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Improve StaticString hashing

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In a lot of case the StaticString hash can be computed a compile time,
so we now take advantage of that.

Removed StaticString(const char*) ctor, and replaced it with a
StaticString::make() method.

Fixed a couple wrong uses of the old StaticString(const char*) ctor.
This commit is contained in:
Mathias Agopian
2018-12-12 17:47:21 -08:00
committed by Mathias Agopian
parent d135108763
commit 2d6b43827e
8 changed files with 76 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files
filament/src/DebugRegistry.cpp
+1 -1
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@@ -34,7 +34,7 @@ FDebugRegistry::FDebugRegistry() noexcept {
UTILS_NOINLINE
void *FDebugRegistry::getPropertyAddress(const char *name) noexcept {
StaticString key(name, strlen(name));
StaticString key = StaticString::make(name, strlen(name));
auto &propertyMap = mPropertyMap;
if (propertyMap.find(key) == propertyMap.end()) {
return nullptr;
filament/src/driver/opengl/OpenGLDriver.cpp
+1 -1
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@@ -165,7 +165,7 @@ OpenGLDriver::OpenGLDriver(OpenGLPlatform* platform) noexcept
ExtentionSet exts;
for (GLint i = 0; i < n; i++) {
const char * const ext = (const char*)glGetStringi(GL_EXTENSIONS, (GLuint)i);
exts.emplace(ext, strlen(ext));
exts.insert(StaticString::make(ext, strlen(ext)));
if (DEBUG_PRINT_EXTENSIONS) {
slog.d << ext << io::endl;
}
filament/src/driver/vulkan/VulkanDriver.cpp
+1 -1
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@@ -948,7 +948,7 @@ void VulkanDriver::debugCommand(const char* methodName) {
static const utils::StaticString BEGIN_COMMAND = "beginRenderPass";
static const utils::StaticString END_COMMAND = "endRenderPass";
static bool inRenderPass = false;
const utils::StaticString command(methodName, strlen(methodName));
const utils::StaticString command = utils::StaticString::make(methodName, strlen(methodName));
if (command == BEGIN_COMMAND) {
assert(!inRenderPass);
inRenderPass = true;
libs/filabridge/include/private/filament/SamplerInterfaceBlock.h
+4 -2
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@@ -55,9 +55,10 @@ public:
Builder& name(utils::CString const& interfaceBlockName);
Builder& name(utils::CString&& interfaceBlockName);
Builder& name(utils::StaticString const& interfaceBlockName);
template<size_t N>
Builder& name(utils::StringLiteral<N> const& interfaceBlockName) {
return name(utils::StaticString{interfaceBlockName, N - 1});
return name(utils::StaticString{ interfaceBlockName });
}
// Add a sampler
@@ -70,10 +71,11 @@ public:
Builder& add(utils::StaticString const& samplerName, Type type, Format format,
Precision precision = Precision::MEDIUM,
bool multisample = false) noexcept;
template<size_t N>
Builder& add(utils::StringLiteral<N> const& samplerName, Type type, Format format,
Precision precision = Precision::MEDIUM, bool multisample = false) {
return add(utils::StaticString{ samplerName, N - 1 }, type, format, precision);
return add(utils::StaticString{ samplerName }, type, format, precision);
}
// build and return the SamplerInterfaceBlock
libs/filabridge/include/private/filament/UniformInterfaceBlock.h
+4 -2
View File
@@ -51,9 +51,10 @@ public:
Builder& name(utils::CString const& interfaceBlockName);
Builder& name(utils::CString&& interfaceBlockName);
Builder& name(utils::StaticString const& interfaceBlockName);
template<size_t N>
Builder& name(utils::StringLiteral<N> const& interfaceBlockName) {
return name(utils::StaticString{ interfaceBlockName, (utils::CString::size_type)(N - 1) });
return name(utils::StaticString{ interfaceBlockName });
}
// Add a uniform
@@ -63,10 +64,11 @@ public:
Type type, Precision precision = Precision::DEFAULT);
Builder& add(utils::StaticString const& uniformName, size_t size,
Type type, Precision precision = Precision::DEFAULT);
template<size_t N>
Builder& add(utils::StringLiteral<N> const& uniformName, size_t size,
Type type, Precision precision = Precision::DEFAULT) {
