github.com/linapex/ethereum-go-chinese@v0.0.0-20190316121929-f8b7a73c3fa1/swarm/storage/feed/cacheentry.go (about)

     1  
     2  //<developer>
     3  //    <name>linapex 曹一峰</name>
     4  //    <email>linapex@163.com</email>
     5  //    <wx>superexc</wx>
     6  //    <qqgroup>128148617</qqgroup>
     7  //    <url>https://jsq.ink</url>
     8  //    <role>pku engineer</role>
     9  //    <date>2019-03-16 19:16:44</date>
    10  //</624450118682152960>
    11  
    12  
    13  package feed
    14  
    15  import (
    16  	"bytes"
    17  	"context"
    18  	"time"
    19  
    20  	"github.com/ethereum/go-ethereum/swarm/storage"
    21  )
    22  
    23  const (
    24  	hasherCount            = 8
    25  	feedsHashAlgorithm     = storage.SHA3Hash
    26  	defaultRetrieveTimeout = 100 * time.Millisecond
    27  )
    28  
    29  //cacheEntry缓存特定群源的最后一次已知更新。
    30  type cacheEntry struct {
    31  	Update
    32  	*bytes.Reader
    33  	lastKey storage.Address
    34  }
    35  
    36  //实现Storage.LazySectionReader
    37  func (r *cacheEntry) Size(ctx context.Context, _ chan bool) (int64, error) {
    38  	return int64(len(r.Update.data)), nil
    39  }
    40  
    41  //返回源的主题
    42  func (r *cacheEntry) Topic() Topic {
    43  	return r.Feed.Topic
    44  }
    45