Initial project import

tools/v/vlib/context/onecontext/README.md

@@ -0,0 +1,40 @@
+# onecontext
+
+A library to merge existing V contexts.
+
+## Overview
+
+Have you ever faced the situation where you have to merge multiple existing contexts?
+If not, then you might, eventually.
+
+For example, we can face the situation where we are building an application
+using a library that gives us a global context.
+This context expires once the application is stopped.
+
+Meanwhile, we are exposing a service like this:
+
+```v ignore
+fn (f Foo) get(ctx context.Context, bar Bar) ?Baz {
+	. . .
+}
+```
+
+Here, we receive another context provided by the service.
+
+Then, in the `get` implementation, we want for example to query a database and
+we must provide a context for that.
+
+Ideally, we would like to provide a merged context that would expire either:
+
+- When the application is stopped
+- Or when the received service context expires
+
+This is exactly the purpose of this library.
+
+In our case, we can now merge the two contexts in a single one like this:
+
+```v ignore
+ctx, cancel := onecontext.merge(ctx1, ctx2)
+```
+
+This returns a merged context that we can now propagate