From 7aa1fb4e2494a372ba513b2775d1134180aff3a1 Mon Sep 17 00:00:00 2001 From: Tao Zhu Date: Fri, 4 Feb 2022 18:57:02 -0600 Subject: [PATCH] 1. Persist to blockstore less frequently; 2. reduce alpha for EMA to 1 percent to have roughly 200 data points for estimatio --- core/src/cost_update_service.rs | 235 +++++++++++++++--------------- core/src/tvu.rs | 8 +- runtime/src/cost_model.rs | 80 ++++++---- runtime/src/execute_cost_table.rs | 85 +++++++---- 4 files changed, 232 insertions(+), 176 deletions(-) diff --git a/core/src/cost_update_service.rs b/core/src/cost_update_service.rs index a7f1571aca..8e472b51f5 100644 --- a/core/src/cost_update_service.rs +++ b/core/src/cost_update_service.rs @@ -9,18 +9,16 @@ use { solana_measure::measure::Measure, solana_program_runtime::timings::ExecuteTimings, solana_runtime::{bank::Bank, cost_model::CostModel}, - solana_sdk::{pubkey::Pubkey, timing::timestamp}, + solana_sdk::timing::timestamp, std::{ - collections::HashMap, - sync::{ - atomic::{AtomicBool, Ordering}, - Arc, RwLock, - }, + sync::{Arc, RwLock}, thread::{self, Builder, JoinHandle}, - time::Duration, }, }; +// Update blockstore persistence storage when accumulated cost_table updates count exceeds the threshold +const PERSIST_THRESHOLD: u64 = 1_000; + #[derive(Default)] pub struct CostUpdateServiceTiming { last_print: u64, @@ -32,20 +30,25 @@ pub struct CostUpdateServiceTiming { impl CostUpdateServiceTiming { fn update( &mut self, - update_cost_model_count: u64, - update_cost_model_elapsed: u64, - persist_cost_table_elapsed: u64, + update_cost_model_count: Option, + update_cost_model_elapsed: Option, + persist_cost_table_elapsed: Option, ) { - self.update_cost_model_count += update_cost_model_count; - self.update_cost_model_elapsed += update_cost_model_elapsed; - self.persist_cost_table_elapsed += persist_cost_table_elapsed; + if let Some(update_cost_model_count) = update_cost_model_count { + self.update_cost_model_count += update_cost_model_count; + } + if let Some(update_cost_model_elapsed) = update_cost_model_elapsed { + self.update_cost_model_elapsed += update_cost_model_elapsed; + } + if let Some(persist_cost_table_elapsed) = persist_cost_table_elapsed { + self.persist_cost_table_elapsed += persist_cost_table_elapsed; + } let now = timestamp(); let elapsed_ms = now - self.last_print; if elapsed_ms > 1000 { datapoint_info!( "cost-update-service-stats", - ("total_elapsed_us", elapsed_ms * 1000, i64), ( "update_cost_model_count", self.update_cost_model_count as i64, @@ -87,7 +90,6 @@ pub struct CostUpdateService { impl CostUpdateService { #[allow(clippy::new_ret_no_self)] pub fn new( - exit: Arc, blockstore: Arc, cost_model: Arc>, cost_update_receiver: CostUpdateReceiver, @@ -95,7 +97,7 @@ impl CostUpdateService { let thread_hdl = Builder::new() .name("solana-cost-update-service".to_string()) .spawn(move || { - Self::service_loop(exit, blockstore, cost_model, cost_update_receiver); + Self::service_loop(blockstore, cost_model, cost_update_receiver); }) .unwrap(); @@ -107,58 +109,53 @@ impl CostUpdateService { } fn service_loop( - exit: Arc, blockstore: Arc, cost_model: Arc>, cost_update_receiver: CostUpdateReceiver, ) { let mut cost_update_service_timing = CostUpdateServiceTiming::default(); - let mut update_count: u64; - let mut updated_program_costs = HashMap::::new(); - let wait_timer = Duration::from_millis(100); + let mut update_count = 0_u64; - loop { - if exit.load(Ordering::Relaxed) { - break; - } + for cost_update in cost_update_receiver.iter() { + match cost_update { + CostUpdate::FrozenBank { bank } => { + bank.read_cost_tracker().unwrap().report_stats(bank.slot()); + } + CostUpdate::ExecuteTiming { + mut execute_timings, + } => { + let mut update_cost_model_time = Measure::start("update_cost_model_time"); + update_count += Self::update_cost_model(&cost_model, &mut execute_timings); + update_cost_model_time.stop(); + cost_update_service_timing.update( + Some(update_count), + Some(update_cost_model_time.as_us()), + None, + ); - update_count = 0_u64; - let mut update_cost_model_time = Measure::start("update_cost_model_time"); - for cost_update in cost_update_receiver.try_iter() { - match cost_update { - CostUpdate::FrozenBank { bank } => { - bank.read_cost_tracker().unwrap().report_stats(bank.slot()); - } - CostUpdate::ExecuteTiming { - mut execute_timings, - } => { - updated_program_costs = - Self::update_cost_model(&cost_model, &mut execute_timings); - update_count += 1; + if update_count > PERSIST_THRESHOLD { + let mut persist_cost_table_time = Measure::start("persist_cost_table_time"); + Self::persist_cost_table(&blockstore, &cost_model); + update_count = 0_u64; + persist_cost_table_time.stop(); + cost_update_service_timing.update( + None, + None, + Some(persist_cost_table_time.as_us()), + ); } } } - update_cost_model_time.stop(); - - let mut persist_cost_table_time = Measure::start("persist_cost_table_time"); - Self::persist_cost_table(&blockstore, &updated_program_costs); - persist_cost_table_time.stop(); - - cost_update_service_timing.update( - update_count, - update_cost_model_time.as_us(), - persist_cost_table_time.as_us(), - ); - - thread::sleep(wait_timer); } } + // Normalize `program_timings` with current estimated cost, update instruction_cost table + // Returns number of updates applied fn update_cost_model( cost_model: &RwLock, execute_timings: &mut ExecuteTimings, - ) -> HashMap { - let mut updated_program_costs = HashMap::::new(); + ) -> u64 { + let mut update_count = 0_u64; for (program_id, program_timings) in &mut execute_timings.details.per_program_timings { let current_estimated_program_cost = cost_model.read().unwrap().find_instruction_cost(program_id); @@ -169,50 +166,42 @@ impl CostUpdateService { } let units = program_timings.accumulated_units / program_timings.count as u64; - match cost_model + cost_model .write() .unwrap() - .upsert_instruction_cost(program_id, units) - { - Ok(cost) => { - debug!( - "after replayed into bank, instruction {:?} has averaged cost {}", - program_id, cost - ); - updated_program_costs.insert(*program_id, cost); - } - Err(err) => { - debug!( - "after replayed into bank, instruction {:?} failed to update cost, err: {}", - program_id, err - ); - } - } + .upsert_instruction_cost(program_id, units); + update_count += 1; + debug!( + "After replayed into bank, updated cost for instruction {:?}, update_value {}, pre_aggregated_value {}", + program_id, units, current_estimated_program_cost + ); } - updated_program_costs + update_count } - fn persist_cost_table(blockstore: &Blockstore, updated_program_costs: &HashMap) { - if updated_program_costs.is_empty() { - return; - } - + // 1. Remove obsolete program entries from persisted table to limit its size + // 2. Update persisted program cost. This involves EMA cost calculation at + // execute_cost_table.get_cost() + fn persist_cost_table(blockstore: &Blockstore, cost_model: &RwLock) { let db_records = blockstore.read_program_costs().expect("read programs"); + let cost_model = cost_model.read().unwrap(); + let active_program_keys = cost_model.get_program_keys(); // delete records from blockstore if they are no longer in cost_table db_records.iter().for_each(|(pubkey, _)| { - if !updated_program_costs.contains_key(pubkey) { + if !active_program_keys.contains(&pubkey) { blockstore .delete_program_cost(pubkey) .expect("delete old program"); } }); - for (key, cost) in updated_program_costs.iter() { + active_program_keys.iter().for_each(|program_id| { + let cost = cost_model.find_instruction_cost(program_id); blockstore - .write_program_cost(key, cost) + .write_program_cost(program_id, &cost) .expect("persist program costs to blockstore"); - } + }); } } @@ -224,9 +213,9 @@ mod tests { fn test_update_cost_model_with_empty_execute_timings() { let cost_model = Arc::new(RwLock::new(CostModel::default())); let mut empty_execute_timings = ExecuteTimings::default(); - assert!( - CostUpdateService::update_cost_model(&cost_model, &mut empty_execute_timings) - .is_empty() + assert_eq!