diff options
| -rw-r--r-- | common/copy.go | 153 | ||||
| -rw-r--r-- | common/minmax.go | 27 |
2 files changed, 0 insertions, 180 deletions
diff --git a/common/copy.go b/common/copy.go deleted file mode 100644 index 02e33a5..0000000 --- a/common/copy.go +++ /dev/null @@ -1,153 +0,0 @@ -package common - -/* -Copied from https://ixday.github.io/post/golang-cancel-copy/ -*/ - -import ( - "context" - "fmt" - "io" - "os" - "sync" -) - -// CopyToFileWithBuffer copies data from io.Reader to os.File with given buffer and read chunk size. -// The reader and writer may not be synchronized if any error occurs. -// A block contains one or more chunks. -// Every syscall reads at most one chunk. -// Every disk-write writes at most one block. -// The buffer is a ring contains one or more blocks. -// The reader and file won't be closed. -// If syncFile is set, the file will be synced after every read. -// ringSize: how many blocks are in the buffer ring. -func CopyToFileWithBuffer( - ctx context.Context, - out *os.File, - in io.Reader, - buffer []byte, - syncFile bool, - ringSize uint, -) (written int64, err error) { - var blkSize uint - bufSize := uint(len(buffer)) - if bufSize%ringSize != 0 { - err = fmt.Errorf("len(buffer) %% ringSize != 0") - } else { - blkSize = bufSize / ringSize - } - - chWriteQue := make(chan uint, ringSize) // buffer write task queue - chReadQue := make(chan uint, ringSize) // buffer read task queue - - // when reader and writer are stopped, this channel must have 2 elements - chResult := make(chan error, 2) - - type task struct { - Offset uint - Length uint - } - - chLastWrite := make(chan task, 1) - - rwCtx, cancelReadWrite := context.WithCancel(ctx) - - // wait reader and writer to finish - wg := sync.WaitGroup{} - - // buffer reader - // buffer -> file - go func() { - var err error - wg.Add(1) - defer wg.Done() - defer func() { - chResult <- err - }() - for { - select { - case <-rwCtx.Done(): - return - default: - // get the next available block to read from - // this block is fully written in the buffer - off := <-chReadQue - - // read the entire block to file - n, err2 := out.Write(buffer[off : off+blkSize]) - if err2 != nil { - // failed to write to the file - // we can do nothing more than stop reading and writing - err = fmt.Errorf("write error (%v byte written in this call): %w", n, err2) - cancelReadWrite() - return - } - } - } - }() - - // buffer writer - // reader -> buffer - go func() { - var err error - wg.Add(1) - defer wg.Done() - defer func() { - chResult <- err - }() - for { - select { - case <-rwCtx.Done(): - chLastWrite <- task{ - Offset: 0, - Length: 0, - } - return - default: - // get the next free block for writing - off := <-chWriteQue // byte offset - - // fully fill the block - nWritten := uint(0) // bytes written in this block currently - for nWritten < blkSize { - n, err := in.Read(buffer[off+nWritten : off+blkSize]) - nWritten += uint(n) - if err != nil { - // if we can't fully fill current block (e.g. EOF or IO error), - // set nLeft to make the main goroutine handle that - cancelReadWrite() - err = fmt.Errorf("reader failed: %w", err) - chLastWrite <- task{ - Offset: off, - Length: nWritten, // bytes of valid data in the last incomplete block - } - return - } - } - } - } - }() - - // init write tasks, all buffer blocks are available for writing initially - for i := uint(0); i < bufSize; i += blkSize { - chWriteQue <- i - } - - wg.Wait() - - for i := 0; i < 2; i++ { - if err2 := <-chResult; err2 != nil { - err = err2 - return - } - } - - // write the remaining data - last := <-chLastWrite - if last.Length > 0 { - var n int - n, err = out.Write(buffer[last.Offset : last.Offset+last.Length]) - written += int64(n) - } - return -} diff --git a/common/minmax.go b/common/minmax.go deleted file mode 100644 index b670887..0000000 --- a/common/minmax.go +++ /dev/null @@ -1,27 +0,0 @@ -package common - -/* -Golang is a piece of shit. Its creators are paranoids. -*/ - -import ( - "golang.org/x/exp/constraints" -) - -type Number interface { - constraints.Integer | constraints.Float -} - -func Min[T Number](t1 T, t2 T) T { - if t1 < t2 { - return t1 - } - return t2 -} - -func Max[T Number](t1 T, t2 T) T { - if t1 > t2 { - return t1 - } - return t2 -} |