+------------------------------------------------------------------------
+r49 | snappy.mirrorbot@gmail.com | 2011-09-15 11:50:05 +0200 (Thu, 15 Sep 2011) | 5 lines
+
+Fix public issue #50: Include generic byteswap macros.
+Also include Solaris 10 and FreeBSD versions.
+
+R=csilvers
+
+------------------------------------------------------------------------
+r48 | snappy.mirrorbot@gmail.com | 2011-08-10 20:57:27 +0200 (Wed, 10 Aug 2011) | 5 lines
+
+Partially fix public issue 50: Remove an extra comma from the end of some
+enum declarations, as it seems the Sun compiler does not like it.
+
+Based on patch by Travis Vitek.
+
+------------------------------------------------------------------------
+r47 | snappy.mirrorbot@gmail.com | 2011-08-10 20:44:16 +0200 (Wed, 10 Aug 2011) | 4 lines
+
+Use the right #ifdef test for sys/mman.h.
+
+Based on patch by Travis Vitek.
+
+------------------------------------------------------------------------
+r46 | snappy.mirrorbot@gmail.com | 2011-08-10 03:22:09 +0200 (Wed, 10 Aug 2011) | 6 lines
+
+Fix public issue #47: Small comment cleanups in the unit test.
+
+Originally based on a patch by Patrick Pelletier.
+
+R=sanjay
+
+------------------------------------------------------------------------
+r45 | snappy.mirrorbot@gmail.com | 2011-08-10 03:14:43 +0200 (Wed, 10 Aug 2011) | 8 lines
+
+Fix public issue #46: Format description said "3-byte offset"
+instead of "4-byte offset" for the longest copies.
+
+Also fix an inconsistency in the heading for section 2.2.3.
+Both patches by Patrick Pelletier.
+
+R=csilvers
+
+------------------------------------------------------------------------
+r44 | snappy.mirrorbot@gmail.com | 2011-06-28 13:40:25 +0200 (Tue, 28 Jun 2011) | 8 lines
+
+Fix public issue #44: Make the definition and declaration of CompressFragment
+identical, even regarding cv-qualifiers.
+
+This is required to work around a bug in the Solaris Studio C++ compiler
+(it does not properly disregard cv-qualifiers when doing name mangling).
+
+R=sanjay
+
+------------------------------------------------------------------------
+r43 | snappy.mirrorbot@gmail.com | 2011-06-04 12:19:05 +0200 (Sat, 04 Jun 2011) | 7 lines
+
+Correct an inaccuracy in the Snappy format description.
+(I stumbled into this when changing the way we decompress literals.)
+
+R=csilvers
+
+Revision created by MOE tool push_codebase.
+
+------------------------------------------------------------------------
+r42 | snappy.mirrorbot@gmail.com | 2011-06-03 22:53:06 +0200 (Fri, 03 Jun 2011) | 50 lines
+
+Speed up decompression by removing a fast-path attempt.
+
+Whenever we try to enter a copy fast-path, there is a certain cost in checking
+that all the preconditions are in place, but it's normally offset by the fact
+that we can usually take the cheaper path. However, in a certain path we've
+already established that "avail < literal_length", which usually means that
+either the available space is small, or the literal is big. Both will disqualify
+us from taking the fast path, and thus we take the hit from the precondition
+checking without gaining much from having a fast path. Thus, simply don't try
+the fast path in this situation -- we're already on a slow path anyway
+(one where we need to refill more data from the reader).
+
+I'm a bit surprised at how much this gained; it could be that this path is
+more common than I thought, or that the simpler structure somehow makes the
+compiler happier. I haven't looked at the assembler, but it's a win across
+the board on both Core 2, Core i7 and Opteron, at least for the cases we
+typically care about. The gains seem to be the largest on Core i7, though.
