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SkBitmapHasher: use 64-bit-truncated MD5 instead of 64-bit CityHash

Browse Source 
BUG=https://code.google.com/p/skia/issues/detail?id=1257

(if we change our mind within the next few days, we can toggle the
BITMAPHASHER_USES_TRUNCATED_MD5 #ifdef ; at some point, we'll remove that
option so we can delete our CityHash implementation entirely)

R=bungeman@google.com

Review URL: https://codereview.chromium.org/14054012

git-svn-id: http://skia.googlecode.com/svn/trunk@8992 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
epoger@google.com 2013-05-03 17:35:39 +00:00
parent 25720b4d7e
commit b4ca46d748
16 changed files with 134 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
gm/tests/outputs/compared-against-different-pixels-images/output-expected/json-summary.txt
View File

@ -2,10 +2,10 @@
"actual-results" : {
"failed" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
},
"failure-ignored" : null,
@ -14,11 +14,11 @@
},
"expected-results" : {
"565/selftest1" : {
"allowed-bitmap-cityhashes" : [ 11071285354315388429 ],
"allowed-bitmap-cityhashes" : [ 8863920166200910451 ],
"ignore-failure" : false
},
"8888/selftest1" : {
"allowed-bitmap-cityhashes" : [ 16527650414256125612 ],
"allowed-bitmap-cityhashes" : [ 13451349865803053525 ],
"ignore-failure" : false
}
}

8
gm/tests/outputs/compared-against-different-pixels-json/output-expected/json-summary.txt
View File

@ -2,10 +2,10 @@
"actual-results" : {
"failed" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
},
"failure-ignored" : null,
@ -14,11 +14,11 @@
},
"expected-results" : {
"565/selftest1" : {
"allowed-bitmap-cityhashes" : [ 11071285354315388429 ],
"allowed-bitmap-cityhashes" : [ 8863920166200910451 ],
"ignore-failure" : false
},
"8888/selftest1" : {
"allowed-bitmap-cityhashes" : [ 16527650414256125612 ],
"allowed-bitmap-cityhashes" : [ 13451349865803053525 ],
"ignore-failure" : false
}
}

4
gm/tests/outputs/compared-against-empty-dir/output-expected/json-summary.txt
View File

@ -4,10 +4,10 @@
"failure-ignored" : null,
"no-comparison" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
},
"succeeded" : null

8
gm/tests/outputs/compared-against-identical-bytes-images/output-expected/json-summary.txt
View File

@ -5,20 +5,20 @@
"no-comparison" : null,
"succeeded" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
}
},
"expected-results" : {
"565/selftest1" : {
"allowed-bitmap-cityhashes" : [ 9512553915271796906 ],
"allowed-bitmap-cityhashes" : [ 12927999507540085554 ],
"ignore-failure" : false
},
"8888/selftest1" : {
"allowed-bitmap-cityhashes" : [ 14022967492765711532 ],
"allowed-bitmap-cityhashes" : [ 1209453360120438698 ],
"ignore-failure" : false
}
}

8
gm/tests/outputs/compared-against-identical-bytes-json/output-expected/json-summary.txt
View File

@ -5,20 +5,20 @@
"no-comparison" : null,
"succeeded" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
}
},
"expected-results" : {
"565/selftest1" : {
"allowed-bitmap-cityhashes" : [ 9512553915271796906 ],
"allowed-bitmap-cityhashes" : [ 12927999507540085554 ],
"ignore-failure" : false
},
"8888/selftest1" : {
"allowed-bitmap-cityhashes" : [ 14022967492765711532 ],
"allowed-bitmap-cityhashes" : [ 1209453360120438698 ],
"ignore-failure" : false
}
}

8
gm/tests/outputs/compared-against-identical-pixels-images/output-expected/json-summary.txt
View File

@ -5,20 +5,20 @@
"no-comparison" : null,
"succeeded" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
}
},
"expected-results" : {
"565/selftest1" : {
"allowed-bitmap-cityhashes" : [ 9512553915271796906 ],
"allowed-bitmap-cityhashes" : [ 12927999507540085554 ],
"ignore-failure" : false
},
"8888/selftest1" : {
"allowed-bitmap-cityhashes" : [ 14022967492765711532 ],
"allowed-bitmap-cityhashes" : [ 1209453360120438698 ],
"ignore-failure" : false
}
}

