documentation improvements (#1550)

* log, handler doc update

* bytes mod doc added

* callback doc moved to lib.rs

* absloute paths added

* minor corrections

* modules doc update

* typo fixes

commons/zenoh-util/src/log.rs

@@ -22,13 +22,13 @@ use tracing_subscriber::{
 
 /// A utility function to enable the tracing formatting subscriber.
 ///
-/// The tracing formatting subscriber is initialized from the `RUST_LOG` environment variable.
+/// The [`tracing_subscriber`]` is initialized from the `RUST_LOG` environment variable.
 /// If `RUST_LOG` is not set, then logging is not enabled.
 ///
 /// # Safety
 ///
-/// Calling this function initializes a `lazy_static` in the `tracing` crate
-/// such static is not deallocated prior to process existing, thus tools such as `valgrind`
+/// Calling this function initializes a `lazy_static` in the [`tracing`] crate.
+/// Such static is not deallocated prior to process exiting, thus tools such as `valgrind`
 /// will report a memory leak.
 /// Refer to this issue: <https://github.com/tokio-rs/tracing/issues/2069>
 pub fn try_init_log_from_env() {
@@ -39,12 +39,12 @@ pub fn try_init_log_from_env() {
 
 /// A utility function to enable the tracing formatting subscriber.
 ///
-/// The tracing formatting subscriber is initialized from the `RUST_LOG` environment variable.
+/// The [`tracing_subscriber`] is initialized from the `RUST_LOG` environment variable.
 /// If `RUST_LOG` is not set, then fallback directives are used.
 ///
 /// # Safety
-/// Calling this function initializes a `lazy_static` in the `tracing` crate
-/// such static is not deallocated prior to process existing, thus tools such as `valgrind`
+/// Calling this function initializes a `lazy_static` in the [`tracing`] crate.
+/// Such static is not deallocated prior to process existing, thus tools such as `valgrind`
 /// will report a memory leak.
 /// Refer to this issue: <https://github.com/tokio-rs/tracing/issues/2069>
 pub fn init_log_from_env_or<S>(fallback: S)

zenoh/src/lib.rs

@@ -180,6 +180,8 @@ pub mod key_expr {
 }
 
 /// Zenoh [`Session`] and associated types
+///
+/// The [`Session`] is the main component of the Zenoh.
 pub mod session {
     #[zenoh_macros::unstable]
     pub use zenoh_config::wrappers::EntityGlobalId;
@@ -202,6 +204,9 @@ pub mod session {
 }
 
 /// Sample primitives
+///
+/// The [`Sample`](crate::sample::Sample) structure is the data unit received from [`Subscriber`](crate::pubsub::Subscriber)
+/// or [`Queryable`](crate::query::Queryable) instances. It contains the payload and all the metadata associated with the data.
 pub mod sample {
     #[zenoh_macros::unstable]
     pub use crate::api::sample::Locality;
@@ -216,6 +221,16 @@ pub mod sample {
 }
 
 /// Payload primitives
+///
+/// The [`ZBytes`](crate::bytes::ZBytes) type is Zenoh's representation of raw byte data.
+/// It provides mechanisms for zero-copy creation and access (`From<Vec<u8>>` and
+/// [`ZBytes::slices`](crate::bytes::ZBytes::slices)), as well as methods for sequential
+/// reading/writing ([`ZBytes::reader`](crate::bytes::ZBytes::reader), [`ZBytes::writer`](crate::bytes::ZBytes::writer)).
+///
+/// The`zenoh_ext` crate provides serialization and deserialization of basic types and structures for `ZBytes`
+/// [`z_serialize`](../../zenoh_ext/fn.z_serialize.html) /
+/// [`z_deserialize`](../../zenoh_ext/fn.z_deserialize.html).
+
 pub mod bytes {
     pub use crate::api::{
         bytes::{OptionZBytes, ZBytes, ZBytesReader, ZBytesSliceIterator, ZBytesWriter},
@@ -224,6 +239,14 @@ pub mod bytes {
 }
 
