chore: move utils/root_cache.zig -> cache/RootCache.zig

src/state_transition/block/process_attestation_altair.zig

@@ -7,7 +7,7 @@ const Epoch = types.primitive.Epoch.Type;
 const preset = @import("preset").preset;
 const ForkSeq = @import("config").ForkSeq;
 const c = @import("constants");
-const RootCache = @import("../utils/root_cache.zig").RootCache;
+const RootCache = @import("../cache/RootCache.zig");
 const validateAttestation = @import("./process_attestation_phase0.zig").validateAttestation;
 const getAttestationWithIndicesSignatureSet = @import("../signature_sets/indexed_attestation.zig").getAttestationWithIndicesSignatureSet;
 const verifyAggregatedSignatureSet = @import("../utils/signature_sets.zig").verifyAggregatedSignatureSet;

src/state_transition/cache/RootCache.zig

@@ -0,0 +1,69 @@
+const RootCache = @This();
+
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const CachedBeaconState = @import("../cache/state_cache.zig").CachedBeaconState;
+const BeaconState = @import("../types/beacon_state.zig").BeaconState;
+const getBlockRootFn = @import("../utils/block_root.zig").getBlockRoot;
+const getBlockRootAtSlotFn = @import("../utils/block_root.zig").getBlockRootAtSlot;
+const types = @import("consensus_types");
+const Checkpoint = types.phase0.Checkpoint.Type;
+const Epoch = types.primitive.Epoch.Type;
+const Slot = types.primitive.Slot.Type;
+const Root = types.primitive.Root.Type;
+
+allocator: Allocator,
+current_justified_checkpoint: Checkpoint,
+previous_justified_checkpoint: Checkpoint,
+state: *BeaconState,
+block_root_epoch_cache: std.AutoHashMap(Epoch, *const Root),
+block_root_slot_cache: std.AutoHashMap(Slot, *const Root),
+
+pub fn init(allocator: Allocator, cached_state: *CachedBeaconState) !*RootCache {
+    const instance = try allocator.create(RootCache);
+    errdefer allocator.destroy(instance);
+    const state = cached_state.state;
+
+    var current_justified_checkpoint: Checkpoint = undefined;
+    var previous_justified_checkpoint: Checkpoint = undefined;
+    try state.currentJustifiedCheckpoint(&current_justified_checkpoint);
+    try state.previousJustifiedCheckpoint(&previous_justified_checkpoint);
+    instance.* = RootCache{
+        .allocator = allocator,
+        .current_justified_checkpoint = current_justified_checkpoint,
+        .previous_justified_checkpoint = previous_justified_checkpoint,
+        .state = state,
+        .block_root_epoch_cache = std.AutoHashMap(Epoch, *const Root).init(allocator),
+        .block_root_slot_cache = std.AutoHashMap(Slot, *const Root).init(allocator),
+    };
+
+    return instance;
+}
+
+pub fn getBlockRoot(self: *RootCache, epoch: Epoch) !*const Root {
+    if (self.block_root_epoch_cache.get(epoch)) |root| {
+        return root;
+    } else {
+        const root = try getBlockRootFn(self.state, epoch);
+        try self.block_root_epoch_cache.put(epoch, root);
+        return root;
+    }
+}
+
+pub fn getBlockRootAtSlot(self: *RootCache, slot: Slot) !*const Root {
+    if (self.block_root_slot_cache.get(slot)) |root| {
+        return root;
+    } else {
+        const root = try getBlockRootAtSlotFn(self.state, slot);
+        try self.block_root_slot_cache.put(slot, root);
+        return root;
+    }
+}
+
+pub fn deinit(self: *RootCache) void {
+    self.block_root_epoch_cache.deinit();
+    self.block_root_slot_cache.deinit();
+    self.allocator.destroy(self);
+}
+
+// TODO: unit tests

src/state_transition/slot/upgrade_state_to_altair.zig

@@ -8,7 +8,7 @@ const sumTargetUnslashedBalanceIncrements = @import("../utils/target_unslashed_b
 const computePreviousEpoch = @import("../utils/epoch.zig").computePreviousEpoch;
 const types = @import("consensus_types");
 const ValidatorIndex = types.primitive.ValidatorIndex.Type;
-const RootCache = @import("../utils/root_cache.zig").RootCache;
+const RootCache = @import("../cache/RootCache.zig");
 const getAttestationParticipationStatus = @import("../block//process_attestation_altair.zig").getAttestationParticipationStatus;
 
 pub fn upgradeStateToAltair(allocator: Allocator, cached_state: *CachedBeaconState) !void {