feat(vm-runner): Implement batch data prefetching (#2724)

## What ❔

- Implements prefetching of storage slots / bytecodes accessed by a VM
in a batch. Enables it for the VM playground. Optionally shadows
prefetched snapshot storage.
- Makes RocksDB cache optional for VM playground.

## Why ❔

- Prefetching will allow to load storage slots / bytecodes for a batch
in O(1) DB queries, which is very efficient for local debugging etc. It
may be on par or faster than using RocksDB cache. (There's a caveat:
prefetching doesn't work w/o protective reads.)
- Disabling RocksDB cache is useful for local testing, since the cache
won't catch up during a single batch run anyway.

## Checklist

- [x] PR title corresponds to the body of PR (we generate changelog
entries from PRs).
- [x] Tests for the changes have been added / updated.
- [x] Documentation comments have been added / updated.
- [x] Code has been formatted via `zk fmt` and `zk lint`.

core/lib/config/src/configs/experimental.rs

@@ -65,8 +65,7 @@ pub struct ExperimentalVmPlaygroundConfig {
     #[serde(default)]
     pub fast_vm_mode: FastVmMode,
     /// Path to the RocksDB cache directory.
-    #[serde(default = "ExperimentalVmPlaygroundConfig::default_db_path")]
-    pub db_path: String,
+    pub db_path: Option<String>,
     /// First L1 batch to consider processed. Will not be used if the processing cursor is persisted, unless the `reset` flag is set.
     #[serde(default)]
     pub first_processed_batch: L1BatchNumber,
@@ -83,7 +82,7 @@ impl Default for ExperimentalVmPlaygroundConfig {
     fn default() -> Self {
         Self {
             fast_vm_mode: FastVmMode::default(),
-            db_path: Self::default_db_path(),
+            db_path: None,
             first_processed_batch: L1BatchNumber(0),
             window_size: Self::default_window_size(),
             reset: false,
@@ -92,10 +91,6 @@ impl Default for ExperimentalVmPlaygroundConfig {
 }
 
 impl ExperimentalVmPlaygroundConfig {
-    pub fn default_db_path() -> String {
-        "./db/vm_playground".to_owned()
-    }
-
     pub fn default_window_size() -> NonZeroU32 {
         NonZeroU32::new(1).unwrap()
     }

core/lib/env_config/src/vm_runner.rs

@@ -65,7 +65,7 @@ mod tests {
         let config = ExperimentalVmConfig::from_env().unwrap();
         assert_eq!(config.state_keeper_fast_vm_mode, FastVmMode::New);
         assert_eq!(config.playground.fast_vm_mode, FastVmMode::Shadow);
-        assert_eq!(config.playground.db_path, "/db/vm_playground");
+        assert_eq!(config.playground.db_path.unwrap(), "/db/vm_playground");
         assert_eq!(config.playground.first_processed_batch, L1BatchNumber(123));
         assert!(config.playground.reset);
 
@@ -83,6 +83,6 @@ mod tests {
 
         lock.remove_env(&["EXPERIMENTAL_VM_PLAYGROUND_DB_PATH"]);
         let config = ExperimentalVmConfig::from_env().unwrap();
-        assert!(!config.playground.db_path.is_empty());
+        assert!(config.playground.db_path.is_none());
     }
 }

core/lib/protobuf_config/src/experimental.rs

@@ -80,10 +80,7 @@ impl ProtoRepr for proto::VmPlayground {
                 .transpose()
                 .context("fast_vm_mode")?
                 .map_or_else(FastVmMode::default, |mode| mode.parse()),
-            db_path: self
-                .db_path
-                .clone()
-                .unwrap_or_else(Self::Type::default_db_path),
+            db_path: self.db_path.clone(),
             first_processed_batch: L1BatchNumber(self.first_processed_batch.unwrap_or(0)),
             window_size: NonZeroU32::new(self.window_size.unwrap_or(1))
                 .context("window_size cannot be 0")?,
@@ -94,7 +91,7 @@ impl ProtoRepr for proto::VmPlayground {
     fn build(this: &Self::Type) -> Self {
         Self {
             fast_vm_mode: Some(proto::FastVmMode::new(this.fast_vm_mode).into()),
-            db_path: Some(this.db_path.clone()),
+            db_path: this.db_path.clone(),
             first_processed_batch: Some(this.first_processed_batch.0),
             window_size: Some(this.window_size.get()),
             reset: Some(this.reset),