( + CostUpdateService::update_cost_model(&cost_model, &mut empty_execute_timings), + 0 ); } @@ -256,12 +245,15 @@ mod tests { total_errored_units, }, ); - let updated_program_costs = + let update_count = CostUpdateService::update_cost_model(&cost_model, &mut execute_timings); - assert_eq!(1, updated_program_costs.len()); + assert_eq!(1, update_count); assert_eq!( - Some(&expected_cost), - updated_program_costs.get(&program_key_1) + expected_cost, + cost_model + .read() + .unwrap() + .find_instruction_cost(&program_key_1) ); } @@ -270,8 +262,8 @@ mod tests { let accumulated_us: u64 = 2000; let accumulated_units: u64 = 200; let count: u32 = 10; - // to expect new cost = (mean + 2 * std) - expected_cost = 24; + // to expect new cost = (mean + 2 * std) of [10, 20] + expected_cost = 13; execute_timings.details.per_program_timings.insert( program_key_1, @@ -283,12 +275,15 @@ mod tests { total_errored_units: 0, }, ); - let updated_program_costs = + let update_count = CostUpdateService::update_cost_model(&cost_model, &mut execute_timings); - assert_eq!(1, updated_program_costs.len()); + assert_eq!(1, update_count); assert_eq!( - Some(&expected_cost), - updated_program_costs.get(&program_key_1) + expected_cost, + cost_model + .read() + .unwrap() + .find_instruction_cost(&program_key_1) ); } } @@ -314,8 +309,9 @@ mod tests { ); // If both the `errored_txs_compute_consumed` is empty and `count == 0`, then // nothing should be inserted into the cost model - assert!( - CostUpdateService::update_cost_model(&cost_model, &mut execute_timings).is_empty() + assert_eq!( + CostUpdateService::update_cost_model(&cost_model, &mut execute_timings), + 0 ); } @@ -332,12 +328,15 @@ mod tests { total_errored_units: 0, }, ); - let updated_program_costs = + let update_count = CostUpdateService::update_cost_model(&cost_model, &mut execute_timings); - assert_eq!(1, updated_program_costs.len()); + assert_eq!(1, update_count); assert_eq!( - Some(¤t_program_cost), - updated_program_costs.get(&program_key_1) + current_program_cost, + cost_model + .read() + .unwrap() + .find_instruction_cost(&program_key_1) ); } @@ -345,6 +344,12 @@ mod tests { // greater than the current instruction cost for the program. Should update with the // new erroring compute costs let cost_per_error = 1000; + // expected_cost = (mean + 2*std) of data points: + // [ + // 100, // original program_cost + // 1000, // cost_per_error + // ] + let expected_cost = 289u64; { let errored_txs_compute_consumed = vec![cost_per_error; 3]; let total_errored_units = errored_txs_compute_consumed.iter().sum(); @@ -358,26 +363,23 @@ mod tests { total_errored_units, }, ); - let updated_program_costs = + let update_count = CostUpdateService::update_cost_model(&cost_model, &mut execute_timings); - // expected_cost = (mean + 2*std) of data points: - // [ - // 100, // original program_cost - // 1000, // cost_per_error - // ] - let expected_cost = 1342u64; - assert_eq!(1, updated_program_costs.len()); + assert_eq!(1, update_count); assert_eq!( - Some(&expected_cost), - updated_program_costs.get(&program_key_1) + expected_cost, + cost_model + .read() + .unwrap() + .find_instruction_cost(&program_key_1) ); } // Test updating cost model with only erroring compute costs where the error cost is // `smaller_cost_per_error`, less than the current instruction cost for the program. // The cost should not decrease for these new lesser errors - let smaller_cost_per_error = cost_per_error - 10; + let smaller_cost_per_error = expected_cost - 10; { let errored_txs_compute_consumed = vec![smaller_cost_per_error; 3]; let total_errored_units = errored_txs_compute_consumed.iter().sum(); @@ -391,20 +393,23 @@ mod tests { total_errored_units, }, ); - let updated_program_costs = + let update_count = CostUpdateService::update_cost_model(&cost_model, &mut execute_timings); // expected_cost = (mean = 2*std) of data points: // [ // 100, // original program cost, // 1000, // cost_per_error from above test - // 1450, // the smaller_cost_per_error will be coalesced to prev cost + // 289, // the smaller_cost_per_error will be coalesced to prev cost // ] - let expected_cost = 1915u64; - assert_eq!