Simplified distributed block storage with strong consistency, like in Ceph
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// Copyright (c) Vitaliy Filippov, 2019+
// License: VNPL-1.0 or GNU GPL-2.0+ (see README.md for details)
#include <stdexcept>
#include "cluster_client.h"
cluster_client_t::cluster_client_t(ring_loop_t *ringloop, timerfd_manager_t *tfd, json11::Json & config)
{
this->ringloop = ringloop;
this->tfd = tfd;
msgr.osd_num = 0;
msgr.tfd = tfd;
msgr.ringloop = ringloop;
msgr.repeer_pgs = [this](osd_num_t peer_osd)
{
if (msgr.osd_peer_fds.find(peer_osd) != msgr.osd_peer_fds.end())
{
// peer_osd just connected
continue_ops();
}
else if (unsynced_writes.size())
{
// peer_osd just dropped connection
for (auto op: syncing_writes)
{
for (auto & part: op->parts)
{
if (part.osd_num == peer_osd && part.done)
{
// repeat this operation
part.osd_num = 0;
part.done = false;
assert(!part.sent);
op->done_count--;
}
}
}
for (auto op: unsynced_writes)
{
for (auto & part: op->parts)
{
if (part.osd_num == peer_osd && part.done)
{
// repeat this operation
part.osd_num = 0;
part.done = false;
assert(!part.sent);
op->done_count--;
}
}
if (op->done_count < op->parts.size())
{
cur_ops.insert(op);
}
}
continue_ops();
}
};
msgr.exec_op = [this](osd_op_t *op)
{
// Garbage in
printf("Incoming garbage from peer %d\n", op->peer_fd);
msgr.stop_client(op->peer_fd);
delete op;
};
msgr.use_sync_send_recv = config["use_sync_send_recv"].bool_value() ||
config["use_sync_send_recv"].uint64_value();
st_cli.tfd = tfd;
st_cli.on_load_config_hook = [this](json11::Json::object & cfg) { on_load_config_hook(cfg); };
st_cli.on_change_osd_state_hook = [this](uint64_t peer_osd) { on_change_osd_state_hook(peer_osd); };
st_cli.on_change_hook = [this](json11::Json::object & changes) { on_change_hook(changes); };
st_cli.on_load_pgs_hook = [this](bool success) { on_load_pgs_hook(success); };
log_level = config["log_level"].int64_value();
st_cli.parse_config(config);
st_cli.load_global_config();
if (ringloop)
{
consumer.loop = [this]()
{
msgr.read_requests();
msgr.send_replies();
this->ringloop->submit();
};
ringloop->register_consumer(&consumer);
}
}
cluster_client_t::~cluster_client_t()
{
if (ringloop)
{
ringloop->unregister_consumer(&consumer);
}
}
void cluster_client_t::stop()
{
while (msgr.clients.size() > 0)
{
msgr.stop_client(msgr.clients.begin()->first);
}
}
void cluster_client_t::continue_ops(bool up_retry)
{
for (auto op_it = cur_ops.begin(); op_it != cur_ops.end(); )
{
if ((*op_it)->up_wait)
{
if (up_retry)
{
(*op_it)->up_wait = false;
continue_rw(*op_it++);
}
else
op_it++;
}
else
continue_rw(*op_it++);
}
}
static uint32_t is_power_of_two(uint64_t value)
{
uint32_t l = 0;
while (value > 1)
{
if (value & 1)
{
return 64;
}
value = value >> 1;
l++;
}
return l;
}
void cluster_client_t::on_load_config_hook(json11::Json::object & config)
{
bs_block_size = config["block_size"].uint64_value();
bs_disk_alignment = config["disk_alignment"].uint64_value();
bs_bitmap_granularity = config["bitmap_granularity"].uint64_value();
if (!bs_block_size)
{
bs_block_size = DEFAULT_BLOCK_SIZE;
}
if (!bs_disk_alignment)
{
bs_disk_alignment = DEFAULT_DISK_ALIGNMENT;
}
if (!bs_bitmap_granularity)
{
bs_bitmap_granularity = DEFAULT_BITMAP_GRANULARITY;
}
uint32_t block_order;
if ((block_order = is_power_of_two(bs_block_size)) >= 64 || bs_block_size < MIN_BLOCK_SIZE || bs_block_size >= MAX_BLOCK_SIZE)
{
throw std::runtime_error("Bad block size");
}
if (config["immediate_commit"] == "all")
{
// Cluster-wide immediate_commit mode
