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PXC-4433: Create file with current MySQL state
https://perconadev.atlassian.net/browse/PXC-4433 server.state file containing current server state is being created in data directory if the server is started with create_server_state_file=ON option. create_server_state_file default value is OFF.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,191 @@ | ||
| #include "server_status_file.h" | ||
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| #include <assert.h> | ||
| #include <sys/file.h> | ||
| #include <chrono> | ||
| #include <filesystem> | ||
| #include <map> | ||
| #include <string> | ||
| #include <thread> | ||
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| #include "my_alloc.h" | ||
| #include "my_getopt.h" | ||
| #include "my_io.h" | ||
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| #include "mysqld_error.h" | ||
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| #include <mysql/components/services/log_builtins.h> | ||
| #include <sql/server_component/log_builtins_internal.h> | ||
| #include "sql/mysqld.h" | ||
| #include "sql/raii/sentry.h" // raii::Sentry | ||
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| namespace fs = std::filesystem; | ||
| using namespace std::chrono_literals; | ||
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| namespace Server_status_file { | ||
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| static constexpr auto path_separator = | ||
| std::filesystem::path::preferred_separator; | ||
| static const std::string m_server_state_filename("server.state"); | ||
| static bool m_create_server_state_file = false; | ||
| static std::string m_server_state_file_path; | ||
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| static std::map<Status, std::string> status2string{ | ||
| {Status::INITIALIZING, "INITIALIZING"}, | ||
| {Status::DOWNGRADING, "DOWNGRADING"}, | ||
| {Status::UPGRADING, "UPGRADING"}, | ||
| {Status::READY, "READY"}, | ||
| {Status::STOPPING, "STOPPING"}, | ||
| {Status::STOPPED, "STOPPED"}, | ||
| {Status::UNKNOWN, "UNKNOWN"}}; | ||
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| void log(const char *msg) { | ||
| /* It is not nice to call from internals, but if we are just | ||
| deinitializing the server, log may be disabled already. */ | ||
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| if (log_builtins_started()) { | ||
| LogErr(WARNING_LEVEL, ER_LOG_PRINTF_MSG, msg); | ||
| } | ||
| } | ||
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| static int delete_status_file() { | ||
| return unlink(m_server_state_file_path.c_str()); | ||
| } | ||
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||
| /* Try to acquire desired lock on file within a specified time. | ||
| Returns 0 in case of success, -1 otherwise. */ | ||
| static int flockt(int fd, int operation, std::chrono::milliseconds timeout) { | ||
| static const std::chrono::milliseconds loop_wait_time = 500ms; | ||
| std::chrono::milliseconds wait_total = 0ms; | ||
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| while (flock(fd, operation | LOCK_NB) == -1) { | ||
| if (errno == EWOULDBLOCK) { | ||
| if (wait_total >= timeout) { | ||
| // failed to lock | ||
| return -1; | ||
| } | ||
| std::this_thread::sleep_for(loop_wait_time); | ||
| wait_total += loop_wait_time; | ||
| } else { | ||
| return -1; | ||
| } | ||
| } | ||
| return 0; | ||
| } | ||
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| static const std::string &get_status_string(Status status) { | ||
| if (status2string.find(status) != status2string.end()) { | ||
| return status2string[status]; | ||
| } | ||
| return status2string[Status::UNKNOWN]; | ||
| } | ||
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| /* Store string representation of status to the server.status file. | ||
| If the file does not exist, it is created. | ||
| If the file exists, try to acquire exclusive lock with 5s timeout. | ||
| Regardless of the lock being acquired or not store the status in file. */ | ||
| void set_status(Status status) { | ||
| if (!m_create_server_state_file) { | ||
| return; | ||
| } | ||
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| int fd = open(m_server_state_file_path.c_str(), O_WRONLY | O_CREAT, 0644); | ||
| if (fd == -1) { | ||
| log("Cannot open server.status file"); | ||
| return; | ||
| } | ||
| // close() will release the file lock if acquired | ||
| raii::Sentry file_close{[fd] { close(fd); }}; | ||
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| /* Let's try acquire exclusive lock on server.status file. | ||
| We will give up after a short time. It is to avoid the case when someone | ||
