Check transaction number on total chains (#4325)

## Motivation

Right now we're checking just the number of chains in a wallet, but if
we're using cross wallet transfers, we need to take all chains from all
wallets into consideration.

## Proposal

Take all chains from all wallets used in the benchmark into
consideration

## Test Plan

Ran this against a deployed network

## Release Plan

- Nothing to do / These changes follow the usual release cycle.

Author: ndr-ds

linera-client/src/benchmark.rs

@@ -643,16 +643,16 @@ impl<Env: Environment> Benchmark<Env> {
         Ok(all_chains)
     }
 
-    /// Generates information related to one block per chain.
     pub fn make_benchmark_block_info(
         benchmark_chains: Vec<(ChainId, AccountOwner)>,
         transactions_per_block: usize,
         fungible_application_id: Option<ApplicationId>,
         all_chains: Vec<ChainId>,
     ) -> Result<Vec<Vec<Operation>>, BenchmarkError> {
         let mut blocks_infos = Vec::new();
+        let amount = Amount::from_attos(1);
+
         for (current_chain_id, owner) in benchmark_chains.iter() {
-            let amount = Amount::from(1);
             let mut operations = Vec::new();
 
             let mut other_chains: Vec<_> = if all_chains.len() == 1 {
@@ -669,6 +669,22 @@ impl<Env: Environment> Benchmark<Env> {
             };
 
             other_chains.shuffle(&mut thread_rng());
+
+            // Calculate adjusted transactions_per_block to ensure even distribution
+            let num_destinations = other_chains.len();
+            let adjusted_transactions_per_block = if transactions_per_block % num_destinations != 0
+            {
+                let adjusted = transactions_per_block.div_ceil(num_destinations) * num_destinations;
+                warn!(
+                    "Requested transactions_per_block ({}) is not evenly divisible by number of destination chains ({}). \
+                    Adjusting to {} transactions per block to ensure transfers cancel each other out.",
+                    transactions_per_block, num_destinations, adjusted
+                );
+                adjusted
+            } else {
+                transactions_per_block
+            };
+
             for recipient_chain_id in other_chains {
                 let operation = match fungible_application_id {
                     Some(application_id) => Self::fungible_transfer(
@@ -690,7 +706,7 @@ impl<Env: Environment> Benchmark<Env> {
             let operations = operations
                 .into_iter()
                 .cycle()
-                .take(transactions_per_block)
+                .take(adjusted_transactions_per_block)
                 .collect();
             blocks_infos.push(operations);
         }

linera-service/src/cli/main.rs

@@ -829,22 +829,12 @@ impl Runnable for Job {
                     "max_pending_message_bundles must be set to at least the same as the \
                      number of transactions per block ({transactions_per_block}) for benchmarking",
                 );
-                assert!(
-                    num_chains > 0,
-                    "Number of chain groups must be greater than 0"
-                );
+                assert!(num_chains > 0, "Number of chains must be greater than 0");
                 assert!(
                     transactions_per_block > 0,
                     "Number of transactions per block must be greater than 0"
                 );
                 assert!(bps > 0, "BPS must be greater than 0");
-                if num_chains > 1 {
-                    assert!(
-                        transactions_per_block % (num_chains - 1) == 0,
-                        "Number of transactions per block must be a multiple of the number of \
-                         chains minus 1, to make sure transactions always cancel each other out"
-                    );
-                }
 
                 let listener_config = ChainListenerConfig {
                     skip_process_inbox: true,