 /// Pub/sub primitives
+///
+/// The [`Publisher`](crate::pubsub::Publisher) instance is declared by a
+/// [`Session::declare_publisher`](crate::Session::declare_publisher) method.
+///
+/// The data [`Sample`](crate::sample::Sample)s
+/// are received by [`Subscriber`](crate::pubsub::Subscriber)s
+/// declared by a [`Session::declare_subscriber`](crate::Session::declare_subscriber)
+///
 pub mod pubsub {
     #[zenoh_macros::unstable]
     pub use crate::api::{
@@ -244,6 +267,12 @@ pub mod pubsub {
 }
 
 /// Query/reply primitives
+///
+/// The [`Queryable`](crate::query::Queryable) instance is declared by a
+/// [`Session::declare_queryable`](crate::Session::declare_queryable) method.
+/// It is requested by a [`Session::get`](crate::Session::get) operation which
+/// receives data in [`Reply`](crate::query::Reply) structures.
+///
 pub mod query {
     pub use zenoh_protocol::core::Parameters;
     #[zenoh_macros::unstable]
@@ -264,7 +293,35 @@ pub mod query {
     pub use crate::api::{query::ReplyKeyExpr, selector::ZenohParameters};
 }
 
-/// Callback handler trait
+/// Callback handler trait.
+///
+/// Zenoh primitives that receive data (e.g., [`Subscriber`](crate::pubsub::Subscriber),
+/// [`Query`](crate::query::Query), etc.) have a
+/// [`with`](crate::pubsub::SubscriberBuilder::with) method which accepts a handler for the data.
+///
+/// The handler is a pair of a [`Callback`](crate::handlers::Callback) and an arbitrary `Handler`
+/// object used to access data received by the callback. When the data is processed by the callback itself
+/// the handler type can be `()`. For convenience, the
+/// [`callback`](crate::pubsub::SubscriberBuilder::callback) method, which accepts
+/// a `Fn(T)` only can be used in this case.
+///
+/// The [`with`](crate::pubsub::SubscriberBuilder::with) method accepts any type that
+/// implements the [`IntoHandler`](crate::handlers::IntoHandler) trait, which provides a
+/// conversion to a pair of [`Callback`](crate::handlers::Callback) and handler.
+///
+/// The `IntoHandler` for channels [`FifoChannel`](crate::handlers::FifoChannel) and
+/// [`RingChannel`](crate::handlers::RingChannel)
+/// return a pair of ([`Callback`](crate::handlers::Callback), channel_handler).
+///
+/// The callback pushes data to the channel, the
+/// channel handler [`FifoChannelHandler`](crate::handlers::FifoChannelHandler) or
+/// [`RingChannelHandler`](crate::handlers::RingChannelHandler) allows to take data
+/// from the channel.
+///
+/// The channel handler is stored
+/// in the Zenoh object (e.g., [`Subscriber`](crate::pubsub::Subscriber)). It can be accessed
+/// by [`handler`](crate::pubsub::Subscriber::handler) method or just directly by dereferencing the
+/// Zenoh object.
 pub mod handlers {
     #[zenoh_macros::internal]
     pub use crate::api::handlers::locked;
@@ -289,6 +346,11 @@ pub mod qos {
 }
 
 /// Scouting primitives
+///
+/// Scouting is the process of discovering Zenoh nodes in the network.
+/// The scouting process depends on the transport layer and on the zenoh configuration.
+/// See more details at <https://zenoh.io/docs/getting-started/deployment/#scouting>.
+///
 pub mod scouting {
     pub use zenoh_config::wrappers::Hello;
 
@@ -362,7 +424,17 @@ pub mod time {
     pub use zenoh_protocol::core::{Timestamp, TimestampId, NTP64};
 }
 
-/// Configuration to pass to [`open`] and [`scout`] functions and associated constants
+/// Configuration to pass to [`open`] and [`scout`] functions and associated constants.
+///
+/// The zenoh configurattion is stored in a JSON file. The [`Config`] can be constructed from it using
+/// the corresponding `from_...` methods. It's also possible to read or
+/// modify individual elements of the [`Config`] with [`Config::insert_json5`](crate::config::Config::insert_json5)
+/// and [`Config::get_json`](crate::config::Config::get_json) methods.
+///
+/// The example of the configuration file is
+/// [available](https://github.com/eclipse-zenoh/zenoh/blob/release/1.0.0/DEFAULT_CONFIG.json5)
+/// in the zenoh repository.
+///
 pub mod config {
     pub use zenoh_config::{EndPoint, Locator, WhatAmI, WhatAmIMatcher, ZenohId};