github.com/uber/kraken@v0.1.4/lib/metainfogen/generator.go (about)

     1  // Copyright (c) 2016-2019 Uber Technologies, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  package metainfogen
    15  
    16  import (
    17  	"fmt"
    18  
    19  	"github.com/uber/kraken/core"
    20  	"github.com/uber/kraken/lib/store"
    21  	"github.com/uber/kraken/lib/store/metadata"
    22  )
    23  
    24  // Generator wraps static piece length configuration in order to determinstically
    25  // generate metainfo.
    26  type Generator struct {
    27  	pieceLengthConfig *pieceLengthConfig
    28  	cas               *store.CAStore
    29  }
    30  
    31  // New creates a new Generator.
    32  func New(config Config, cas *store.CAStore) (*Generator, error) {
    33  	plConfig, err := newPieceLengthConfig(config.PieceLengths)
    34  	if err != nil {
    35  		return nil, fmt.Errorf("piece length config: %s", err)
    36  	}
    37  	return &Generator{plConfig, cas}, nil
    38  }
    39  
    40  // Generate generates metainfo for the blob of d and writes it to disk.
    41  func (g *Generator) Generate(d core.Digest) error {
    42  	info, err := g.cas.GetCacheFileStat(d.Hex())
    43  	if err != nil {
    44  		return fmt.Errorf("cache stat: %s", err)
    45  	}
    46  	f, err := g.cas.GetCacheFileReader(d.Hex())
    47  	if err != nil {
    48  		return fmt.Errorf("get cache file: %s", err)
    49  	}
    50  	pieceLength := g.pieceLengthConfig.get(info.Size())
    51  	mi, err := core.NewMetaInfo(d, f, pieceLength)
    52  	if err != nil {
    53  		return fmt.Errorf("create metainfo: %s", err)
    54  	}
    55  	if _, err := g.cas.SetCacheFileMetadata(d.Hex(), metadata.NewTorrentMeta(mi)); err != nil {
    56  		return fmt.Errorf("set metainfo: %s", err)
    57  	}
    58  	return nil
    59  }