847f03ab20
This will allow these types to be used as the key in an SkTHashSet/Map without providing a custom Traits class. Change-Id: I41bfc1d43f3909d3653b4f12ac39e2a288235052 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/515356 Auto-Submit: John Stiles <johnstiles@google.com> Reviewed-by: Ben Wagner <bungeman@google.com>
100 lines
4.0 KiB
C++
100 lines
4.0 KiB
C++
/*
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* Copyright 2012 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "include/core/SkTypes.h"
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#include "include/private/SkChecksum.h"
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#include "include/utils/SkRandom.h"
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#include "src/core/SkOpts.h"
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#include "tests/Test.h"
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DEF_TEST(Checksum, r) {
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// Put 128 random bytes into two identical buffers. Any multiple of 4 will do.
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const size_t kBytes = SkAlign4(128);
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SkRandom rand;
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uint32_t data[kBytes/4], tweaked[kBytes/4];
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for (size_t i = 0; i < SK_ARRAY_COUNT(tweaked); ++i) {
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data[i] = tweaked[i] = rand.nextU();
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}
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// Hash of nullptr is always 0.
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REPORTER_ASSERT(r, SkOpts::hash(nullptr, 0) == 0);
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const uint32_t hash = SkOpts::hash(data, kBytes);
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// Should be deterministic.
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REPORTER_ASSERT(r, hash == SkOpts::hash(data, kBytes));
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// Changing any single element should change the hash.
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for (size_t j = 0; j < SK_ARRAY_COUNT(tweaked); ++j) {
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const uint32_t saved = tweaked[j];
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tweaked[j] = rand.nextU();
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const uint32_t tweakedHash = SkOpts::hash(tweaked, kBytes);
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REPORTER_ASSERT(r, tweakedHash != hash);
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REPORTER_ASSERT(r, tweakedHash == SkOpts::hash(tweaked, kBytes));
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tweaked[j] = saved;
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}
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}
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DEF_TEST(GoodHash, r) {
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// 4 bytes --> hits SkChecksum::Mix fast path.
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REPORTER_ASSERT(r, SkGoodHash()(( int32_t)4) == 614249093);
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REPORTER_ASSERT(r, SkGoodHash()((uint32_t)4) == 614249093);
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}
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DEF_TEST(ChecksumCollisions, r) {
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// We noticed a few workloads that would cause hash collisions due to the way
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// our optimized hashes split into three concurrent hashes and merge those hashes together.
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//
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// One of these two workloads ought to cause an unintentional hash collision on very similar
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// data in those old algorithms, the float version on 32-bit x86 and double elsewhere.
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{
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float a[9] = { 0, 1, 2,
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3, 4, 5,
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6, 7, 8, };
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float b[9] = { 1, 2, 0,
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4, 5, 3,
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7, 8, 6, };
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REPORTER_ASSERT(r, SkOpts::hash(a, sizeof(a)) != SkOpts::hash(b, sizeof(b)));
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}
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{
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double a[9] = { 0, 1, 2,
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3, 4, 5,
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6, 7, 8, };
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double b[9] = { 1, 2, 0,
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4, 5, 3,
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7, 8, 6, };
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REPORTER_ASSERT(r, SkOpts::hash(a, sizeof(a)) != SkOpts::hash(b, sizeof(b)));
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}
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}
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DEF_TEST(ChecksumConsistent, r) {
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// We've decided to make SkOpts::hash() always return consistent results, so spot check a few:
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uint8_t bytes[256];
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for (int i = 0; i < 256; i++) {
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bytes[i] = i;
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}
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REPORTER_ASSERT(r, SkOpts::hash(bytes, 0) == 0x00000000, "%08x", SkOpts::hash(bytes, 0));
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REPORTER_ASSERT(r, SkOpts::hash(bytes, 1) == 0x00000000, "%08x", SkOpts::hash(bytes, 1));
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REPORTER_ASSERT(r, SkOpts::hash(bytes, 2) == 0xf26b8303, "%08x", SkOpts::hash(bytes, 2));
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REPORTER_ASSERT(r, SkOpts::hash(bytes, 7) == 0x18678721, "%08x", SkOpts::hash(bytes, 7));
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REPORTER_ASSERT(r, SkOpts::hash(bytes, 32) == 0x9d1ef96b, "%08x", SkOpts::hash(bytes, 32));
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REPORTER_ASSERT(r, SkOpts::hash(bytes, 63) == 0xc4b07d3a, "%08x", SkOpts::hash(bytes, 63));
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REPORTER_ASSERT(r, SkOpts::hash(bytes, 64) == 0x3535a461, "%08x", SkOpts::hash(bytes, 64));
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REPORTER_ASSERT(r, SkOpts::hash(bytes, 99) == 0x3f98a130, "%08x", SkOpts::hash(bytes, 99));
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REPORTER_ASSERT(r, SkOpts::hash(bytes,255) == 0x3b9ceab2, "%08x", SkOpts::hash(bytes,255));
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}
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DEF_TEST(ChecksumStrings, r) {
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constexpr char kMessage[] = "Checksums are supported for SkString, string, and string_view.";
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const uint32_t expectedHash = SkOpts::hash(kMessage, strlen(kMessage));
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REPORTER_ASSERT(r, expectedHash == SkGoodHash()(SkString(kMessage)));
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REPORTER_ASSERT(r, expectedHash == SkGoodHash()(std::string(kMessage)));
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REPORTER_ASSERT(r, expectedHash == SkGoodHash()(std::string_view(kMessage)));
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}
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