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// Copyright 2020 The Pigweed Authors
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
syntax = "proto3";
package pw.metric.proto;
// A metric, described by the name (path + name), and the value.
// This flattened representation, while more complicated than the obvious tree
// structure alternative, enables streaming metrics from the device in low
// memory or low compute situations.
message Metric {
// The token path from the root. The last token is the metric name, and
// previous tokens are the parent group names. This could be converted from
// the tokens into a string; for example the token path {0xfaff, 0xabcd}:
// - The group is 0xfaff (root, parent)
// - The metric is 0xabcd
// Given the token database, this might be converted into:
// /i2c_bus_1/failed_transactions
// Note: This uses a repeated fixed32 instead of a "Oneof" with the string
// path to reduce the encoded size. Using a repeated Oneof name { str,
// fixed32 } would cost approximately 6N bytes for N path elements, vs 2 + 4N
// bytes in the packed case.
repeated fixed32 token_path = 1;
// The string path from the root. Similar to token path, but with strings.
// Note: This is currently unsupported.
repeated string string_path = 2;
// The metric value. This field should be omitted when used as a query.
oneof value {
float as_float = 3;
uint32 as_int = 4;
message MetricRequest {
// Metrics or the groups matched to the given paths are returned. The intent
// is to support matching semantics, with at least subsetting to e.g. collect
// all the metrics in a group and its children. We may also implement
// wildcard matchers.
// Value fields in the metrics will be ignored, since this is a query.
// Note: This is currently unsupported.
repeated Metric metrics = 1;
message MetricResponse {
repeated Metric metrics = 1;
service MetricService {
// Returns metrics or groups matching the requested paths.
rpc Get(MetricRequest) returns (stream MetricResponse) {}