本篇博客主要解说fastdfs中tracker协议的解说。
fastdfs主要是存储文件。直接把整个文件存储到磁盘上，所以。简单直接。可是也有非常大的局限性。
因此，fastdfs对文件的文件夹设置和存储是最为核心的。
为什么这么突然的解说这些。由于我已经看了一段时间的fastdfs，主要结构都已经搞的比較清晰了。因此，这篇文章。我就主要一tracker这一部分的协议来分析。
其它详细介绍tracker的请百度。我就不介绍了，我就直接从
int tracker_deal_task(struct fast_task_info *pTask)
这种方法開始对每一个case分析。
1、storage心跳协议
case TRACKER_PROTO_CMD_STORAGE_BEAT: TRACKER_CHECK_LOGINED(pTask) result = tracker_deal_storage_beat(pTask); break;
自然。该协议是从storage层发送给tracker层的数据包，
#define TRACKER_PROTO_CMD_STORAGE_BEAT 83 //storage heart beat
那么，storage主要是做了什么：
storage在启动的时候，会开启一个线程，该线程为
static void *tracker_report_thread_entrance(void *arg)
该函数主要是做了依据配置连接对应的它的组的tacker。做一些事情，这里有个while循环，代码例如以下
current_time = g_current_time;
if (current_time - last_beat_time >=
g_heart_beat_interval)
{
if (tracker_heart_beat(pTrackerServer,
&stat_chg_sync_count,
&bServerPortChanged) != 0)
{
break;
}也就是至少30秒钟来一次心跳。心跳包的主要数据是包头和当前storage的状态信息，
char out_buff[sizeof(TrackerHeader) + sizeof(FDFSStorageStatBuff)];
/* struct for network transfering */
typedef struct
{
char sz_total_upload_count[8];
char sz_success_upload_count[8];
char sz_total_append_count[8];
char sz_success_append_count[8];
char sz_total_modify_count[8];
char sz_success_modify_count[8];
char sz_total_truncate_count[8];
char sz_success_truncate_count[8];
char sz_total_set_meta_count[8];
char sz_success_set_meta_count[8];
char sz_total_delete_count[8];
char sz_success_delete_count[8];
char sz_total_download_count[8];
char sz_success_download_count[8];
char sz_total_get_meta_count[8];
char sz_success_get_meta_count[8];
char sz_total_create_link_count[8];
char sz_success_create_link_count[8];
char sz_total_delete_link_count[8];
char sz_success_delete_link_count[8];
char sz_total_upload_bytes[8];
char sz_success_upload_bytes[8];
char sz_total_append_bytes[8];
char sz_success_append_bytes[8];
char sz_total_modify_bytes[8];
char sz_success_modify_bytes[8];
char sz_total_download_bytes[8];
char sz_success_download_bytes[8];
char sz_total_sync_in_bytes[8];
char sz_success_sync_in_bytes[8];
char sz_total_sync_out_bytes[8];
char sz_success_sync_out_bytes[8];
char sz_total_file_open_count[8];
char sz_success_file_open_count[8];
char sz_total_file_read_count[8];
char sz_success_file_read_count[8];
char sz_total_file_write_count[8];
char sz_success_file_write_count[8];
char sz_last_source_update[8];
char sz_last_sync_update[8];
char sz_last_synced_timestamp[8];
char sz_last_heart_beat_time[8];
} FDFSStorageStatBuff;
tracker主要是做了什么呢？
对其进行解包，然后对这个保存在本地的storage的信息进行保存到文件里，调用
status = tracker_save_storages();
调用
tracker_mem_active_store_server(pClientInfo->pGroup, pClientInfo->pStorage);将这个存储服务器假设没有，就插入到group中。
最后调用
static int tracker_check_and_sync(struct fast_task_info *pTask, const int status)
检查对应的改变状态。并将其同步等。
（须要再具体看看）
2、报告对应同步时间
#define TRACKER_PROTO_CMD_STORAGE_SYNC_REPORT 89 //report src last synced time as dest server
if (sync_time_chg_count != g_sync_change_count &&
