本篇博客主要讲解fastdfs中tracker协议的讲解。
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。但是也有很大的局限性。
因此,fastdfs对文件的目录设置和存储是最为核心的。
为什么这么突然的讲解这些。因为我已经看了一段时间的fastdfs,主要结构都已经搞的比较清晰了。因此,这篇文章,我就主要一tracker这一部分的协议来分析。
其他具体介绍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)
这个方法开始对每个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)
该函数主要是做了根据配置连接相应的它的组的tacker,做一些事情,这里有个while循环,代码如下

- 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中,调用

- status = tracker_save_storages();
调用

- tracker_mem_active_store_server(pClientInfo->pGroup, \
- pClientInfo->pStorage);
最后调用

- static int tracker_check_and_sync(struct fast_task_info *pTask, \
- const int status)
检查相应的改变状态,并将其同步等。(需要再详细看看)
2、报告相应同步时间

- #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;
- }
具体的数据包为

- 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所有storage服务器,和上次同步的时间戳,给tracker服务器。
然后tracker的服务器存储结构为

- 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;
- }
因为 本链接的storage是固定不变的,而src_index就是为本组的其他storage的id索引,
首相通过id,(ip地址)找到具体的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
同样线程定时调用,

- 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服加入到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;
当赋值完成后,在气候变加入

- 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;
- }
加入所有tracker的服务器信息格式为ip:port
tracker 服务器接收

- 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
同时插入本地内存
result = tracker_mem_add_group_and_storage(pClientInfo, \
pTask->client_ip, &joinBody, true);
同时把发消息报的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
storage服务器调用

- 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));
其结构体如下

- 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
调用流程如下:

- 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通过获取了相应的数据,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获取所有storage服务器

- #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,遍历所有的trackers服务器
tracker服务器获取

- case TRACKER_PROTO_CMD_STORAGE_FETCH_STORAGE_IDS:
- result = tracker_deal_fetch_storage_ids(pTask);
- break;
然后通过这种协议格式

- </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\n", 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
storage服务器调用流程:
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;
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