Add a type for modeling multiple-dimensional gas

arbitrum/multigas/doc.go

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+// Package multigas defines multi-dimensional gas for the EVM.
+//
+// This package introduces mechanisms to track each resource used by the EVM separately. The
+// possible resources are computation, history growth, storage access, and storage growth. By
+// tracking each one individually and setting specific constraints, we can increase the overall gas
+// target for the chain.
+package multigas

arbitrum/multigas/resources.go

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+package multigas
+
+// ResourceKind represents a dimension for the multi-dimensional gas.
+type ResourceKind uint8
+
+const (
+	ResourceKindUnknown ResourceKind = iota
+	ResourceKindComputation
+	ResourceKindHistoryGrowth
+	ResourceKindStorageAccess
+	ResourceKindStorageGrowth
+	NumResourceKind
+)
+
+// MultiGas tracks gas for each resource separately.
+type MultiGas [NumResourceKind]uint64