current_time - last_sync_report_time >=
g_heart_beat_interval)
{
if (tracker_report_sync_timestamp(
pTrackerServer, &bServerPortChanged)!=0)
{
break;
}
sync_time_chg_count = g_sync_change_count;
last_sync_report_time = current_time;
}详细的数据包为
pEnd = g_storage_servers + g_storage_count;
for (pServer=g_storage_servers; pServer<pEnd; pServer++)
{
memcpy(p, pServer->server.id, FDFS_STORAGE_ID_MAX_SIZE);
p += FDFS_STORAGE_ID_MAX_SIZE;
int2buff(pServer->last_sync_src_timestamp, p);
p += 4;
}也就是遍历当前进程的本组全部storageserver，和上次同步的时间戳。给trackerserver。
然后tracker的server存储结构为
pClientInfo->pGroup->last_sync_timestamps [src_index][dest_index] = sync_timestamp;
dest_index 值为当前连接所在组的索引值
dest_index = tracker_mem_get_storage_index(pClientInfo->pGroup,
pClientInfo->pStorage);
if (dest_index < 0 || dest_index >= pClientInfo->pGroup->count)
{
status = 0;
break;
}由于 本链接的storage是固定不变的，而src_index就是为本组的其它storage的id索引，
首相通过id。（ip地址）找到详细的storage。然后在通过指针找到索引位置，
最后。调用
if (++g_storage_sync_time_chg_count %
TRACKER_SYNC_TO_FILE_FREQ == 0)
{
status = tracker_save_sync_timestamps();
}
else
{
status = 0;
}
} while (0);
return tracker_check_and_sync(pTask, status);定时保存文件和检查等
3、上报磁盘情况
#define TRACKER_PROTO_CMD_STORAGE_REPORT_DISK_USAGE 84 //report disk usage
相同线程定时调用。
if (current_time - last_df_report_time >=
g_stat_report_interval)
{
if (tracker_report_df_stat(pTrackerServer,
&bServerPortChanged) != 0)
{
break;
}
last_df_report_time = current_time;
}
for (i=0; i<g_fdfs_store_paths.count; i++)
{
if (statvfs(g_fdfs_store_paths.paths[i], &sbuf) != 0)
{
logError("file: "__FILE__", line: %d, "
"call statfs fail, errno: %d, error info: %s.",
__LINE__, errno, STRERROR(errno));
if (pBuff != out_buff)
{
free(pBuff);
}
return errno != 0 ? errno : EACCES;
}
g_path_space_list[i].total_mb = ((int64_t)(sbuf.f_blocks) *
sbuf.f_frsize) / FDFS_ONE_MB;
g_path_space_list[i].free_mb = ((int64_t)(sbuf.f_bavail) *
sbuf.f_frsize) / FDFS_ONE_MB;
long2buff(g_path_space_list[i].total_mb, pStatBuff->sz_total_mb);
long2buff(g_path_space_list[i].free_mb, pStatBuff->sz_free_mb);
pStatBuff++;
}tracker这边存储在
int64_t *path_total_mbs; //total disk storage in MB
int64_t *path_free_mbs; //free disk storage in MB
这里
path_total_mbs[i] = buff2long(pStatBuff->sz_total_mb); path_free_mbs[i] = buff2long(pStatBuff->sz_free_mb); pClientInfo->pStorage->total_mb += path_total_mbs[i]; pClientInfo->pStorage->free_mb += path_free_mbs[i];
4、storage服增加到tracker
#define TRACKER_PROTO_CMD_STORAGE_JOIN 81
if (tracker_report_join(pTrackerServer, tracker_index,
sync_old_done) != 0)
{
sleep(g_heart_beat_interval);
continue;
}发送的包体数据包为：
typedef struct
{
char group_name[FDFS_GROUP_NAME_MAX_LEN+1];
char storage_port[FDFS_PROTO_PKG_LEN_SIZE];
char storage_http_port[FDFS_PROTO_PKG_LEN_SIZE];
char store_path_count[FDFS_PROTO_PKG_LEN_SIZE];
char subdir_count_per_path[FDFS_PROTO_PKG_LEN_SIZE];
char upload_priority[FDFS_PROTO_PKG_LEN_SIZE];
char join_time[FDFS_PROTO_PKG_LEN_SIZE]; //storage join timestamp
