Provided by: libpmempool-dev_1.13.1-1.1_amd64 bug

NAME

       libpmempool - persistent memory pool management library

              NOTE: Support for Windows and FreeBSD deprecated since PMDK 1.13.0 release and will
              be removed in the PMDK 1.14.0 release.

SYNOPSIS

              #include <libpmempool.h>
              cc -std=gnu99 ... -lpmempool -lpmem

   Library API versioning:
              const char *pmempool_check_version(
                  unsigned major_required,
                  unsigned minor_required);

   Error handling:
              const char *pmempool_errormsg(void);

   Other library functions:
       A description of other libpmempool functions can be found on the following manual pages:

       • health check functions: pmempool_check_init(3)

       • pool set synchronization and transformation: pmempool_sync(3)

       • pool set management functions: pmempool_rm(3)

       • toggle or query pool set features: pmempool_feature_query(3)

DESCRIPTION

       libpmempool provides a set of utilities for off-line analysis and manipulation of a  pool.
       A  pool  in  this  manpage means a pmemobj pool, pmemblk pool, pmemlog pool or BTT layout,
       independent of the underlying storage.  Some libpmempool functions are  required  to  work
       without any impact on the pool but some may create a new or modify an existing pool.

       libpmempool  is  for  applications that need high reliability or built-in troubleshooting.
       It may be useful for testing and debugging purposes also.

       libpmempool  introduces  functionality  of  pool  set   health   check,   synchronization,
       transformation and removal.

CAVEATS

       libpmempool  relies on the library destructor being called from the main thread.  For this
       reason, all functions that might trigger destruction (e.g.  dlclose(3)) should  be  called
       in the main thread.  Otherwise some of the resources associated with that thread might not
       be cleaned up properly.

       libpmempool requires the -std=gnu99 compilation flag to build properly.

LIBRARY API VERSIONING

       This section describes how the library API is versioned,  allowing  applications  to  work
       with an evolving API.

       The pmempool_check_version() function is used to see if the installed libpmempool supports
       the version of the library API required by an application.  The easiest way to do this for
       the  application is to supply the compile-time version information, supplied by defines in
       <libpmempool.h>, like this:

              reason = pmempool_check_version(PMEMPOOL_MAJOR_VERSION,
                                              PMEMPOOL_MINOR_VERSION);
              if (reason != NULL) {
                  /* version check failed, reason string tells you why */
              }

       Any mismatch in the major version number is considered a failure, but  a  library  with  a
       newer  minor  version  number  will  pass this check since increasing minor versions imply
       backwards compatibility.

       An application can also check specifically for the existence of an interface  by  checking
       for  the  version  where  that interface was introduced.  These versions are documented in
       this man page as follows: unless otherwise specified, all interfaces  described  here  are
       available  in version 1.0 of the library.  Interfaces added after version 1.0 will contain
       the text introduced in version x.y in the section of this manual describing the feature.

       When the version check performed by pmempool_check_version()  is  successful,  the  return
       value  is  NULL.   Otherwise the return value is a static string describing the reason for
       failing the version check.  The string returned by pmempool_check_version()  must  not  be
       modified or freed.

DEBUGGING AND ERROR HANDLING

       If  an  error  is  detected during the call to a libpmempool function, the application may
       retrieve an error message describing the reason for the failure from  pmempool_errormsg().
       This  function  returns  a  pointer  to  a static buffer containing the last error message
       logged for the current thread.  If  errno  was  set,  the  error  message  may  include  a
       description of the corresponding error code as returned by strerror(3).  The error message
       buffer is thread-local; errors encountered in one thread do not affect its value in  other
       threads.   The buffer is never cleared by any library function; its content is significant
       only when the return value of the immediately preceding call  to  a  libpmempool  function
       indicated  an  error,  or  if  errno was set.  The application must not modify or free the
       error message string, but it  may  be  modified  by  subsequent  calls  to  other  library
       functions.

       Two  versions  of libpmempool are typically available on a development system.  The normal
       version, accessed when a program is linked using the -lpmempool option, is  optimized  for
       performance.   That  version skips checks that impact performance and never logs any trace
       information or performs any run-time assertions.