8
gm/tests/outputs/compared-against-identical-pixels-json/output-expected/json-summary.txt
View File

@ -5,20 +5,20 @@
"no-comparison" : null,
"succeeded" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
}
},
"expected-results" : {
"565/selftest1" : {
"allowed-bitmap-cityhashes" : [ 9512553915271796906 ],
"allowed-bitmap-cityhashes" : [ 12927999507540085554 ],
"ignore-failure" : false
},
"8888/selftest1" : {
"allowed-bitmap-cityhashes" : [ 14022967492765711532 ],
"allowed-bitmap-cityhashes" : [ 1209453360120438698 ],
"ignore-failure" : false
}
}

8
gm/tests/outputs/ignore-expectations-mismatch/output-expected/json-summary.txt
View File

@ -2,10 +2,10 @@
"actual-results" : {
"failed" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
},
"failure-ignored" : null,
@ -14,11 +14,11 @@
},
"expected-results" : {
"565/selftest1" : {
"allowed-bitmap-cityhashes" : [ 11071285354315388429 ],
"allowed-bitmap-cityhashes" : [ 8863920166200910451 ],
"ignore-failure" : false
},
"8888/selftest1" : {
"allowed-bitmap-cityhashes" : [ 16527650414256125612 ],
"allowed-bitmap-cityhashes" : [ 13451349865803053525 ],
"ignore-failure" : false
}
}

8
gm/tests/outputs/intentionally-skipped-tests/output-expected/json-summary.txt
View File

@ -4,16 +4,16 @@
"failure-ignored" : null,
"no-comparison" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"565/selftest2" : {
"bitmap-cityhash" : 11071285354315388429
"bitmap-cityhash" : 8863920166200910451
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
},
"8888/selftest2" : {
"bitmap-cityhash" : 16527650414256125612
"bitmap-cityhash" : 13451349865803053525
}
},
"succeeded" : null

4
gm/tests/outputs/no-readpath/output-expected/json-summary.txt
View File

@ -4,10 +4,10 @@
"failure-ignored" : null,
"no-comparison" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
},
"succeeded" : null

4
gm/tests/outputs/nonverbose/output-expected/json-summary.txt
View File

@ -4,10 +4,10 @@
"failure-ignored" : null,
"no-comparison" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
},
"succeeded" : null

12
gm/tests/outputs/pipe-playback-failure/output-expected/json-summary.txt
View File

@ -2,31 +2,31 @@
"actual-results" : {
"failed" : {
"comparison/selftest1-pipe" : {
"bitmap-cityhash" : 4259036727585789440
"bitmap-cityhash" : 6140979239232854774
}
},
"failure-ignored" : null,
"no-comparison" : null,
"succeeded" : {
"565/selftest1" : {
"bitmap-cityhash" : 9512553915271796906
"bitmap-cityhash" : 12927999507540085554
},
"8888/selftest1" : {
"bitmap-cityhash" : 14022967492765711532
"bitmap-cityhash" : 1209453360120438698
}
}
},
"expected-results" : {
"565/selftest1" : {
"allowed-bitmap-cityhashes" : [ 9512553915271796906 ],
"allowed-bitmap-cityhashes" : [ 12927999507540085554 ],
"ignore-failure" : false
},
"8888/selftest1" : {
"allowed-bitmap-cityhashes" : [ 14022967492765711532 ],
"allowed-bitmap-cityhashes" : [ 1209453360120438698 ],
"ignore-failure" : false
},
"comparison/selftest1-pipe" : {
"allowed-bitmap-cityhashes" : [ 14022967492765711532 ],
"allowed-bitmap-cityhashes" : [ 1209453360120438698 ],
"ignore-failure" : false
}
}

