forked from sneak/bsdaily
sneak
7316054b07
Add a detailed README, WTFPL LICENSE, and build/CI tooling modeled on the vaultik repo (Makefile, multi-stage digest-pinned Dockerfile, .gitea/workflows/check.yml). Bump Go to 1.26.4 and pin golangci-lint to v2.12.2. gofmt existing sources so the new fmt-check gate passes.
73 lines
1.8 KiB
Go
73 lines
1.8 KiB
Go
package bsdaily
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import (
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"fmt"
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"io"
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"log/slog"
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"os"
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"time"
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)
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const (
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copyBufferSize = 256 * 1024 * 1024 // 256MB buffer for large file copies from fast storage
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oneGB = 1024 * 1024 * 1024
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)
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func CopyFile(src, dst string) (err error) {
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startTime := time.Now()
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slog.Info("copying file", "src", src, "dst", dst)
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srcFile, err := os.Open(src)
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if err != nil {
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return fmt.Errorf("opening source %s: %w", src, err)
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}
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defer srcFile.Close()
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srcInfo, err := srcFile.Stat()
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if err != nil {
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return fmt.Errorf("stat source %s: %w", src, err)
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}
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// For large files, advise kernel about sequential read pattern
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if srcInfo.Size() > oneGB {
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applyFileAdvice(srcFile, srcInfo.Size())
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}
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dstFile, err := os.Create(dst)
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if err != nil {
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return fmt.Errorf("creating destination %s: %w", dst, err)
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}
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defer func() {
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if cerr := dstFile.Close(); cerr != nil && err == nil {
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err = fmt.Errorf("closing destination %s: %w", dst, cerr)
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}
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}()
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// Pre-allocate space for the destination file to avoid fragmentation
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if err := dstFile.Truncate(srcInfo.Size()); err != nil {
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slog.Warn("failed to pre-allocate destination file", "error", err)
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}
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// Use a much larger buffer for NVMe-speed copies
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buf := make([]byte, copyBufferSize)
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written, err := io.CopyBuffer(dstFile, srcFile, buf)
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if err != nil {
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return fmt.Errorf("copying data: %w", err)
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}
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if written != srcInfo.Size() {
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return fmt.Errorf("short copy: wrote %d bytes, expected %d", written, srcInfo.Size())
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}
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if err := dstFile.Sync(); err != nil {
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return fmt.Errorf("syncing destination %s: %w", dst, err)
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}
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elapsed := time.Since(startTime)
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throughputMBps := float64(written) / elapsed.Seconds() / (1024 * 1024)
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slog.Info("file copied", "dst", dst, "bytes", written,
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"elapsed", elapsed.Round(time.Millisecond),
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"throughput_mbps", fmt.Sprintf("%.1f", throughputMBps))
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return nil
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}
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