| 摘要 |
A method for updating and formatting a local file is described. An update file, having a newer version of the local file, is accessed from a server over a network and a list of new hash values corresponding to data blocks of the update file is retrieved. Divisions between the data blocks are located when a value of a rolling checksum reaches a particular value, the data blocks being of variable size. New hash values of the update file are compared with local hash values of the local file. For each of the new hash values not having a matching local hash value, the corresponding data block is downloaded from the server and written to a new file. For each of the new hash values having a matching local hash value, the corresponding block is copied from the local file to the new file. |
| 主权项 |
1. A method comprising:
identifying, by a client computer, a first sync directory for a first version of a file stored locally on the client computer, wherein the first sync directory includes a plurality of first hash values, each first hash value corresponding to a respective one of a plurality of blocks in the first version of the file, and wherein the first sync directory also includes a first global hash value based on the contents of all the blocks of the first version of the file; obtaining, from a remote server computer, a second sync directory for a second version of the file, wherein the second sync directory includes a plurality of second hash values, each second hash value corresponding to a respective one of a plurality of blocks in the second version of the file, and wherein the second sync directory also includes a second global hash value based on the contents of all the blocks of the second version of the file; wherein divisions between the plurality of blocks in the first version of the file and the plurality of blocks in the second version of the file are generated according to an algorithm, the algorithm locating divisions between blocks at positions within a particular file when a value of a rolling checksum reaches a particular value; determining whether the first global hash value and the second global hash value match; and in response to determining that the first global hash value and the second global hash value do not match, generating a new copy of the second version of the file stored locally on the client computer using the first hash values in the first sync directory and the second hash values in the second sync directory. |