immediate_commit = true;
}
else if (config.find("client_dirty_limit") != config.end())
{
client_dirty_limit = config["client_dirty_limit"].uint64_value();
}
if (!client_dirty_limit)
{
client_dirty_limit = DEFAULT_CLIENT_DIRTY_LIMIT;
}
up_wait_retry_interval = config["up_wait_retry_interval"].uint64_value();
if (!up_wait_retry_interval)
{
up_wait_retry_interval = 500;
}
else if (up_wait_retry_interval < 50)
{
up_wait_retry_interval = 50;
}
msgr.peer_connect_interval = config["peer_connect_interval"].uint64_value();
if (!msgr.peer_connect_interval)
{
msgr.peer_connect_interval = DEFAULT_PEER_CONNECT_INTERVAL;
}
msgr.peer_connect_timeout = config["peer_connect_timeout"].uint64_value();
if (!msgr.peer_connect_timeout)
{
msgr.peer_connect_timeout = DEFAULT_PEER_CONNECT_TIMEOUT;
}
st_cli.start_etcd_watcher();
st_cli.load_pgs();
}
void cluster_client_t::on_load_pgs_hook(bool success)
{
for (auto pool_item: st_cli.pool_config)
{
pg_counts[pool_item.first] = pool_item.second.real_pg_count;
}
pgs_loaded = true;
for (auto fn: on_ready_hooks)
{
fn();
}
on_ready_hooks.clear();
for (auto op: offline_ops)
{
execute(op);
}
offline_ops.clear();
continue_ops();
}
void cluster_client_t::on_change_hook(json11::Json::object & changes)
{
for (auto pool_item: st_cli.pool_config)
{
if (pg_counts[pool_item.first] != pool_item.second.real_pg_count)
{
// At this point, all pool operations should have been suspended
// And now they have to be resliced!
for (auto op: cur_ops)
{
if (INODE_POOL(op->inode) == pool_item.first)
{
op->needs_reslice = true;
}
}
for (auto op: unsynced_writes)
{
if (INODE_POOL(op->inode) == pool_item.first)
{
op->needs_reslice = true;
}
}
for (auto op: syncing_writes)
{
if (INODE_POOL(op->inode) == pool_item.first)
{
op->needs_reslice = true;
}
}
pg_counts[pool_item.first] = pool_item.second.real_pg_count;
}
}
continue_ops();
}
void cluster_client_t::on_change_osd_state_hook(uint64_t peer_osd)
{
if (msgr.wanted_peers.find(peer_osd) != msgr.wanted_peers.end())
{
msgr.connect_peer(peer_osd, st_cli.peer_states[peer_osd]);
}
}
void cluster_client_t::on_ready(std::function<void(void)> fn)
{
if (pgs_loaded)
{
fn();
}
else
{
on_ready_hooks.push_back(fn);
}
}
/**
* How writes are synced when immediate_commit is false
*
* 1) accept up to <client_dirty_limit> write operations for execution,
* queue all subsequent writes into <next_writes>
* 2) accept exactly one SYNC, queue all subsequent SYNCs into <next_writes>, too
* 3) "continue" all accepted writes
*
* "Continue" WRITE:
* 1) if the operation is not a copy yet - copy it (required for replay)
* 2) if the operation is not sliced yet - slice it
* 3) if the operation doesn't require reslice - try to connect & send all remaining parts
* 4) if any of them fail due to disconnected peers or PGs not up, repeat after reconnecting or small timeout
* 5) if any of them fail due to other errors, fail the operation and forget it from the current "unsynced batch"
* 6) if PG count changes before all parts are done, wait for all in-progress parts to finish,
* throw all results away, reslice and resubmit op
* 7) when all parts are done, try to "continue" the current SYNC
* 8) if the operation succeeds, but then some OSDs drop their connections, repeat
* parts from the current "unsynced batch" previously sent to those OSDs in any order
*
* "Continue" current SYNC:
* 1) take all unsynced operations from the current batch
* 2) check if all affected OSDs are still alive
* 3) if yes, send all SYNCs. otherwise, leave current SYNC as is.