| acquires a shared lock on this file without releasing it. That would block | ||
| the server forever. | ||
| We will update the status file anyway. In worst case the reader will | ||
| receive garbage if it reads in the middle of the write, but it is up to | ||
| reader to not lock for a long time. */ | ||
| int res = flockt(fd, LOCK_EX, 5000ms); | ||
| if (res) { | ||
| log("Failed to acquire exclusive lock on server.status file. Reporting " | ||
| "status anyway."); | ||
| } | ||
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||
| // truncate only after acquiring the lock | ||
| res = ftruncate(fd, 0); | ||
| if (res) { | ||
| log("Failed to truncate server.status file. Trying to delete."); | ||
| if (delete_status_file()) { | ||
| log("Failed to delete server.status file"); | ||
| return; | ||
| } | ||
| } | ||
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| const std::string &status_str = get_status_string(status); | ||
| size_t s = write(fd, status_str.c_str(), status_str.length()); | ||
| if (s != status_str.length()) { | ||
| log("Error writing data to server.status file"); | ||
| } | ||
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| // file is closed by file_close Sentry | ||
| } | ||
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| int init(int *argc, char ***argv) { | ||
| int temp_argc = *argc; | ||
| MEM_ROOT alloc{PSI_NOT_INSTRUMENTED, 512}; | ||
| char *ptr, **res, *datadir = nullptr; | ||
| char local_datadir_buffer[FN_REFLEN] = {0}; | ||
|
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||
| /* mysql_real_data_home_ptr is initialized in init_common_variables(). | ||
| We want to store the status file much earlier. Similar code exists in | ||
| Persisted_variables_cache::init() */ | ||
| my_option persist_options[] = { | ||
| {"create_server_state_file", 0, "", &m_create_server_state_file, | ||
| &m_create_server_state_file, nullptr, GET_BOOL, OPT_ARG, 1, 0, 0, | ||
| nullptr, 0, nullptr}, | ||
| {"datadir", 0, "", &datadir, nullptr, nullptr, GET_STR, OPT_ARG, 0, 0, 0, | ||
| nullptr, 0, nullptr}, | ||
| {nullptr, 0, nullptr, nullptr, nullptr, nullptr, GET_NO_ARG, NO_ARG, 0, 0, | ||
| 0, nullptr, 0, nullptr}}; | ||
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| /* create temporary args list and pass it to handle_options */ | ||
| if (!(ptr = | ||
| (char *)alloc.Alloc(sizeof(alloc) + (*argc + 1) * sizeof(char *)))) | ||
| return 1; | ||
| memset(ptr, 0, (sizeof(char *) * (*argc + 1))); | ||
| res = (char **)(ptr); | ||
| memcpy((uchar *)res, (char *)(*argv), (*argc) * sizeof(char *)); | ||
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| my_getopt_skip_unknown = true; | ||
| if (my_handle_options(&temp_argc, &res, persist_options, nullptr, nullptr, | ||
| true)) { | ||
| alloc.Clear(); | ||
| return 1; | ||
| } | ||
| my_getopt_skip_unknown = false; | ||
| alloc.Clear(); | ||
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| if (!datadir) { | ||
| // mysql_real_data_home must be initialized at this point | ||
| assert(mysql_real_data_home[0]); | ||
| /* | ||
| mysql_home_ptr should also be initialized at this point. | ||
| See calculate_mysql_home_from_my_progname() for details | ||
| */ | ||
| assert(mysql_home_ptr && mysql_home_ptr[0]); | ||
| convert_dirname(local_datadir_buffer, mysql_real_data_home, NullS); | ||
| (void)my_load_path(local_datadir_buffer, local_datadir_buffer, | ||
| mysql_home_ptr); | ||
| datadir = local_datadir_buffer; | ||
| } | ||
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| m_server_state_file_path = | ||
| std::string(datadir) + path_separator + m_server_state_filename; | ||
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| // Ignore the error. Server starts and it is possible there is no | ||
| // server.status file | ||
| delete_status_file(); | ||
|
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| return 0; | ||
| } | ||
|
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| } // namespace Server_status_file |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,19 @@ | ||
| #ifndef SERVER_STATUS_FILE_INCLUDED | ||
| #define SERVER_STATUS_FILE_INCLUDED | ||
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| namespace Server_status_file { | ||
| enum Status { | ||
| INITIALIZING, | ||
| DOWNGRADING, | ||
| UPGRADING, | ||
| READY, | ||
| STOPPING, | ||
| STOPPED, | ||
| UNKNOWN | ||
| }; | ||
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| int init(int *argc, char ***argv); | ||
| void set_status(Status status); | ||
| } // namespace Server_status_file | ||
|
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| #endif /* SERVER_STATUS_FILE_INCLUDED */ |
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