We previously used string in the codebase to represent component type
(as it is known to factories and referred to in the config).
Now we have configmodels.Type alias that provides stronger compile-time
type checks.
This is a breaking change for components but fixing the components is easy.
Resolves: https://github.com/open-telemetry/opentelemetry-collector/issues/762
Added GetFactory function to Host interface. This allows components
to fetch factories and create components dynamically. The functionality
will be used by receiver creator that creates and destroys other receivers
as it discovers relevant external endpoints from which these receivers
can get data.
As we are preparing for Beta release we want to cleanup publicly exported
types and interfaces and do all necessary refactoring and breaking changes
now, before the Beta release. We will have a lot less leeway for breaking
changes after the Beta release.
Component related type declarations are now all in the `component` package.
This makes it possible for the interfaces to reference each other. This
was were very restricted earlier because component interfaces were in 5
different packages and many proposals were impossible to implement because
they would result in circular dependencies between packages.
(An example upcoming new capability that is enabled by this refactoring
is for components to query the Host for other components and for factories).
List of changes in this commit:
- Move all factory interfaces and component interfaces to component package.
- Rename old factories and components interfaces to use "Old" suffix for clarity.
- Eliminate forced checks that components implement factories. This is already
enforced by the compiler when the factory is added to the Defaults() and
was unnecessary code.
- Eliminated some unnecessary codes (removed overall over 200 lines).
- Run `go mod tidy` on testbed.
Warning: this is a breaking change to publicly exported types and function
signatures. We announced that a breaking change is comming. Once we agree
to merge this commit we will need to announce the exact list of changes
and guide component authors to modify their components accordingly.
Future changes:
- Once all components are migrated to the new internal representation,
delete all "Old"-suffixed definitions. This will likely be done while
we are still in Beta phase, before the Stable release.
This change fixes inconsistencies in component interfaces. Motivation:
- Uniformness results in reduction of code that currently has to
deal with differences.
- Processor.Start is missing and is important for allowing processors
to communicate with the Host.
What's changed:
- Introduced Component interface.
- Unified Host interface.
- Added a Start function to processors (via Component interface).
- Start/Shutdown is now called for Processors from service start/shutdown.
- Receivers, Exporters, Processors, Extensions now embed Component interface.
- Replaced StartTraceReception/StartMetricsReception by single Start function for receivers.
- Replaced StopTraceReception/StopMetricsReception by single Shutdown function for receivers.
Note: before merging this we need to announce the change in Gitter since it
breaks existing implementations in contrib (although the fix is easy).
Resolves#477Resolves#262
Bogdan Drutu
Bruno Garcia
Tigran Najaryan
Paulo Janotti