* 4) if any of them fail due to disconnected peers, repeat SYNC after repeating all writes
* 5) if any of them fail due to other errors, fail the SYNC operation
*/
void cluster_client_t::execute(cluster_op_t *op)
{
if (!pgs_loaded)
{
// We're offline
offline_ops.push_back(op);
return;
}
op->retval = 0;
if (op->opcode != OSD_OP_SYNC && op->opcode != OSD_OP_READ && op->opcode != OSD_OP_WRITE ||
(op->opcode == OSD_OP_READ || op->opcode == OSD_OP_WRITE) && (!op->inode || !op->len ||
op->offset % bs_disk_alignment || op->len % bs_disk_alignment))
{
op->retval = -EINVAL;
std::function<void(cluster_op_t*)>(op->callback)(op);
return;
}
if (op->opcode == OSD_OP_SYNC)
{
execute_sync(op);
return;
}
if (op->opcode == OSD_OP_WRITE && !immediate_commit)
{
if (next_writes.size() > 0)
{
assert(cur_sync);
next_writes.push_back(op);
return;
}
if (queued_bytes >= client_dirty_limit)
{
// Push an extra SYNC operation to flush previous writes
next_writes.push_back(op);
cluster_op_t *sync_op = new cluster_op_t;
sync_op->is_internal = true;
sync_op->opcode = OSD_OP_SYNC;
sync_op->callback = [](cluster_op_t* sync_op) {};
execute_sync(sync_op);
return;
}
queued_bytes += op->len;
}
cur_ops.insert(op);
continue_rw(op);
}
void cluster_client_t::continue_rw(cluster_op_t *op)
{
pool_id_t pool_id = INODE_POOL(op->inode);
if (!pool_id)
{
op->retval = -EINVAL;
std::function<void(cluster_op_t*)>(op->callback)(op);
return;
}
if (st_cli.pool_config.find(pool_id) == st_cli.pool_config.end() ||
st_cli.pool_config[pool_id].real_pg_count == 0)
{
// Postpone operations to unknown pools
return;
}
if (op->opcode == OSD_OP_WRITE && !immediate_commit && !op->is_internal)
{
// Save operation for replay when PG goes out of sync
// (primary OSD drops our connection in this case)
cluster_op_t *op_copy = new cluster_op_t();
op_copy->is_internal = true;
op_copy->orig_op = op;
op_copy->opcode = op->opcode;
op_copy->inode = op->inode;
op_copy->offset = op->offset;
op_copy->len = op->len;
op_copy->buf = malloc_or_die(op->len);
op_copy->iov.push_back(op_copy->buf, op->len);
op_copy->callback = [](cluster_op_t* op_copy)
{
if (op_copy->orig_op)
{
// Acknowledge write and forget the original pointer
op_copy->orig_op->retval = op_copy->retval;
std::function<void(cluster_op_t*)>(op_copy->orig_op->callback)(op_copy->orig_op);
op_copy->orig_op = NULL;
}
};
void *cur_buf = op_copy->buf;
for (int i = 0; i < op->iov.count; i++)
{
memcpy(cur_buf, op->iov.buf[i].iov_base, op->iov.buf[i].iov_len);
cur_buf += op->iov.buf[i].iov_len;
}
unsynced_writes.push_back(op_copy);
cur_ops.erase(op);
cur_ops.insert(op_copy);
op = op_copy;
}
if (!op->parts.size())
{
// Slice the operation into parts
slice_rw(op);
}
if (!op->needs_reslice)
{
// Send unsent parts, if they're not subject to change
for (auto & op_part: op->parts)
{
if (!op_part.sent && !op_part.done)
{
try_send(op, &op_part);
}
}
}
if (!op->sent_count)
{
if (op->done_count >= op->parts.size())
{
// Finished successfully
// Even if the PG count has changed in meanwhile we treat it as success
// because if some operations were invalid for the new PG count we'd get errors
cur_ops.erase(op);
op->retval = op->len;
std::function<void(cluster_op_t*)>(op->callback)(op);
continue_sync();
return;
}
else if (op->retval != 0 && op->retval != -EPIPE)
{
// Fatal error (not -EPIPE)
cur_ops.erase(op);
if (!immediate_commit && op->opcode == OSD_OP_WRITE)
{
for (int i = 0; i < unsynced_writes.size(); i++)