(1, updated_program_costs.len()); + let expected_cost = 293u64; + assert_eq!(1, update_count); assert_eq!( - Some(&expected_cost), - updated_program_costs.get(&program_key_1) + expected_cost, + cost_model + .read() + .unwrap() + .find_instruction_cost(&program_key_1) ); } } diff --git a/core/src/tvu.rs b/core/src/tvu.rs index 8e6069ea0f..ec30d9921b 100644 --- a/core/src/tvu.rs +++ b/core/src/tvu.rs @@ -305,12 +305,8 @@ impl Tvu { ); let (cost_update_sender, cost_update_receiver) = unbounded(); - let cost_update_service = CostUpdateService::new( - exit.clone(), - blockstore.clone(), - cost_model.clone(), - cost_update_receiver, - ); + let cost_update_service = + CostUpdateService::new(blockstore.clone(), cost_model.clone(), cost_update_receiver); let (drop_bank_sender, drop_bank_receiver) = unbounded(); diff --git a/runtime/src/cost_model.rs b/runtime/src/cost_model.rs index 534dae0470..f42521fa09 100644 --- a/runtime/src/cost_model.rs +++ b/runtime/src/cost_model.rs @@ -96,17 +96,11 @@ impl CostModel { tx_cost } - pub fn upsert_instruction_cost( - &mut self, - program_key: &Pubkey, - cost: u64, - ) -> Result { + // update-or-insert op is always successful. However the result of upsert, eg the aggregated + // value, requires additional calculation, which should only be envoked when needed. + pub fn upsert_instruction_cost(&mut self, program_key: &Pubkey, cost: u64) { self.instruction_execution_cost_table .upsert(program_key, cost); - match self.instruction_execution_cost_table.get_cost(program_key) { - Some(cost) => Ok(cost), - None => Err("failed to upsert to ExecuteCostTable"), - } } pub fn find_instruction_cost(&self, program_key: &Pubkey) -> u64 { @@ -115,7 +109,7 @@ impl CostModel { None => { let default_value = self.instruction_execution_cost_table.get_default(); debug!( - "Program key {:?} does not have assigned cost, using default value {}", + "instruction {:?} does not have aggregated cost, using default {}", program_key, default_value ); default_value @@ -123,6 +117,10 @@ impl CostModel { } } + pub fn get_program_keys(&self) -> Vec<&Pubkey> { + self.instruction_execution_cost_table.get_program_keys() + } + fn get_signature_cost(&self, transaction: &SanitizedTransaction) -> u64 { transaction.signatures().len() as u64 * SIGNATURE_COST } @@ -246,6 +244,7 @@ mod tests { transaction::Transaction, }, std::{ + collections::HashMap, str::FromStr, sync::{Arc, RwLock}, thread::{self, JoinHandle}, @@ -269,13 +268,11 @@ mod tests { let mut testee = CostModel::default(); let known_key = Pubkey::from_str("known11111111111111111111111111111111111111").unwrap(); - testee.upsert_instruction_cost(&known_key, 100).unwrap(); + testee.upsert_instruction_cost(&known_key, 100); // find cost for known programs assert_eq!(100, testee.find_instruction_cost(&known_key)); - testee - .upsert_instruction_cost(&bpf_loader::id(), 1999) - .unwrap(); + testee.upsert_instruction_cost(&bpf_loader::id(), 1999); assert_eq!(1999, testee.find_instruction_cost(&bpf_loader::id())); // unknown program is assigned with default cost @@ -287,6 +284,35 @@ mod tests { ); } + #[test] + fn test_iterating_instruction_cost_by_program_keys() { + solana_logger::setup(); + let mut testee = CostModel::default(); + + let mut test_key_and_cost = HashMap::::new(); + (0u64..10u64).for_each(|n| { + test_key_and_cost.insert(Pubkey::new_unique(), n); + }); + + test_key_and_cost.iter().for_each(|(key, cost)| { + testee.upsert_instruction_cost(key, *cost); + info!("key {:?} cost {}", key, cost); + }); + + let keys = testee.get_program_keys(); + // verify each key has pre-set value + keys.iter().for_each(|key| { + let expected_cost = test_key_and_cost.get(key).unwrap(); + info!( + "check key {:?} expect {} find {}", + key, + expected_cost, + testee.find_instruction_cost(key) + ); + assert_eq!