go-ceph/rados/read_op_omap_get_vals_by_keys.go
John Mulligan 863d71caa5 rados: various readop & writeop apis are now stable
These apis are now stable as per the stability plan.

Signed-off-by: John Mulligan <jmulligan@redhat.com>
2022-06-14 16:01:43 +00:00

113 lines
2.7 KiB
Go

package rados
// #cgo LDFLAGS: -lrados
// #include <rados/librados.h>
// #include <stdlib.h>
//
import "C"
import (
"unsafe"
"github.com/ceph/go-ceph/internal/cutil"
)
// ReadOpOmapGetValsByKeysStep holds the result of the
// GetOmapValuesByKeys read operation.
// Result is valid only after Operate() was called.
type ReadOpOmapGetValsByKeysStep struct {
// C arguments
iter C.rados_omap_iter_t
prval *C.int
// Internal state
// canIterate is only set after the operation is performed and is
// intended to prevent premature fetching of data.
canIterate bool
}
func newReadOpOmapGetValsByKeysStep() *ReadOpOmapGetValsByKeysStep {
s := &ReadOpOmapGetValsByKeysStep{
prval: (*C.int)(C.malloc(C.sizeof_int)),
}
return s
}
func (s *ReadOpOmapGetValsByKeysStep) free() {
s.canIterate = false
C.rados_omap_get_end(s.iter)
C.free(unsafe.Pointer(s.prval))
s.prval = nil
}
func (s *ReadOpOmapGetValsByKeysStep) update() error {
err := getError(*s.prval)
s.canIterate = (err == nil)
return err
}
// Next gets the next omap key/value pair referenced by
// ReadOpOmapGetValsByKeysStep's internal iterator.
// If there are no more elements to retrieve, (nil, nil) is returned.
// May be called only after Operate() finished.
func (s *ReadOpOmapGetValsByKeysStep) Next() (*OmapKeyValue, error) {
if !s.canIterate {
return nil, ErrOperationIncomplete
}
var (
cKey *C.char
cVal *C.char
cKeyLen C.size_t
cValLen C.size_t
)
ret := C.rados_omap_get_next2(s.iter, &cKey, &cVal, &cKeyLen, &cValLen)
if ret != 0 {
return nil, getError(ret)
}
if cKey == nil {
// Iterator has reached the end of the list.
return nil, nil
}
return &OmapKeyValue{
Key: string(C.GoBytes(unsafe.Pointer(cKey), C.int(cKeyLen))),
Value: C.GoBytes(unsafe.Pointer(cVal), C.int(cValLen)),
}, nil
}
// GetOmapValuesByKeys starts iterating over specific key/value pairs.
//
// Implements:
// void rados_read_op_omap_get_vals_by_keys2(rados_read_op_t read_op,
// char const * const * keys,
// size_t num_keys,
// const size_t * key_lens,
// rados_omap_iter_t * iter,
// int * prval)
func (r *ReadOp) GetOmapValuesByKeys(keys []string) *ReadOpOmapGetValsByKeysStep {
s := newReadOpOmapGetValsByKeysStep()
r.steps = append(r.steps, s)
cKeys := cutil.NewBufferGroupStrings(keys)
defer cKeys.Free()
C.rados_read_op_omap_get_vals_by_keys2(
r.op,
(**C.char)(cKeys.BuffersPtr()),
C.size_t(len(keys)),
(*C.size_t)(cKeys.LengthsPtr()),
&s.iter,
s.prval,
)
return s
}