{
if (unsynced_writes[i] == op)
{
unsynced_writes.erase(unsynced_writes.begin()+i, unsynced_writes.begin()+i+1);
break;
}
}
}
bool del = op->is_internal;
std::function<void(cluster_op_t*)>(op->callback)(op);
if (del)
{
if (op->buf)
free(op->buf);
delete op;
}
continue_sync();
return;
}
else
{
// -EPIPE or no error - clear the error
op->retval = 0;
if (op->needs_reslice)
{
op->parts.clear();
op->done_count = 0;
op->needs_reslice = false;
continue_rw(op);
}
}
}
}
void cluster_client_t::slice_rw(cluster_op_t *op)
{
// Slice the request into individual object stripe requests
// Primary OSDs still operate individual stripes, but their size is multiplied by PG minsize in case of EC
auto & pool_cfg = st_cli.pool_config[INODE_POOL(op->inode)];
uint64_t pg_block_size = bs_block_size * (
pool_cfg.scheme == POOL_SCHEME_REPLICATED ? 1 : pool_cfg.pg_minsize
);
uint64_t first_stripe = (op->offset / pg_block_size) * pg_block_size;
uint64_t last_stripe = ((op->offset + op->len + pg_block_size - 1) / pg_block_size - 1) * pg_block_size;
op->retval = 0;
op->parts.resize((last_stripe - first_stripe) / pg_block_size + 1);
int iov_idx = 0;
size_t iov_pos = 0;
int i = 0;
for (uint64_t stripe = first_stripe; stripe <= last_stripe; stripe += pg_block_size)
{
pg_num_t pg_num = (op->inode + stripe/pool_cfg.pg_stripe_size) % pool_cfg.real_pg_count + 1;
uint64_t begin = (op->offset < stripe ? stripe : op->offset);
uint64_t end = (op->offset + op->len) > (stripe + pg_block_size)
? (stripe + pg_block_size) : (op->offset + op->len);
op->parts[i] = {
.parent = op,
.offset = begin,
.len = (uint32_t)(end - begin),
.pg_num = pg_num,
.sent = false,
.done = false,
};
int left = end-begin;
while (left > 0 && iov_idx < op->iov.count)
{
if (op->iov.buf[iov_idx].iov_len - iov_pos < left)
{
op->parts[i].iov.push_back(op->iov.buf[iov_idx].iov_base + iov_pos, op->iov.buf[iov_idx].iov_len - iov_pos);
left -= (op->iov.buf[iov_idx].iov_len - iov_pos);
iov_pos = 0;
iov_idx++;
}
else
{
op->parts[i].iov.push_back(op->iov.buf[iov_idx].iov_base + iov_pos, left);
iov_pos += left;
left = 0;
}
}
assert(left == 0);
i++;
}
}
bool cluster_client_t::try_send(cluster_op_t *op, cluster_op_part_t *part)
{
auto & pool_cfg = st_cli.pool_config[INODE_POOL(op->inode)];
auto pg_it = pool_cfg.pg_config.find(part->pg_num);
if (pg_it != pool_cfg.pg_config.end() &&
!pg_it->second.pause && pg_it->second.cur_primary)
{
osd_num_t primary_osd = pg_it->second.cur_primary;
auto peer_it = msgr.osd_peer_fds.find(primary_osd);
if (peer_it != msgr.osd_peer_fds.end())
{
int peer_fd = peer_it->second;
part->osd_num = primary_osd;
part->sent = true;
op->sent_count++;
part->op = {
.op_type = OSD_OP_OUT,
.peer_fd = peer_fd,
.req = { .rw = {
.header = {
.magic = SECONDARY_OSD_OP_MAGIC,
.id = op_id++,
.opcode = op->opcode,
},
.inode = op->inode,
.offset = part->offset,
.len = part->len,
} },
.callback = [this, part](osd_op_t *op_part)
{
handle_op_part(part);
},
};
part->op.iov = part->iov;
msgr.outbox_push(&part->op);
return true;
}
else if (msgr.wanted_peers.find(primary_osd) == msgr.wanted_peers.end())
{
msgr.connect_peer(primary_osd, st_cli.peer_states[primary_osd]);
}
}
return false;
}
void cluster_client_t::execute_sync(cluster_op_t *op)
{
if (immediate_commit)
{
// Syncs are not required in the immediate_commit mode
op->retval = 0;
std::function<void(cluster_op_t*)>(op->callback)(op);
}
else if (cur_sync != NULL)
