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//! Handles and monitors JSONRPC v2 method calls and subscriptions
//!
//! Definitions:
//!
//! - RequestId: request ID in the JSONRPC-v2 specification
//! > **Note**: The spec allow number, string or null but this crate only supports numbers.
//! - SubscriptionId: unique ID generated by server
use fnv::FnvHashMap;
use futures::channel::{mpsc, oneshot};
use jsonrpsee_types::{
error::Error,
jsonrpc::{JsonValue, SubscriptionId},
};
use std::collections::{
hash_map::{Entry, HashMap},
VecDeque,
};
enum Kind {
PendingMethodCall(PendingCallOneshot),
PendingSubscription((PendingSubscriptionOneshot, UnsubscribeMethod)),
Subscription((SubscriptionSink, UnsubscribeMethod)),
}
/// Indicates the status of a given request/response.
pub enum RequestStatus {
/// The method call is waiting for a response,
PendingMethodCall,
/// The subscription is waiting for a response to become an active subscription.
PendingSubscription,
/// An active subscription.
Subscription,
/// Invalid request ID.
Invalid,
}
type PendingCallOneshot = Option<oneshot::Sender<Result<JsonValue, Error>>>;
type PendingBatchOneshot = oneshot::Sender<Result<Vec<JsonValue>, Error>>;
type PendingSubscriptionOneshot = oneshot::Sender<Result<(mpsc::Receiver<JsonValue>, SubscriptionId), Error>>;
type SubscriptionSink = mpsc::Sender<JsonValue>;
type UnsubscribeMethod = String;
/// Unique ID that are generated by the RequestManager.
// TODO: new type for this https://github.com/paritytech/jsonrpsee/issues/249
/// Wrapping counter for requests within a batch request.
// TODO: new type for this https://github.com/paritytech/jsonrpsee/issues/249
type BatchId = u64;
#[derive(Debug)]
/// Batch state.
pub struct BatchState {
/// Order that the request was performed in.
pub order: FnvHashMap<BatchId, usize>,
/// Request ID fetch from the `RequestManager`
pub request_id: RequestId,
/// Oneshot send back.
pub send_back: PendingBatchOneshot,
}
#[derive(Debug)]
/// Manages and monitors JSONRPC v2 method calls and subscriptions.
pub struct RequestManager {
/// Vacant requestIDs.
free_slots: VecDeque<RequestId>,
/// List of requests that are waiting for a response from the server.
// NOTE: FnvHashMap is used here because RequestId is not under the caller's control and is known to be a short key.
requests: FnvHashMap<RequestId, Kind>,
/// Reverse lookup, to find a request ID in constant time by `subscription ID` instead of looking through all requests.
subscriptions: HashMap<SubscriptionId, RequestId>,
/// Pending batch requests
batches: FnvHashMap<Vec<BatchId>, BatchState>,
/// Create a new `RequestManager` with specified capacity.
pub fn new(slot_capacity: usize) -> Self {
Self {
free_slots: (0..slot_capacity as u64).collect(),
requests: FnvHashMap::default(),
subscriptions: HashMap::new(),
}
}
/// Get next batch ID.
pub fn next_batch_id(&mut self) -> BatchId {
let id = self.batch_id;
self.batch_id = self.batch_id.wrapping_add(1);
id
}
/// Mark a used RequestID as free again.
pub fn reclaim_request_id(&mut self, request_id: RequestId) {
self.free_slots.push_back(request_id);
}
/// Get the next available request ID.
pub fn next_request_id(&mut self) -> Result<RequestId, Error> {
self.free_slots.pop_front().ok_or(Error::MaxSlotsExceeded)
}
/// Tries to insert a new pending call.
///
/// Returns `Ok` if the pending request was successfully inserted otherwise `Err`.
pub fn insert_pending_call(
&mut self,
id: RequestId,
send_back: PendingCallOneshot,
) -> Result<(), PendingCallOneshot> {
if let Entry::Vacant(v) = self.requests.entry(id) {
v.insert(Kind::PendingMethodCall(send_back));
Ok(())
} else {
Err(send_back)
}
}
/// Tries to insert a new batch request
///
/// Returns `Ok` if the pending request was successfully inserted otherwise `Err`.
pub fn insert_pending_batch(
&mut self,
mut batch: Vec<BatchId>,
send_back: PendingBatchOneshot,
request_id: RequestId,
) -> Result<(), PendingBatchOneshot> {
let mut order = FnvHashMap::with_capacity_and_hasher(batch.len(), Default::default());
for (idx, batch_id) in batch.iter().enumerate() {
order.insert(*batch_id, idx);
}
batch.sort_unstable();
if let Entry::Vacant(v) = self.batches.entry(batch) {
v.insert(BatchState { order, request_id, send_back });
Ok(())
} else {
Err(send_back)
}
}
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/// Tries to insert a new pending subscription.
