go-ceph/rados/read_op_read.go

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package rados
// #cgo LDFLAGS: -lrados
// #include <rados/librados.h>
// #include <stdlib.h>
//
import "C"
import (
"unsafe"
)
// ReadOpReadStep holds the result of the Read read operation.
// Result is valid only after Operate() was called.
type ReadOpReadStep struct {
// C returned data:
bytesRead *C.size_t
prval *C.int
BytesRead int64 // Bytes read by this action.
Result int // Result of this action.
}
func (s *ReadOpReadStep) update() error {
s.BytesRead = (int64)(*s.bytesRead)
s.Result = (int)(*s.prval)
return nil
}
func (s *ReadOpReadStep) free() {
C.free(unsafe.Pointer(s.bytesRead))
C.free(unsafe.Pointer(s.prval))
s.bytesRead = nil
s.prval = nil
}
func newReadOpReadStep() *ReadOpReadStep {
return &ReadOpReadStep{
bytesRead: (*C.size_t)(C.malloc(C.sizeof_size_t)),
prval: (*C.int)(C.malloc(C.sizeof_int)),
}
}
// Read bytes from offset into buffer.
// len(buffer) is the maximum number of bytes read from the object.
// buffer[:ReadOpReadStep.BytesRead] then contains object data.
//
// Implements:
//
// void rados_read_op_read(rados_read_op_t read_op,
// uint64_t offset,
// size_t len,
// char * buffer,
// size_t * bytes_read,
// int * prval)
func (r *ReadOp) Read(offset uint64, buffer []byte) *ReadOpReadStep {
oe := newReadStep(buffer, offset)
readStep := newReadOpReadStep()
r.steps = append(r.steps, oe, readStep)
C.rados_read_op_read(
r.op,
oe.cOffset,
oe.cReadLen,
oe.cBuffer,
readStep.bytesRead,
readStep.prval,
)
return readStep
}