core/lib/protobuf_config/src/proto/config/experimental.proto

@@ -28,7 +28,7 @@ enum FastVmMode {
 // Experimental VM configuration
 message VmPlayground {
   optional FastVmMode fast_vm_mode = 1; // optional; if not set, fast VM is not used
-  optional string db_path = 2; // optional; defaults to `./db/vm_playground`
+  optional string db_path = 2; // optional; if not set, playground will not use RocksDB cache
   optional uint32 first_processed_batch = 3; // optional; defaults to 0
   optional bool reset = 4; // optional; defaults to false
   optional uint32 window_size = 5; // optional; non-zero; defaults to 1

core/lib/state/src/lib.rs

@@ -20,7 +20,7 @@ pub use self::{
     },
     shadow_storage::ShadowStorage,
     storage_factory::{
-        BatchDiff, OwnedStorage, PgOrRocksdbStorage, ReadStorageFactory, RocksdbWithMemory,
+        BatchDiff, CommonStorage, OwnedStorage, ReadStorageFactory, RocksdbWithMemory,
     },
 };
 

core/lib/state/src/rocksdb/mod.rs

@@ -347,7 +347,7 @@ impl RocksdbStorage {
         let to_l1_batch_number = if let Some(to_l1_batch_number) = to_l1_batch_number {
             if to_l1_batch_number > latest_l1_batch_number {
                 let err = anyhow::anyhow!(
-                    "Requested to update RocksDB to L1 batch number ({current_l1_batch_number}) that \
+                    "Requested to update RocksDB to L1 batch number ({to_l1_batch_number}) that \
                      is greater than the last sealed L1 batch number in Postgres ({latest_l1_batch_number})"
                 );
                 return Err(err.into());

core/lib/state/src/shadow_storage.rs

@@ -1,10 +1,12 @@
+use std::fmt;
+
 use vise::{Counter, Metrics};
 use zksync_types::{L1BatchNumber, StorageKey, StorageValue, H256};
 use zksync_vm_interface::storage::ReadStorage;
 
-#[allow(clippy::struct_field_names)]
 #[derive(Debug, Metrics)]
 #[metrics(prefix = "shadow_storage")]
+#[allow(clippy::struct_field_names)] // false positive
 struct ShadowStorageMetrics {
     /// Number of mismatches when reading a value from a shadow storage.
     read_value_mismatch: Counter,
@@ -19,60 +21,78 @@ struct ShadowStorageMetrics {
 #[vise::register]
 static METRICS: vise::Global<ShadowStorageMetrics> = vise::Global::new();
 
-/// [`ReadStorage`] implementation backed by 2 different backends:
-/// source_storage -- backend that will return values for function calls and be the source of truth
-/// to_check_storage -- secondary storage, which will verify it's own return values against source_storage
-/// Note that if to_check_storage value is different than source value, execution continues and metrics/ logs are emitted.
+/// [`ReadStorage`] implementation backed by 2 different backends which are compared for each performed operation.
+///
+/// - `Ref` is the backend that will return values for function calls and be the source of truth
+/// - `Check` is the secondary storage, which will have its return values verified against `Ref`
+///
+/// If `Check` value is different from a value from `Ref`, storage behavior depends on the [panic on divergence](Self::set_panic_on_divergence()) flag.
+/// If this flag is set (which it is by default), the storage panics; otherwise, execution continues and metrics / logs are emitted.
 #[derive(Debug)]
-pub struct ShadowStorage<'a> {
-    source_storage: Box<dyn ReadStorage + 'a>,
-    to_check_storage: Box<dyn ReadStorage + 'a>,
-    metrics: &'a ShadowStorageMetrics,
+pub struct ShadowStorage<Ref, Check> {
+    source_storage: Ref,
+    to_check_storage: Check,
+    metrics: &'static ShadowStorageMetrics,
     l1_batch_number: L1BatchNumber,
+    panic_on_divergence: bool,
 }
 
