Lucent Technologies Inc.

At+t Corp.

Philip Steven Winterbottom

Lorenz Francis Huelsbergen

Gerard Johan Holzmann

Kenneth Lane Thompson

A technique for testing event driven software. In accordance with the technique, the source code of the event driven software is directly converted to an automation based model useful in verifying that the program code complies with the desired properties defined by the user. More particularly, the event driven system program code is translated into a target language for a particular model checker. Such a translation results in a model which contains statements directed at whether execution of the program code will affect the behavior of the event driven system. Thus, this model extraction process can be used as input to a logic model checker for determining whether event driven system complies with the desired correctness properties specified by the user. Advantageously, the model extraction process and application of the model checker occurs in a direct and dynamic fashion from the subject event driven system program code without the need for user intervention.

Method and apparatus for testing event driven software

A garbage collection technique for the concurrent operation of a mutator and garbage collector (e.g., marker and sweeper) without requiring fine-grain synchronization or atomicity amongst the mutator, marker and sweeper. The garbage collector employs three threads for concurrently executing the mutator, marker and sweeper, and operates through a series of so called epochs (i.e., individual garbage collection cycles) wherein each epoch (1) runs the mutator; (2) marks all objects that were reachable (i.e., allocated) in the previous epoch with the present epoch's color; and (3) reclaims any objects marked as garbage. Significantly, the object coloring scheme used in the garbage collector eliminates the need for fine-grain synchronization or atomicity by maintaining the invariant that the mutator never sees an object colored with the sweeper's color. Further, only the marker may alter an object's color during an epoch further eliminating the need for fine-grain synchronization or atomicity between the mutator, marker and sweeper.

Garbage collection without fine-grain synchronization

A distributed computing environment is disclosed which allows a user at one location to access resources at other locations. Each resource in the distributed computing environment is represented as a hierarchical file system. A user or process has a name space comprised of at least one hierarchical file system provided by a connected resource. The distributed computing environment allows a first processor to invoke execution of a processing task by a remote processor. The first processor transmits a representation of its current name space to the remote processor. The remote processor will execute the processing task on a name space modified in accordance with the name space representation received from the first processor. The transmitted representation of the name space associated with the first processor includes at least one dynamic name space modification command, such as those executed by a user after logging into the distributed computing system. A plurality of data structures are provided for storing path information which allows the pathname of a given channel, which represents a file, to be determined. The stored path information allows the hierarchical file tree of a connected file system to be generated.

Methods and apparatus for storage and retrieval of name space

Apparatus and methods for incorporating a portion (including all) of a first name space into a second name space. An agent operating in the first name space receives first operation specifiers which use names as they are used in the second name space from an entity operating in the first name space and translates the first operation specifiers into second operation specifiers which specify the same operations and use the names as they are used in the first name space. The apparatus and methods are implemented in the Plan 9 operating system. The first and second name spaces are organized as trees and belong to a first process operating on a first processor and a second process operating on a second processor. The first operation specifiers are Plan 9 file protocols which the first process receives from the second process. The second operation specifiers are Plan 9 file system calls made by the first process. The translation between the file protocols and the system calls is made using a data structure which permits the names in the portion as they are used in the second name space to be mapped onto the names as they are used in the first name space.

Growing community of inventors

Gillette, NJ, United States of America

Philip Steven Winterbottom