1 files changed, 134 insertions, 0 deletions
diff --git a/vendor/codeberg.org/gruf/go-fastcopy/copy.go b/vendor/codeberg.org/gruf/go-fastcopy/copy.go
new file mode 100644
index 000000000..4716b140f
--- /dev/null
+++ b/vendor/codeberg.org/gruf/go-fastcopy/copy.go
@@ -0,0 +1,134 @@
+package fastcopy
+
+import (
+	"io"
+	"sync"
+	_ "unsafe" // link to io.errInvalidWrite.
+)
+
+var (
+	// global pool instance.
+	pool = CopyPool{size: 4096}
+
+	//go:linkname errInvalidWrite io.errInvalidWrite
+	errInvalidWrite error
+)
+
+// CopyPool provides a memory pool of byte
+// buffers for io copies from readers to writers.
+type CopyPool struct {
+	size int
+	pool sync.Pool
+}
+
+// See CopyPool.Buffer().
+func Buffer(sz int) int {
+	return pool.Buffer(sz)
+}
+
+// See CopyPool.CopyN().
+func CopyN(dst io.Writer, src io.Reader, n int64) (int64, error) {
+	return pool.CopyN(dst, src, n)
+}
+
+// See CopyPool.Copy().
+func Copy(dst io.Writer, src io.Reader) (int64, error) {
+	return pool.Copy(dst, src)
+}
+
+// Buffer sets the pool buffer size to allocate. Returns current size.
+// Note this is NOT atomically safe, please call BEFORE other calls to CopyPool.
+func (cp *CopyPool) Buffer(sz int) int {
+	if sz > 0 {
+		// update size
+		cp.size = sz
+	} else if cp.size < 1 {
+		// default size
+		return 4096
+	}
+	return cp.size
+}
+
+// CopyN performs the same logic as io.CopyN(), with the difference
+// being that the byte buffer is acquired from a memory pool.
+func (cp *CopyPool) CopyN(dst io.Writer, src io.Reader, n int64) (int64, error) {
+	written, err := cp.Copy(dst, io.LimitReader(src, n))
+	if written == n {
+		return n, nil
+	}
+	if written < n && err == nil {
+		// src stopped early; must have been EOF.
+		err = io.EOF
+	}
+	return written, err
+}
+
+// Copy performs the same logic as io.Copy(), with the difference
+// being that the byte buffer is acquired from a memory pool.
+func (cp *CopyPool) Copy(dst io.Writer, src io.Reader) (int64, error) {
+	// Prefer using io.WriterTo to do the copy (avoids alloc + copy)
+	if wt, ok := src.(io.WriterTo); ok {
+		return wt.WriteTo(dst)
+	}
+
+	// Prefer using io.ReaderFrom to do the copy.
+	if rt, ok := dst.(io.ReaderFrom); ok {
+		return rt.ReadFrom(src)
+	}
+
+	var buf []byte
+
+	if b, ok := cp.pool.Get().([]byte); ok {
+		// Acquired buf from pool
+		buf = b
+	} else {
+		// Allocate new buffer of size
+		buf = make([]byte, cp.Buffer(0))
+	}
+
+	// Defer release to pool
+	defer cp.pool.Put(buf)
+
+	var n int64
+	for {
+		// Perform next read into buf
+		nr, err := src.Read(buf)
+		if nr > 0 {
+			// We error check AFTER checking
+			// no. read bytes so incomplete
+			// read still gets written up to nr.
+
+			// Perform next write from buf
+			nw, ew := dst.Write(buf[0:nr])
+
+			// Check for valid write
+			if nw < 0 || nr < nw {
+				if ew == nil {
+					ew = errInvalidWrite
+				}
+				return n, ew
+			}
+
+			// Incr total count
+			n += int64(nw)
+
+			// Check write error
+			if ew != nil {
+				return n, ew
+			}
+
+			// Check unequal read/writes
+			if nr != nw {
+				return n, io.ErrShortWrite
+			}
+		}
+
+		// Return on err
+		if err != nil {
+			if err == io.EOF {
+				err = nil // expected
+			}
+			return n, err
+		}
+	}
+}