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Code Issues Releases Wiki Activity

[api] Use StringRef for HomeassistantServiceMap.value to eliminate heap allocations (#13154)

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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
This commit is contained in:
J. Nick Koston
2026-01-11 17:54:06 -10:00
committed by GitHub
parent ea8ae2ae60
commit 912f94d1e8
9 changed files with 61 additions and 58 deletions
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4
esphome/components/api/api.proto
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@@ -763,7 +763,7 @@ message SubscribeHomeassistantServicesRequest {
message HomeassistantServiceMap {
string key = 1;
string value = 2 [(no_zero_copy) = true];
string value = 2;
}
message HomeassistantActionRequest {
@@ -779,7 +779,7 @@ message HomeassistantActionRequest {
bool is_event = 5;
uint32 call_id = 6 [(field_ifdef) = "USE_API_HOMEASSISTANT_ACTION_RESPONSES"];
bool wants_response = 7 [(field_ifdef) = "USE_API_HOMEASSISTANT_ACTION_RESPONSES_JSON"];
string response_template = 8 [(no_zero_copy) = true, (field_ifdef) = "USE_API_HOMEASSISTANT_ACTION_RESPONSES_JSON"];
string response_template = 8 [(field_ifdef) = "USE_API_HOMEASSISTANT_ACTION_RESPONSES_JSON"];
}
// Message sent by Home Assistant to ESPHome with service call response data

1
esphome/components/api/api_options.proto
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@@ -27,7 +27,6 @@ extend google.protobuf.MessageOptions {
extend google.protobuf.FieldOptions {
optional string field_ifdef = 1042;
optional uint32 fixed_array_size = 50007;
optional bool no_zero_copy = 50008 [default=false];
optional bool fixed_array_skip_zero = 50009 [default=false];
optional string fixed_array_size_define = 50010;
optional string fixed_array_with_length_define = 50011;

4
esphome/components/api/api_pb2.h
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@@ -1053,7 +1053,7 @@ class SubscribeHomeassistantServicesRequest final : public ProtoMessage {
class HomeassistantServiceMap final : public ProtoMessage {
public:
StringRef key{};
std::string value{};
StringRef value{};
void encode(ProtoWriteBuffer buffer) const override;
void calculate_size(ProtoSize &size) const override;
#ifdef HAS_PROTO_MESSAGE_DUMP
@@ -1081,7 +1081,7 @@ class HomeassistantActionRequest final : public ProtoMessage {
bool wants_response{false};
#endif
#ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES_JSON
std::string response_template{};
StringRef response_template{};
#endif
void encode(ProtoWriteBuffer buffer) const override;
void calculate_size(ProtoSize &size) const override;

4
esphome/components/api/custom_api_device.h
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@@ -265,7 +265,7 @@ class CustomAPIDevice {
for (auto &it : data) {
auto &kv = resp.data.emplace_back();
kv.key = StringRef(it.first);
kv.value = it.second; // value is std::string (no_zero_copy), assign directly
kv.value = StringRef(it.second); // data map lives until send completes
}
global_api_server->send_homeassistant_action(resp);
}
@@ -308,7 +308,7 @@ class CustomAPIDevice {
for (auto &it : data) {
auto &kv = resp.data.emplace_back();
kv.key = StringRef(it.first);
kv.value = it.second; // value is std::string (no_zero_copy), assign directly
kv.value = StringRef(it.second); // data map lives until send completes
}
global_api_server->send_homeassistant_action(resp);
}

43
esphome/components/api/homeassistant_service.h
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@@ -149,11 +149,21 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
std::string service_value = this->service_.value(x...);
resp.service = StringRef(service_value);
resp.is_event = this->flags_.is_event;
this->populate_service_map(resp.data, this->data_, x...);
this->populate_service_map(resp.data_template, this->data_template_, x...);
this->populate_service_map(resp.variables, this->variables_, x...);
// Local storage for lambda-evaluated strings - lives until after send
FixedVector<std::string> data_storage;
FixedVector<std::string> data_template_storage;
FixedVector<std::string> variables_storage;
this->populate_service_map(resp.data, this->data_, data_storage, x...);
this->populate_service_map(resp.data_template, this->data_template_, data_template_storage, x...);
this->populate_service_map(resp.variables, this->variables_, variables_storage, x...);
#ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES
#ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES_JSON
// IMPORTANT: Declare at outer scope so it lives until send_homeassistant_action returns.
std::string response_template_value;
#endif
if (this->flags_.wants_status) {
// Generate a unique call ID for this service call
static uint32_t call_id_counter = 1;
@@ -164,8 +174,8 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
resp.wants_response = true;
// Set response template if provided
if (this->flags_.has_response_template) {
std::string response_template_value = this->response_template_.value(x...);
resp.response_template = response_template_value;
response_template_value = this->response_template_.value(x...);
resp.response_template = StringRef(response_template_value);
}
}
#endif
@@ -205,12 +215,31 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
}
template<typename VectorType, typename SourceType>
static void populate_service_map(VectorType &dest, SourceType &source, Ts... x) {
static void populate_service_map(VectorType &dest, SourceType &source, FixedVector<std::string> &value_storage,
Ts... x) {
dest.init(source.size());
// Count non-static strings to allocate exact storage needed
size_t lambda_count = 0;
for (const auto &it : source) {
if (!it.value.is_static_string()) {
lambda_count++;
}
}
value_storage.init(lambda_count);
for (auto &it : source) {
auto &kv = dest.emplace_back();
kv.key = StringRef(it.key);
kv.value = it.value.value(x...);
if (it.value.is_static_string()) {
// Static string from YAML - zero allocation
kv.value = StringRef(it.value.get_static_string());
} else {
// Lambda evaluation - store result, reference it
value_storage.push_back(it.value.value(x...));
kv.value = StringRef(value_storage.back());
}
}
}

