2665 results about "Hash table" patented technology

According to an embodiment of the invention, cache management comprises maintaining a cache comprising a hash table including rows of data items in the cache, wherein each row in the hash table is associated with a hash value representing a logical block address (LBA) of each data item in that row. Searching for a target data item in the cache includes calculating a hash value representing a LBA of the target data item, and using the hash value to index into a counting Bloom filter that indicates that the target data item is either not in the cache, indicating a cache miss, or that the target data item may be in the cache. If a cache miss is not indicated, using the hash value to select a row in the hash table, and indicating a cache miss if the target data item is not found in the selected row.

A system and method for “on-the-fly” de-duplication of data before storing the data in a storage system is provided. A data de-duplication module illustratively cooperates with protocol servers and a file system of a storage operating system executing on the storage system to implement the novel de-duplication technique. The de-duplication module illustratively generates a block store, an index file and a hash table on storage space provided by the storage system. The hash table is utilized for tracking fingerprints and locations of blocks within the block store. The index file is utilized for storing directory information identifying the contents of data containers stored on the storage system, while the block store is utilized to store raw data blocks that comprise the data containers.

The invention discloses a block chain data comparison and consensus method used for hash value calculation of content of each transaction. By changing the random numbers, the numbers of some bits of the hash values are set not to be repeated in a time period, and can be called as unrepeated serial numbers. Accounting servers are used to compare the numbers of the preset bits of the hash values to determine whether the transactions are identical or not. The unrepeated serial number comparison can be carried out in a way of establishing the Merkle-like tree, and because the numbers of the preset bits of the hash values of the transactions are not repeated, and can be used as the serial numbers, and can be disposed in the Merkle-like tree according to the certain rule, and therefore for different accounting servers, the positions of the hash values of the same transaction on the Merkle trees are totally identical, and the differences can be found out quickly, the data transfer amount can be reduced, and the time required by the consensus can be greatly accelerated.

A computer filing system includes a data access and allocation mechanism including a directory and a plurality of indexed data files or hash tables. The directory is preferably a radix tree including directory entries which contain pointers to respective ones of the hash tables. Using a plurality of hash tables avoids the whole database ever having to be re-hashed all at once. If a hash table exceeds a preset maximum size as data is added, it is replaced by two hash tables and the directory is updated to include two separate directory entries each containing a pointer to one of the new hash tables. The directory is locally extensible such that new levels are added to the directory only where necessary to distinguish between the hash tables. Local extensibility prevents unnecessary expansion of the size of the directory while also allowing the size of the hash tables to be controlled. This allows optimisation of the data access mechanism such that an optimal combination of directory-look-up and hashing processes is used. Additionally, if the number of keys mapped to an indexed data file is less than a threshold number (corresponding to the number of entries which can be held in a reasonable index), the index for the data file is built with a one-to-one relationship between keys and index entries such that each index entry identifies a data block holding data for only one key. This avoids the overhead of the collision detection of hashing when it ceases to be useful.

Techniques for enhancing the security of storing sensitive information or a token on a communication device may include sending a request for the sensitive information or token. The communication device may receive a session key encrypted with a hash value derived from user authentication data that authenticates the user of the communication device, and the sensitive information or token encrypted with the session key. The session key encrypted with the hash value, and the sensitive information or token encrypted with the session key can be stored in a memory of the communication device.

A system and method for creating computer system backups, particularly well-suited for performing backups of virtual machines. The method starts by reading the current state of the machine, in blocks of a constant size, and creates a “FULL” index of block numbers and a hash value associated with the data within that block, while at the same time creating a FULL backup of the machine (the FULL backup then stored at an off-site target location). Once the FULL index map is defined, subsequent DELTA backups are created by reading the current state of the device in the same block fashion and generating updated hash values for each data block. The newly-generated hash values are compared against the values stored in the FULL index map. If the hash numbers for a particular block do not match, this is an indication that the data within that block has changed since the last FULL backup was created. Once all of the “changed” data blocks have been identified to form a DELTA backup, a communication connection is opened in the network and the DELTA backup is sent to the off-site target location.

