laconicd-deprecated/x/evm/keeper/context_stack.go
yihuang 9227e78c79
evm: use stack of contexts to implement snapshot revert (#399)
* use stack of contexts to implement snapshot revert

Closes #338

add exception revert test case

verify partial revert

mutate state after the reverted subcall

polish

update comments

name the module after the type name

remove the unnecessary Snapshot in outer layer

and add snapshot unit test

assert context stack is clean after tx processing

cleanups

fix context revert

fix comments

update comments

it's ok to commit in failed case too

Update x/evm/keeper/context_stack.go

Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>

Update x/evm/keeper/context_stack.go

Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>

Update x/evm/keeper/context_stack.go

Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>

update comment and error message

add comment to cacheContext

k -> cs

Update x/evm/keeper/context_stack.go

Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>

evm can handle state revert

renames and unit tests

* use table driven tests

* keep all the cosmos events

* changelog

* check for if commit function is nil

* fix changelog

* Update x/evm/keeper/context_stack.go

Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>
2021-08-10 07:22:46 +00:00

88 lines
2.7 KiB
Go

package keeper
import (
"fmt"
sdk "github.com/cosmos/cosmos-sdk/types"
)
// cachedContext is a pair of cache context and its corresponding commit method.
// They are obtained from the return value of `context.CacheContext()`.
type cachedContext struct {
ctx sdk.Context
commit func()
}
// ContextStack manages the initial context and a stack of cached contexts,
// to support the `StateDB.Snapshot` and `StateDB.RevertToSnapshot` methods.
type ContextStack struct {
// Context of the initial state before transaction execution.
// It's the context used by `StateDB.CommitedState`.
initialCtx sdk.Context
cachedContexts []cachedContext
}
// CurrentContext returns the top context of cached stack,
// if the stack is empty, returns the initial context.
func (cs *ContextStack) CurrentContext() sdk.Context {
l := len(cs.cachedContexts)
if l == 0 {
return cs.initialCtx
}
return cs.cachedContexts[l-1].ctx
}
// Reset sets the initial context and clear the cache context stack.
func (cs *ContextStack) Reset(ctx sdk.Context) {
cs.initialCtx = ctx
if len(cs.cachedContexts) > 0 {
cs.cachedContexts = []cachedContext{}
}
}
// IsEmpty returns true if the cache context stack is empty.
func (cs *ContextStack) IsEmpty() bool {
return len(cs.cachedContexts) == 0
}
// Commit commits all the cached contexts from top to bottom in order and clears the stack by setting an empty slice of cache contexts.
func (cs *ContextStack) Commit() {
// commit in order from top to bottom
for i := len(cs.cachedContexts) - 1; i >= 0; i-- {
// keep all the cosmos events
cs.initialCtx.EventManager().EmitEvents(cs.cachedContexts[i].ctx.EventManager().Events())
if cs.cachedContexts[i].commit == nil {
panic(fmt.Sprintf("commit function at index %d should not be nil", i))
} else {
cs.cachedContexts[i].commit()
}
}
cs.cachedContexts = []cachedContext{}
}
// Snapshot pushes a new cached context to the stack,
// and returns the index of it.
func (cs *ContextStack) Snapshot() int {
i := len(cs.cachedContexts)
ctx, commit := cs.CurrentContext().CacheContext()
cs.cachedContexts = append(cs.cachedContexts, cachedContext{ctx: ctx, commit: commit})
return i
}
// RevertToSnapshot pops all the cached contexts after the target index (inclusive).
// the target should be snapshot index returned by `Snapshot`.
// This function panics if the index is out of bounds.
func (cs *ContextStack) RevertToSnapshot(target int) {
if target < 0 || target >= len(cs.cachedContexts) {
panic(fmt.Errorf("snapshot index %d out of bound [%d..%d)", target, 0, len(cs.cachedContexts)))
}
cs.cachedContexts = cs.cachedContexts[:target]
}
// RevertAll discards all the cache contexts.
func (cs *ContextStack) RevertAll() {
if len(cs.cachedContexts) > 0 {
cs.RevertToSnapshot(0)
}
}