Fires to determine how much free space is available for growing a callback mode vault.
The 'callback' is called when the 'VaultGetParentSize' event is emited.
The argument 'e' has the following properties:
e.vault e.vaultHandle e.freeSpace e.resultCode
This event fires when the class needs to determine how much free space is available for growing the callback mode vault specified by VaultHandle.
This event only needs to be handled if the CallbackMode property is enabled; please refer to the Callback Mode topic for more information. To handle this event properly, applications must set FreeSpace to indicate how many bytes of free space are available in the "parent storage" of the vault specified by VaultHandle. For example:
- If the vault is stored in a file, return the amount of free space on the associated disk.
- If the vault is stored in memory, return the amount of memory available to the application (keeping in mind any other memory needs the application may have).
- If the vault is stored on some remote system, query it to determine how much free space is available.
The Vault parameter contains an application-defined vault identifier (name, file path, etc.). The value of this parameter will always match the current value of the VaultFile property.
The VaultHandle parameter contains an application-defined handle to an open callback mode vault, as returned by the application in an earlier VaultOpen event.
The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource isn't available, security checks failed, etc.), set it to a non-zero value to report an appropriate error. Please refer to the Error Reporting and Handling topic for more information.
Note: An application should not attempt to call class's methods from handlers of this event. Doing this is guaranteed to cause a deadlock.
Note: when a storage is opened concurrently in read-only mode by several applications using CBDrive or CBMemDrive class, the event will fire only in the first application. To prevent such a situation, always open a vault in read-write mode.