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Update DESIGN.txt and code accordingly

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cozis
2025-11-13 17:27:00 +01:00
parent facd220c59
commit cdce267768
7 changed files with 278 additions and 420 deletions
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src/metadata_server.c
+120 -195
View File
@@ -1,3 +1,8 @@
#include "basic.h"
#include "byte_queue.h"
#include "config.h"
#include "file_tree.h"
#include "tcp.h"
#define _GNU_SOURCE
#include <string.h>
@@ -59,18 +64,18 @@ static void chunk_server_peer_init(ChunkServerPeer *chunk_server, Time current_t
chunk_server->used = true;
chunk_server->auth = false;
chunk_server->num_addrs = 0;
hash_list_init(&chunk_server->old_list);
hash_list_init(&chunk_server->add_list);
hash_list_init(&chunk_server->rem_list);
hash_list_init(&chunk_server->ms_old_list);
hash_list_init(&chunk_server->ms_add_list);
hash_list_init(&chunk_server->ms_rem_list);
chunk_server->last_sync_time = current_time;
chunk_server->last_response_time = current_time;
}
static void chunk_server_peer_free(ChunkServerPeer *chunk_server)
{
hash_list_free(&chunk_server->rem_list);
hash_list_free(&chunk_server->add_list);
hash_list_free(&chunk_server->old_list);
hash_list_free(&chunk_server->ms_rem_list);
hash_list_free(&chunk_server->ms_add_list);
hash_list_free(&chunk_server->ms_old_list);
chunk_server->used = false;
}
@@ -284,6 +289,7 @@ process_client_delete(MetadataServer *state, int conn_idx, ByteView msg)
if (binary_read(&reader, NULL, 1))
return -1;
// TODO: return unused hashes and add them to the ms_rem_list of holder chunk servers
int ret = file_tree_delete_entity(&state->file_tree, path);
if (ret < 0) {
@@ -671,7 +677,7 @@ process_client_write(MetadataServer *state, int conn_idx, ByteView msg)
int k = find_chunk_server_by_addr(state, results[i].addrs[j]);
if (k == -1) return -1;
if (hash_list_insert(&state->chunk_servers[k].add_list, new_hashes[i]) < 0)
if (hash_list_insert(&state->chunk_servers[k].ms_add_list, new_hashes[i]) < 0)
return -1;
}
}
@@ -684,7 +690,7 @@ process_client_write(MetadataServer *state, int conn_idx, ByteView msg)
// Add to rem_list for all chunk servers that have this chunk
for (int j = 0; j < state->num_chunk_servers; j++) {
if (chunk_server_peer_contains(&state->chunk_servers[j], removed_hash)) {
if (!hash_list_insert(&state->chunk_servers[j].rem_list, removed_hash))
if (!hash_list_insert(&state->chunk_servers[j].ms_rem_list, removed_hash))
return -1;
}
}
@@ -726,36 +732,6 @@ chunk_server_from_conn(MetadataServer *state, int conn_idx)
return &state->chunk_servers[tag];
}
static int send_state_update(MetadataServer *state, int chunk_server_idx)
{
ChunkServerPeer *chunk_server = &state->chunk_servers[chunk_server_idx];
int conn_idx = tcp_index_from_tag(&state->tcp, chunk_server_idx);
assert(conn_idx > -1);
ByteQueue *output = tcp_output_buffer(&state->tcp, conn_idx);
assert(output);
MessageWriter writer;
message_writer_init(&writer, output, MESSAGE_TYPE_STATE_UPDATE);
uint32_t add_count = chunk_server->add_list.count;
uint32_t rem_count = chunk_server->rem_list.count;
message_write(&writer, &add_count, sizeof(add_count));
message_write(&writer, &rem_count, sizeof(rem_count));
for (uint32_t i = 0; i < add_count; i++)
message_write(&writer, &chunk_server->add_list.items[i], sizeof(SHA256));
for (uint32_t i = 0; i < rem_count; i++)
message_write(&writer, &chunk_server->rem_list.items[i], sizeof(SHA256));
if (!message_writer_free(&writer))
return -1;
return 0;
}
static int process_chunk_server_auth(MetadataServer *state,
int conn_idx, ByteView msg)
{
@@ -838,172 +814,130 @@ static int process_chunk_server_auth(MetadataServer *state,
return 0;
}
static int process_chunk_server_chunk_list(MetadataServer *state,
static int process_chunk_server_sync(MetadataServer *state,
int conn_idx, ByteView msg)
{
int chunk_server_idx = tcp_get_tag(&state->tcp, conn_idx);
assert(chunk_server_idx > -1);
assert(chunk_server_idx < MAX_CHUNK_SERVERS);
assert(state->chunk_servers[chunk_server_idx].used);
ChunkServerPeer *chunk_server = &state->chunk_servers[chunk_server_idx];
assert(chunk_server_idx <= MAX_CHUNK_SERVERS);
// Iterate over each chunk held by this chunk
// server and determine whether it's useless,
// under-replicated, over-replicated, or
// properly replicated.
