Method of sharing memory between an operating system and an application program

A method of accessing a file stored on a computer storage device, the storage device operatively connected to a computer, the computer having an operating system and a computer memory, the operating system having a file system, the method comprising the steps of:

• requesting the file system to load the file into computer memory for access by an application program;
• and
• for each of a plurality of portions of the file, performing the following steps by the file system:
• retrieving the portion of the file from the storage device;
• storing the retrieved portion of the file in the computer memory;
• and
• updating a pointer to point to the stored portion of the file;
• and
• performing the following steps by the application program:
• waiting until the file system updates the pointer;
• and
• concurrently reading the stored portion of the file pointed to by the updated pointer from the computer memory while the file system is performing the steps of retrieving and storing another portion of the file.

A method for transporting data from a storage device onto a computer network, the storage device and the computer network operatively connected to a file server computer having a file system, a file server, and a transport system, the file system having data descriptors and cache buffers, each data descriptor having a pointer to a cache buffer, the method comprising the steps of:

• receiving a request to transport data onto the computer network;
• performing the following steps by the file system:
• selecting a set of data descriptors to be updated as the data is loaded from the storage device into the cache buffers;
• and
• for each of a plurality of portions of the data,
• selecting the next data descriptor from the selected set of data descriptors, starting with the first data descriptor;
• selecting a cache buffer to receive the portion of the data to be loaded from the storage device;
• loading the portion of the data from the storage device into the selected cache buffer;
• and
• updating the selected data descriptor to point to the selected cache buffer;
• for each portion of the data loaded, performing the following steps by the file server:
• selecting a next data descriptor from the selected set of data descriptors, starting with the first data descriptor;
• waiting for the file system to update the selected data descriptor to point to a cache buffer;
• and
• signalling the transport system to transport onto the computer network the portion of the data in the cache buffer pointed to by the selected data descriptor;
• and
• performing the following steps by the transport system:
• for each signal to transport a portion of the data in a cache buffer,
• reading the portion of the data stored in the cache buffer;
• and
• writing the data onto the computer network to effect the transport of the data.

A method for receiving data from a computer network and storing the data on a storage device, the computer network and the storage device operatively connected to a file server computer having a file system, a file server, and a transport system, the file system having data descriptors and cache buffers, each data descriptor having a pointer for pointing to a cache buffer, the method comprising the steps of:

• receiving a request to store data received from a computer network onto the storage device;
• selecting a set of data descriptors to be updated as the data is loaded from the computer network into the cache buffers;
• setting the pointer in each selected data descriptor to point to a cache buffer;
• performing the following steps by the transport system:
• for each of a plurality of portions of the data,
• selecting a next data descriptor from the selected set of data descriptors, starting with the first data descriptor;
• receiving the portion of the data from the computer network;
• and
• storing the received portion of the data in a cache buffer pointed to by the selected data descriptor;
• and
• signalling the file server that all the data has been received;
• when signalled that all the data has been received, signalling the file system by the file server that the cache buffers contain the received data;
• and
• when signalled that the cache buffer contains the received data, for each portion of the data stored in the cache buffers, performing the following steps by the file system:
• selecting a next data descriptor from the selected set of data descriptors, starting with the first data descriptor;
• and
• writing the portion of the data stored in the cache buffer pointed to by the selected data descriptor to the storage device.

A method in a computer system for accessing a plurality of portions of external data loaded by an operating system for an application program, the computer having computer memory, the method comprising the steps of:

• performing the following steps by the operating system:
• receiving a request of an application program for access to the external data;
• retrieving a portion of the external data;
• storing the retrieved portion in a buffer;
• setting a pointer to the buffer containing the retrieved portion;
• and
• for each remaining portion of the external data,
• retrieving a new portion of the external data;
• storing the retrieved new portion in a buffer other than the buffer pointed to by the pointer;
• waiting until the application program accesses the pointer;
• and
• updating the pointer to point to the buffer containing the retrieved new portion;
• and
• performing the following steps by the application program:
• waiting until the operating system sets the pointer to point to the buffer containing the retrieved portion;
• when the pointer has been set, accessing the retrieved portion of the external data stored in the buffer pointed to by the set pointer, while the operating system is retrieving a new portion of the external data;
• for another portion of the external data, waiting until the operating system updates the pointer to point to the buffer containing the retrieved new portion;
• and
• when the pointer has been updated, accessing the portion of the external data stored in the buffer pointed to by the updated pointer, while the operating system is retrieving a new portion of the external data.