Defines a Storage API. This is a simple, all-at-once BLOB storage and retrieval API that is intended for robust long-term storage. Some platforms have different mechanisms for this kind of storage, so this API exists to allow a client application to access this kind of storage.
Note that there can be only one storage record and, thus, a maximum of one open storage record can exist. Attempting to open a second record will result in undefined behavior.
These APIs are NOT expected to be thread-safe, so either call them from a single thread, or perform proper synchronization around all calls.
Macros
kSbStorageInvalidRecord
Well-defined value for an invalid storage record handle.
Typedefs
SbStorageRecord
A handle to an open storage record.
Definition
typedef SbStorageRecordPrivate* SbStorageRecord
Functions
SbStorageCloseRecord
Closes record, synchronously ensuring that all written data is flushed. This
function performs blocking I/O on the calling thread.
The return value indicates whether the operation succeeded. Storage writes should be as atomic as possible, so the record should either be fully written or deleted (or, even better, untouched).
record: The storage record to close. record is invalid after this point, and
subsequent calls referring to record will fail.
Declaration
bool SbStorageCloseRecord(SbStorageRecord record)
SbStorageDeleteRecord
Deletes the SbStorageRecord named name. The return value indicates whether
the record existed and was successfully deleted. If the record did not exist or
could not be deleted, the function returns false.
If name is NULL, deletes the default storage record, like what would have been
deleted with the previous version of SbStorageDeleteRecord.
This function must not be called while the storage record is open. This function performs blocking I/O on the calling thread.
name: The filesystem-safe name of the record to open.
Declaration
bool SbStorageDeleteRecord(const char *name)
SbStorageGetRecordSize
Returns the size of record, or -1 if there is an error. This function
performs blocking I/O on the calling thread.
record: The record to retrieve the size of.
Declaration
int64_t SbStorageGetRecordSize(SbStorageRecord record)
SbStorageIsValidRecord
Returns whether the given storage record handle is valid.
Declaration
static bool SbStorageIsValidRecord(SbStorageRecord record)
SbStorageOpenRecord
Opens and returns the SbStorageRecord named name, blocking I/O on the calling
thread until the open is completed. Will return an SbStorageRecord of size
zero if the record does not yet exist. Opening an already-open SbStorageRecord
has undefined behavior.
If name is NULL, opens the default storage record, like what would have been
saved with the previous version of SbStorageOpenRecord.
name: The filesystem-safe name of the record to open.
Declaration
SbStorageRecord SbStorageOpenRecord(const char *name)
SbStorageReadRecord
Reads up to data_size bytes from record, starting at the beginning of the
record. The function returns the actual number of bytes read, which must be <=
data_size. The function returns -1 in the event of an error. This function
makes a best-effort to read the entire record, and it performs blocking I/O on
the calling thread until the entire record is read or an error is encountered.
record: The record to be read. out_data: The data read from the record.
data_size: The amount of data, in bytes, to read.
Declaration
int64_t SbStorageReadRecord(SbStorageRecord record, char *out_data, int64_t data_size)
SbStorageWriteRecord
Replaces the data in record with data_size bytes from data. This function
always deletes any previous data in that record. The return value indicates
whether the write succeeded. This function makes a best-effort to write the
entire record, and it may perform blocking I/O on the calling thread until the
entire record is written or an error is encountered.
While SbStorageWriteRecord() may defer the persistence,
SbStorageReadRecord() is expected to work as expected immediately afterwards,
even without a call to SbStorageCloseRecord(). The data should be persisted
after a short time, even if there is an unexpected process termination before
SbStorageCloseRecord() is called.
record: The record to be written to. data: The data to write to the record.
data_size: The amount of data, in bytes, to write to the record.
Declaration
bool SbStorageWriteRecord(SbStorageRecord record, const char *data, int64_t data_size)