Methods and apparatus are provided for performing spelling corrections using one or more variant hash tables. The spelling of at least one candidate word is corrected by obtaining at least one variant dictionary hash table based on variants of a set of known correctly spelled words, wherein the variants are obtained by applying one or more of a deletion, insertion, replacement, and transposition operation on the correctly spelled words; obtaining from the candidate word one or more lookup variants using one or more of the deletion, insertion, replacement, and transposition operations; evaluating one or more of the candidate word and the lookup variants against the at least one variant dictionary hash table; and indicating a candidate correction if there is at least one match in the at least one variant dictionary hash table.

Fast, scalable methods and devices are provided for layer four switching in a router as might be found in the Internet. In a first method, a grid of tries, which are binary branching trees, is constructed from the set of routing filters. The grid includes a dest-trie and a number of source tries. To avoid memory blowup, each filter is stored in exactly one trie. The tries are traversed to find the lowest cost routing. Switch pointers are used to improve the search cost. In an extension of this method, hash tables may be constructed that point to grid-of-tries structures. The hash tables may be used to handle combinations of port fields and protocol fields. Another method is based on hashing, in which searches for lowest cost matching filters take place in bit length tuple space. Rectangle searching with precomputation and markers are used to eliminate a whole column of tuple space when a match occurs, and to eliminate the rest of a row when no match is found. Various optimizations of these methods are also provided. A router incorporating memory and processors implementing these methods is capable of rapid, selective switching of data packets on various types of networks, and is particularly suited to switching on Internet Protocol networks.

Computer systems are typically designed with multiple levels of memory hierarchy. Prefetching has been employed to overcome the latency of fetching data or instructions from or to memory. Prefetching works well for data structures with regular memory access patterns, but less so for data structures such as trees, hash tables, and other structures in which the datum that will be used is not known a priori. The present invention significantly increases the cache hit rates of many important data structure traversals, and thereby the potential throughput of the computer system and application in which it is employed. The invention is applicable to those data structure accesses in which the traversal path is dynamically determined. The invention does this by aggregating traversal requests and then pipelining the traversal of aggregated requests on the data structure. Once enough traversal requests have been accumulated so that most of the memory latency can be hidden by prefetching the accumulated requests, the data structure is traversed by performing software pipelining on some or all of the accumulated requests. As requests are completed and retired from the set of requests that are being traversed, additional accumulated requests are added to that set. This process is repeated until either an upper threshold of processed requests or a lower threshold of residual accumulated requests has been reached. At that point, the traversal results may be processed.

Techniques detect bootkits resident on a computer by detecting a change or attempted change to contents of boot locations (e.g., the master boot record) of persistent storage, which may evidence a resident bootkit. Some embodiments may monitor computer operations seeking to change the content of boot locations of persistent storage, where the monitored operations may include API calls performing, for example, WRITE, READ or APPEND operations with respect to the contents of the boot locations. Other embodiments may generate a baseline hash of the contents of the boot locations at a first point of time and a hash snapshot of the boot locations at a second point of time, and compare the baseline hash and hash snapshot where any difference between the two hash values constitutes evidence of a resident bootkit.

A data chunking system divides data into predominantly fixed-sized chunks such that duplicate data may be identified. The data chunking system may be used to reduce the data storage and save network bandwidth by allowing storage or transmission of primarily unique data chunks. The system may also be used to increase reliability in data storage and network transmission, by allowing an error affecting a data chunk to be repaired with an identified duplicate chunk. The data chunking system chunks data by selecting a chunk of fixed size, then moving a window along the data until a match to existing data is found. As the window moves across the data, unique chunks predominantly of fixed size are formed in the data passed over. Several embodiments provide alternate methods of determining whether a selected chunk matches existing data and methods by which the window is moved through the data. To locate duplicate data, the data chunking system remembers data by computing a mathematical function of a data chunk and inserting the computed value into a hash table.

