At Mon, 10 Oct 2011 15:34:44 +0800, Liu Yuan wrote: > > On 10/10/2011 01:46 PM, MORITA Kazutaka wrote: > > Currently Sheepdog vdi operations (create/delete/lookup/...) are > > processed in two phase multicasting: > > > > 1. multicasts a vdi request > > 2. only the master node handles the request and multicasts the > > response > > > > During this two phase, we cannot allow any other vdi operations and > > membership changes, and this makes sheep/group.c a bit hard to read. > > > > This patch simplifies this by adding a blocking callback to the > > notification function in the cluster driver. If the caller of > > cdrv->notify() sets 'block_cb' as an argument, block_cb() is called > > from the cluster driver before the message is notified to any node. > > All the cluster events are blocked in every nodes until the caller > > finishes the vdi operation in block_cb(). > > > > With this change, the master node is no longer in charge of vdi > > operations, but this is a good change to make Sheepdog more symmetric. > > > > Signed-off-by: MORITA Kazutaka<morita.kazutaka at lab.ntt.co.jp> > > --- > > sheep/cluster.h | 10 ++- > > sheep/cluster/corosync.c | 209 +++++++++++++++++++++++++++++++++++++++------- > > sheep/group.c | 12 ++-- > > 3 files changed, 191 insertions(+), 40 deletions(-) > > > > diff --git a/sheep/cluster.h b/sheep/cluster.h > > index 43f4575..25b2d48 100644 > > --- a/sheep/cluster.h > > +++ b/sheep/cluster.h > > @@ -71,11 +71,17 @@ struct cluster_driver { > > * > > * This function sends 'msg' to all the nodes. The notified > > * messages can be read through notify_handler() in > > - * cdrv_handlers. > > + * cdrv_handlers. If 'block_cb' is specified, block_cb() is > > + * called before 'msg' is notified to all the nodes. All the > > + * cluster events including this notification are blocked > > + * until block_cb() returns or this blocking node leaves the > > + * cluster. The sheep daemon can sleep in block_cb(), so this > > + * callback must be called from other than the dispatch > > + * thread. > > * > > * Returns zero on success, -1 on error > > */ > > - int (*notify)(void *msg, size_t msg_len); > > + int (*notify)(void *msg, size_t msg_len, void (*block_cb)(void *arg)); > > > > /* > > * Dispatch handlers > > diff --git a/sheep/cluster/corosync.c b/sheep/cluster/corosync.c > > index e0f9a9c..022912b 100644 > > --- a/sheep/cluster/corosync.c > > +++ b/sheep/cluster/corosync.c > > @@ -14,20 +14,27 @@ > > #include<corosync/cfg.h> > > > > #include "cluster.h" > > +#include "work.h" > > > > static cpg_handle_t cpg_handle; > > static struct cpg_name cpg_group = { 9, "sheepdog" }; > > > > static corosync_cfg_handle_t cfg_handle; > > +static struct sheepid this_sheepid; > > + > > +static struct work_queue *corosync_block_wq; > > > > static struct cdrv_handlers corosync_handlers; > > > > static LIST_HEAD(corosync_event_list); > > +static LIST_HEAD(corosync_block_list); > > > > enum corosync_event_type { > > COROSYNC_EVENT_TYPE_JOIN, > > COROSYNC_EVENT_TYPE_LEAVE, > > COROSYNC_EVENT_TYPE_NOTIFY, > > + COROSYNC_EVENT_TYPE_BLOCK, > > + COROSYNC_EVENT_TYPE_UNBLOCK, > > }; > > > > how about separate block/unblock message handling from cluster message? > More and more message handling, if any in the later dev, would make > corosync_dispatch() more complicated and bloated. Current unblock > message handling in corosync_dispatch() already looks odd (tricky) to me. Thanks for your comment. How about splitting into two enums? /* event types which