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Implement CAS writes

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From now on, reads will return the server-side object version numbers
and writes and deletes will have an additional "version" parameter
which, if set to a non-zero value, will be atomically compared with
the current version of the object plus 1 and the modification will
fail if it doesn't match.

This feature opens the road to correct online flattening of snapshot
layers and other interesting things.
This commit is contained in:
Vitaliy Filippov
2021-06-15 00:12:35 +03:00
parent f9fe72d40a
commit 891250d355
7 changed files with 55 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/cluster_client.cpp
+17 -5
View File
@@ -633,6 +633,13 @@ resume_1:
// Slice the operation into parts
slice_rw(op);
op->needs_reslice = false;
if (op->opcode == OSD_OP_WRITE && op->version && op->parts.size() > 1)
{
// Atomic writes to multiple stripes are unsupported
op->retval = -EINVAL;
erase_op(op);
return 1;
}
resume_2:
// Send unsent parts, if they're not subject to change
op->state = 3;
@@ -922,6 +929,7 @@ bool cluster_client_t::try_send(cluster_op_t *op, int i)
.offset = part->offset,
.len = part->len,
.meta_revision = meta_rev,
.version = op->opcode == OSD_OP_WRITE ? op->version : 0,
} },
.bitmap = op->opcode == OSD_OP_WRITE ? NULL : op->part_bitmaps + pg_bitmap_size*i,
.bitmap_len = (unsigned)(op->opcode == OSD_OP_WRITE ? 0 : pg_bitmap_size),
@@ -1072,10 +1080,6 @@ void cluster_client_t::handle_op_part(cluster_op_part_t *part)
if (part->op.reply.hdr.retval != expected)
{
// Operation failed, retry
fprintf(
stderr, "%s operation failed on OSD %lu: retval=%ld (expected %d), dropping connection\n",
osd_op_names[part->op.req.hdr.opcode], part->osd_num, part->op.reply.hdr.retval, expected
);
if (part->op.reply.hdr.retval == -EPIPE)
{
// Mark op->up_wait = true before stopping the client
@@ -1094,7 +1098,14 @@ void cluster_client_t::handle_op_part(cluster_op_part_t *part)
// Don't overwrite other errors with -EPIPE
op->retval = part->op.reply.hdr.retval;
}
msgr.stop_client(part->op.peer_fd);
if (op->retval != -EINTR && op->retval != -EIO)
{
fprintf(
stderr, "%s operation failed on OSD %lu: retval=%ld (expected %d), dropping connection\n",
osd_op_names[part->op.req.hdr.opcode], part->osd_num, part->op.reply.hdr.retval, expected
);
msgr.stop_client(part->op.peer_fd);
}
part->flags |= PART_ERROR;
}
else
@@ -1106,6 +1117,7 @@ void cluster_client_t::handle_op_part(cluster_op_part_t *part)
if (op->opcode == OSD_OP_READ)
{
copy_part_bitmap(op, part);
op->version = op->parts.size() == 1 ? part->op.reply.rw.version : 0;
}
}
if (op->inflight_count == 0)