In one embodiment, use of hashing in a file system metadata arrangement reduces an amount of metadata stored in a memory of a node in a cluster and reduces the amount of metadata needed to process an input/output (I/O) request at the node. Illustratively, cuckoo hashing may be modified and applied to construct the file system metadata arrangement. The file system metadata arrangement may be illustratively configured as a key-value extent store embodied as a data structure, e.g., a cuckoo hash table, wherein a value, such as a hash table index, may be configured as an index and applied to the cuckoo hash table to obtain a key, such as an extent key, configured to reference a location of an extent on one or more storage devices, such as solid state drives.

A method of performing a translation from a guest virtual address to a host physical address in a virtual machine environment includes receiving a guest virtual address from a host computer executing a guest virtual machine program and using the hardware oriented method of the host CPU to determine the guest physical address. A second level address translation to a host physical address is then performed. In one embodiment, a multiple tier tree is traversed which translates the guest physical address into a host physical address. In another embodiment, the second level of address translation is performed by employing a hash function of the guest physical address and a reference to a hash table. One aspect of the invention is the incorporation of access overrides associated with the host physical address which can control the access permissions of the host memory.

A technique efficiently searches a hash table. Conventionally, a predetermined set of “signature” information is hashed to generate a hash-table index which, in turn, is associated with a corresponding linked list accessible through the hash table. The indexed list is sequentially searched, beginning with the first list entry, until a “matching” list entry is located containing the signature information. For long list lengths, this conventional approach may search a substantially large number of list entries. In contrast, the inventive technique reduces, on average, the number of list entries that are searched to locate the matching list entry. To that end, list entries are partitioned into different groups within each linked list. Thus, by searching only a selected group (e.g., subset) of entries in the indexed list, the technique consumes fewer resources, such as processor bandwidth and processing time, than previous implementations.

The embodiment of the invention discloses a micro service registration method and a micro service registration system, wherein one registration center is started on each node in a cluster, and the method comprises the following steps that: the registration center receives registration request information transmitted by a local micro service corresponding to the registration center, wherein a registration information carried by the registration request information comprises micro service access address information, service providing information and service consumption information; the registration center adds the registration information to a hash table of the registration center; and the registration center synchronizes the registration information of all the micro services in the local hash table to other registration centers except the registration center itself in the cluster. With the mode of starting one registration center on each node in the cluster provided by the embodiment of the invention, maintaining one highly available registration center is not necessary, and if one of the registration centers is crashed, other registration centers in the cluster cannot be affected, and risk of breakdown of system caused by crash of only one registration center is avoided effectively.

Provided is a process including: obtaining a plurality of records to be protected; forming a tamper-evident log configured to prevent an attacker from undetectably modifying any of the plurality of records stored in the tamper-evident log, wherein the cryptographic hash value of a given entry in the tamper-evident log is sequence agnostic to the sequence of entries in virtue of being based on values that do not specify a position in the sequence of entries; and storing the tamper-evident log in memory.

An aspect of the invention provides a method for managing information associated with a hierarchical key. A plurality of hash tables are created for a plurality of levels of a hierarchy associated with a hierarchical key, wherein each hash table is associated with a corresponding level of the hierarchy. Entries are stored within each of the plurality of hash tables, wherein the entries are associated with key names that have as many levels as the level associated with the respective hash table. Furthermore, a reference to a descendant entry that is in a respective hash table may be stored within each entry.

In one embodiment, an extent store layer of a storage input/output (I/O) stack executing on one or more nodes of a cluster manages efficient logging and checkpointing of metadata. The metadata managed by the extent store layer, i.e., the extent store metadata, resides in a memory (in-core) of each node and is illustratively organized as a key-value extent store embodied as one or more data structures, e.g., a set of hash tables. Changes to the set of hash tables are recorded as a continuous stream of changes to SSD embodied as an extent store layer log. A separate log stream structure (e.g., an in-core buffer) may be associated respectively with each hash table such that changed (i.e., dirtied) slots of the hash table are recorded as entries in the log stream structure. The hash tables are written to SSD using a fuzzy checkpointing technique.

