Event engine endpoint read and write API changes (#29450)

* Event engine endpoint read and write API changes

* updating api change

* set google_specific  to nullptr by default

* Event-Engine --> EventEngine

* life-time --> lifetime

* removing default args to make sanity checks pass

include/grpc/event_engine/event_engine.h

@@ -138,6 +138,18 @@ class EventEngine {
     /// Shuts down all connections and invokes all pending read or write
     /// callbacks with an error status.
     virtual ~Endpoint() = default;
+    /// A struct representing optional arguments that may be provided to an
+    /// EventEngine Endpoint Read API  call.
+    ///
+    /// Passed as argument to an Endpoint \a Read
+    struct ReadArgs {
+      // A suggestion to the endpoint implementation to read at-least the
+      // specified number of bytes over the network connection before marking
+      // the endpoint read operation as complete. gRPC may use this argument
+      // to minimize the number of endpoint read API calls over the lifetime
+      // of a connection.
+      int64_t read_hint_bytes;
+    };
     /// Reads data from the Endpoint.
     ///
     /// When data is available on the connection, that data is moved into the
@@ -156,7 +168,21 @@ class EventEngine {
     /// statuses to \a on_read. For example, callbacks might expect to receive
     /// CANCELLED on endpoint shutdown.
     virtual void Read(std::function<void(absl::Status)> on_read,
-                      SliceBuffer* buffer) = 0;
+                      SliceBuffer* buffer, const ReadArgs* args) = 0;
+    /// A struct representing optional arguments that may be provided to an
+    /// EventEngine Endpoint Write API call.
+    ///
+    /// Passed as argument to an Endpoint \a Write
+    struct WriteArgs {
+      // Represents private information that may be passed by gRPC for
+      // select endpoints expected to be used only within google.
+      void* google_specific = nullptr;
+      // A suggestion to the endpoint implementation to group data to be written
+      // into frames of the specified max_frame_size. gRPC may use this
+      // argument to dynamically control the max sizes of frames sent to a
+      // receiver in response to high receiver memory pressure.
+      int64_t max_frame_size;
+    };
     /// Writes data out on the connection.
     ///
     /// \a on_writable is called when the connection is ready for more data. The
@@ -176,7 +202,7 @@ class EventEngine {
     /// statuses to \a on_writable. For example, callbacks might expect to
     /// receive CANCELLED on endpoint shutdown.
     virtual void Write(std::function<void(absl::Status)> on_writable,
-                       SliceBuffer* data) = 0;
+                       SliceBuffer* data, const WriteArgs* args) = 0;
     /// Returns an address in the format described in DNSResolver. The returned
     /// values are expected to remain valid for the life of the Endpoint.
     virtual const ResolvedAddress& GetPeerAddress() const = 0;