fix (EXC-1590): make burning cycles configurable

.gitignore

@@ -6,5 +6,6 @@
 target
 .dfx
 canister_ids.json
+.canbench
 
 *.wasm.gz

canister/candid.did

@@ -35,6 +35,7 @@ type config = record {
   api_access : flag;
   disable_api_if_not_fully_synced : flag;
   watchdog_canister : opt principal;
+  burn_cycles : flag;
 };
 
 type fees = record {
@@ -89,6 +90,7 @@ type set_config_request = record {
   api_access : opt flag;
   disable_api_if_not_fully_synced : opt flag;
   watchdog_canister : opt opt principal;
+  burn_cycles : opt flag;
 };
 
 service bitcoin : (config) -> {

canister/src/heartbeat.rs

@@ -18,9 +18,7 @@ use ic_btc_types::{Block, BlockHash};
 pub async fn heartbeat() {
     print("Starting heartbeat...");
 
-    // Burn any cycles in the canister's balance (to count towards the IC's cycles burn rate)
-    let cycles_burnt = cycles_burn();
-    add_cycles_burnt_to_metric(cycles_burnt);
+    maybe_burn_cycles();
 
     if ingest_stable_blocks_into_utxoset() {
         // Exit the heartbeat if stable blocks had been ingested.
@@ -243,6 +241,14 @@ fn add_cycles_burnt_to_metric(cycles_burnt: u128) {
     });
 }
 
+/// Burns any cycles in the canister's balance (to count towards the IC's cycles burn rate).
+fn maybe_burn_cycles() {
+    if with_state(|s| s.burn_cycles == Flag::Enabled) {
+        let cycles_burnt = cycles_burn();
+        add_cycles_burnt_to_metric(cycles_burnt);
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;

canister/src/lib.rs

@@ -93,6 +93,7 @@ pub fn init(config: Config) {
     with_state_mut(|s| s.syncing_state.syncing = config.syncing);
     with_state_mut(|s| s.disable_api_if_not_fully_synced = config.disable_api_if_not_fully_synced);
     with_state_mut(|s| s.watchdog_canister = config.watchdog_canister);
+    with_state_mut(|s| s.burn_cycles = config.burn_cycles);
     with_state_mut(|s| s.fees = config.fees);
 }
 
@@ -143,6 +144,7 @@ pub fn get_config() -> Config {
         api_access: s.api_access,
         disable_api_if_not_fully_synced: s.disable_api_if_not_fully_synced,
         watchdog_canister: s.watchdog_canister,
+        burn_cycles: s.burn_cycles,
     })
 }
 

canister/src/state.rs

@@ -60,6 +60,12 @@ pub struct State {
     /// The watchdog canister has the authority to disable the Bitcoin canister's API
     /// if it suspects that there is a problem.
     pub watchdog_canister: Option<Principal>,
+
+    /// If enabled, continuously burns all cycles in the canister's balance
+    /// to count towards the IC's burn rate.
+    /// NOTE: serde(default) is used here for backward-compatibility.
+    #[serde(default)]
+    pub burn_cycles: Flag,
 }
 
 impl State {
@@ -85,6 +91,7 @@ impl State {
             api_access: Flag::Enabled,
             disable_api_if_not_fully_synced: Flag::Enabled,
             watchdog_canister: None,
+            burn_cycles: Flag::Disabled,
         }
     }
 

canister/src/tests.rs

@@ -15,7 +15,7 @@ use crate::{init, test_utils::random_p2pkh_address, Config};
 use bitcoin::consensus::{Decodable, Encodable};
 use bitcoin::{Block as BitcoinBlock, BlockHeader};
 use byteorder::{LittleEndian, ReadBytesExt};
-use ic_btc_interface::{GetUtxosResponse, Network, Txid, UtxosFilter};
+use ic_btc_interface::{Flag, GetUtxosResponse, Network, Txid, UtxosFilter};
 use ic_btc_interface::{OutPoint, Utxo};
 use ic_btc_types::{Block, BlockHash};
 use ic_cdk::api::call::RejectionCode;
@@ -719,7 +719,10 @@ async fn test_syncing_with_next_block_headers() {
 
 #[async_std::test]
 async fn cycles_burnt_are_tracked_in_metrics() {
-    crate::init(crate::Config::default());
+    crate::init(crate::Config {
+        burn_cycles: Flag::Enabled,
+        ..Default::default()
+    });
 
     let cycles_burnt_0 = crate::with_state(|state| state.metrics.cycles_burnt);
 