{
next_writes.push_back(op);
}
else
{
cur_sync = op;
continue_sync();
}
}
void cluster_client_t::continue_sync()
{
if (!cur_sync || cur_sync->parts.size() > 0)
{
// Already submitted
return;
}
cur_sync->retval = 0;
std::set<osd_num_t> sync_osds;
for (auto prev_op: unsynced_writes)
{
if (prev_op->done_count < prev_op->parts.size())
{
// Writes not finished yet
return;
}
for (auto & part: prev_op->parts)
{
if (part.osd_num)
{
sync_osds.insert(part.osd_num);
}
}
}
if (!sync_osds.size())
{
// No dirty writes
finish_sync();
return;
}
// Check that all OSD connections are still alive
for (auto sync_osd: sync_osds)
{
auto peer_it = msgr.osd_peer_fds.find(sync_osd);
if (peer_it == msgr.osd_peer_fds.end())
{
// SYNC is pointless to send to a non connected OSD
return;
}
}
syncing_writes.swap(unsynced_writes);
// Post sync to affected OSDs
cur_sync->parts.resize(sync_osds.size());
int i = 0;
for (auto sync_osd: sync_osds)
{
cur_sync->parts[i] = {
.parent = cur_sync,
.osd_num = sync_osd,
.sent = false,
.done = false,
};
send_sync(cur_sync, &cur_sync->parts[i]);
i++;
}
}
void cluster_client_t::finish_sync()
{
int retval = cur_sync->retval;
if (retval != 0)
{
for (auto op: syncing_writes)
{
if (op->done_count < op->parts.size())
{
cur_ops.insert(op);
}
}
unsynced_writes.insert(unsynced_writes.begin(), syncing_writes.begin(), syncing_writes.end());
syncing_writes.clear();
}
if (retval == -EPIPE)
{
// Retry later
cur_sync->parts.clear();
cur_sync->retval = 0;
cur_sync->sent_count = 0;
cur_sync->done_count = 0;
return;
}
std::function<void(cluster_op_t*)>(cur_sync->callback)(cur_sync);
if (!retval)
{
for (auto op: syncing_writes)
{
assert(op->sent_count == 0);
if (op->is_internal)
{
if (op->buf)
free(op->buf);
delete op;
}
}
syncing_writes.clear();
}
cur_sync = NULL;
queued_bytes = 0;
std::vector<cluster_op_t*> next_wr_copy;
next_wr_copy.swap(next_writes);
for (auto next_op: next_wr_copy)
{
execute(next_op);
}
}
void cluster_client_t::send_sync(cluster_op_t *op, cluster_op_part_t *part)
{
auto peer_it = msgr.osd_peer_fds.find(part->osd_num);
assert(peer_it != msgr.osd_peer_fds.end());
part->sent = true;
op->sent_count++;
part->op = {
.op_type = OSD_OP_OUT,
.peer_fd = peer_it->second,
.req = {
.hdr = {
.magic = SECONDARY_OSD_OP_MAGIC,
.id = op_id++,
.opcode = OSD_OP_SYNC,
},
},
.callback = [this, part](osd_op_t *op_part)
{
handle_op_part(part);
},
};
msgr.outbox_push(&part->op);
}
void cluster_client_t::handle_op_part(cluster_op_part_t *part)
{
cluster_op_t *op = part->parent;
part->sent = false;
op->sent_count--;
int expected = part->op.req.hdr.opcode == OSD_OP_SYNC ? 0 : part->op.req.rw.len;
if (part->op.reply.hdr.retval != expected)
{
// Operation failed, retry
printf(
"Operation failed on OSD %lu: retval=%ld (expected %d), dropping connection\n",
part->osd_num, part->op.reply.hdr.retval, expected
);
msgr.stop_client(part->op.peer_fd);
if (part->op.reply.hdr.retval == -EPIPE)
{
op->up_wait = true;
if (!retry_timeout_id)
{
retry_timeout_id = tfd->set_timer(up_wait_retry_interval, false, [this](int)
{
retry_timeout_id = 0;
continue_ops(true);
});
}
}
if (!op->retval || op->retval == -EPIPE)
{
// Don't overwrite other errors with -EPIPE
op->retval = part->op.reply.hdr.retval;
}
}
else
{
// OK
part->done = true;
op->done_count++;
}
if (op->sent_count == 0)
{
if (op->opcode == OSD_OP_SYNC)
{
assert(op == cur_sync);
finish_sync();
}
else
{
continue_rw(op);
}
}
}