README.md
1# gRPC EventEngine
2
3An EventEngine handles all cross-platform I/O, task execution, and DNS
4resolution for gRPC. A default, cross-platform implementation is provided with
5gRPC, but part of the intent here is to provide an interface for external
6integrators to bring their own functionality. This allows for integration with
7external event loops, siloing I/O and task execution between channels or
8servers, and other custom integrations that were previously unsupported.
9
10*WARNING*: This is experimental code and is subject to change.
11
12## High level expectations of an EventEngine implementation
13
14### Provide their own I/O threads
15EventEngines are expected to internally create whatever threads are required to
16perform I/O and execute callbacks. For example, an EventEngine implementation
17may want to spawn separate thread pools for polling and callback execution.
18
19### Provisioning data buffers via Slice allocation
20At a high level, gRPC provides a `ResourceQuota` system that allows gRPC to
21reclaim memory and degrade gracefully when memory reaches application-defined
22thresholds. To enable this feature, the memory allocation of read/write buffers
23within an EventEngine must be acquired in the form of Slices from
24SliceAllocators. This is covered more fully in the gRFC and code.
25
26### Documentating expectations around callback execution
27Some callbacks may be expensive to run. EventEngines should decide on and
28document whether callback execution might block polling operations. This way,
29application developers can plan accordingly (e.g., run their expensive callbacks
30on a separate thread if necessary).
31
32### Handling concurrent usage
33Assume that gRPC may use an EventEngine concurrently across multiple threads.
34
35## TODO: documentation
36
37* Example usage
38* Link to gRFC
39