7
esphome/components/homeassistant/number/homeassistant_number.cpp
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@@ -91,11 +91,14 @@ void HomeassistantNumber::control(float value) {
resp.data.init(2);
auto &entity_id = resp.data.emplace_back();
entity_id.key = ENTITY_ID_KEY;
entity_id.value = this->entity_id_;
entity_id.value = StringRef(this->entity_id_);
auto &entity_value = resp.data.emplace_back();
entity_value.key = VALUE_KEY;
entity_value.value = to_string(value);
// Stack buffer - no heap allocation; %g produces shortest representation
char value_buf[16];
snprintf(value_buf, sizeof(value_buf), "%g", value);
entity_value.value = StringRef(value_buf);
api::global_api_server->send_homeassistant_action(resp);
}

2
esphome/components/homeassistant/switch/homeassistant_switch.cpp
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@@ -55,7 +55,7 @@ void HomeassistantSwitch::write_state(bool state) {
resp.data.init(1);
auto &entity_id_kv = resp.data.emplace_back();
entity_id_kv.key = ENTITY_ID_KEY;
entity_id_kv.value = this->entity_id_;
entity_id_kv.value = StringRef(this->entity_id_);
api::global_api_server->send_homeassistant_action(resp);
}

6
esphome/core/automation.h
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@@ -159,6 +159,12 @@ template<typename T, typename... X> class TemplatableValue {
return this->value(x...);
}
/// Check if this holds a static string (const char* stored without allocation)
bool is_static_string() const { return this->type_ == STATIC_STRING; }
/// Get the static string pointer (only valid if is_static_string() returns true)
const char *get_static_string() const { return this->static_str_; }
protected:
enum : uint8_t {
NONE,

48
script/api_protobuf/api_protobuf.py
View File

@@ -376,10 +376,8 @@ def create_field_type_info(
return BytesType(field, needs_decode, needs_encode)
# Special handling for string fields - use StringRef for zero-copy unless no_zero_copy is set
# Special handling for string fields - use StringRef for zero-copy
if field.type == 9:
if get_field_opt(field, pb.no_zero_copy, False):
return StringType(field, needs_decode, needs_encode)
return PointerToStringBufferType(field, None)
validate_field_type(field.type, field.name)
@@ -585,15 +583,12 @@ class StringType(TypeInfo):
def public_content(self) -> list[str]:
content: list[str] = []
# Check if no_zero_copy option is set
no_zero_copy = get_field_opt(self._field, pb.no_zero_copy, False)
# Add std::string storage if message needs decoding OR if no_zero_copy is set
if self._needs_decode or no_zero_copy:
# Add std::string storage if message needs decoding
if self._needs_decode:
content.append(f"std::string {self.field_name}{{}};")
# Only add StringRef if encoding is needed AND no_zero_copy is not set
if self._needs_encode and not no_zero_copy:
# Add StringRef if encoding is needed
if self._needs_encode:
content.extend(
[
# Add StringRef field if message needs encoding
@@ -608,27 +603,14 @@ class StringType(TypeInfo):
@property
def encode_content(self) -> str:
# Check if no_zero_copy option is set
no_zero_copy = get_field_opt(self._field, pb.no_zero_copy, False)
if no_zero_copy:
# Use the std::string directly
return f"buffer.encode_string({self.number}, this->{self.field_name});"
# Use the StringRef
return f"buffer.encode_string({self.number}, this->{self.field_name}_ref_);"
def dump(self, name):
# Check if no_zero_copy option is set
no_zero_copy = get_field_opt(self._field, pb.no_zero_copy, False)
# If name is 'it', this is a repeated field element - always use string
if name == "it":
return "append_quoted_string(out, StringRef(it));"
# If no_zero_copy is set, always use std::string
if no_zero_copy:
return f'out.append("\'").append(this->{self.field_name}).append("\'");'
# For SOURCE_CLIENT only, always use std::string
if not self._needs_encode:
return f'out.append("\'").append(this->{self.field_name}).append("\'");'
@@ -648,13 +630,6 @@ class StringType(TypeInfo):
@property
def dump_content(self) -> str:
# Check if no_zero_copy option is set
no_zero_copy = get_field_opt(self._field, pb.no_zero_copy, False)
# If no_zero_copy is set, always use std::string
if no_zero_copy:
return f'dump_field(out, "{self.name}", this->{self.field_name});'
# For SOURCE_CLIENT only, use std::string
if not self._needs_encode:
return f'dump_field(out, "{self.name}", this->{self.field_name});'
@@ -670,17 +645,8 @@ class StringType(TypeInfo):
return o
def get_size_calculation(self, name: str, force: bool = False) -> str:
# Check if no_zero_copy option is set
no_zero_copy = get_field_opt(self._field, pb.no_zero_copy, False)
# For SOURCE_CLIENT only messages or no_zero_copy, use the string field directly
if not self._needs_encode or no_zero_copy:
# For no_zero_copy, we need to use .size() on the string
if no_zero_copy and name != "it":
field_id_size = self.calculate_field_id_size()
return (
f"size.add_length({field_id_size}, this->{self.field_name}.size());"
)
# For SOURCE_CLIENT only messages, use the string field directly
if not self._needs_encode:
return self._get_simple_size_calculation(name, force, "add_length")
# Check if this is being called from a repeated field context