Common: Extract a Digester trait from the ImmutableDigester in order to mock it easily

Author: Alenar

mithril-aggregator/src/runtime.rs

@@ -2,9 +2,9 @@ use super::dependency::{BeaconStoreWrapper, MultiSignerWrapper, SnapshotStoreWra
 use super::{BeaconStoreError, ProtocolError, SnapshotError, Snapshotter};
 
 use mithril_common::crypto_helper::Bytes;
+use mithril_common::digesters::{Digester, DigesterError, ImmutableDigester};
 use mithril_common::entities::Beacon;
 use mithril_common::fake_data;
-use mithril_common::immutable_digester::{ImmutableDigester, ImmutableDigesterError};
 
 use crate::snapshot_stores::SnapshotStoreError;
 use crate::snapshot_uploaders::{SnapshotLocation, SnapshotUploader};
@@ -30,8 +30,8 @@ pub enum RuntimeError {
     #[error("snapshotter error")]
     Snapshotter(#[from] SnapshotError),
 
-    #[error("immutable digester error")]
-    ImmutableDigester(#[from] ImmutableDigesterError),
+    #[error("digester error")]
+    Digester(#[from] DigesterError),
 
     #[error("snapshot store error")]
     SnapshotStore(#[from] SnapshotStoreError),
@@ -154,7 +154,7 @@ impl AggregatorRuntime {
             Err(err) => {
                 let mut beacon_store = self.beacon_store.write().await;
                 beacon_store.reset_current_beacon().await?;
-                Err(RuntimeError::ImmutableDigester(err))
+                Err(RuntimeError::Digester(err))
             }
         }
     }

mithril-common/src/digesters/digester.rs

@@ -0,0 +1,51 @@
+use crate::entities::ImmutableFileNumber;
+use std::io;
+use thiserror::Error;
+
+#[derive(Debug, Clone)]
+pub struct DigesterResult {
+    /// The computed digest
+    pub digest: String,
+
+    /// The number of the last immutable file used to compute the digest
+    pub last_immutable_file_number: ImmutableFileNumber,
+}
+
+#[derive(Error, Debug)]
+pub enum DigesterError {
+    #[error("Immutable files listing failed: `{0}`")]
+    ListImmutablesError(String),
+
+    #[error("At least two immutables chunk should exists")]
+    NotEnoughImmutable(),
+
+    #[error("Digest computation failed:")]
+    DigestComputationError(#[from] io::Error),
+}
+
+/// A digester than can compute the digest used for mithril signatures
+///
+/// If you want to mock it using mockall:
+/// ```
+/// mod test {
+///     use mithril_common::digesters::{Digester, DigesterError, DigesterResult};
+///     use mockall::mock;
+///
+///     mock! {
+///         pub DigesterImpl { }
+///         impl Digester for DigesterImpl {
+///             fn compute_digest(&self) -> Result<DigesterResult, DigesterError>;
+///         }
+///     }
+///
+///     #[test]
+///     fn test_mock() {
+///         let mut mock = MockDigesterImpl::new();
+///         mock.expect_compute_digest()
+///             .return_once(|| Err(DigesterError::NotEnoughImmutable()));
+///     }
+/// }
+/// ```
+pub trait Digester {
+    fn compute_digest(&self) -> Result<DigesterResult, DigesterError>;
+}

mithril-common/src/immutable_digester.rs renamed to mithril-common/src/digesters/immutable_digester.rs

@@ -1,3 +1,4 @@
+use crate::digesters::{Digester, DigesterError, DigesterResult};
 use crate::entities::ImmutableFileNumber;
 
 use sha2::{Digest, Sha256};
@@ -6,11 +7,10 @@ use std::ffi::OsStr;
 use std::fs::File;
 use std::io;
 use std::path::{Path, PathBuf};
-use thiserror::Error;
 
 use walkdir::WalkDir;
 
-/// ImmutableDigester
+/// A digester working directly on a Cardano DB immutables files
 pub struct ImmutableDigester {
     /// A cardano node DB directory
     db_directory: PathBuf,
@@ -19,27 +19,6 @@ pub struct ImmutableDigester {
     logger: Logger,
 }
 
-#[derive(Error, Debug)]
-pub enum ImmutableDigesterError {
-    #[error("Immutable files listing failed: `{0}`")]
-    ListImmutablesError(String),
-
-    #[error("At least two immutables chunk should exists")]
-    NotEnoughImmutable(),
-
-    #[error("Digest computation failed:")]
-    DigestComputationError(#[from] io::Error),
-}
-
-#[derive(Debug)]
-pub struct ImmutableDigesterResult {
-    /// The computed digest
-    pub digest: String,
-
-    /// The number of the last immutable file used to compute the digest
-    pub last_immutable_file_number: ImmutableFileNumber,
-}
-
 impl ImmutableDigester {
     /// ImmutableDigester factory
     pub fn new(db_directory: PathBuf, logger: Logger) -> Self {
@@ -49,28 +28,6 @@ impl ImmutableDigester {
         }
     }
 
-    pub fn compute_digest(&self) -> Result<ImmutableDigesterResult, ImmutableDigesterError> {
-        let immutables = ImmutableFile::list_in_dir(&*self.db_directory)
-            .map_err(ImmutableDigesterError::ListImmutablesError)?;
-        let last_immutable = immutables
-            .last()
-            .ok_or(ImmutableDigesterError::NotEnoughImmutable())?;
-
-        info!(self.logger, "#immutables: {}", immutables.len());
-
-        let hash = self
-            .compute_hash(&immutables)
-            .map_err(ImmutableDigesterError::DigestComputationError)?;
-        let digest = hex::encode(hash);
-
-        debug!(self.logger, "#computed digest: {:?}", digest);
-
-        Ok(ImmutableDigesterResult {
-            digest,
-            last_immutable_file_number: last_immutable.number,
-        })
-    }
-
     fn compute_hash(&self, entries: &[ImmutableFile]) -> Result<[u8; 32], io::Error> {
         let mut hasher = Sha256::new();
         let mut progress = Progress {
@@ -92,6 +49,30 @@ impl ImmutableDigester {
     }
 }
 
+impl Digester for ImmutableDigester {
+    fn compute_digest(&self) -> Result<DigesterResult, DigesterError> {
+        let immutables = ImmutableFile::list_in_dir(&*self.db_directory)
+            .map_err(DigesterError::ListImmutablesError)?;
+        let last_immutable = immutables
+            .last()
+            .ok_or(DigesterError::NotEnoughImmutable())?;
+
+        info!(self.logger, "#immutables: {}", immutables.len());
+
+        let hash = self
+            .compute_hash(&immutables)
+            .map_err(DigesterError::DigestComputationError)?;
+        let digest = hex::encode(hash);
+
+        debug!(self.logger, "#computed digest: {:?}", digest);
+
+        Ok(DigesterResult {
+            digest,
+            last_immutable_file_number: last_immutable.number,
+        })
+    }
+}
+
 struct Progress {
     index: usize,
     total: usize,

mithril-common/src/digesters/mod.rs

@@ -0,0 +1,5 @@
+mod digester;
+mod immutable_digester;
+
+pub use digester::{Digester, DigesterError, DigesterResult};
+pub use immutable_digester::ImmutableDigester;

mithril-common/src/lib.rs

@@ -1,5 +1,5 @@
 pub mod apispec;
 pub mod crypto_helper;
+pub mod digesters;
 pub mod entities;
 pub mod fake_data;
-pub mod immutable_digester;