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Optimize storage of tiny strings (up to 3 characters)

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This commit is contained in:
Benoit Blanchon
2025-04-09 08:55:08 +02:00
parent 7f75985e47
commit 91397f9f06
16 changed files with 229 additions and 57 deletions
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58
extras/tests/ResourceManager/StringBuilder.cpp
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@ -6,8 +6,8 @@
#include <catch.hpp>
#include "Allocators.hpp"
#include "Literals.hpp"
using namespace ArduinoJson;
using namespace ArduinoJson::detail;
TEST_CASE("StringBuilder") {
@ -22,13 +22,31 @@ TEST_CASE("StringBuilder") {
str.startString();
str.save(&data);
REQUIRE(resources.size() == sizeofString(""));
REQUIRE(resources.overflowed() == false);
REQUIRE(spyingAllocator.log() ==
AllocatorLog{
Allocate(sizeofStringBuffer()),
Reallocate(sizeofStringBuffer(), sizeofString("")),
});
REQUIRE(spyingAllocator.log() == AllocatorLog{
Allocate(sizeofStringBuffer()),
});
REQUIRE(data.type() == VariantType::TinyString);
}
SECTION("Tiny string") {
StringBuilder str(&resources);
str.startString();
str.append("url");
REQUIRE(str.isValid() == true);
REQUIRE(str.str() == "url");
REQUIRE(spyingAllocator.log() == AllocatorLog{
Allocate(sizeofStringBuffer()),
});
VariantData data;
str.save(&data);
REQUIRE(resources.overflowed() == false);
REQUIRE(data.type() == VariantType::TinyString);
REQUIRE(data.asString() == "url");
}
SECTION("Short string fits in first allocation") {
@ -98,12 +116,12 @@ TEST_CASE("StringBuilder") {
}
}
static const char* saveString(StringBuilder& builder, const char* s) {
static JsonString saveString(StringBuilder& builder, const char* s) {
VariantData data;
builder.startString();
builder.append(s);
builder.save(&data);
return data.asString().c_str();
return data.asString();
}
TEST_CASE("StringBuilder::save() deduplicates strings") {
@ -116,9 +134,9 @@ TEST_CASE("StringBuilder::save() deduplicates strings") {
auto s2 = saveString(builder, "world");
auto s3 = saveString(builder, "hello");
REQUIRE(s1 == "hello"_s);
REQUIRE(s2 == "world"_s);
REQUIRE(+s1 == +s3); // same address
REQUIRE(s1 == "hello");
REQUIRE(s2 == "world");
REQUIRE(+s1.c_str() == +s3.c_str()); // same address
REQUIRE(spy.log() ==
AllocatorLog{
@ -134,9 +152,9 @@ TEST_CASE("StringBuilder::save() deduplicates strings") {
auto s1 = saveString(builder, "hello world");
auto s2 = saveString(builder, "hello");
REQUIRE(s1 == "hello world"_s);
REQUIRE(s2 == "hello"_s);
REQUIRE(+s2 != +s1); // different address
REQUIRE(s1 == "hello world");
REQUIRE(s2 == "hello");
REQUIRE(+s2.c_str() != +s1.c_str()); // different address
REQUIRE(spy.log() ==
AllocatorLog{
@ -149,18 +167,18 @@ TEST_CASE("StringBuilder::save() deduplicates strings") {
SECTION("Don't overrun") {
auto s1 = saveString(builder, "hello world");
auto s2 = saveString(builder, "wor");
auto s2 = saveString(builder, "worl");
REQUIRE(s1 == "hello world"_s);
REQUIRE(s2 == "wor"_s);
REQUIRE(s2 != s1);
REQUIRE(s1 == "hello world");
REQUIRE(s2 == "worl");
REQUIRE(s2.c_str() != s1.c_str()); // different address
REQUIRE(spy.log() ==
AllocatorLog{
Allocate(sizeofStringBuffer()),
Reallocate(sizeofStringBuffer(), sizeofString("hello world")),
Allocate(sizeofStringBuffer()),
Reallocate(sizeofStringBuffer(), sizeofString("wor")),
Reallocate(sizeofStringBuffer(), sizeofString("worl")),
});
}
}