FCL/sf/os/kernelhwsrv: comparison userlibandfileserver/fileserver/inc/f32file.h

equal deleted inserted replaced

-:e880629062dd
+:e4a7b1cbe40c
 Not all file systems may support this query.
 A boolean value is returned within the buffer defined as TPckgBuf<TBool>.
 ETrue value means that the drive is finalised
 */
 EIsDriveFinalised,
+/**
+Query the volume to ascertain whether File system extensions
+are supported on this volume.
+A boolean value is returned within the buffer defined as TPckgBuf<TBool>.
+ETrue value means that extensions are supported.
+EFalse means they are not supported.
+*/
+EFSysExtensionsSupported,
 	};
 /**
 @publishedAll
 @released
 */
 class TVolumeIOParamInfo
 	{
 public:
 	/**
-	The size of a block in bytes.
+	The size of a media block in bytes. This is a physical property of a media and returned by the corresponding media driver.
+	This value is usually at least 512 bytes and always a power of 2. For some media types the meaning of this value is
-	Reads and writes that are aligned on block boundaries are up to twice as fast as when
+"the min. size of the aligned data buffer which write onto the media doesn't lead to read-modify-write operation."
-	mis-aligned.
+Therefore, reads and writes that are aligned on block boundaries and with lenght of a multiple block size can be much faster.
+	Read and write operations on certain underlying media is done in blocks. A write operation that modifies only part of a block is less efficient,
-	Read and write operations on certain underlying media is done in blocks.
+in general, than one that modifies an entire block. Data throughput degrades linearly for reads and writes in smaller sized units.
-	A write operation that modifies only part of a block is less efficient, in general, than
-	one that modifies an entire block. Data throughput degrades linearly for reads and writes in smaller
-	sized units.
 	*/
 	TInt iBlockSize;
-	/**
-	The size in bytes of a single disk cluster.
+	/**
+	The size in bytes of a single file system cluster. This is a logical property of the file system.
-	Read and write operations that are aligned on cluster boundaries are more efficient.
+	The file system organises and allocates the data on the disk in clusters where each cluster usually consists of one or more blocks.
+Cluster is a minimal unit that the file system allocates on the volume. Thus, a file of 1 byte length occupies 1 cluster.
-	The file system organises and allocates the file data on the disk in clusters where each cluster is
-	one or more blocks. Files that are not zero length occupy at least one cluster of the disk,
+	Read and write operations that are aligned on cluster boundaries are more efficient from the file system point of view.
-	so large numbers of very small files use up more disk space than expected.
+In some circumstances cluster size can be less than a block size, but it is very inefficient.
+This value is reported by a file system. The value less than 0 indicates a error.
 	*/
 	TInt iClusterSize;
 	/**
 	The recommended buffer size for optimised reading performance.
 	The given buffer size is based on sensible benchmark testing results produced by the mobile device vendor.
 	The buffer size is then added to the estart.txt file
 	TInt iRecWriteBufSize;
 /**
 The maximum file size that is supported by the file system mounted on this volume.
-Not all file system may provide this parameter;  The value KMaxTUint64 (0xffffffffffffffff) means that this particular file system hasn't
+Not all file system may report this parameter;  The value KMaxTUint64 (0xffffffffffffffff) means that this particular file system hasn't
 provided this information.
 */
 TUint64 iMaxSupportedFileSize;
 private:
 	Enables operations on large files.
 	@internalTechnology
 	*/
-	EFileBigFile        =0x00040000
+	EFileBigFile        =0x00040000,
+	/**
+	Using this flag implies that the client is making large sequential reads and/or writes
+	and it is interested in maximising the performance of the large reads and/or writes.
+	The flag gives a hint to the file server and filesystem to adjust to a streaming
+	data pattern and try their best to make it optimal.
+	Some conditions apply:
+	- This does not guarantee that the performance of read/write operations will increase.
+	- Using this flag for other purposes other than data streaming may lead to performance degradation.
+	- This may sacrifice user data integrity for the sake of performance.
+	If a file is opened by Client A with EFileSequential, and the file is then opened
+	without EFileSequential by Client B, then this file mode will be disabled.
+	When the file handle is closed by Client B, then the EFileSequential file mode
+	will be enabled again.
+	Therefore, this mode will only be enabled if all clients set the file as such,
+	otherwise the file mode will be disabled.
+	FAT file system specific information:
+	This flag improves write and file expansion performance whilst decreasing robustness
+	on a "Rugged-FAT" file system, which is applicable to internal non-removable drives.
+	*/
+	EFileSequential		=0x00080000
 	};

changeset 132	e4a7b1cbe40c
parent 90	947f0dc9f7a8
child 189	a5496987b1da