+Results from my Core i7 workstation:
+
+
+ Benchmark Time(ns) CPU(ns) Iterations
+ ---------------------------------------------------
+ BM_UFlat/0 73337 73091 190996 1.3GB/s html [ +1.7%]
+ BM_UFlat/1 696379 693501 20173 965.5MB/s urls [ +2.7%]
+ BM_UFlat/2 9765 9734 1472135 12.1GB/s jpg [ +0.7%]
+ BM_UFlat/3 29720 29621 472973 3.0GB/s pdf [ +1.8%]
+ BM_UFlat/4 294636 293834 47782 1.3GB/s html4 [ +2.3%]
+ BM_UFlat/5 28399 28320 494700 828.5MB/s cp [ +3.5%]
+ BM_UFlat/6 12795 12760 1000000 833.3MB/s c [ +1.2%]
+ BM_UFlat/7 3984 3973 3526448 893.2MB/s lsp [ +5.7%]
+ BM_UFlat/8 991996 989322 14141 992.6MB/s xls [ +3.3%]
+ BM_UFlat/9 228620 227835 61404 636.6MB/s txt1 [ +4.0%]
+ BM_UFlat/10 197114 196494 72165 607.5MB/s txt2 [ +3.5%]
+ BM_UFlat/11 605240 603437 23217 674.4MB/s txt3 [ +3.7%]
+ BM_UFlat/12 804157 802016 17456 573.0MB/s txt4 [ +3.9%]
+ BM_UFlat/13 347860 346998 40346 1.4GB/s bin [ +1.2%]
+ BM_UFlat/14 44684 44559 315315 818.4MB/s sum [ +2.3%]
+ BM_UFlat/15 5120 5106 2739726 789.4MB/s man [ +3.3%]
+ BM_UFlat/16 76591 76355 183486 1.4GB/s pb [ +2.8%]
+ BM_UFlat/17 238564 237828 58824 739.1MB/s gaviota [ +1.6%]
+ BM_UValidate/0 42194 42060 333333 2.3GB/s html [ -0.1%]
+ BM_UValidate/1 433182 432005 32407 1.5GB/s urls [ -0.1%]
+ BM_UValidate/2 197 196 71428571 603.3GB/s jpg [ +0.5%]
+ BM_UValidate/3 14494 14462 972222 6.1GB/s pdf [ +0.5%]
+ BM_UValidate/4 168444 167836 83832 2.3GB/s html4 [ +0.1%]
+
+R=jeff
+
+Revision created by MOE tool push_codebase.
+
+------------------------------------------------------------------------
+r41 | snappy.mirrorbot@gmail.com | 2011-06-03 22:47:14 +0200 (Fri, 03 Jun 2011) | 43 lines
+
+Speed up decompression by not needing a lookup table for literal items.
+
+Looking up into and decoding the values from char_table has long shown up as a
+hotspot in the decompressor. While it turns out that it's hard to make a more
+efficient decoder for the copy ops, the literals are simple enough that we can
+decode them without needing a table lookup. (This means that 1/4 of the table
+is now unused, although that in itself doesn't buy us anything.)
+
+The gains are small, but definitely present; some tests win as much as 10%,
+but 1-4% is more typical. These results are from Core i7, in 64-bit mode;
+Core 2 and Opteron show similar results. (I've run with more iterations
+than unusual to make sure the smaller gains don't drown entirely in noise.)
