* Reintroduce the EventEngine default factory
An application can provide an EventEngine factory function that allows
gRPC internals to create EventEngines as needed. This factory would be
used when no EventEngine is provided for some given channel or server,
and where an EventEngine otherwise could not be provided by the
application. Note that there currently is no API to provide an
EventEngine per channel or per server.
I've also deleted some previous iterations on global EventEngine and
EventEngine factory ideas. This new code lives in a public API, and
coexists with iomgr instead of being isolated to an EventEngine-specific
iomgr implementation.
* add proper namespaces, and fix description
* put factory functions in their own file (for replaceability)
* add synchronization
* generate_projects.sh
* extract event_engine_base and event_engine_factory targets
Also separate iomgr/event_engine files in the BUILD, with comments
* gpr_platform
* move all EE factory declarations to event_engine_base
Makes internal hackery easier.
* add missing deps
* reorder dep alphabetically
* comment style change
A reusable test suite for EventEngine implementations.
To exercise a custom EventEngine, simply link against :event_engine_test_suite
and provide a testing main function that sets a custom EventEngine factory:
```
#include "path/to/my_custom_event_engine.h"
#include "src/core/event_engine/test_suite/event_engine_test.h"
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
SetEventEngineFactory(
[]() { return absl::make_unique<MyCustomEventEngine>(); });
auto result = RUN_ALL_TESTS();
return result;
}
```
This code adds an iomgr implementation that's backed by an EventEngine. This uses the EventEngine API alone, and separate work will introduce an EventEngine prototype to plug into it.
See also drfloob#1: @nicolasnoble has a pull request against this branch, implementing the libuv-based EventEngine. One goal here is to implement the iomgr code such that it can be merged independently without affecting normal builds.
This implementation can be built using bazel build --cxxopt='-DGRPC_USE_EVENT_ENGINE' :all
Some shortcuts are being taken to get a working, testable version of the engine. EventEngines are not pluggable, for example.
The source code is moved from src/python to
src/python/src. A setup.py is added at
src/python. The build_python.sh and
run_python.sh scripts are updated to build
and run the Python tests by building a
package and installing it in the developer's
Python 2.7 virtual environment.