46
include/core/SkEndian.h
View File

@ -65,7 +65,7 @@ template<uint32_t N> struct SkTEndianSwap32 {
(N >> 24);
};
/** Vector version of SkEndianSwap16(), which swaps the
/** Vector version of SkEndianSwap32(), which swaps the
bytes of each value in the array.
*/
static inline void SkEndianSwap32s(uint32_t array[], int count) {
@ -77,26 +77,70 @@ static inline void SkEndianSwap32s(uint32_t array[], int count) {
}
}
/** Reverse all 8 bytes in a 64bit value.
e.g. 0x1122334455667788 -> 0x8877665544332211
*/
static inline uint64_t SkEndianSwap64(uint64_t value) {
return (((value & 0x00000000000000FFULL) << (8*7)) |
((value & 0x000000000000FF00ULL) << (8*5)) |
((value & 0x0000000000FF0000ULL) << (8*3)) |
((value & 0x00000000FF000000ULL) << (8*1)) |
((value & 0x000000FF00000000ULL) >> (8*1)) |
((value & 0x0000FF0000000000ULL) >> (8*3)) |
((value & 0x00FF000000000000ULL) >> (8*5)) |
((value) >> (8*7)));
}
template<uint64_t N> struct SkTEndianSwap64 {
static const uint64_t value = (((N & 0x00000000000000FFULL) << (8*7)) |
((N & 0x000000000000FF00ULL) << (8*5)) |
((N & 0x0000000000FF0000ULL) << (8*3)) |
((N & 0x00000000FF000000ULL) << (8*1)) |
((N & 0x000000FF00000000ULL) >> (8*1)) |
((N & 0x0000FF0000000000ULL) >> (8*3)) |
((N & 0x00FF000000000000ULL) >> (8*5)) |
((N) >> (8*7)));
};
/** Vector version of SkEndianSwap64(), which swaps the
bytes of each value in the array.
*/
static inline void SkEndianSwap64s(uint64_t array[], int count) {
SkASSERT(count == 0 || array != NULL);
while (--count >= 0) {
*array = SkEndianSwap64(*array);
array += 1;
}
}
#ifdef SK_CPU_LENDIAN
#define SkEndian_SwapBE16(n) SkEndianSwap16(n)
#define SkEndian_SwapBE32(n) SkEndianSwap32(n)
#define SkEndian_SwapBE64(n) SkEndianSwap64(n)
#define SkEndian_SwapLE16(n) (n)
#define SkEndian_SwapLE32(n) (n)
#define SkEndian_SwapLE64(n) (n)
#define SkTEndian_SwapBE16(n) SkTEndianSwap16<n>::value
#define SkTEndian_SwapBE32(n) SkTEndianSwap32<n>::value
#define SkTEndian_SwapBE64(n) SkTEndianSwap64<n>::value
#define SkTEndian_SwapLE16(n) (n)
#define SkTEndian_SwapLE32(n) (n)
#define SkTEndian_SwapLE64(n) (n)
#else // SK_CPU_BENDIAN
#define SkEndian_SwapBE16(n) (n)
#define SkEndian_SwapBE32(n) (n)
#define SkEndian_SwapBE64(n) (n)
#define SkEndian_SwapLE16(n) SkEndianSwap16(n)
#define SkEndian_SwapLE32(n) SkEndianSwap32(n)
#define SkEndian_SwapLE64(n) SkEndianSwap64(n)
#define SkTEndian_SwapBE16(n) (n)
#define SkTEndian_SwapBE32(n) (n)
#define SkTEndian_SwapBE64(n) (n)
#define SkTEndian_SwapLE16(n) SkTEndianSwap16<n>::value
#define SkTEndian_SwapLE32(n) SkTEndianSwap32<n>::value
#define SkTEndian_SwapLE64(n) SkTEndianSwap64<n>::value
#endif
// When a bytestream is embedded in a 32-bit word, how far we need to

