### DbEnv::set_thread_id_string |

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###

    #include <db_cxx.h>

    int
    DbEnv::set_thread_id(char *(*thread_id_string)(DbEnv *dbenv,
        pid_t pid, db_threadid_t tid, char *buf));

### Description: DbEnv::set_thread_id_string

Declare a function that formats a process ID and thread ID identifier pair for display into a caller-supplied buffer. The function must return a reference to the caller-specified buffer. The DbEnv::set_thread_id_string method supports the DbEnv::set_thread_id method.

The DbEnv::set_thread_id_string method configures operations performed using the specified DbEnv handle, not all operations performed on the underlying database environment.

The DbEnv::set_thread_id_string method may be called at any time during the life of the application.

The DbEnv::set_thread_id_string method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

### Parameters

thread_id_string
  The thread_id_string parameter is a function which returns a buffer in which is an identifier pair formatted for display. The function takes four arguments:
  dbenv
    The dbenv parameter is the enclosing database environment handle, allowing application access to the application-private fields of that object.
  pid
    The pid argument is a process ID.
  tid
    The tid argument is a thread ID.
  buf
    The buf argument is character array of at least DB_THREADID_STRLEN bytes in length, into which the identifier pair should be formatted.

If no thread_id_string function is specified, the default routine displays the identifier pair as "pid/tid", that is, the process ID represented as an unsigned integer value, a slash ('/') character, then the thread ID represented as an unsigned integer value.

### Errors

The DbEnv::set_thread_id_string method may fail and throw DbException, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:

EINVAL
  An invalid flag value or parameter was specified.

### Class

DbEnv

### See Also

Database Environments and Related Methods`

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