GWR Track

gwr_track is the logging library used by the GWR engine and all components. It can be used to generate either text-based or Cap’n Proto-based binary log files.

Entities

gwr_track provides the Entity struct. It is designed to represent a unique simulation Entity/component which exists within the simulation hierarchy.

An Entity will have a unique location within the simulation hierarchy and are each assigned a unique Id. For example:

top::processor0::cpu102::memory

Tracing can be configured globally or enabled/disabled depending on regular expressions matching entity names.

EntitiyMonitor

The EntityMonitor allows the user to create helper structs that can monitor an Entity and emit useful statistics through track_value() calls.

Objects

For short-lived parts of the simulations (like an Ethernet frame or a memory access) the user can create a track object. These are given unique Ids like Entities and Entities so that their lifecycle can be tracked across the simulation.

IDs

Each Entity will have a unique 64-bit Id. This ID is used throughout the log/bin files in order to identify the originator of messages and to reduce the size of the files.

Ids are also assigned to track Objects. Objects do not contain an Entity because they flow through the simulation and so their location within the simulation changes. However, the logging of packets is controlled by the Entity that creates the object.

Macros

The library provides a number of macros that provide the logging functionlity with a minimal run-time overhead when not enabled.

There are the macros that map to log messages of the specified level:

• trace! - a message that will only be emitted if log level is Trace.
• debug! - a message that will only be emitted if log level is Debug or above.
• info! - a message that will only be emitted if log level is Info or above.
• warn! - a message that will only be emitted if log level is Warn or above.
• error! - a message that will only be emitted if log level is Error or above.

Note: the logging level is controlled globally with the ability to configure it at the level of any Entity within the simulation hierarchy.