32
src/utils/SkBitmapHasher.cpp
View File

@ -7,15 +7,20 @@
#include "SkBitmap.h"
#include "SkBitmapHasher.h"
#include "SkCityHash.h"
#include "SkEndian.h"
#include "SkImageEncoder.h"
#ifdef BITMAPHASHER_USES_TRUNCATED_MD5
#include "SkMD5.h"
#else
#include "SkCityHash.h"
#include "SkStream.h"
#endif
/**
* Write an integer value to a stream in little-endian order.
* Write an int32 value to a stream in little-endian order.
*/
static void write_int_to_buffer(uint32_t val, SkWStream* out) {
static void write_int32_to_buffer(uint32_t val, SkWStream* out) {
val = SkEndian_SwapLE32(val);
for (size_t byte = 0; byte < 4; ++byte) {
out->write8((uint8_t)(val & 0xff));
@ -23,18 +28,29 @@ static void write_int_to_buffer(uint32_t val, SkWStream* out) {
}
}
/**
* Return the first 8 bytes of a bytearray, encoded as a little-endian uint64.
*/
static inline uint64_t first_8_bytes_as_uint64(const uint8_t *bytearray) {
return SkEndian_SwapLE64(*(reinterpret_cast<const uint64_t *>(bytearray)));
}
/*static*/ bool SkBitmapHasher::ComputeDigestInternal(const SkBitmap& bitmap,
SkHashDigest *result) {
#ifdef BITMAPHASHER_USES_TRUNCATED_MD5
SkMD5 out;
#else
size_t pixelBufferSize = bitmap.width() * bitmap.height() * 4;
size_t totalBufferSize = pixelBufferSize + 2 * sizeof(uint32_t);
SkAutoMalloc bufferManager(totalBufferSize);
char *bufferStart = static_cast<char *>(bufferManager.get());
SkMemoryWStream out(bufferStart, totalBufferSize);
#endif
// start with the x/y dimensions
write_int_to_buffer(SkToU32(bitmap.width()), &out);
write_int_to_buffer(SkToU32(bitmap.height()), &out);
write_int32_to_buffer(SkToU32(bitmap.width()), &out);
write_int32_to_buffer(SkToU32(bitmap.height()), &out);
// add all the pixel data
SkAutoTDelete<SkImageEncoder> enc(CreateARGBImageEncoder());
@ -42,7 +58,13 @@ static void write_int_to_buffer(uint32_t val, SkWStream* out) {
return false;
}
#ifdef BITMAPHASHER_USES_TRUNCATED_MD5
SkMD5::Digest digest;
out.finish(digest);
*result = first_8_bytes_as_uint64(digest.data);
#else
*result = SkCityHash::Compute64(bufferStart, totalBufferSize);
#endif
return true;
}

2
src/utils/SkBitmapHasher.h
View File

@ -11,6 +11,8 @@
#include "SkBitmap.h"
#define BITMAPHASHER_USES_TRUNCATED_MD5
// TODO(epoger): Soon, SkHashDigest will become a real class of its own,
// and callers won't be able to assume it converts to/from a uint64_t.
typedef uint64_t SkHashDigest;

16
tests/BitmapHasherTest.cpp
View File

@ -42,19 +42,35 @@ namespace skiatest {
// initial test case
CreateTestBitmap(bitmap, SkBitmap::kARGB_8888_Config, 333, 555, SK_ColorBLUE);
REPORTER_ASSERT(fReporter, SkBitmapHasher::ComputeDigest(bitmap, &digest));
#ifdef BITMAPHASHER_USES_TRUNCATED_MD5
REPORTER_ASSERT(fReporter, digest == 0xfb2903562766ef87ULL);
#else
REPORTER_ASSERT(fReporter, digest == 0x18f9df68b1b02f38ULL);
#endif
// same pixel data but different dimensions should yield a different checksum
CreateTestBitmap(bitmap, SkBitmap::kARGB_8888_Config, 555, 333, SK_ColorBLUE);
REPORTER_ASSERT(fReporter, SkBitmapHasher::ComputeDigest(bitmap, &digest));
#ifdef BITMAPHASHER_USES_TRUNCATED_MD5
REPORTER_ASSERT(fReporter, digest == 0xfe04023fb97d0f61ULL);
#else
REPORTER_ASSERT(fReporter, digest == 0x6b0298183f786c8eULL);
#endif
// same dimensions but different color should yield a different checksum
CreateTestBitmap(bitmap, SkBitmap::kARGB_8888_Config, 555, 333, SK_ColorGREEN);
REPORTER_ASSERT(fReporter, SkBitmapHasher::ComputeDigest(bitmap, &digest));
#ifdef BITMAPHASHER_USES_TRUNCATED_MD5
REPORTER_ASSERT(fReporter, digest == 0x2423c51cad6d1edcULL);
#else
REPORTER_ASSERT(fReporter, digest == 0xc6b4b3f6fadaaf37ULL);
#endif
// same pixel colors in a different config should yield the same checksum
CreateTestBitmap(bitmap, SkBitmap::kARGB_4444_Config, 555, 333, SK_ColorGREEN);
REPORTER_ASSERT(fReporter, SkBitmapHasher::ComputeDigest(bitmap, &digest));
#ifdef BITMAPHASHER_USES_TRUNCATED_MD5
REPORTER_ASSERT(fReporter, digest == 0x2423c51cad6d1edcULL);
#else
REPORTER_ASSERT(fReporter, digest == 0xc6b4b3f6fadaaf37ULL);
#endif
}
Reporter* fReporter;