char up_time[FDFS_PROTO_PKG_LEN_SIZE]; //storage service started timestamp
char version[FDFS_VERSION_SIZE]; //storage version
char domain_name[FDFS_DOMAIN_NAME_MAX_SIZE];
char init_flag;
signed char status;
char tracker_count[FDFS_PROTO_PKG_LEN_SIZE]; //all tracker server count
} TrackerStorageJoinBody;
当赋值完毕后。在气候变增加
p = out_buff + sizeof(TrackerHeader) + sizeof(TrackerStorageJoinBody);
pServerEnd = g_tracker_group.servers + g_tracker_group.server_count;
for (pServer=g_tracker_group.servers; pServer<pServerEnd; pServer++)
{
/*
if (strcmp(pServer->ip_addr, pTrackerServer->ip_addr) == 0 &&
pServer->port == pTrackerServer->port)
{
continue;
}
tracker_count++;
*/
sprintf(p, "%s:%d", pServer->ip_addr, pServer->port);
p += FDFS_PROTO_IP_PORT_SIZE;
}增加全部tracker的server信息格式为ip:port
tracker server接收
case TRACKER_PROTO_CMD_STORAGE_JOIN: result = tracker_deal_storage_join(pTask); break;
typedef struct
{
int storage_port;
int storage_http_port;
int store_path_count;
int subdir_count_per_path;
int upload_priority;
int join_time; //storage join timestamp (create timestamp)
int up_time; //storage service started timestamp
char version[FDFS_VERSION_SIZE]; //storage version
char group_name[FDFS_GROUP_NAME_MAX_LEN + 1];
char domain_name[FDFS_DOMAIN_NAME_MAX_SIZE];
char init_flag;
signed char status;
int tracker_count;
ConnectionInfo tracker_servers[FDFS_MAX_TRACKERS];
} FDFSStorageJoinBody;
这些结构体内
同一时候插入本地内存
result = tracker_mem_add_group_and_storage(pClientInfo,
pTask->client_ip, &joinBody, true);
同一时候把发消息报的id传过来
pJoinBodyResp = (TrackerStorageJoinBodyResp *)(pTask->data +
sizeof(TrackerHeader));
memset(pJoinBodyResp, 0, sizeof(TrackerStorageJoinBodyResp));
if (pClientInfo->pStorage->psync_src_server != NULL)
{
strcpy(pJoinBodyResp->src_id,
pClientInfo->pStorage->psync_src_server->id);
}5、报告存储状态
#define TRACKER_PROTO_CMD_STORAGE_REPORT_STATUS 76 //report specified storage server status
storageserver调用
int tracker_report_storage_status(ConnectionInfo *pTrackerServer, FDFSStorageBrief *briefServer)
内容主要是组名字
strcpy(out_buff + sizeof(TrackerHeader), g_group_name);
和简要信息
memcpy(out_buff + sizeof(TrackerHeader) + FDFS_GROUP_NAME_MAX_LEN, briefServer, sizeof(FDFSStorageBrief));
其结构体例如以下
typedef struct
{
char status;
char port[4];
char id[FDFS_STORAGE_ID_MAX_SIZE];
char ip_addr[IP_ADDRESS_SIZE];
} FDFSStorageBrief;
6、从tracker获取storage状态。
#define TRACKER_PROTO_CMD_STORAGE_GET_STATUS 71 //get storage status from tracker
该协议是由client发起
调用流程例如以下：
int tracker_get_storage_status(ConnectionInfo *pTrackerServer, const char *group_name, const char *ip_addr, FDFSStorageBrief *pDestBuff) int tracker_get_storage_max_status(TrackerServerGroup *pTrackerGroup, const char *group_name, const char *ip_addr, char *storage_id, int *status) int tracker_get_storage_status(ConnectionInfo *pTrackerServer, const char *group_name, const char *ip_addr, FDFSStorageBrief *pDestBuff)
获取自己的状态，
包体格式 组名 ip的字符串
