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- 增加多线程分片下载文件 - 增加下载文件但是进程退出后，重新下载恢复之前的进度
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,31 @@ | ||
| package partial | ||
|
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| type Chunk struct { | ||
| Start int64 | ||
| End int64 | ||
| Error error | ||
| Buffer []byte | ||
| } | ||
|
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| func cut(chunks []*Chunk, i int) ([]*Chunk, []*Chunk) { | ||
|
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| if len(chunks) <= i { | ||
| return chunks, []*Chunk{} | ||
| } | ||
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| return chunks[0:i], chunks[i:] | ||
| } | ||
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| func (p *MultiPartialDownloader) retryDownloadChunk(start, end int64) ([]byte, error) { | ||
| var err error | ||
| var buffer []byte | ||
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| // 重试三次 | ||
| for t := 0; t < 3; t++ { | ||
| buffer, err = p.DownFunc(p, start, end-1) | ||
| if err == nil { | ||
| break | ||
| } | ||
| } | ||
| return buffer, nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,67 @@ | ||
| package partial | ||
|
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| import ( | ||
| "errors" | ||
| "os" | ||
| "sync" | ||
| ) | ||
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| func (p *MultiPartialDownloader) Download() error { | ||
| fileinfo, err := os.Stat(p.FilePath) | ||
| if err == nil { | ||
| p.LocalSize = fileinfo.Size() | ||
| } | ||
|
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| // 计算需要下载的块数 | ||
| needDownSize := p.FinalSize - p.LocalSize | ||
| chunkCount := needDownSize / ChunkSize | ||
| if needDownSize%ChunkSize != 0 { | ||
| chunkCount++ | ||
| } | ||
|
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| // 下载任务队列 | ||
| var queue []*Chunk | ||
| for i := 0; i < int(chunkCount); i++ { | ||
| start := p.LocalSize + int64(i)*ChunkSize | ||
| end := p.LocalSize + int64(i+1)*ChunkSize | ||
| if end > p.FinalSize { | ||
| end = p.FinalSize | ||
| } | ||
| queue = append(queue, &Chunk{ | ||
| Start: start, | ||
| End: end, | ||
| }) | ||
| } | ||
|
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| for { | ||
| var chunks []*Chunk | ||
| chunks, queue = cut(queue, p.Works) | ||
| if len(chunks) <= 0 { | ||
| break | ||
| } | ||
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| var wg sync.WaitGroup | ||
| for _, chunk := range chunks { | ||
| wg.Add(1) | ||
| go func(c *Chunk) { | ||
| defer wg.Done() | ||
| buffer, err := p.retryDownloadChunk(c.Start, c.End) | ||
| c.Buffer = buffer | ||
| c.Error = err | ||
| }(chunk) | ||
| } | ||
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| wg.Wait() | ||
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| for _, chunk := range chunks { | ||
| if chunk.Error != nil { | ||
| return chunk.Error | ||
| } | ||
| if len(chunk.Buffer) == 0 { | ||
| return errors.New("chunk buffer download but size is 0") | ||
| } | ||
| p.Writer.Write(chunk.Buffer) | ||
| } | ||
| } | ||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,18 @@ | ||
| package partial | ||
|
|
||
| import ( | ||
| "io" | ||
| ) | ||
|
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| const ChunkSize = 1024 * 1024 * 10 | ||
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| type MultiPartialDownloader struct { | ||
| FilePath string | ||
| FinalSize int64 | ||
| LocalSize int64 | ||
| Writer io.Writer | ||
| Works int | ||
| DownFunc ChunkDownFunc | ||
| } | ||
|
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| type ChunkDownFunc func(file *MultiPartialDownloader, start, end int64) ([]byte, error) |
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