Fetch decimals from the chain for AH

Kalapaja · Mar 5, 2024 · d790ed6 · d790ed6
1 parent 9a94b3c
commit d790ed6
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Showing 2 changed files with 37 additions and 9 deletions.
diff --git a/kalatori-ah/src/lib.rs b/kalatori-ah/src/lib.rs
@@ -2,7 +2,7 @@ use anyhow::{Context, Error, Result};
 use database::Database;
 use env_logger::{Builder, Env};
 use environment_variables::{
-    DATABASE, DECIMALS, DESTINATION, HOST, IN_MEMORY_DB, LOG, LOG_STYLE, OVERRIDE_RPC, RPC, SEED,
+    DATABASE, DESTINATION, HOST, IN_MEMORY_DB, LOG, LOG_STYLE, OVERRIDE_RPC, RPC, SEED,
 };
 use log::LevelFilter;
 use rpc::Processor;
@@ -41,7 +41,6 @@ pub mod environment_variables {
     pub const RPC: &str = "KALATORI_RPC";
     pub const OVERRIDE_RPC: &str = "KALATORI_OVERRIDE_RPC";
     pub const IN_MEMORY_DB: &str = "KALATORI_IN_MEMORY_DB";
-    pub const DECIMALS: &str = "KALATORI_DECIMALS";
     pub const DESTINATION: &str = "KALATORI_DESTINATION";
 }
 
@@ -190,11 +189,6 @@ pub async fn main() -> Result<()> {
         None
     };
 
-    let decimals = env::var(DECIMALS)
-        .with_context(|| format!("`{DECIMALS}` isn't set"))?
-        .parse()
-        .with_context(|| format!("failed to convert `{DECIMALS}` to decimals"))?;
-
     let destination = match env::var(DESTINATION) {
         Ok(destination) => Ok(Some(
             AccountId32::try_from(hex::decode(&destination[2..])?.as_ref())
@@ -214,7 +208,7 @@ pub async fn main() -> Result<()> {
     let (error_tx, mut error_rx) = mpsc::unbounded_channel();
 
     let (api_config, endpoint_properties, updater) =
-        rpc::prepare(endpoint, decimals, shutdown_notification.clone())
+        rpc::prepare(endpoint, shutdown_notification.clone())
             .await
             .context("failed to prepare the node module")?;
 

diff --git a/kalatori-ah/src/rpc.rs b/kalatori-ah/src/rpc.rs
@@ -117,6 +117,29 @@ async fn fetch_metadata(backend: &impl Backend<RuntimeConfig>, at: Hash) -> Resu
         .map_err(Into::into)
 }
 
+async fn fetch_decimals(storage: Storage<RuntimeConfig, OnlineClient>) -> Result<Decimals> {
+    const METADATA: &str = "Metadata";
+    const DECIMALS: &str = "decimals";
+
+    let asset_metadata = storage
+        .fetch(&dynamic::storage(ASSETS, METADATA, vec![USDT_ID]))
+        .await
+        .context("failed to fetch asset info from the chain")?
+        .context("received nothing after fetching asset info from the chain")?
+        .to_value()
+        .context("failed to decode account info")?;
+    let encoded_decimals = asset_metadata
+        .at(DECIMALS)
+        .with_context(|| format!("{DECIMALS} field wasn't found in asset info"))?;
+
+    encoded_decimals
+        .as_u128()
+        .map(|num| num.try_into().expect("must be less than u64"))
+        .with_context(|| {
+            format!("expected `u128` as the type of the min balance, got {encoded_decimals}")
+        })
+}
+
 fn fetch_constant<T: DecodeAsType>(
     constants: &ConstantsClient<RuntimeConfig, OnlineClient>,
     constant: (&str, &str),
@@ -174,7 +197,6 @@ impl CheckedUrl {
 
 pub async fn prepare(
     url: String,
-    decimals: Decimals,
     shutdown_notification: CancellationToken,
 ) -> Result<(ApiConfig, EndpointProperties, Updater)> {
     // TODO:
@@ -214,6 +236,7 @@ pub async fn prepare(
             .await?,
     )
     .await?;
+    let decimals = fetch_decimals(api.storage().at_latest().await?).await?;
     let properties = ChainProperties::fetch_only_constants(min_balance, decimals, &constants)?;
 
     log::info!(
@@ -584,6 +607,8 @@ impl ProcessorFinalized {
             const UPDATE: &str = "CodeUpdated";
             const TRANSFERRED: &str = "Transferred";
             const ASSET_MIN_BALANCE_CHANGED: &str = "AssetMinBalanceChanged";
+            const METADATA_SET: &str = "MetadataSet";
+
             let event = event_result.context("failed to decode an event")?;
             let metadata = event.event_metadata();
 
@@ -603,6 +628,15 @@ impl ProcessorFinalized {
 
                     props.existential_deposit = new_min_balance;
                 }
+                (ASSETS, METADATA_SET) => {
+                    let new_decimals =
+                        fetch_decimals(self.client.storage().at_latest().await?).await?;
+                    let props = self.database.properties_write().await;
+
+                    if props.decimals != new_decimals {
+                        anyhow::bail!("decimals have been changed: {new_decimals}");
+                    }
+                }
                 _ => {}
             }
         }