(*expected_cost, testee.find_instruction_cost(key)); + }); + } + #[test] fn test_cost_model_data_len_cost() { let lamports = 0; @@ -351,9 +377,7 @@ mod tests { let expected_cost = 8; let mut testee = CostModel::default(); - testee - .upsert_instruction_cost(&system_program::id(), expected_cost) - .unwrap(); + testee.upsert_instruction_cost(&system_program::id(), expected_cost); assert_eq!( expected_cost, testee.get_transaction_cost(&simple_transaction) @@ -381,9 +405,7 @@ mod tests { let expected_cost = program_cost * 2; let mut testee = CostModel::default(); - testee - .upsert_instruction_cost(&system_program::id(), program_cost) - .unwrap(); + testee.upsert_instruction_cost(&system_program::id(), program_cost); assert_eq!(expected_cost, testee.get_transaction_cost(&tx)); } @@ -464,7 +486,7 @@ mod tests { ); // insert instruction cost to table - assert!(cost_model.upsert_instruction_cost(&key1, cost1).is_ok()); + cost_model.upsert_instruction_cost(&key1, cost1); // now it is known insturction with known cost assert_eq!(cost1, cost_model.find_instruction_cost(&key1)); @@ -484,9 +506,7 @@ mod tests { let expected_execution_cost = 8; let mut cost_model = CostModel::default(); - cost_model - .upsert_instruction_cost(&system_program::id(), expected_execution_cost) - .unwrap(); + cost_model.upsert_instruction_cost(&system_program::id(), expected_execution_cost); let tx_cost = cost_model.calculate_cost(&tx); assert_eq!(expected_account_cost, tx_cost.write_lock_cost); assert_eq!(expected_execution_cost, tx_cost.execution_cost); @@ -498,17 +518,17 @@ mod tests { let key1 = Pubkey::new_unique(); let cost1 = 100; let cost2 = 200; - // updated_cost = (mean + 2*std) - let updated_cost = 238; + // updated_cost = (mean + 2*std) of [100, 200] => 120.899 + let updated_cost = 121; let mut cost_model = CostModel::default(); // insert instruction cost to table - assert!(cost_model.upsert_instruction_cost(&key1, cost1).is_ok()); + cost_model.upsert_instruction_cost(&key1, cost1); assert_eq!(cost1, cost_model.find_instruction_cost(&key1)); // update instruction cost - assert!(cost_model.upsert_instruction_cost(&key1, cost2).is_ok()); + cost_model.upsert_instruction_cost(&key1, cost2); assert_eq!(updated_cost, cost_model.find_instruction_cost(&key1)); } @@ -550,8 +570,8 @@ mod tests { if i == 5 { thread::spawn(move || { let mut cost_model = cost_model.write().unwrap(); - assert!(cost_model.upsert_instruction_cost(&prog1, cost1).is_ok()); - assert!(cost_model.upsert_instruction_cost(&prog2, cost2).is_ok()); + cost_model.upsert_instruction_cost(&prog1, cost1); + cost_model.upsert_instruction_cost(&prog2, cost2); }) } else { thread::spawn(move || { diff --git a/runtime/src/execute_cost_table.rs b/runtime/src/execute_cost_table.rs index c779164609..d45bce0ffb 100644 --- a/runtime/src/execute_cost_table.rs +++ b/runtime/src/execute_cost_table.rs @@ -4,7 +4,10 @@ /// When its capacity limit is reached, it prunes old and less-used programs /// to make room for new ones. use log::*; -use {solana_sdk::pubkey::Pubkey, std::collections::HashMap}; +use { + solana_sdk::pubkey::Pubkey, + std::collections::{hash_map::Entry, HashMap}, +}; // prune is rather expensive op, free up bulk space in each operation // would be more efficient. PRUNE_RATIO defines the after prune table @@ -18,7 +21,8 @@ const DEFAULT_CAPACITY: usize = 1024; // The coefficient represents the degree of weighting decrease in EMA, // a constant smoothing factor between 0 and 1. A higher alpha // discounts older observations faster. -const COEFFICIENT: f64 = 0.4; +// Setting it using `2/(N+1)` where N is 200 samples +const COEFFICIENT: f64 = 0.01; #[derive(Debug, Default)] struct AggregatedVarianceStats { @@ -53,19 +57,27 @@ impl ExecuteCostTable { self.table.len() } - // default prorgam cost to max + // default program cost to max pub fn get_default(&self) -> u64 { - // default max comoute units per program + // default max compute units per program 200_000u64 } // returns None if program doesn't exist in table. In this case, - // it is advised to