int
log_get(DB_ENV *env, DB_LSN *lsn, DBT *data, u_int32_t flags);
Description
The log_get function implements a cursor inside of the log,
retrieving records from the log according to the lsn and
flags arguments.
The data field of the data structure is set to the record
retrieved and the size field indicates the number of bytes in the record.
See DBT for a description of other fields in the data
structure. When multiple threads are using the returned log handle
concurrently, one of the DB_DBT_MALLOC, DB_DBT_REALLOC or
DB_DBT_USERMEM flags must be specified for any DBT used
for data retrieval.
The flags argument must be set to exactly one of the following values:
The last record written with the DB_CHECKPOINT flag specified to the
log_put function is returned in the data argument. The
lsn argument is overwritten with the DB_LSN of the record
returned. If no record has been previously written with the DB_CHECKPOINT
flag specified, the first record in the log is returned.
If the log is empty, the log_get function will return DB_NOTFOUND.
The first record from any of the log files found in the log directory
is returned in the data argument.
The lsn argument is overwritten with the DB_LSN of the
record returned.
If the log is empty, the log_get function will return DB_NOTFOUND.
The current log position is advanced to the next record in the log and that
record is returned in the data argument.
The lsn argument is overwritten with the DB_LSN of the
record returned.
If the pointer has not been initialized via DB_FIRST, DB_LAST, DB_SET,
DB_NEXT, or DB_PREV, log_get will return the first record in the log.
If the last log record has already been returned or the log is empty, the
log_get function will return DB_NOTFOUND.
If the log was opened with the DB_THREAD flag set, calls to
log_get with the DB_NEXT flag set will return EINVAL.
The current log position is moved to the previous record in the log and that
record is returned in the data argument.
The lsn argument is overwritten with the DB_LSN of the
record returned.
If the pointer has not been initialized via DB_FIRST, DB_LAST, DB_SET,
DB_NEXT, or DB_PREV,
log_get will return the last record in the log.
If the first log record has already been returned or the log is empty, the
log_get function will return DB_NOTFOUND.
If the log was opened with the DB_THREAD flag set, calls to
log_get with the DB_PREV flag set will return EINVAL.
Return the log record currently referenced by the log.
If the log pointer has not been initialized via DB_FIRST, DB_LAST, DB_SET,
DB_NEXT, or DB_PREV, or if the log was opened with the DB_THREAD flag set,
log_get will return EINVAL.
Retrieve the record specified by the lsn argument. If the
specified DB_LSN is invalid (e.g., does not appear in the log)
log_get will return EINVAL.
Otherwise, the log_get function returns a non-zero error value on failure and 0 on success.
Errors
The log_get function may fail and return a non-zero error for the following conditions:
EINVAL
An invalid flag value or parameter was specified.
The DB_FIRST flag was specified and no log files were found.
The log_get function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions.
If a catastrophic error has occurred, the log_get function may fail and return
DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail
in the same way.