///
/// Returns `Ok` if the pending request was successfully inserted otherwise `Err`.
pub fn insert_pending_subscription(
&mut self,
id: RequestId,
send_back: PendingSubscriptionOneshot,
unsubscribe_method: UnsubscribeMethod,
) -> Result<(), PendingSubscriptionOneshot> {
if let Entry::Vacant(v) = self.requests.entry(id) {
v.insert(Kind::PendingSubscription((send_back, unsubscribe_method)));
Ok(())
} else {
Err(send_back)
}
}
/// Tries to insert a new subscription.
///
/// Returns `Ok` if the pending request was successfully inserted otherwise `Err`.
pub fn insert_subscription(
&mut self,
request_id: RequestId,
subscription_id: SubscriptionId,
send_back: SubscriptionSink,
unsubscribe_method: String,
) -> Result<(), SubscriptionSink> {
if let (Entry::Vacant(request), Entry::Vacant(subscription)) =
(self.requests.entry(request_id), self.subscriptions.entry(subscription_id))
{
request.insert(Kind::Subscription((send_back, unsubscribe_method)));
subscription.insert(request_id);
Ok(())
} else {
Err(send_back)
}
}
/// Tries to complete a pending subscription.
///
/// Returns `Some` if the subscription was completed otherwise `None`.
pub fn complete_pending_subscription(
&mut self,
request_id: RequestId,
) -> Option<(PendingSubscriptionOneshot, UnsubscribeMethod)> {
match self.requests.entry(request_id) {
Entry::Occupied(request) if matches!(request.get(), Kind::PendingSubscription(_)) => {
let (_req_id, kind) = request.remove_entry();
if let Kind::PendingSubscription(send_back) = kind {
Some(send_back)
} else {
unreachable!("Pending subscription is Pending subscription checked above; qed");
}
}
_ => None,
}
}
/// Tries to complete a pending batch request
///
/// Returns `Some` if the subscription was completed otherwise `None`.
pub fn complete_pending_batch(&mut self, batch: Vec<BatchId>) -> Option<BatchState> {
match self.batches.entry(batch) {
Entry::Occupied(request) => {
let (_digest, state) = request.remove_entry();
Some(state)
}
_ => None,
}
}
/// Tries to complete a pending call..
///
/// Returns `Some` if the call was completed otherwise `None`.
pub fn complete_pending_call(&mut self, request_id: RequestId) -> Option<PendingCallOneshot> {
match self.requests.entry(request_id) {
Entry::Occupied(request) if matches!(request.get(), Kind::PendingMethodCall(_)) => {
let (_req_id, kind) = request.remove_entry();
if let Kind::PendingMethodCall(send_back) = kind {
Some(send_back)
} else {
unreachable!("Pending call is Pending call checked above; qed");
}
}
_ => None,
}
}
/// Tries to remove a subscription.
///
/// Returns `Some` if the subscription was removed otherwise `None`.
pub fn remove_subscription(
&mut self,
request_id: RequestId,
subscription_id: SubscriptionId,
) -> Option<(SubscriptionSink, UnsubscribeMethod, SubscriptionId)> {
match (self.requests.entry(request_id), self.subscriptions.entry(subscription_id)) {
(Entry::Occupied(request), Entry::Occupied(subscription))
if matches!(request.get(), Kind::Subscription(_)) =>
{
let (_req_id, kind) = request.remove_entry();
let (sub_id, _req_id) = subscription.remove_entry();
if let Kind::Subscription((send_back, unsub)) = kind {
Some((send_back, unsub, sub_id))
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} else {
unreachable!("Subscription is Subscription checked above; qed");
}
}
_ => None,
}
}
/// Returns the status of a request ID
pub fn request_status(&mut self, id: &RequestId) -> RequestStatus {
self.requests.get(id).map_or(RequestStatus::Invalid, |kind| match kind {
Kind::PendingMethodCall(_) => RequestStatus::PendingMethodCall,
Kind::PendingSubscription(_) => RequestStatus::PendingSubscription,
Kind::Subscription(_) => RequestStatus::Subscription,
})
}
/// Get a mutable reference to underlying `Sink` in order to send messages to the subscription.
///
/// Returns `Some` if the `request_id` was registered as a subscription otherwise `None`.
pub fn as_subscription_mut(&mut self, request_id: &RequestId) -> Option<&mut SubscriptionSink> {
if let Some(Kind::Subscription((sink, _))) = self.requests.get_mut(request_id) {
Some(sink)
} else {
None
}
}
/// Reverse lookup to get the request ID for a subscription ID.
///
/// Returns `Some` if the subscription ID was registered as a subscription otherwise `None`.
