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# Resource Attribution Overview
[TOC]
# Overview
The Resource Attribution component, part of Performance Manager, centralizes
data about the resources the browser uses and provides a unified interface to query
them. It will manage scheduling of resource measurements so that multiple
callers requesting information about the same resources don’t schedule redundant
measurements.
# API
The public interface is documented at bit.ly/resource-attribution-api.
* Public headers are in
components/performance_manager/public/resource_attribution/.
* Public symbols are in the `resource_attribution` namespace.
* Private symbols that must be referenced from
components/performance_manager/public/ (eg. in templates) are in the
`resource_attribution::internal` namespace.
# Implementation
Here’s an overview picture of the architecture:
The important classes, from the bottom up, are:
* **Measurement Delegates** (`MemoryMeasurementDelegate`, `CPUMeasurementDelegate`, etc):
Interface directly with OS or common Chrome functions to perform measurements.
Can be replaced by test stubs to simulate measurements. *Measurement
Providers* create delegates through factory classes as needed.
* **Measurement Providers** (`MemoryMeasurementProvider`,
`CPUMeasurementMonitor`, etc):
Own and control the *Measurement Delegates*. Convert measurements they return
to a common format, aggregate and store them.
* **QueryScheduler**:
Central rendezvous point for queries from the public API. Owns and controls
the *Measurement Providers* and schedules measurements from them based on incoming
queries. Filters and combines results from the providers into responses
containing the data each query expects.
* **Public API classes** (`ResourceContext`, `QueryBuilder`, `QueryResult`,
etc):
Described at bit.ly/resource-attribution-api.
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