       A second version of  libpmempool,  accessed  when  a  program  uses  the  libraries  under
       /usr/lib/pmdk_debug,  contains  run-time  assertions and trace points.  The typical way to
       access  the  debug  version  is  to  set  the  environment  variable  LD_LIBRARY_PATH   to
       /usr/lib/pmdk_debug   or  /usr/lib64/pmdk_debug,  as  appropriate.   Debugging  output  is
       controlled using the following environment variables.  These variables have no  effect  on
       the non-debug version of the library.

              NOTE:  On Debian/Ubuntu systems, this extra debug version of the library is shipped
              in the respective -debug Debian package and placed in the  /usr/lib/$ARCH/pmdk_dbg/
              directory.

       • PMEMPOOL_LOG_LEVEL

       The  value of PMEMPOOL_LOG_LEVEL enables trace points in the debug version of the library,
       as follows:

       • 0 - This is the default level when PMEMPOOL_LOG_LEVEL is not set.  No log  messages  are
         emitted at this level.

       • 1  -  Additional details on any errors detected are logged (in addition to returning the
         errno-based  errors  as  usual).   The  same  information   may   be   retrieved   using
         pmempool_errormsg().

       • 2 - A trace of basic operations is logged.

       • 3 - Enables a very verbose amount of function call tracing in the library.

       • 4 - Enables voluminous and fairly obscure tracing information that is likely only useful
         to the libpmempool developers.

       Unless PMEMPOOL_LOG_FILE is set, debugging output is written to stderr.

       • PMEMPOOL_LOG_FILE

       Specifies the name of a file where all logging information should be written.  If the last
       character  in the name is “-”, the PID of the current process will be appended to the file
       name when the log file is created.  If PMEMPOOL_LOG_FILE is not set, output is written  to
       stderr.

EXAMPLE

       The  following  example  illustrates how the libpmempool API is used.  The program detects
       the type and checks consistency of given pool.  If there are any issues detected, the pool
       is automatically repaired.

              #include <stddef.h>
              #include <unistd.h>
              #include <stdlib.h>
              #include <stdio.h>
              #include <libpmempool.h>

              #define PATH "./pmem-fs/myfile"
              #define CHECK_FLAGS (PMEMPOOL_CHECK_FORMAT_STR|PMEMPOOL_CHECK_REPAIR|\
                                   PMEMPOOL_CHECK_VERBOSE)

              int
              main(int argc, char *argv[])
              {
                  PMEMpoolcheck *ppc;
                  struct pmempool_check_status *status;
                  enum pmempool_check_result ret;

                  /* arguments for check */
                  struct pmempool_check_args args = {
                      .path       = PATH,
                      .backup_path    = NULL,
                      .pool_type  = PMEMPOOL_POOL_TYPE_DETECT,
                      .flags      = CHECK_FLAGS
                  };

                  /* initialize check context */
                  if ((ppc = pmempool_check_init(&args, sizeof(args))) == NULL) {
                      perror("pmempool_check_init");
                      exit(EXIT_FAILURE);
                  }

                  /* perform check and repair, answer 'yes' for each question */
                  while ((status = pmempool_check(ppc)) != NULL) {
                      switch (status->type) {
                      case PMEMPOOL_CHECK_MSG_TYPE_ERROR:
                          printf("%s\n", status->str.msg);
                          break;
                      case PMEMPOOL_CHECK_MSG_TYPE_INFO:
                          printf("%s\n", status->str.msg);
                          break;
                      case PMEMPOOL_CHECK_MSG_TYPE_QUESTION:
                          printf("%s\n", status->str.msg);
                          status->str.answer = "yes";
                          break;
                      default:
                          pmempool_check_end(ppc);
                          exit(EXIT_FAILURE);
                      }
                  }

                  /* finalize the check and get the result */
                  ret = pmempool_check_end(ppc);
                  switch (ret) {
                      case PMEMPOOL_CHECK_RESULT_CONSISTENT:
                      case PMEMPOOL_CHECK_RESULT_REPAIRED:
                          return 0;
                      default:
                          return 1;
                  }
              }

       See <https://pmem.io/pmdk/libpmempool> for more examples using the libpmempool API.

ACKNOWLEDGEMENTS

       libpmempool  builds on the persistent memory programming model recommended by the SNIA NVM
       Programming Technical Work Group: <https://snia.org/nvmp>

SEE ALSO

       dlclose(3),     pmempool_check_init(3),     pmempool_feature_query(3),     pmempool_rm(3),
       pmempool_sync(3), strerror(3), libpmem(7), libpmemblk(7), libpmemlog(7), libpmemobj(7) and
       <https://pmem.io>**