pub fn get_request_id_by_subscription_id(&self, sub_id: &SubscriptionId) -> Option<RequestId> {
self.subscriptions.get(sub_id).copied()
}
}
#[cfg(test)]
mod tests {
use super::{Error, RequestManager};
use futures::channel::{mpsc, oneshot};
use jsonrpsee_types::jsonrpc::{JsonValue, SubscriptionId};
const TEST_LIMIT: usize = 10;
#[test]
fn insert_remove_pending_request_works() {
let (request_tx, _) = oneshot::channel::<Result<JsonValue, Error>>();
let mut manager = RequestManager::new(TEST_LIMIT);
assert!(manager.insert_pending_call(0, Some(request_tx)).is_ok());
assert!(manager.complete_pending_call(0).is_some());
}
#[test]
fn insert_remove_subscription_works() {
let (pending_sub_tx, _) = oneshot::channel::<Result<(mpsc::Receiver<JsonValue>, SubscriptionId), Error>>();
let (sub_tx, _) = mpsc::channel::<JsonValue>(1);
let mut manager = RequestManager::new(TEST_LIMIT);
assert!(manager.insert_pending_subscription(1, pending_sub_tx, "unsubscribe_method".into()).is_ok());
let (_send_back_oneshot, unsubscribe_method) = manager.complete_pending_subscription(1).unwrap();
assert!(manager
.insert_subscription(1, SubscriptionId::Str("uniq_id_from_server".to_string()), sub_tx, unsubscribe_method)
.is_ok());
assert!(manager.as_subscription_mut(&1).is_some());
assert!(manager.remove_subscription(1, SubscriptionId::Str("uniq_id_from_server".to_string())).is_some());
}
#[test]
fn pending_method_call_faulty() {
let (request_tx1, _) = oneshot::channel::<Result<JsonValue, Error>>();
let (request_tx2, _) = oneshot::channel::<Result<JsonValue, Error>>();
let (pending_sub_tx, _) = oneshot::channel::<Result<(mpsc::Receiver<JsonValue>, SubscriptionId), Error>>();
let (sub_tx, _) = mpsc::channel::<JsonValue>(1);
let mut manager = RequestManager::new(TEST_LIMIT);
assert!(manager.insert_pending_call(0, Some(request_tx1)).is_ok());
assert!(manager.insert_pending_call(0, Some(request_tx2)).is_err());
assert!(manager.insert_pending_subscription(0, pending_sub_tx, "beef".to_string()).is_err());
assert!(manager.insert_subscription(0, SubscriptionId::Num(137), sub_tx, "bibimbap".to_string()).is_err());
assert!(manager.remove_subscription(0, SubscriptionId::Num(137)).is_none());
assert!(manager.complete_pending_subscription(0).is_none());
assert!(manager.complete_pending_call(0).is_some());
}
#[test]
fn pending_subscription_faulty() {
let (request_tx, _) = oneshot::channel::<Result<JsonValue, Error>>();
let (pending_sub_tx1, _) = oneshot::channel::<Result<(mpsc::Receiver<JsonValue>, SubscriptionId), Error>>();
let (pending_sub_tx2, _) = oneshot::channel::<Result<(mpsc::Receiver<JsonValue>, SubscriptionId), Error>>();
let (sub_tx, _) = mpsc::channel::<JsonValue>(1);
let mut manager = RequestManager::new(TEST_LIMIT);
assert!(manager.insert_pending_subscription(99, pending_sub_tx1, "beef".to_string()).is_ok());
assert!(manager.insert_pending_call(99, Some(request_tx)).is_err());
assert!(manager.insert_pending_subscription(99, pending_sub_tx2, "vegan".to_string()).is_err());
assert!(manager.insert_subscription(99, SubscriptionId::Num(0), sub_tx, "bibimbap".to_string()).is_err());
assert!(manager.remove_subscription(99, SubscriptionId::Num(0)).is_none());
assert!(manager.complete_pending_call(99).is_none());
assert!(manager.complete_pending_subscription(99).is_some());
}
#[test]
fn active_subscriptions_faulty() {
let (request_tx, _) = oneshot::channel::<Result<JsonValue, Error>>();
let (pending_sub_tx, _) = oneshot::channel::<Result<(mpsc::Receiver<JsonValue>, SubscriptionId), Error>>();
let (sub_tx1, _) = mpsc::channel::<JsonValue>(1);
let (sub_tx2, _) = mpsc::channel::<JsonValue>(1);
let mut manager = RequestManager::new(TEST_LIMIT);
assert!(manager.insert_subscription(3, SubscriptionId::Num(0), sub_tx1, "bibimbap".to_string()).is_ok());
assert!(manager.insert_subscription(3, SubscriptionId::Num(1), sub_tx2, "bibimbap".to_string()).is_err());
assert!(manager.insert_pending_subscription(3, pending_sub_tx, "beef".to_string()).is_err());
assert!(manager.insert_pending_call(3, Some(request_tx)).is_err());
assert!(manager.remove_subscription(3, SubscriptionId::Num(7)).is_none());
assert!(manager.complete_pending_call(3).is_none());
assert!(manager.complete_pending_subscription(3).is_none());
assert!(manager.remove_subscription(3, SubscriptionId::Num(1)).is_none());
assert!(manager.remove_subscription(3, SubscriptionId::Num(0)).is_some());
}
#[test]
fn request_manager_limit_works() {
let mut manager = RequestManager::new(TEST_LIMIT);
for id in 0..TEST_LIMIT {
assert_eq!(id as u64, manager.next_request_id().unwrap());
}
assert!(matches!(manager.next_request_id().unwrap_err(), Error::MaxSlotsExceeded));
manager.reclaim_request_id(5);
assert_eq!(5, manager.next_request_id().unwrap());
}