call `get_default()` for default program costdefault/ + // it is advised to call `get_default()` for default program cost. // Program cost is estimated as 2 standard deviations above mean, eg // cost = (mean + 2 * std) pub fn get_cost(&self, key: &Pubkey) -> Option { let aggregated = self.table.get(key)?; - Some((aggregated.ema + 2.0 * aggregated.ema_var.sqrt()).ceil() as u64) + let cost_f64 = (aggregated.ema + 2.0 * aggregated.ema_var.sqrt()).ceil(); + + // check if cost:f64 can be losslessly convert to u64, otherwise return None + let cost_u64 = cost_f64 as u64; + if cost_f64 == cost_u64 as f64 { + Some(cost_u64) + } else { + None + } } pub fn upsert(&mut self, key: &Pubkey, value: u64) { @@ -77,21 +89,21 @@ impl ExecuteCostTable { // exponential moving average algorithm // https://en.wikipedia.org/wiki/Moving_average#Exponentially_weighted_moving_variance_and_standard_deviation - if self.table.contains_key(key) { - let aggregated = self.table.get_mut(key).unwrap(); - let theta = value as f64 - aggregated.ema; - aggregated.ema += theta * COEFFICIENT; - aggregated.ema_var = - (1.0 - COEFFICIENT) * (aggregated.ema_var + COEFFICIENT * theta * theta) - } else { - // the starting values - self.table.insert( - *key, - AggregatedVarianceStats { + match self.table.entry(*key) { + Entry::Occupied(mut entry) => { + let aggregated = entry.get_mut(); + let theta = value as f64 - aggregated.ema; + aggregated.ema += theta * COEFFICIENT; + aggregated.ema_var = + (1.0 - COEFFICIENT) * (aggregated.ema_var + COEFFICIENT * theta * theta); + } + Entry::Vacant(entry) => { + // the starting values + entry.insert(AggregatedVarianceStats { ema: value as f64, ema_var: 0.0, - }, - ); + }); + } } let (count, timestamp) = self @@ -102,6 +114,10 @@ impl ExecuteCostTable { *timestamp = Self::micros_since_epoch(); } + pub fn get_program_keys(&self) -> Vec<&Pubkey> { + self.table.keys().collect() + } + // prune the old programs so the table contains `new_size` of records, // where `old` is defined as weighted age, which is negatively correlated // with program's age and @@ -189,9 +205,9 @@ mod tests { let key2 = Pubkey::new_unique(); let key3 = Pubkey::new_unique(); - // simulate a lot of occurences to key1, so even there're longer than + // simulate a lot of occurrences to key1, so even there're longer than // usual delay between upsert(key1..) and upsert(key2, ..), test - // would still satisfy as key1 has enough occurences to compensate + // would still satisfy as key1 has enough occurrences to compensate // its age. for i in 0..1000 { testee.upsert(&key1, i); @@ -235,8 +251,8 @@ mod tests { // update 1st record testee.upsert(&key1, cost2); assert_eq!(2, testee.get_count()); - // expected key1 cost = (mean + 2*std) = (105 + 2*5) = 115 - let expected_cost = 114; + // expected key1 cost is EMA of [100, 110] with alpha=0.01 => 103 + let expected_cost = 103; assert_eq!(expected_cost, testee.get_cost(&key1).unwrap()); assert_eq!(cost2, testee.get_cost(&key2).unwrap()); } @@ -280,10 +296,29 @@ mod tests { testee.upsert(&key4, cost4); assert_eq!(2, testee.get_count()); assert!(testee.get_cost(&key1).is_none()); - // expected key2 cost = (mean + 2*std) = (105 + 2*5) = 115 - let expected_cost_2 = 116; + // expected key2 cost = (mean + 2*std) of [110, 100] => 112 + let expected_cost_2 = 112; assert_eq!(expected_cost_2, testee.get_cost(&key2).unwrap()); assert!(testee.get_cost(&key3).is_none()); assert_eq!(cost4, testee.get_cost(&key4).unwrap()); } + + #[test] + fn test_get_cost_overflow_u64() { + solana_logger::setup(); + let mut testee = ExecuteCostTable::default(); + + let key1 = Pubkey::new_unique(); + let cost1: u64 = f64::MAX as u64; + let cost2: u64 = u64::MAX / 2; // create large variance so the final result will overflow + + // insert one record + testee.upsert(&key1, cost1); + assert_eq!(1, testee.get_count()); + assert_eq!(cost1, testee.get_cost(&key1).unwrap()); + + // update cost + testee.upsert(&key1, cost2); + assert!(testee.get_cost(&key1).is_none()); + } }