tracker通过获取了对应的数据。查找到storage的信息
结构体为：
typedef struct
{
char status;
char port[4];
char id[FDFS_STORAGE_ID_MAX_SIZE];
char ip_addr[IP_ADDRESS_SIZE];
} FDFSStorageBrief;赋值后。返回
7、通过tracker获取storageid
#define TRACKER_PROTO_CMD_STORAGE_GET_SERVER_ID
70 //get storage server id from tracker
和上以协议请求一样 groupname+ip 组成。
tracker处理方法
static int tracker_deal_get_storage_id(struct fast_task_info *pTask)
tracker最后通过
FDFSStorageIdInfo *fdfs_get_storage_id_by_ip(const char *group_name,
const char *pIpAddr)
{
FDFSStorageIdInfo target;
memset(&target, 0, sizeof(FDFSStorageIdInfo));
snprintf(target.group_name, sizeof(target.group_name), "%s", group_name);
snprintf(target.ip_addr, sizeof(target.ip_addr), "%s", pIpAddr);
return (FDFSStorageIdInfo *)bsearch(&target, g_storage_ids_by_ip,
g_storage_id_count, sizeof(FDFSStorageIdInfo),
fdfs_cmp_group_name_and_ip);
}该方法获取了了
FDFSStorageIdInfo
信息。然后赋值，返回。
8、通过tracker获取全部storageserver
#define TRACKER_PROTO_CMD_STORAGE_FETCH_STORAGE_IDS 69 //get all storage ids from tracker
for (i=0; i<5; i++)
{
for (pGServer=pServerStart; pGServer<pServerEnd; pGServer++)
{
memcpy(pTServer, pGServer, sizeof(ConnectionInfo));
pTServer->sock = -1;
result = fdfs_get_storage_ids_from_tracker_server(pTServer);
if (result == 0)
{
return result;
}
}
if (pServerStart != pTrackerGroup->servers)
{
pServerStart = pTrackerGroup->servers;
}
sleep(1);
}调用顺序
int storage_func_init(const char *filename, char *bind_addr, const int addr_size) int fdfs_get_storage_ids_from_tracker_group(TrackerServerGroup *pTrackerGroup) int fdfs_get_storage_ids_from_tracker_server(ConnectionInfo *pTrackerServer)
tracker函数。每秒钟中调用。遍历全部的trackersserver
trackerserver获取
case TRACKER_PROTO_CMD_STORAGE_FETCH_STORAGE_IDS: result = tracker_deal_fetch_storage_ids(pTask); break;
然后通过这样的协议格式
</pre></p><p>返回的数据</p><p></p><pre name="code" class="cpp">pIdsStart = g_storage_ids_by_ip + start_index;
pIdsEnd = g_storage_ids_by_ip + g_storage_id_count;
for (pIdInfo = pIdsStart; pIdInfo < pIdsEnd; pIdInfo++)
{
if ((int)(p - pTask->data) > pTask->size - 64)
{
break;
}
p += sprintf(p, "%s %s %s
", pIdInfo->id,
pIdInfo->group_name, pIdInfo->ip_addr);
}返回给请求者。
9、回复给新的storage
#define TRACKER_PROTO_CMD_STORAGE_REPLICA_CHG 85 //repl new storage servers
storageserver调用流程：
剩下的协议
static int tracker_merge_servers(ConnectionInfo *pTrackerServer, FDFSStorageBrief *briefServers, const int server_count)
case TRACKER_PROTO_CMD_SERVICE_QUERY_FETCH_ONE: result = tracker_deal_service_query_fetch_update( pTask, pHeader->cmd); break; case TRACKER_PROTO_CMD_SERVICE_QUERY_UPDATE: result = tracker_deal_service_query_fetch_update( pTask, pHeader->cmd); break; case TRACKER_PROTO_CMD_SERVICE_QUERY_FETCH_ALL: result = tracker_deal_service_query_fetch_update( pTask, pHeader->cmd); break; case TRACKER_PROTO_CMD_SERVICE_QUERY_STORE_WITHOUT_GROUP_ONE: result = tracker_deal_service_query_storage( pTask, pHeader->cmd); break; case TRACKER_PROTO_CMD_SERVICE_QUERY_STORE_WITH_GROUP_ONE: