen; - unsigned char ctrl_dummy = 0; - unsigned char *ctrlp = &ctrl_dummy; - unsigned char ctrlb = 0; - unsigned char ctrl = 0; - bool found_match = false; - int32 match_len; - int32 match_off; - int32 good_match; - int32 good_drop; - int32 result_size; - int32 result_max; - int32 need_rate; - int hashsz; - int mask; - - /* - * Our fallback strategy is the default. - */ - if (strategy == NULL) - strategy = PGLZ_strategy_default; - - /* - * If the strategy forbids compression (at all or if source chunk size out - * of range), fail. - */ - if (strategy->match_size_good <= 0 || - slen < strategy->min_input_size || - slen > strategy->max_input_size) - return false; - - /* - * Save the original source size in the header. - */ - dest->rawsize = slen; - - /* - * Limit the match parameters to the supported range. - */ - good_match = strategy->match_size_good; - if (good_match > PGLZ_MAX_MATCH) - good_match = PGLZ_MAX_MATCH; - else if (good_match < 17) - good_match = 17; - - good_drop = strategy->match_size_drop; - if (good_drop < 0) - good_drop = 0; - else if (good_drop > 100) - good_drop = 100; - - need_rate = strategy->min_comp_rate; - if (need_rate < 0) - need_rate = 0; - else if (need_rate > 99) - need_rate = 99; - - /* - * Compute the maximum result size allowed by the strategy, namely the - * input size minus the minimum wanted compression rate. This had better - * be <= slen, else we might overrun the provided output buffer. - */ - if (slen > (INT_MAX / 100)) - { - /* Approximate to avoid overflow */ - result_max = (slen / 100) * (100 - need_rate); - } - else - result_max = (slen * (100 - need_rate)) / 100; - - /* - * Experiments suggest that these hash sizes work pretty well. A large - * hash table minimizes collision, but has a higher startup cost. For a - * small input, the startup cost dominates. The table size must be a power - * of two. - */ - if (slen < 128) - hashsz = 512; - else if (slen < 256) - hashsz = 1024; - else if (slen < 512) - hashsz = 2048; - else if (slen < 1024) - hashsz = 4096; - else - hashsz = 8192; - mask = hashsz - 1; - - /* - * Initialize the history lists to empty. We do not need to zero the - * hist_entries[] array; its entries are initialized as they are used. - */ - memset(hist_start, 0, hashsz * sizeof(int16)); - - /* - * Compress the source directly into the output buffer. - */ - while (dp < dend) - { - /* - * If we already exceeded the maximum result size, fail. - * - * We check once per loop; since the loop body could emit as many as 4 - * bytes (a control byte and 3-byte tag), PGLZ_MAX_OUTPUT() had better - * allow 4 slop bytes. - */ - if (bp - bstart >= result_max) - return false; - - /* - * If we've emitted more than first_success_by bytes without finding - * anything compressible at all, fail. This lets us fall out - * reasonably quickly when looking at incompressible input (such as - * pre-compressed data). - */ - if (!found_match && bp - bstart >= strategy->first_success_by) - return false; - - /* - * Try to find a match in the history - */ - if (pglz_find_match(hist_start, dp, dend, &match_len, - &match_off, good_match, good_drop, mask)) - { - /* - * Create the tag and add history entries for all matched - * characters. - */ - pglz_out_tag(ctrlp, ctrlb, ctrl, bp, match_len, match_off); - while (match_len--) - { - pglz_hist_add(hist_start, hist_entries, - hist_next, hist_recycle, - dp, dend, mask); - dp++; /* Do not do this ++ in the line above! */ - /* The macro would do it four times - Jan. */ - } - found_match = true; - } - else - { - /* - * No match found. Copy one literal byte. - */ - pglz_out_literal(ctrlp, ctrlb, ctrl, bp, *dp); - pglz_hist_add(hist_start, hist_entries, - hist_next, hist_recycle, - dp, dend, mask); - dp++; /* Do not do this ++ in the line above! */ - /* The macro would do it four times - Jan. */ - } - } - - /* - * Write out the last control byte and check that we haven't overrun the - * output size allowed by the strategy. - */ - *ctrlp = ctrlb; - result_size = bp - bstart; - if (result_size >= result_max) - return false; - - /* - * Success - need only fill in the actual length of the compressed datum. - */ - SET_VARSIZE_COMPRESSED(dest, result_size + sizeof(PGLZ_Header)); - - return true; -} - - -/* ---------- - * pglz_decompress - - * - * Decompresses source into dest. Returns false if a failure - * occurred, true in case of success. - * ---------- - */ -bool -pglz_decompress(const PGLZ_Header *source, char *dest) -{ - const unsigned char *sp; - const