+
+ Benchmark Time(ns) CPU(ns) Iterations
+ ---------------------------------------------------
+ BM_UFlat/0 74665 74428 182055 1.3GB/s html [ +3.1%]
+ BM_UFlat/1 714106 711997 19663 940.4MB/s urls [ +4.4%]
+ BM_UFlat/2 9820 9789 1427115 12.1GB/s jpg [ -1.2%]
+ BM_UFlat/3 30461 30380 465116 2.9GB/s pdf [ +0.8%]
+ BM_UFlat/4 301445 300568 46512 1.3GB/s html4 [ +2.2%]
+ BM_UFlat/5 29338 29263 479452 801.8MB/s cp [ +1.6%]
+ BM_UFlat/6 13004 12970 1000000 819.9MB/s c [ +2.1%]
+ BM_UFlat/7 4180 4168 3349282 851.4MB/s lsp [ +1.3%]
+ BM_UFlat/8 1026149 1024000 10000 959.0MB/s xls [+10.7%]
+ BM_UFlat/9 237441 236830 59072 612.4MB/s txt1 [ +0.3%]
+ BM_UFlat/10 203966 203298 69307 587.2MB/s txt2 [ +0.8%]
+ BM_UFlat/11 627230 625000 22400 651.2MB/s txt3 [ +0.7%]
+ BM_UFlat/12 836188 833979 16787 551.0MB/s txt4 [ +1.3%]
+ BM_UFlat/13 351904 350750 39886 1.4GB/s bin [ +3.8%]
+ BM_UFlat/14 45685 45562 308370 800.4MB/s sum [ +5.9%]
+ BM_UFlat/15 5286 5270 2656546 764.9MB/s man [ +1.5%]
+ BM_UFlat/16 78774 78544 178117 1.4GB/s pb [ +4.3%]
+ BM_UFlat/17 242270 241345 58091 728.3MB/s gaviota [ +1.2%]
+ BM_UValidate/0 42149 42000 333333 2.3GB/s html [ -3.0%]
+ BM_UValidate/1 432741 431303 32483 1.5GB/s urls [ +7.8%]
+ BM_UValidate/2 198 197 71428571 600.7GB/s jpg [+16.8%]
+ BM_UValidate/3 14560 14521 965517 6.1GB/s pdf [ -4.1%]
+ BM_UValidate/4 169065 168671 83832 2.3GB/s html4 [ -2.9%]
+
+R=jeff
+
+Revision created by MOE tool push_codebase.
+
+------------------------------------------------------------------------
+r40 | snappy.mirrorbot@gmail.com | 2011-06-03 00:57:41 +0200 (Fri, 03 Jun 2011) | 2 lines
+
+Release Snappy 1.0.3.
+
------------------------------------------------------------------------
r39 | snappy.mirrorbot@gmail.com | 2011-06-02 20:06:54 +0200 (Thu, 02 Jun 2011) | 11 lines
// Returns an "end" pointer into "op" buffer.
// "end - op" is the compressed size of "input".
namespace internal {
-char* CompressFragment(const char* const input,
- const size_t input_size,
+char* CompressFragment(const char* input,
+ size_t input_size,
char* op,
uint16* table,
const int table_size) {
}
const unsigned char c = *(reinterpret_cast<const unsigned char*>(ip++));
- const uint32 entry = char_table[c];
- const uint32 trailer = LittleEndian::Load32(ip) & wordmask[entry >> 11];
- ip += entry >> 11;
- const uint32 length = entry & 0xff;
if ((c & 0x3) == LITERAL) {
- uint32 literal_length = length + trailer;
+ uint32 literal_length = c >> 2;
+ if (PREDICT_FALSE(literal_length >= 60)) {
+ // Long literal.
+ const uint32 literal_length_length = literal_length - 59;
+ literal_length =
+ LittleEndian::Load32(ip) & wordmask[literal_length_length];
+ ip += literal_length_length;
+ }
+ ++literal_length;
+
uint32 avail = ip_limit_ - ip;
while (avail < literal_length) {
- bool allow_fast_path = (avail >= 16);
- if (!writer->Append(ip, avail, allow_fast_path)) return;
+ if (!writer->Append(ip, avail, false)) return;
literal_length -= avail;
reader_->Skip(peeked_);
size_t n;
}
ip += literal_length;
} else {
+ const uint32 entry = char_table[c];
+ const uint32 trailer = LittleEndian::Load32(ip) & wordmask[entry >> 11];
+ const uint32 length = entry & 0xff;
+ ip += entry >> 11;
+
// copy_offset/256 is encoded in bits 8..10. By just fetching
// those bits, we get copy_offset (since the bit-field starts at
// bit 8).
projects / apitrace / commitdiff