-impl<'a> ShadowStorage<'a> {
+impl<Ref: ReadStorage, Check: ReadStorage> ShadowStorage<Ref, Check> {
     /// Creates a new storage using the 2 underlying [`ReadStorage`]s, first as source, the second to be checked
     /// against the source.
     pub fn new(
-        source_storage: Box<dyn ReadStorage + 'a>,
-        to_check_storage: Box<dyn ReadStorage + 'a>,
+        source_storage: Ref,
+        to_check_storage: Check,
         l1_batch_number: L1BatchNumber,
     ) -> Self {
         Self {
             source_storage,
             to_check_storage,
             metrics: &METRICS,
             l1_batch_number,
+            panic_on_divergence: true,
+        }
+    }
+
+    /// Sets behavior if a storage divergence is detected.
+    pub fn set_panic_on_divergence(&mut self, panic_on_divergence: bool) {
+        self.panic_on_divergence = panic_on_divergence;
+    }
+
+    fn error_or_panic(&self, args: fmt::Arguments<'_>) {
+        if self.panic_on_divergence {
+            panic!("{args}");
+        } else {
+            tracing::error!(l1_batch_number = self.l1_batch_number.0, "{args}");
         }
     }
 }
 
-impl ReadStorage for ShadowStorage<'_> {
+impl<Ref: ReadStorage, Check: ReadStorage> ReadStorage for ShadowStorage<Ref, Check> {
     fn read_value(&mut self, key: &StorageKey) -> StorageValue {
-        let source_value = self.source_storage.as_mut().read_value(key);
-        let expected_value = self.to_check_storage.as_mut().read_value(key);
+        let source_value = self.source_storage.read_value(key);
+        let expected_value = self.to_check_storage.read_value(key);
         if source_value != expected_value {
             self.metrics.read_value_mismatch.inc();
-            tracing::error!(
+            self.error_or_panic(format_args!(
                 "read_value({key:?}) -- l1_batch_number={:?} -- expected source={source_value:?} \
                  to be equal to to_check={expected_value:?}",
                 self.l1_batch_number
-            );
+            ));
         }
         source_value
     }
 
     fn is_write_initial(&mut self, key: &StorageKey) -> bool {
-        let source_value = self.source_storage.as_mut().is_write_initial(key);
-        let expected_value = self.to_check_storage.as_mut().is_write_initial(key);
+        let source_value = self.source_storage.is_write_initial(key);
+        let expected_value = self.to_check_storage.is_write_initial(key);
         if source_value != expected_value {
             self.metrics.is_write_initial_mismatch.inc();
-            tracing::error!(
+            self.error_or_panic(format_args!(
                 "is_write_initial({key:?}) -- l1_batch_number={:?} -- expected source={source_value:?} \
                  to be equal to to_check={expected_value:?}",
                 self.l1_batch_number
-            );
+            ));
         }
         source_value
     }
@@ -82,25 +102,25 @@ impl ReadStorage for ShadowStorage<'_> {
         let expected_value = self.to_check_storage.load_factory_dep(hash);
         if source_value != expected_value {
             self.metrics.load_factory_dep_mismatch.inc();
-            tracing::error!(
+            self.error_or_panic(format_args!(
                 "load_factory_dep({hash:?}) -- l1_batch_number={:?} -- expected source={source_value:?} \
                  to be equal to to_check={expected_value:?}",
-                 self.l1_batch_number
-            );
+                self.l1_batch_number
+            ));
         }
         source_value
     }
 
     fn get_enumeration_index(&mut self, key: &StorageKey) -> Option<u64> {
-        let source_value = self.source_storage.as_mut().get_enumeration_index(key);
-        let expected_value = self.to_check_storage.as_mut().get_enumeration_index(key);
+        let source_value = self.source_storage.get_enumeration_index(key);
+        let expected_value = self.to_check_storage.get_enumeration_index(key);
         if source_value != expected_value {
-            tracing::error!(
+            self.metrics.get_enumeration_index_mismatch.inc();
+            self.error_or_panic(format_args!(
                 "get_enumeration_index({key:?}) -- l1_batch_number={:?} -- \
                  expected source={source_value:?} to be equal to to_check={expected_value:?}",
                 self.l1_batch_number
-            );
-            self.metrics.get_enumeration_index_mismatch.inc();
+            ));
         }
         source_value
     }