github.com/cryptotooltop/go-ethereum@v0.0.0-20231103184714-151d1922f3e5/eth/tracers/native/tracer.go (about) 1 // Copyright 2021 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 /* 18 Package native is a collection of tracers written in go. 19 20 In order to add a native tracer and have it compiled into the binary, a new 21 file needs to be added to this folder, containing an implementation of the 22 `eth.tracers.Tracer` interface. 23 24 Aside from implementing the tracer, it also needs to register itself, using the 25 `register` method -- and this needs to be done in the package initialization. 26 27 Example: 28 29 ```golang 30 func init() { 31 register("noopTracerNative", newNoopTracer) 32 } 33 ``` 34 */ 35 package native 36 37 import ( 38 "errors" 39 40 "github.com/scroll-tech/go-ethereum/eth/tracers" 41 ) 42 43 // init registers itself this packages as a lookup for tracers. 44 func init() { 45 tracers.RegisterLookup(false, lookup) 46 } 47 48 /* 49 ctors is a map of package-local tracer constructors. 50 51 We cannot be certain about the order of init-functions within a package, 52 The go spec (https://golang.org/ref/spec#Package_initialization) says 53 54 > To ensure reproducible initialization behavior, build systems 55 > are encouraged to present multiple files belonging to the same 56 > package in lexical file name order to a compiler. 57 58 Hence, we cannot make the map in init, but must make it upon first use. 59 */ 60 var ctors map[string]func() tracers.Tracer 61 62 // register is used by native tracers to register their presence. 63 func register(name string, ctor func() tracers.Tracer) { 64 if ctors == nil { 65 ctors = make(map[string]func() tracers.Tracer) 66 } 67 ctors[name] = ctor 68 } 69 70 // lookup returns a tracer, if one can be matched to the given name. 71 func lookup(name string, ctx *tracers.Context) (tracers.Tracer, error) { 72 if ctors == nil { 73 ctors = make(map[string]func() tracers.Tracer) 74 } 75 if ctor, ok := ctors[name]; ok { 76 return ctor(), nil 77 } 78 return nil, errors.New("no tracer found") 79 }