unsigned char *srcend; - unsigned char *dp; - unsigned char *destend; - - sp = ((const unsigned char *) source) + sizeof(PGLZ_Header); - srcend = ((const unsigned char *) source) + VARSIZE(source); - dp = (unsigned char *) dest; - destend = dp + source->rawsize; - - while (sp < srcend && dp < destend) - { - /* - * Read one control byte and process the next 8 items (or as many as - * remain in the compressed input). - */ - unsigned char ctrl = *sp++; - int ctrlc; - - for (ctrlc = 0; ctrlc < 8 && sp < srcend; ctrlc++) - { - if (ctrl & 1) - { - /* - * Otherwise it contains the match length minus 3 and the - * upper 4 bits of the offset. The next following byte - * contains the lower 8 bits of the offset. If the length is - * coded as 18, another extension tag byte tells how much - * longer the match really was (0-255). - */ - int32 len; - int32 off; - - len = (sp[0] & 0x0f) + 3; - off = ((sp[0] & 0xf0) << 4) | sp[1]; - sp += 2; - if (len == 18) - len += *sp++; - - /* - * Check for output buffer overrun, to ensure we don't clobber - * memory in case of corrupt input. Note: we must advance dp - * here to ensure the error is detected below the loop. We - * don't simply put the elog inside the loop since that will - * probably interfere with optimization. - */ - if (dp + len > destend) - { - dp += len; - break; - } - - /* - * Now we copy the bytes specified by the tag from OUTPUT to - * OUTPUT. It is dangerous and platform dependent to use - * memcpy() here, because the copied areas could overlap - * extremely! - */ - while (len--) - { - *dp = dp[-off]; - dp++; - } - } - else - { - /* - * An unset control bit means LITERAL BYTE. So we just copy - * one from INPUT to OUTPUT. - */ - if (dp >= destend) /* check for buffer overrun */ - break; /* do not clobber memory */ - - *dp++ = *sp++; - } - - /* - * Advance the control bit - */ - ctrl >>= 1; - } - } - - /* - * Check we decompressed the right amount. - */ - if (dp != destend || sp != srcend) - return false; - - /* - * That's it. - */ - return true; -} diff --git a/src/include/common/pg_lzcompress.h b/src/include/common/pg_lzcompress.h deleted file mode 100644 index f36d2da8eea..00000000000 --- a/src/include/common/pg_lzcompress.h +++ /dev/null @@ -1,112 +0,0 @@ -/* ---------- - * pg_lzcompress.h - - * - * Definitions for the builtin LZ compressor - * - * src/include/common/pg_lzcompress.h - * ---------- - */ - -#ifndef _PG_LZCOMPRESS_H_ -#define _PG_LZCOMPRESS_H_ - - -/* ---------- - * PGLZ_Header - - * - * The information at the start of the compressed data. - * ---------- - */ -typedef struct PGLZ_Header -{ - int32 vl_len_; /* varlena header (do not touch directly!) */ - int32 rawsize; -} PGLZ_Header; - - -/* ---------- - * PGLZ_MAX_OUTPUT - - * - * Macro to compute the buffer size required by pglz_compress(). - * We allow 4 bytes for overrun before detecting compression failure. - * ---------- - */ -#define PGLZ_MAX_OUTPUT(_dlen) ((_dlen) + 4 + sizeof(PGLZ_Header)) - -/* ---------- - * PGLZ_RAW_SIZE - - * - * Macro to determine the uncompressed data size contained - * in the entry. - * ---------- - */ -#define PGLZ_RAW_SIZE(_lzdata) ((_lzdata)->rawsize) - - -/* ---------- - * PGLZ_Strategy - - * - * Some values that control the compression algorithm. - * - * min_input_size Minimum input data size to consider compression. - * - * max_input_size Maximum input data size to consider compression. - * - * min_comp_rate Minimum compression rate (0-99%) to require. - * Regardless of min_comp_rate, the output must be - * smaller than the input, else we don't store - * compressed. - * - * first_success_by Abandon compression if we find no compressible - * data within the first this-many bytes. - * - * match_size_good The initial GOOD match size when starting history - * lookup. When looking up the history to find a - * match that could be expressed as a tag, the - * algorithm does not always walk back entirely. - * A good match fast is usually better than the - * best possible one very late. For each iteration - * in the lookup, this value is lowered so the - * longer the lookup takes, the smaller matches - * are considered good. - * - * match_size_drop The percentage by which match_size_good is lowered - * after each history check. Allowed values are - * 0 (no change until end) to 100 (only check - * latest history entry at all). - * ---------- - */ -typedef struct PGLZ_Strategy -{ - int32 min_input_size; - int32 max_input_size; - int32 min_comp_rate; - int32 first_success_by; - int32 