are dispatched in corosync_dispatc() */ enum corosync_event_type { COROSYNC_EVENT_TYPE_JOIN, COROSYNC_EVENT_TYPE_LEAVE, COROSYNC_EVENT_TYPE_NOTIFY, }; /* corosync multicast message type */ enum corosync_message_type { COROSYNC_MSG_TYPE_NOTIFY, COROSYNC_MSG_TYPE_BLOCK, COROSYNC_MSG_TYPE_UNBLOCK, }; > > > struct corosync_event { > > @@ -42,6 +49,17 @@ struct corosync_event { > > void *msg; > > size_t msg_len; > > > > + int blocked; > > + > > + struct list_head list; > > +}; > > + > > +struct corosync_block_msg { > > + void *msg; > > + size_t msg_len; > > + void (*cb)(void *arg); > > + > > + struct work work; > > struct list_head list; > > }; > > > > @@ -91,9 +109,70 @@ static void cpg_addr_to_sheepid(const struct cpg_address *cpgs, > > } > > } > > > > +static int send_message(uint64_t type, void *msg, size_t msg_len) > > +{ > > + struct iovec iov[2]; > > + int ret, iov_cnt = 1; > > + > > + iov[0].iov_base =&type; > > + iov[0].iov_len = sizeof(type); > > + if (msg) { > > + iov[1].iov_base = msg; > > + iov[1].iov_len = msg_len; > > + iov_cnt++; > > + } > > +retry: > > + ret = cpg_mcast_joined(cpg_handle, CPG_TYPE_AGREED, iov, iov_cnt); > > + switch (ret) { > > + case CPG_OK: > > + break; > > + case CPG_ERR_TRY_AGAIN: > > + dprintf("failed to send message. try again\n"); > > + sleep(1); > > + goto retry; > > + default: > > + eprintf("failed to send message, %d\n", ret); > > + return -1; > > + } > > + return 0; > > +} > > + > > +static void corosync_block(struct work *work, int idx) > > +{ > > + struct corosync_block_msg *bm = container_of(work, typeof(*bm), work); > > + > > + bm->cb(bm->msg); > > +} > > + > > +static void corosync_block_done(struct work *work, int idx) > > +{ > > + struct corosync_block_msg *bm = container_of(work, typeof(*bm), work); > > + > > + send_message(COROSYNC_EVENT_TYPE_UNBLOCK, bm->msg, bm->msg_len); > > + > > + free(bm->msg); > > + free(bm); > > +} > > + > > +static struct corosync_event *find_block_event(struct sheepid *sender) > > +{ > > + struct corosync_event *cevent; > > + > > + list_for_each_entry(cevent,&corosync_event_list, list) { > > + if (cevent->type != COROSYNC_EVENT_TYPE_BLOCK) > > + continue; > > + > > + if (sheepid_cmp(&cevent->sender, sender) == 0) > > + return cevent; > > + } > > + > > + return NULL; > > +} > > + > > static void __corosync_dispatch(void) > > { > > struct corosync_event *cevent; > > + struct corosync_block_msg *bm; > > > > while (!list_empty(&corosync_event_list)) { > > cevent = list_first_entry(&corosync_event_list, typeof(*cevent), list); > > @@ -114,11 +193,36 @@ static void __corosync_dispatch(void) > > cevent->msg, > > cevent->msg_len); > > break; > > + case COROSYNC_EVENT_TYPE_BLOCK: > > + if (sheepid_cmp(&cevent->sender,&this_sheepid) != 0) > > + cevent->blocked = 1; > > + > > + if (!cevent->blocked) { > > + /* call a block callback function from a worker thread */ > > + if (list_empty(&corosync_block_list)) > > + panic("cannot call block callback\n"); > > + > > + bm = list_first_entry(&corosync_block_list, typeof(*bm), list); > > + list_del(&bm->list); > > + > > + bm->work.fn = corosync_block; > > + bm->work.done = corosync_block_done; > > + queue_work(corosync_block_wq,&bm->work); > > + cevent->blocked = 1; > > + } > > + > > might variable *blocked* be static local one if no other ref? I guess if we remove COROSYNC_EVENT_TYPE_BLOCK/UNBLOCK from COROSYNC_EVENT_TYPE, we need to access 'blocked' from outside. I'll send a fixed patch, then let's discuss again. Thanks, Kazutaka |