fix: add rate limit to get market price RPC calls

autonomi/src/client/quote.rs

@@ -9,12 +9,16 @@
 use super::{data::CostError, Client};
 use ant_evm::payment_vault::get_market_price;
 use ant_evm::{Amount, PaymentQuote, QuotePayment};
+use ant_networking::target_arch::{sleep, Duration, Instant};
 use ant_networking::{Network, NetworkError};
 use ant_protocol::{storage::ChunkAddress, NetworkAddress};
 use libp2p::PeerId;
 use std::collections::HashMap;
 use xor_name::XorName;
 
+// set rate limit to 2 req/s
+const TIME_BETWEEN_RPC_CALLS_IN_MS: u64 = 500;
+
 /// A quote for a single address
 pub struct QuoteForAddress(pub(crate) Vec<(PeerId, PaymentQuote, Amount)>);
 
@@ -63,15 +67,34 @@ impl Client {
             .collect();
         let raw_quotes_per_addr = futures::future::try_join_all(futures).await?;
 
+        debug!("Fetched store quotes: {raw_quotes_per_addr:?}");
+
         // choose the quotes to pay for each address
         let mut quotes_to_pay_per_addr = HashMap::new();
         for (content_addr, raw_quotes) in raw_quotes_per_addr {
             // ask smart contract for the market price
             let mut prices = vec![];
+
+            // rate limit
+            let mut maybe_last_call: Option<Instant> = None;
+
             for (peer, quote) in raw_quotes {
                 // NB TODO @mick we need to batch this smart contract call
+                // check if we have to wait for the rate limit
+                if let Some(last_call) = maybe_last_call {
+                    let elapsed = Instant::now() - last_call;
+                    let time_to_sleep_ms =
+                        TIME_BETWEEN_RPC_CALLS_IN_MS as u128 - elapsed.as_millis();
+                    if time_to_sleep_ms > 0 {
+                        sleep(Duration::from_millis(time_to_sleep_ms as u64)).await;
+                    }
+                }
+
                 let price =
                     get_market_price(&self.evm_network, quote.quoting_metrics.clone()).await?;
+
+                maybe_last_call = Some(Instant::now());
+
                 prices.push((peer, quote, price));
             }