match_size_good; - int32 match_size_drop; -} PGLZ_Strategy; - - -/* ---------- - * The standard strategies - * - * PGLZ_strategy_default Recommended default strategy for TOAST. - * - * PGLZ_strategy_always Try to compress inputs of any length. - * Fallback to uncompressed storage only if - * output would be larger than input. - * ---------- - */ -extern const PGLZ_Strategy *const PGLZ_strategy_default; -extern const PGLZ_Strategy *const PGLZ_strategy_always; - - -/* ---------- - * Global function declarations - * ---------- - */ -extern bool pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, - const PGLZ_Strategy *strategy); -extern bool pglz_decompress(const PGLZ_Header *source, char *dest); - -#endif /* _PG_LZCOMPRESS_H_ */ diff --git a/src/include/utils/pg_lzcompress.h b/src/include/utils/pg_lzcompress.h new file mode 100644 index 00000000000..4af24a32a49 --- /dev/null +++ b/src/include/utils/pg_lzcompress.h @@ -0,0 +1,112 @@ +/* ---------- + * pg_lzcompress.h - + * + * Definitions for the builtin LZ compressor + * + * src/include/utils/pg_lzcompress.h + * ---------- + */ + +#ifndef _PG_LZCOMPRESS_H_ +#define _PG_LZCOMPRESS_H_ + + +/* ---------- + * PGLZ_Header - + * + * The information at the start of the compressed data. + * ---------- + */ +typedef struct PGLZ_Header +{ + int32 vl_len_; /* varlena header (do not touch directly!) */ + int32 rawsize; +} PGLZ_Header; + + +/* ---------- + * PGLZ_MAX_OUTPUT - + * + * Macro to compute the buffer size required by pglz_compress(). + * We allow 4 bytes for overrun before detecting compression failure. + * ---------- + */ +#define PGLZ_MAX_OUTPUT(_dlen) ((_dlen) + 4 + sizeof(PGLZ_Header)) + +/* ---------- + * PGLZ_RAW_SIZE - + * + * Macro to determine the uncompressed data size contained + * in the entry. + * ---------- + */ +#define PGLZ_RAW_SIZE(_lzdata) ((_lzdata)->rawsize) + + +/* ---------- + * PGLZ_Strategy - + * + * Some values that control the compression algorithm. + * + * min_input_size Minimum input data size to consider compression. + * + * max_input_size Maximum input data size to consider compression. + * + * min_comp_rate Minimum compression rate (0-99%) to require. + * Regardless of min_comp_rate, the output must be + * smaller than the input, else we don't store + * compressed. + * + * first_success_by Abandon compression if we find no compressible + * data within the first this-many bytes. + * + * match_size_good The initial GOOD match size when starting history + * lookup. When looking up the history to find a + * match that could be expressed as a tag, the + * algorithm does not always walk back entirely. + * A good match fast is usually better than the + * best possible one very late. For each iteration + * in the lookup, this value is lowered so the + * longer the lookup takes, the smaller matches + * are considered good. + * + * match_size_drop The percentage by which match_size_good is lowered + * after each history check. Allowed values are + * 0 (no change until end) to 100 (only check + * latest history entry at all). + * ---------- + */ +typedef struct PGLZ_Strategy +{ + int32 min_input_size; + int32 max_input_size; + int32 min_comp_rate; + int32 first_success_by; + int32 match_size_good; + int32 match_size_drop; +} PGLZ_Strategy; + + +/* ---------- + * The standard strategies + * + * PGLZ_strategy_default Recommended default strategy for TOAST. + * + * PGLZ_strategy_always Try to compress inputs of any length. + * Fallback to uncompressed storage only if + * output would be larger than input. + * ---------- + */ +extern const PGLZ_Strategy *const PGLZ_strategy_default; +extern const PGLZ_Strategy *const PGLZ_strategy_always; + + +/* ---------- + * Global function declarations + * ---------- + */ +extern bool pglz_compress(const char *source, int32 slen, PGLZ_Header *dest, + const PGLZ_Strategy *strategy); +extern void pglz_decompress(const PGLZ_Header *source, char *dest); + +#endif /* _PG_LZCOMPRESS_H_ */ diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm index 6779b18300a..004942ca07a 100644 --- a/src/tools/msvc/Mkvcbuild.pm +++ b/src/tools/msvc/Mkvcbuild.pm @@ -76,8 +76,7 @@ sub mkvcbuild push(@pgportfiles, 'rint.c') if ($vsVersion < '12.00'); our @pgcommonallfiles = qw( - exec.c pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c - username.c wait_error.c); + exec.c pgfnames.c psprintf.c relpath.c rmtree.c username.c wait_error.c); our @pgcommonfrontendfiles = (@pgcommonallfiles, qw(fe_memutils.c)); -- cgit v1.2.3