// Chunks that are useless or over-replicated
// are added to the remove list of this chunk
// server (note that any given chunk can only
// be over-replicated by 1, so removing it from
// this chunk server will fix the issue). If
// the chunk is under-replicated or properly
// replicated, do nothing. Note that it's only
// possible for a chunk to be under-replicated
// when the number of chunk servers is lower
// than the replication factor.
ChunkServerPeer *chunk_server = &state->chunk_servers[chunk_server_idx];
assert(chunk_server->used);
BinaryReader reader = { msg.ptr, msg.len, 0 };
// version
if (!binary_read(&reader, NULL, sizeof(uint16_t)))
if (!binary_read(&reader, NULL, sizeof(MessageHeader)))
return -1;
uint16_t type;
if (!binary_read(&reader, &type, sizeof(type)))
uint32_t count;
if (!binary_read(&reader, &count, sizeof(count)))
return -1;
if (type != MESSAGE_TYPE_CHUNK_LIST)
return -1;
// length
if (!binary_read(&reader, NULL, sizeof(uint32_t)))
return -1;
uint32_t num_hashes;
if (!binary_read(&reader, &num_hashes, sizeof(num_hashes)))
return -1;
for (uint32_t i = 0; i < num_hashes; i++) {
for (uint32_t i = 0; i < count; i++) {
SHA256 hash;
if (!binary_read(&reader, &hash, sizeof(hash)))
return -1;
bool drop = false;
// If the chunk is not referenced by the file tree, do
// nothing.
if (!file_tree_uses_hash(&state->file_tree, hash))
drop = true;
else {
continue;
int holders[MAX_CHUNK_SERVERS];
int num_holders = all_chunk_servers_holding_chunk(state, hash, holders, MAX_CHUNK_SERVERS);
assert(num_holders > -1);
assert(num_holders <= MAX_CHUNK_SERVERS);
// If the chunk is properly replicated or under-replicated,
// add it to the ms_add_list.
assert(num_holders <= state->replication_factor);
int holders[MAX_CHUNK_SERVERS];
int num_holders = all_chunk_servers_holding_chunk(state, hash, holders, MAX_CHUNK_SERVERS);
assert(num_holders > -1);
assert(num_holders <= MAX_CHUNK_SERVERS);
// Adding this chunk server as a holder will cause
// the chunk to be over-replicated
if (num_holders == state->replication_factor)
drop = true;
if (num_holders <= state->replication_factor) {
if (hash_list_insert(&chunk_server->ms_add_list, hash) < 0) {
assert(0); // TODO
}
continue;
}
HashList *list;
if (drop) list = &chunk_server->rem_list;
else list = &chunk_server->add_list;
// If the chunk is over-replicated, either don't add
// it to the ms_add_list or add it to the ms_rem_list
// of some other holder.
if (hash_list_insert(list, hash) < 0) {
if (hash_list_insert(xxx, hash) < 0) {
assert(0); // TODO
}
}
if (binary_read(&reader, NULL, 1))
if (binary_read(&reader, NULL, 1)) // TODO: this should probably be an assertion
return -1;
// No need to reply here
return 0;
}
static int process_chunk_server_state_update_success(MetadataServer *state,
int conn_idx, ByteView msg)
{
(void) msg; // Success message has no body
ChunkServerPeer *chunk_server = chunk_server_from_conn(state, conn_idx);
// Merge add_list into old_list
for (int i = 0; i < chunk_server->add_list.count; i++) {
if (!hash_list_contains(&chunk_server->old_list, chunk_server->add_list.items[i]))
hash_list_insert(&chunk_server->old_list, chunk_server->add_list.items[i]); // TODO: what if this fails?