@@ -748,3 +751,25 @@ async fn cycles_burnt_are_tracked_in_metrics() {
 
     assert_eq!(cycles_burnt_3, Some(3 * burn_amount));
 }
+
+#[async_std::test]
+async fn cycles_are_not_burnt_when_flag_is_disabled() {
+    crate::init(crate::Config {
+        burn_cycles: Flag::Disabled,
+        ..Default::default()
+    });
+
+    assert_eq!(
+        crate::with_state(|state| state.metrics.cycles_burnt),
+        Some(0)
+    );
+
+    // Run the heartbeat.
+    heartbeat().await;
+
+    // No cycles should be burnt.
+    assert_eq!(
+        crate::with_state(|state| state.metrics.cycles_burnt),
+        Some(0)
+    );
+}

e2e-tests/charge-cycles-on-reject.sh

@@ -33,6 +33,7 @@ dfx deploy bitcoin --argument "(record {
   api_access = variant { enabled };
   disable_api_if_not_fully_synced = variant { enabled };
   watchdog_canister = null;
+  burn_cycles = variant { enabled };
 })"
 
 check_charging()

e2e-tests/cycles_burn.sh

@@ -35,6 +35,7 @@ dfx deploy --no-wallet --with-cycles "$INITIAL_BALANCE" bitcoin --argument "(rec
   api_access = variant { enabled };
   disable_api_if_not_fully_synced = variant { enabled };
   watchdog_canister = null;
+  burn_cycles = variant { enabled };
 })"
 
 sleep 3

e2e-tests/disable-api-if-not-fully-synced-flag.sh

@@ -35,6 +35,7 @@ dfx deploy --no-wallet bitcoin --argument "(record {
   api_access = variant { enabled };
   disable_api_if_not_fully_synced = variant { enabled };
   watchdog_canister = null;
+  burn_cycles = variant { enabled };
 })"
 
 # Wait until the ingestion of stable blocks is complete.
@@ -135,6 +136,7 @@ dfx deploy --no-wallet bitcoin --argument "(record {
   api_access = variant { enabled };
   disable_api_if_not_fully_synced = variant { disabled };
   watchdog_canister = null;
+  burn_cycles = variant { enabled };
 })"
 
 # Wait until the ingestion of stable blocks is complete.

e2e-tests/scenario-1.sh

@@ -32,6 +32,7 @@ dfx deploy --no-wallet bitcoin --argument "(record {
   api_access = variant { enabled };
   disable_api_if_not_fully_synced = variant { enabled };
   watchdog_canister = null;
+  burn_cycles = variant { enabled };
 })"
 
 # Wait until the ingestion of stable blocks is complete.

e2e-tests/scenario-2.sh

@@ -36,6 +36,7 @@ dfx deploy --no-wallet bitcoin --argument "(record {
   api_access = variant { enabled };
   disable_api_if_not_fully_synced = variant { enabled };
   watchdog_canister = null;
+  burn_cycles = variant { enabled };
 })"
 
 # Wait until the ingestion of stable blocks is complete.

e2e-tests/scenario-3.sh

@@ -32,6 +32,7 @@ dfx deploy --no-wallet bitcoin --argument "(record {
   api_access = variant { enabled };
   disable_api_if_not_fully_synced = variant { enabled };
   watchdog_canister = null;
+  burn_cycles = variant { enabled };
 })"
 
 # Send transaction valid transaction

e2e-tests/set_config.sh

@@ -27,6 +27,7 @@ dfx deploy --no-wallet bitcoin --argument "(record {
   api_access = variant { enabled };
   disable_api_if_not_fully_synced = variant { enabled };
   watchdog_canister = null;
+  burn_cycles = variant { enabled };
 })"
 
 # The stability threshold is zero

e2e-tests/upgradability.sh

@@ -32,6 +32,7 @@ ARGUMENT="(record {
  api_access = variant { enabled };
  disable_api_if_not_fully_synced = variant { enabled };
  watchdog_canister = null;
+ burn_cycles = variant { enabled };
 })"
 
 # Run dfx stop if we run into errors and remove the downloaded wasm.

interface/src/lib.rs

@@ -472,7 +472,7 @@ pub enum Flag {
     Disabled,
 }
 
-/// The payload used to initialize the canister.
+/// The config and payload used to initialize the canister.
 #[derive(CandidType, Deserialize, Debug)]
 pub struct Config {
     pub stability_threshold: u128,
@@ -499,6 +499,10 @@ pub struct Config {
     /// The watchdog canister has the authority to disable the Bitcoin canister's API
     /// if it suspects that there is a problem.
     pub watchdog_canister: Option<Principal>,
+
+    /// If enabled, continuously burns all cycles in its balance
+    /// (to count towards the IC's burn rate).
+    pub burn_cycles: Flag,
 }
 
 impl Default for Config {
@@ -512,6 +516,7 @@ impl Default for Config {
             api_access: Flag::Enabled,
             disable_api_if_not_fully_synced: Flag::Enabled,
             watchdog_canister: None,
+            burn_cycles: Flag::Disabled,
         }
     }
 }