result = tracker_deal_service_query_storage( pTask, pHeader->cmd); break; case TRACKER_PROTO_CMD_SERVICE_QUERY_STORE_WITHOUT_GROUP_ALL: result = tracker_deal_service_query_storage( pTask, pHeader->cmd); break; case TRACKER_PROTO_CMD_SERVICE_QUERY_STORE_WITH_GROUP_ALL: result = tracker_deal_service_query_storage( pTask, pHeader->cmd); break; case TRACKER_PROTO_CMD_SERVER_LIST_ONE_GROUP: result = tracker_deal_server_list_one_group(pTask); break; case TRACKER_PROTO_CMD_SERVER_LIST_ALL_GROUPS: result = tracker_deal_server_list_all_groups(pTask); break; case TRACKER_PROTO_CMD_SERVER_LIST_STORAGE: result = tracker_deal_server_list_group_storages(pTask); break; case TRACKER_PROTO_CMD_STORAGE_SYNC_SRC_REQ: result = tracker_deal_storage_sync_src_req(pTask); break; case TRACKER_PROTO_CMD_STORAGE_SYNC_DEST_REQ: TRACKER_CHECK_LOGINED(pTask) result = tracker_deal_storage_sync_dest_req(pTask); break; case TRACKER_PROTO_CMD_STORAGE_SYNC_NOTIFY: result = tracker_deal_storage_sync_notify(pTask); break; case TRACKER_PROTO_CMD_STORAGE_SYNC_DEST_QUERY: result = tracker_deal_storage_sync_dest_query(pTask); break; case TRACKER_PROTO_CMD_SERVER_DELETE_STORAGE: result = tracker_deal_server_delete_storage(pTask); break; case TRACKER_PROTO_CMD_SERVER_SET_TRUNK_SERVER: result = tracker_deal_server_set_trunk_server(pTask); break; case TRACKER_PROTO_CMD_STORAGE_REPORT_IP_CHANGED: result = tracker_deal_storage_report_ip_changed(pTask); break; case TRACKER_PROTO_CMD_STORAGE_CHANGELOG_REQ: result = tracker_deal_changelog_req(pTask); break; case TRACKER_PROTO_CMD_STORAGE_PARAMETER_REQ: result = tracker_deal_parameter_req(pTask); break; case FDFS_PROTO_CMD_QUIT: close(pTask->ev_read.ev_fd); task_finish_clean_up(pTask); return 0; case FDFS_PROTO_CMD_ACTIVE_TEST: result = tracker_deal_active_test(pTask); break; case TRACKER_PROTO_CMD_TRACKER_GET_STATUS: result = tracker_deal_get_tracker_status(pTask); break; case TRACKER_PROTO_CMD_TRACKER_GET_SYS_FILES_START: result = tracker_deal_get_sys_files_start(pTask); break; case TRACKER_PROTO_CMD_TRACKER_GET_ONE_SYS_FILE: result = tracker_deal_get_one_sys_file(pTask); break; case TRACKER_PROTO_CMD_TRACKER_GET_SYS_FILES_END: result = tracker_deal_get_sys_files_end(pTask); break; case TRACKER_PROTO_CMD_STORAGE_REPORT_TRUNK_FID: TRACKER_CHECK_LOGINED(pTask) result = tracker_deal_report_trunk_fid(pTask); break; case TRACKER_PROTO_CMD_STORAGE_FETCH_TRUNK_FID: TRACKER_CHECK_LOGINED(pTask) result = tracker_deal_get_trunk_fid(pTask); break; case TRACKER_PROTO_CMD_STORAGE_REPORT_TRUNK_FREE: TRACKER_CHECK_LOGINED(pTask) result = tracker_deal_report_trunk_free_space(pTask); break; case TRACKER_PROTO_CMD_TRACKER_PING_LEADER: result = tracker_deal_ping_leader(pTask); break; case TRACKER_PROTO_CMD_TRACKER_NOTIFY_NEXT_LEADER: result = tracker_deal_notify_next_leader(pTask); break; case TRACKER_PROTO_CMD_TRACKER_COMMIT_NEXT_LEADER: result = tracker_deal_commit_next_leader(pTask); break;