Starboard Module Reference: storage.h

Defines a user-based Storage API. This is a simple, all-at-once BLOB storage and retrieval API that is intended for robust long-term, per-user 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 per user and, thus, a maximum of one open storage record can exist for each user. Attempting to open a second record for a user 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 for user 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 for the user, like what would have been deleted with the previous version of SbStorageDeleteRecord.

This function must not be called while the user's storage record is open. This function performs blocking I/O on the calling thread.

user: The user for whom the record will be deleted. name: The filesystem- safe name of the record to open.

Declaration

bool SbStorageDeleteRecord(SbUser user, 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 for user named name, blocking I/O on the calling thread until the open is completed. If user is not a valid SbUser, the function returns kSbStorageInvalidRecord. 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 for the user, like what would have been saved with the previous version of SbStorageOpenRecord.

user: The user for which the storage record will be opened. name: The filesystem-safe name of the record to open.

Declaration

SbStorageRecord SbStorageOpenRecord(SbUser user, 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. Thus, if data_size is smaller than the total size of data, only part of data is written to the record.

Declaration

bool SbStorageWriteRecord(SbStorageRecord record, const char *data, int64_t data_size)