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143 lines
3.4 KiB
Go
143 lines
3.4 KiB
Go
// +build !luminous
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//
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// Ceph Mimic is the first version that supports watchers through librbd.
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package rbd
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/*
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#cgo LDFLAGS: -lrbd
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#include <rbd/librbd.h>
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extern void imageWatchCallback(void *);
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*/
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import "C"
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import (
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"unsafe"
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"github.com/ceph/go-ceph/internal/callbacks"
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"github.com/ceph/go-ceph/internal/cutil"
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"github.com/ceph/go-ceph/internal/retry"
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)
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// ImageWatcher is a representation of the rbd_image_watcher_t from librbd.h
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type ImageWatcher struct {
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Addr string
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Id int64
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Cookie uint64
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}
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// ListWatchers returns the watchers on an RBD image. In case of an error, nil
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// and an error are returned.
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//
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// Note:
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// Only supported in Ceph Mimic and newer.
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//
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// Implements:
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// int rbd_watchers_list(rbd_image_t image,
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// rbd_image_watcher_t *watchers, size_t *max_watchers)
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func (image *Image) ListWatchers() ([]ImageWatcher, error) {
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if err := image.validate(imageIsOpen); err != nil {
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return nil, err
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}
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var (
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err error
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count C.size_t
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watchers []C.rbd_image_watcher_t
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)
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retry.WithSizes(16, 4096, func(size int) retry.Hint {
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count = C.size_t(size)
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watchers = make([]C.rbd_image_watcher_t, count)
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ret := C.rbd_watchers_list(image.image, &watchers[0], &count)
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err = getErrorIfNegative(ret)
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return retry.Size(int(count)).If(err == errRange)
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})
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if err != nil {
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return nil, err
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}
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defer C.rbd_watchers_list_cleanup(&watchers[0], count)
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imageWatchers := make([]ImageWatcher, count)
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for i, watcher := range watchers[:count] {
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imageWatchers[i].Addr = C.GoString(watcher.addr)
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imageWatchers[i].Id = int64(watcher.id)
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imageWatchers[i].Cookie = uint64(watcher.cookie)
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}
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return imageWatchers, nil
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}
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// watchCallbacks tracks the active callbacks for rbd watches
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var watchCallbacks = callbacks.New()
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// WatchCallback defines the function signature needed for the UpdateWatch
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// callback.
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type WatchCallback func(interface{})
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type watchCallbackCtx struct {
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callback WatchCallback
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data interface{}
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}
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// Watch represents an ongoing image metadata watch.
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type Watch struct {
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image *Image
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wcc watchCallbackCtx
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handle C.uint64_t
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cbIndex uintptr
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}
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// UpdateWatch updates the image object to watch metadata changes to the
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// image, returning a Watch object.
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//
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// Implements:
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// int rbd_update_watch(rbd_image_t image, uint64_t *handle,
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// rbd_update_callback_t watch_cb, void *arg);
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func (image *Image) UpdateWatch(cb WatchCallback, data interface{}) (*Watch, error) {
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if err := image.validate(imageIsOpen); err != nil {
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return nil, err
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}
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wcc := watchCallbackCtx{
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callback: cb,
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data: data,
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}
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w := &Watch{
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image: image,
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wcc: wcc,
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cbIndex: watchCallbacks.Add(wcc),
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}
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ret := C.rbd_update_watch(
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image.image,
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&w.handle,
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C.rbd_update_callback_t(C.imageWatchCallback),
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cutil.VoidPtr(w.cbIndex))
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if ret != 0 {
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return nil, getError(ret)
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}
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return w, nil
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}
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// Unwatch un-registers the image watch.
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//
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// Implements:
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// int rbd_update_unwatch(rbd_image_t image, uint64_t handle);
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func (w *Watch) Unwatch() error {
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if w.image == nil {
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return ErrImageNotOpen
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}
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if err := w.image.validate(imageIsOpen); err != nil {
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return err
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}
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ret := C.rbd_update_unwatch(w.image.image, w.handle)
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watchCallbacks.Remove(w.cbIndex)
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return getError(ret)
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}
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//export imageWatchCallback
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func imageWatchCallback(index unsafe.Pointer) {
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v := watchCallbacks.Lookup(uintptr(index))
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wcc := v.(watchCallbackCtx)
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wcc.callback(wcc.data)
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}
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