VM - Virtual Machine #

import msg "github.com/filecoin-project/specs/systems/filecoin_vm/message"
import st "github.com/filecoin-project/specs/systems/filecoin_vm/state_tree"

// VM is the object that controls execution.
// It is a stateless, pure function. It uses no local storage.
//
// TODO: make it just a function: VMExec(...) ?
type VM struct {
    // Execute computes and returns outTree, a new StateTree which is the
    // application of msgs to inTree.
    //
    // *Important:* Execute is intended to be a pure function, with no side-effects.
    // however, storage of the new parts of the computed outTree may exist in
    // local storage.
    //
    // *TODO:* define whether this should take 0, 1, or 2 IpldStores:
    // - (): storage of IPLD datastructures is assumed implicit
    // - (store): get and put to same IpldStore
    // - (inStore, outStore): get from inStore, put new structures into outStore
    //
    // This decision impacts callers, and potentially impacts how we reason about
    // local storage, and intermediate storage. It is definitely the case that
    // implementations may want to operate on this differently, depending on
    // how their IpldStores work.
    Execute(inTree st.StateTree, msgs [msg.UnsignedMessage]) union {outTree st.StateTree, err error}
}