A system and method for providing an actively invalidated client-side network resource cache are disclosed. A particular embodiment includes: a client configured to request, for a client application, data associated with an identifier from a server; the server configured to provide the data associated with the identifier, the data being subject to subsequent change, the server being further configured to establish a queue associated with the identifier at a scalable message queuing system, the scalable message queuing system including a plurality of gateway nodes configured to receive connections from client systems over a network, a plurality of queue nodes containing subscription information about queue subscribers, and a consistent hash table mapping a queue identifier requested on a gateway node to a corresponding queue node for the requested queue identifier; the client being further configured to subscribe to the queue at the scalable message queuing system to receive invalidation information associated with the data; the server being further configured to signal the queue of an invalidation event associated with the data; the scalable message queuing system being configured to convey information indicative of the invalidation event to the client; and the client being further configured to re-request the data associated with the identifier from the server upon receipt of the information indicative of the invalidation event from the scalable message queuing system.

A data processing system has a searching mechanism for finding occurrences of a plurality of key strings within a target string. The searching mechanism forms a hash value from each of the key strings, and adds each key string to a collection of key strings having the same hash value. It then selects a plurality of symbol positions in the target string, and forms a hash value at each selected symbol position in the target string. This hash value is used to select one of the collections of key strings. Each key string in the selected collection of key strings is then compared with the target string.

A hashing-based router and method for network load balancing includes calculating a hash value from header data of incoming data packets and routing incoming packets based on the calculated hash values to permissible output links in desired loading proportions.

A system and method for constructing a document redundancy graph with respect to a document set. The redundancy graph can be constructed with a node for each paragraph associated with the document set such that each node in the redundancy graph represents a unique cluster of information. The nodes can be linked in an order with respect to the information provided in the document set and bundles of redundant information from the document set can be mapped to individual nodes. A data structure (e.g., a hash table) of a paragraph identifier associated with a probability value can be constructed for eliminating inconsistencies with respect to node redundancy. Additionally, a sequence of unique nodes can also be integrated into the graph construction process. The nodes can be connected to the paragraphs associated with the document set via a hyperlink and/or via a label with respect to each node.

The present invention relates to a cache memory management system suitable for use with snapshot applications. The system includes a cache directory including a hash table, hash table elements, cache line descriptors, and cache line functional pointers, and a cache manager running a hashing function that converts a request for data from an application to an index to a first hash table pointer in the hash table. The first hash table pointer in turn points to a first hash table element in a linked list of hash table elements where one of the hash table elements of the linked list of hash table elements points to a first cache line descriptor in the cache directory and a cache memory including a plurality of cache lines, wherein the first cache line descriptor has a one-to-one association with a first cache line. The present invention also provides for a method converting a request for data to an input to a hashing function, addressing a hash table based on a first index output from the hashing function, searching the hash table elements pointed to by the first index for the requested data, determining the requested data is not in cache memory, and allocating a first hash table element and a first cache line descriptor that associates with a first cache line in the cache memory.

Methods and apparatus are disclosed herein for classifying packets using ternary and binary content-addressable memory stages to classify packets. One such system uses a stage of one or more TCAMS followed by a second stage one or more CAMS (or alternatively some other binary associative memories such as hash tables or TRIEs) to classify a packet. One exemplary system includes TCAMs for handling input and output classification and a forwarding CAM to classify packets for Internet Protocol (IP) forwarding decisions on a flow label. This input and output classification may include, but is not limited to routing, access control lists (ACLs), quality of service (QoS), network address translation (NAT), encryption, etc. These IP forwarding decisions may include, but are not limited to IP source and destination addresses, protocol type, flags and layer 4 source and destination ports, a virtual local area network (VLAN) id and/or other fields.