return add(utils::StaticString{ uniformName, N - 1 }, size, type, precision);
return add(utils::StaticString{ uniformName }, size, type, precision);
}
// build and return the UniformInterfaceBlock
libs/image/src/ImageSampler.cpp
+2 -2
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@@ -361,8 +361,8 @@ Filter filterFromString(const char* rawname) {
{ "MINIMUM", Filter::MINIMUM},
};
string name = rawname;
for (auto& c: name) c = toupper((unsigned char) c);
auto iter = map.find({ name.c_str(), name.size() });
for (auto& c: name) { c = toupper((unsigned char)c); }
auto iter = map.find(StaticString::make(name.c_str(), name.size()));
return iter == map.end() ? Filter::DEFAULT : iter->second;
}
libs/utils/include/utils/CString.h
+48 -22
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@@ -27,6 +27,19 @@
namespace utils {
//! \privatesection
struct hashCStrings {
typedef const char* argument_type;
typedef size_t result_type;
result_type operator()(argument_type cstr) const noexcept {
size_t hash = 5381;
while (int c = *cstr++) {
hash = (hash * 33u) ^ size_t(c);
}
return hash;
}
};
//! \privatesection
struct equalCStrings {
typedef const char* first_argument_type;
@@ -37,20 +50,6 @@ struct equalCStrings {
}
};
//! \privatesection
struct hashCStrings {
typedef const char* argument_type;
typedef size_t result_type;
result_type operator()(argument_type cstr) const noexcept {
// TODO: is this good enough?
size_t hash = 5381;
while (int c = *cstr++) {
hash = hash * 33 ^ c;
}
return hash;
}
};
//! \privatesection
struct lessCStrings {
typedef const char* first_argument_type;
@@ -80,24 +79,40 @@ public:
StaticString() noexcept = default;
// initialization from a string literal
template <size_t N>
StaticString(StringLiteral<N> const& other) noexcept // NOLINT(google-explicit-constructor)
: mString(other),
mLength(size_type(N - 1)) {
}
StaticString(const_pointer literal, size_t length) noexcept
: mString(literal),
mLength(size_type(length)) {
mLength(size_type(N - 1)),
mHash(computeHash(other)) {
}
// assignment from a string literal
template<size_t N>
StaticString& operator=(StringLiteral<N> const& other) noexcept {
mString = other;
mLength = size_type(N - 1);
mHash = computeHash(other);
return *this;
}
// helper to make a StaticString from a C string that is known to be a string literal
static constexpr StaticString make(const_pointer literal, size_t length) noexcept {
StaticString r;
r.mString = literal;
r.mLength = size_type(length);
size_type hash = 5381;
while (int c = *literal++) {
hash = (hash * 33u) ^ size_type(c);
}
r.mHash = hash;
return r;
}
static StaticString make(const_pointer literal) noexcept {
return make(literal, strlen(literal));
}
const_pointer c_str() const noexcept { return mString; }
const_pointer data() const noexcept { return mString; }
size_type size() const noexcept { return mLength; }
@@ -130,9 +145,21 @@ public:
return begin()[size() - 1];
}
size_type getHash() const noexcept { return mHash; }
private:
const_pointer mString = nullptr;
size_type mLength = 0;
size_type mHash = 0;
template<size_t N>
static constexpr size_type computeHash(StringLiteral<N> const& s) noexcept {
size_type hash = 5381;
for (size_t i = 0; i < N - 1; i++) {
hash = (hash * 33u) ^ size_type(s[i]);
}
return hash;
}
int compare(const StaticString& rhs) const noexcept;
@@ -344,9 +371,8 @@ template<>
struct hash<utils::StaticString> {
typedef utils::StaticString argument_type;
typedef size_t result_type;
utils::hashCStrings hasher;
size_t operator()(const utils::StaticString& s) const noexcept {
return hasher(s.c_str());
return s.getHash();
}
};
libs/utils/test/test_CString.cpp
+15
View File
@@ -24,3 +24,18 @@ TEST(CString, EmptyString) {
CString emptyString("");
EXPECT_STREQ("", emptyString.c_str_safe());
}
TEST(StaticString, hash) {
StaticString a("Hello World!");
StaticString b = StaticString::make("Hello World!");
StaticString c("Hello World");
StaticString d("Hello World!");
EXPECT_EQ(a.getHash(), b.getHash());
EXPECT_EQ(a.getHash(), d.getHash());
EXPECT_NE(a.getHash(), c.getHash());
EXPECT_NE(b.getHash(), c.getHash());
std::hash<StaticString> ha;
EXPECT_EQ(ha(a), a.getHash());
}