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perf(cpp): simplify TypeMeta index tracking #3932

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Merged
chaokunyang merged 1 commit into from
Aug 12, 2026
+13 −29
Merged

perf(cpp): simplify TypeMeta index tracking #3932

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38 changes: 12 additions & 26 deletions cpp/fory/serialization/context.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -77,31 +77,19 @@ WriteContext::write_type_meta(const std::type_index &type_id) {
}

void WriteContext::write_type_meta(const TypeInfo *type_info) {
const uint64_t key =
static_cast<uint64_t>(reinterpret_cast<uintptr_t>(type_info));
if (!type_info_index_map_active_) {
if (!has_first_type_info_) {
has_first_type_info_ = true;
first_type_info_ = type_info;
buffer_.write_uint8(0); // (index << 1), index=0
buffer_.write_bytes(type_info->type_def.data(),
type_info->type_def.size());
return;
}
if (type_info == first_type_info_) {
buffer_.write_uint8(1); // (index << 1) | 1, index=0
return;
}
type_info_index_map_active_ = true;
write_type_info_index_map_.clear();
const uint64_t first_key =
static_cast<uint64_t>(reinterpret_cast<uintptr_t>(first_type_info_));
write_type_info_index_map_.put(first_key, 0);
} else if (type_info == first_type_info_) {
if (first_type_info_ == nullptr) {
first_type_info_ = type_info;
buffer_.write_uint8(0); // (index << 1), index=0
buffer_.write_bytes(type_info->type_def.data(), type_info->type_def.size());
return;
}
if (type_info == first_type_info_) {
buffer_.write_uint8(1); // (index << 1) | 1, index=0
return;
}

const uint64_t key =
static_cast<uint64_t>(reinterpret_cast<uintptr_t>(type_info));
if (auto *entry = write_type_info_index_map_.find(key)) {
// Reference to previously written type: (index << 1) | 1, LSB=1
uint32_t marker = static_cast<uint32_t>((entry->value << 1) | 1);
Expand All @@ -114,7 +102,7 @@ void WriteContext::write_type_meta(const TypeInfo *type_info) {
}

// New type: index << 1, LSB=0, followed by TypeDef bytes inline
uint32_t index = static_cast<uint32_t>(write_type_info_index_map_.size());
uint32_t index = static_cast<uint32_t>(write_type_info_index_map_.size() + 1);
uint32_t marker = static_cast<uint32_t>(index << 1);
if (marker < 0x80) {
buffer_.write_uint8(static_cast<uint8_t>(marker));
Expand Down Expand Up @@ -404,13 +392,11 @@ void WriteContext::reset() {
if (config_->track_ref) {
ref_writer_.reset();
}
// Clear meta map for streaming TypeMeta (size is used as counter)
if (type_info_index_map_active_) {
// Clear meta map for streaming TypeMeta.
if (!write_type_info_index_map_.empty()) {
write_type_info_index_map_.clear();
}
first_type_info_ = nullptr;
has_first_type_info_ = false;
type_info_index_map_active_ = false;
current_dyn_depth_ = 0;
buffer_.clear_output_stream();
output_stream_ = nullptr;
Expand Down
4 changes: 1 addition & 3 deletions cpp/fory/serialization/context.h
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Original file line number Diff line number Diff line change
Expand Up @@ -356,12 +356,10 @@ class WriteContext {
OutputStream *output_stream_ = nullptr;

// Meta sharing state (for streaming inline TypeMeta)
// Maps TypeInfo* to index for reference tracking - uses map size as counter
// The first TypeInfo has index 0; the map stores later types at size + 1.
util::FlatIntMap<uint64_t, uint32_t> write_type_info_index_map_;
// Fast path for the common single-type stream: avoid hash map lookups.
const TypeInfo *first_type_info_ = nullptr;
bool has_first_type_info_ = false;
bool type_info_index_map_active_ = false;
};

/// Read context for deserialization operations.
Expand Down
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