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82 lines
2.5 KiB
82 lines
2.5 KiB
// Copyright 2021 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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/*
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Package native is a collection of tracers written in go.
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In order to add a native tracer and have it compiled into the binary, a new
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file needs to be added to this folder, containing an implementation of the
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`eth.tracers.Tracer` interface.
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Aside from implementing the tracer, it also needs to register itself, using the
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`register` method -- and this needs to be done in the package initialization.
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Example:
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```golang
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func init() {
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register("noopTracerNative", newNoopTracer)
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}
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```
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*/
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package native
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import (
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"errors"
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"github.com/ethereum/go-ethereum/eth/tracers"
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)
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// init registers itself this packages as a lookup for tracers.
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func init() {
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tracers.RegisterLookup(false, lookup)
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}
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// ctorFn is the constructor signature of a native tracer.
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type ctorFn = func(*tracers.Context) tracers.Tracer
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/*
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ctors is a map of package-local tracer constructors.
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We cannot be certain about the order of init-functions within a package,
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The go spec (https://golang.org/ref/spec#Package_initialization) says
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> To ensure reproducible initialization behavior, build systems
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> are encouraged to present multiple files belonging to the same
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> package in lexical file name order to a compiler.
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Hence, we cannot make the map in init, but must make it upon first use.
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*/
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var ctors map[string]ctorFn
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// register is used by native tracers to register their presence.
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func register(name string, ctor ctorFn) {
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if ctors == nil {
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ctors = make(map[string]ctorFn)
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}
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ctors[name] = ctor
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}
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// lookup returns a tracer, if one can be matched to the given name.
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func lookup(name string, ctx *tracers.Context) (tracers.Tracer, error) {
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if ctors == nil {
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ctors = make(map[string]ctorFn)
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}
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if ctor, ok := ctors[name]; ok {
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return ctor(ctx), nil
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}
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return nil, errors.New("no tracer found")
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}
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