}
// Clear add_list and rem_list
chunk_server->add_list.count = 0;
chunk_server->rem_list.count = 0;
if (state->trace) {
int tag = tcp_get_tag(&state->tcp, conn_idx);
printf("Received STATE_UPDATE_SUCCESS from chunk server %d\n", tag);
}
return 0;
}
static int process_chunk_server_state_update_error(MetadataServer *state,
int conn_idx, ByteView msg)
{
BinaryReader reader = { msg.ptr, msg.len, 0 };
// Read header
if (!binary_read(&reader, NULL, sizeof(MessageHeader)))
return -1;
// Read error message
uint16_t error_len;
if (!binary_read(&reader, &error_len, sizeof(error_len)))
return -1;
char error_msg[256];
int read_len = error_len < sizeof(error_msg) - 1 ? error_len : sizeof(error_msg) - 1;
if (!binary_read(&reader, error_msg, read_len))
return -1;
error_msg[read_len] = '\0';
// Skip remaining error message if it was too long
if (error_len > read_len)
binary_read(&reader, NULL, error_len - read_len);
// Read missing chunks
uint32_t num_missing;
if (!binary_read(&reader, &num_missing, sizeof(num_missing)))
return -1;
SHA256 *missing_chunks = sys_malloc(num_missing * sizeof(SHA256));
if (missing_chunks == NULL)
return -1;
for (uint32_t i = 0; i < num_missing; i++) {
if (!binary_read(&reader, &missing_chunks[i], sizeof(SHA256))) {
sys_free(missing_chunks);
return -1;
}
}
if (state->trace) {
int tag = tcp_get_tag(&state->tcp, conn_idx);
printf("Received STATE_UPDATE_ERROR from chunk server %d: %s (missing %u chunks)\n",
tag, error_msg, num_missing);
}
// Respond with ms_add_list and ms_rem_list
ByteQueue *output = tcp_output_buffer(&state->tcp, conn_idx);
assert(output);
MessageWriter writer;
message_writer_init(&writer, output, MESSAGE_TYPE_DOWNLOAD_LOCATIONS);
message_writer_init(&writer, output, MESSAGE_TYPE_SYNC_2);
message_write(&writer, &num_missing, sizeof(num_missing));
uint32_t add_count = chunk_server->ms_add_list.count; // TODO: check implicit casts
message_write(&writer, &add_count, sizeof(add_count));
for (uint32_t i = 0; i < num_missing; i++) {
for (uint32_t i = 0; i < add_count; i++) {
SHA256 hash = chunk_server->ms_add_list.items[i];
message_write(&writer, &hash, sizeof(hash));
}
SHA256 hash = missing_chunks[i];
uint32_t rem_count = chunk_server->ms_rem_list.count; // TODO: check implicit casts
message_write(&writer, &rem_count, sizeof(rem_count));
for (uint32_t i = 0; i < rem_count; i++) {
SHA256 hash = chunk_server->ms_rem_list.items[i];
message_write(&writer, &hash, sizeof(hash));
}
if (!message_writer_free(&writer))
return -1;
return 0;
}
static int process_chunk_server_sync_3(MetadataServer *state,
int conn_idx, ByteView msg)
{
int chunk_server_idx = tcp_get_tag(&state->tcp, conn_idx);
assert(chunk_server_idx > -1);
assert(chunk_server_idx <= MAX_CHUNK_SERVERS);
ChunkServerPeer *chunk_server = &state->chunk_servers[chunk_server_idx];
assert(chunk_server->used);
BinaryReader reader = { msg.ptr, msg.len, 0 };
if (!binary_read(&reader, NULL, sizeof(MessageHeader)))
return -1;
uint32_t count;
if (!binary_read(&reader, &count, sizeof(count)))
return -1;
ByteQueue *output = tcp_output_buffer(&state->tcp, conn_idx);
assert(output);
MessageWriter writer;
