98 lines
3.4 KiB
Go
98 lines
3.4 KiB
Go
// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// Package tracers is a manager for transaction tracing engines.
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package tracers
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import (
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"encoding/json"
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core/vm"
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)
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// Context contains some contextual infos for a transaction execution that is not
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// available from within the EVM object.
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type Context struct {
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BlockHash common.Hash // Hash of the block the tx is contained within (zero if dangling tx or call)
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BlockNumber *big.Int // Number of the block the tx is contained within (zero if dangling tx or call)
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TxIndex int // Index of the transaction within a block (zero if dangling tx or call)
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TxHash common.Hash // Hash of the transaction being traced (zero if dangling call)
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}
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// Tracer interface extends vm.EVMLogger and additionally
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// allows collecting the tracing result.
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type Tracer interface {
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vm.EVMLogger
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GetResult() (json.RawMessage, error)
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// Stop terminates execution of the tracer at the first opportune moment.
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Stop(err error)
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}
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type ctorFn func(*Context, json.RawMessage) (Tracer, error)
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type jsCtorFn func(string, *Context, json.RawMessage) (Tracer, error)
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type elem struct {
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ctor ctorFn
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isJS bool
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}
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// DefaultDirectory is the collection of tracers bundled by default.
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var DefaultDirectory = directory{elems: make(map[string]elem)}
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// directory provides functionality to lookup a tracer by name
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// and a function to instantiate it. It falls back to a JS code evaluator
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// if no tracer of the given name exists.
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type directory struct {
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elems map[string]elem
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jsEval jsCtorFn
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}
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// Register registers a method as a lookup for tracers, meaning that
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// users can invoke a named tracer through that lookup.
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func (d *directory) Register(name string, f ctorFn, isJS bool) {
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d.elems[name] = elem{ctor: f, isJS: isJS}
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}
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// RegisterJSEval registers a tracer that is able to parse
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// dynamic user-provided JS code.
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func (d *directory) RegisterJSEval(f jsCtorFn) {
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d.jsEval = f
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}
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// New returns a new instance of a tracer, by iterating through the
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// registered lookups. Name is either name of an existing tracer
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// or an arbitrary JS code.
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func (d *directory) New(name string, ctx *Context, cfg json.RawMessage) (Tracer, error) {
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if elem, ok := d.elems[name]; ok {
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return elem.ctor(ctx, cfg)
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}
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// Assume JS code
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return d.jsEval(name, ctx, cfg)
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}
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// IsJS will return true if the given tracer will evaluate
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// JS code. Because code evaluation has high overhead, this
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// info will be used in determining fast and slow code paths.
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func (d *directory) IsJS(name string) bool {
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if elem, ok := d.elems[name]; ok {
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return elem.isJS
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}
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// JS eval will execute JS code
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return true
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}
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