Add tedge_core crate

This patch adds a first implementation of the tedge_core crate.

Its implementation uses an internal `Reactor` type for hiding the actual
implementation from the TedgeApplication type. This is not strictly
necessary, but gives a bit more seperation of concerns with
configuration vs "running" implementation.

The internal buffer size for the communication buffers between
core<->plugin handler is made configurable, so that a user can fine-tune
the core in this regard.

The core itself is implemented as a `CoreTask` type, which handles the
actual message-passing. All messages are routed over this CoreTask.

This ensures that we do only have 3 communication channels in each
PluginTask:

* One for CoreTask -> PluginTask
* One for PluginTask -> CoreTask
* One for Plugin -> PluginTask
(PluginTask -> Plugin is a function call: `Plugin::handle_message()` and
thus does not need a communication channel!)

and we thus do not run into the issue of having n^2 communication
channels for the communication between the PluginTask objects.

Tracing instrumentation is added to be able to have nice logging.

Signed-off-by: Matthias Beyer <matthias.beyer@ifm.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/crates/core/tedge_core/Cargo.toml b/crates/core/tedge_core/Cargo.toml
new file mode 100644
index 00000000..61ff7bea
--- /dev/null
+++ b/crates/core/tedge_core/Cargo.toml
@@ -0,0 +1,22 @@
+[package]
+name = "tedge_core"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+async-trait = "0.1.52"
+futures = "0.3"
+serde = { version = "1.0.136", features = ["derive"] }
+thiserror = "1.0.30"
+tokio = { version = "1.16.1", features = ["sync", "macros"] }
+toml = "0.5.8"
+tracing = "0.1"
+
+tedge_api = { path = "../tedge_api" }
+
+[dev-dependencies]
+anyhow = "1"
+static_assertions = "1.1.0"
+tokio = { version = "1.16.1", features = ["full"] }