message_writer_init(&writer, output, MESSAGE_TYPE_SYNC_4);
HashList tmp_list;
hash_list_init(&tmp_list);
for (uint32_t i = 0; i < count; i++) {
SHA256 hash;
if (!binary_read(&reader, &hash, sizeof(hash)))
return -1;
if (hash_list_insert(&tmp_list, hash) < 0) {
assert(0); // TODO
}
int holders[MAX_CHUNK_SERVERS];
int num_holders = all_chunk_servers_holding_chunk(state, hash, holders, MAX_CHUNK_SERVERS);
@@ -1013,17 +947,26 @@ static int process_chunk_server_state_update_error(MetadataServer *state,
uint32_t tmp = num_holders;
message_write(&writer, &tmp, sizeof(tmp));
for (int j = 0; j < num_holders; j++)
message_write_server_addr(&writer, &state->chunk_servers[holders[j]]);
message_write(&writer, &hash, sizeof(hash));
for (int i = 0; i < num_holders; i++)
message_write_server_addr(&writer, xxx);
}
sys_free(missing_chunks);
if (binary_read(&reader, NULL, 1)) // TODO: this should probably be an assertion
return -1;
if (hash_list_merge(&state->ms_old_list, state->ms_add_list) < 0) {
assert(0); // TODO
}
if (hash_list_remove_set(&state->ms_old_list, tmp_list) < 0) {
assert(0); // TODO
}
hash_list_free(&state->ms_add_list);
state->ms_add_list = tmp_list;
if (!message_writer_free(&writer))
return -1;
return 0;
}
@@ -1035,14 +978,11 @@ process_chunk_server_message(MetadataServer *state,
case MESSAGE_TYPE_AUTH:
return process_chunk_server_auth(state, conn_idx, msg);
case MESSAGE_TYPE_CHUNK_LIST:
return process_chunk_server_chunk_list(state, conn_idx, msg);
case MESSAGE_TYPE_SYNC:
return process_chunk_server_sync(state, conn_idx, msg);
case MESSAGE_TYPE_STATE_UPDATE_SUCCESS:
return process_chunk_server_state_update_success(state, conn_idx, msg);
case MESSAGE_TYPE_STATE_UPDATE_ERROR:
return process_chunk_server_state_update_error(state, conn_idx, msg);
case MESSAGE_TYPE_SYNC_3:
return process_chunk_server_sync_3(state, conn_idx, msg);
}
return -1;
}
@@ -1051,8 +991,7 @@ static bool is_chunk_server_message_type(uint16_t type)
{
switch (type) {
case MESSAGE_TYPE_AUTH:
case MESSAGE_TYPE_STATE_UPDATE_ERROR:
case MESSAGE_TYPE_STATE_UPDATE_SUCCESS:
case MESSAGE_TYPE_SYNC:
return true;
default:
@@ -1115,7 +1054,6 @@ int metadata_server_step(MetadataServer *state, void **contexts, struct pollfd *
Event events[MAX_CONNS+1];
int num_events = tcp_translate_events(&state->tcp, events, contexts, polled, num_polled);
// Implement periodic health checks: send STATE_UPDATE to chunk servers
Time current_time = get_current_time();
if (current_time == INVALID_TIME) {
assert(0); // TODO
@@ -1213,19 +1151,6 @@ int metadata_server_step(MetadataServer *state, void **contexts, struct pollfd *
continue;
}
nearest_deadline(&next_wakeup, response_timeout);
if (chunk_server->auth && chunk_server->last_sync_done) {
Time sync_timeout = chunk_server->last_sync_time + (Time) SYNC_INTERVAL * 1000000000;
if (current_time > sync_timeout) {
if (send_state_update(state, i) < 0) {
assert(0); // TODO
}
chunk_server->last_sync_time = current_time;
chunk_server->last_sync_done = false;
continue;
}
nearest_deadline(&next_wakeup, sync_timeout);
}
}
*timeout = deadline_to_timeout(next_wakeup, current_time);