github.com/calmw/ethereum@v0.1.1/trie/tracer.go (about)

     1  // Copyright 2022 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  package trie
    18  
    19  import (
    20  	"github.com/calmw/ethereum/common"
    21  	"github.com/calmw/ethereum/trie/trienode"
    22  )
    23  
    24  // tracer tracks the changes of trie nodes. During the trie operations,
    25  // some nodes can be deleted from the trie, while these deleted nodes
    26  // won't be captured by trie.Hasher or trie.Committer. Thus, these deleted
    27  // nodes won't be removed from the disk at all. Tracer is an auxiliary tool
    28  // used to track all insert and delete operations of trie and capture all
    29  // deleted nodes eventually.
    30  //
    31  // The changed nodes can be mainly divided into two categories: the leaf
    32  // node and intermediate node. The former is inserted/deleted by callers
    33  // while the latter is inserted/deleted in order to follow the rule of trie.
    34  // This tool can track all of them no matter the node is embedded in its
    35  // parent or not, but valueNode is never tracked.
    36  //
    37  // Besides, it's also used for recording the original value of the nodes
    38  // when they are resolved from the disk. The pre-value of the nodes will
    39  // be used to construct trie history in the future.
    40  //
    41  // Note tracer is not thread-safe, callers should be responsible for handling
    42  // the concurrency issues by themselves.
    43  type tracer struct {
    44  	inserts    map[string]struct{}
    45  	deletes    map[string]struct{}
    46  	accessList map[string][]byte
    47  }
    48  
    49  // newTracer initializes the tracer for capturing trie changes.
    50  func newTracer() *tracer {
    51  	return &tracer{
    52  		inserts:    make(map[string]struct{}),
    53  		deletes:    make(map[string]struct{}),
    54  		accessList: make(map[string][]byte),
    55  	}
    56  }
    57  
    58  // onRead tracks the newly loaded trie node and caches the rlp-encoded
    59  // blob internally. Don't change the value outside of function since
    60  // it's not deep-copied.
    61  func (t *tracer) onRead(path []byte, val []byte) {
    62  	t.accessList[string(path)] = val
    63  }
    64  
    65  // onInsert tracks the newly inserted trie node. If it's already
    66  // in the deletion set (resurrected node), then just wipe it from
    67  // the deletion set as it's "untouched".
    68  func (t *tracer) onInsert(path []byte) {
    69  	if _, present := t.deletes[string(path)]; present {
    70  		delete(t.deletes, string(path))
    71  		return
    72  	}
    73  	t.inserts[string(path)] = struct{}{}
    74  }
    75  
    76  // onDelete tracks the newly deleted trie node. If it's already
    77  // in the addition set, then just wipe it from the addition set
    78  // as it's untouched.
    79  func (t *tracer) onDelete(path []byte) {
    80  	if _, present := t.inserts[string(path)]; present {
    81  		delete(t.inserts, string(path))
    82  		return
    83  	}
    84  	t.deletes[string(path)] = struct{}{}
    85  }
    86  
    87  // reset clears the content tracked by tracer.
    88  func (t *tracer) reset() {
    89  	t.inserts = make(map[string]struct{})
    90  	t.deletes = make(map[string]struct{})
    91  	t.accessList = make(map[string][]byte)
    92  }
    93  
    94  // copy returns a deep copied tracer instance.
    95  func (t *tracer) copy() *tracer {
    96  	var (
    97  		inserts    = make(map[string]struct{})
    98  		deletes    = make(map[string]struct{})
    99  		accessList = make(map[string][]byte)
   100  	)
   101  	for path := range t.inserts {
   102  		inserts[path] = struct{}{}
   103  	}
   104  	for path := range t.deletes {
   105  		deletes[path] = struct{}{}
   106  	}
   107  	for path, blob := range t.accessList {
   108  		accessList[path] = common.CopyBytes(blob)
   109  	}
   110  	return &tracer{
   111  		inserts:    inserts,
   112  		deletes:    deletes,
   113  		accessList: accessList,
   114  	}
   115  }
   116  
   117  // markDeletions puts all tracked deletions into the provided nodeset.
   118  func (t *tracer) markDeletions(set *trienode.NodeSet) {
   119  	for path := range t.deletes {
   120  		// It's possible a few deleted nodes were embedded
   121  		// in their parent before, the deletions can be no
   122  		// effect by deleting nothing, filter them out.
   123  		prev, ok := t.accessList[path]
   124  		if !ok {
   125  			continue
   126  		}
   127  		set.AddNode([]byte(path), trienode.NewWithPrev(common.Hash{}, nil, prev))
   128  	}
   129  }