feat: unify queues in proxy (#976)

* wip: unify queues in proxy

* fix: remove prints, update documentation

* fix: remove sleep

* docs: update changelog

* feat: use struct for queue, add methods for context, move functions to utils

* docs: add separator for structs, add doc comments

* feat: use VecDequeue instead of Vec for queues

* fix: add concurrent to makefile installation

* rename set_available_worker, use assert instead of if

* fix: use constant for interval time

* fix: fix docs, remove unused scope, remove _ from var

* fix: changelog entry

* feat: use u128 for request_id

* docs: update {add, get}_available_worker documentation

* fix: use mayus for structs sections, rename get_available_worker, add info logs, fix documentation

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Changes
 
+- Refactored `miden-tx-prover` proxy load balancing strategy (#976).
 - [BREAKING] Better error display when queues are full in the prover service (#967).
 - [BREAKING] Remove `AccountBuilder::build_testing` and make `Account::initialize_from_components` private (#969).
 - [BREAKING] Add error messages to errors and implement `core::error::Error` (#974).

Makefile

@@ -106,8 +106,8 @@ bench-tx: ## Run transaction benchmarks
 
 .PHONY: install-tx-prover
 install-tx-prover: ## Install transaction prover's CLI
-	cargo install --path bin/tx-prover --bin miden-tx-prover --locked
+	cargo install --path bin/tx-prover --bin miden-tx-prover --locked --features concurrent
 
 .PHONY: install-tx-prover-testing
 install-tx-prover-testing: ## Install transaction prover's CLI intended for testing purposes
-	cargo install --path bin/tx-prover --bin miden-tx-prover --locked --features testing
+	cargo install --path bin/tx-prover --bin miden-tx-prover --locked --features concurrent,testing

bin/tx-prover/README.md

@@ -4,7 +4,7 @@ A service for generating Miden transaction proofs on-demand. The binary enables
 
 The worker is a gRPC service that can receive transaction witnesses and returns the proof. It can only handle one request at a time and returns an error if is already in use.
 
-The proxy uses [Cloudflare's Pingora crate](https://crates.io/crates/pingora), which provides features to create a modular proxy. It is meant to handle multiple workers with a queue for each one, load balancing incoming requests in a round-robin manner. Further information about Pingora and its features can be found in the [official GitHub repository](https://github.com/cloudflare/pingora).
+The proxy uses [Cloudflare's Pingora crate](https://crates.io/crates/pingora), which provides features to create a modular proxy. It is meant to handle multiple workers with a queue, assigning a worker to each request and retrying if the worker is not available. Further information about Pingora and its features can be found in the [official GitHub repository](https://github.com/cloudflare/pingora).
 
 Additionally, the library can be imported to utilize `RemoteTransactionProver`, a client struct that can be used to interact with the prover service from a Rust codebase.
 

bin/tx-prover/src/commands/proxy.rs

@@ -1,7 +1,5 @@
 use clap::Parser;
-use pingora::{
-    apps::HttpServerOptions, lb::LoadBalancer as PingoraLoadBalancer, prelude::Opt, server::Server,
-};
+use pingora::{apps::HttpServerOptions, lb::Backend, prelude::Opt, server::Server};
 use pingora_proxy::http_proxy_service;
 
 use crate::{proxy::LoadBalancer, utils::load_config_from_file};
@@ -24,10 +22,9 @@ impl StartProxy {
         let workers = proxy_config
             .workers
             .iter()
-            .map(|worker| format!("{}:{}", worker.host, worker.port));
-
-        let workers =
-            PingoraLoadBalancer::try_from_iter(workers).expect("PROVER_WORKERS is invalid");
+            .map(|worker| format!("{}:{}", worker.host, worker.port))
+            .map(|worker| Backend::new(&worker).expect("Failed to create backend"))
+            .collect::<Vec<Backend>>();
 
         let worker_lb = LoadBalancer::new(workers, &proxy_config);