Oracle International Corporation

Sun Microsystems, Inc.

Oracle America, Inc.

Oracle America, Inc. Formerly Sun Microsystems, Inc.

John Robert Rose

Brian Goetz

Alexander R Buckley

Gavin Mark Bierman

Michael Haupt

Maurizio Cimadamore

Daniel Smith

Lai Hung Mandy Chung

Vladimir Ivanov

Erik Österlund

Guy L Steele

Paul D Sandoz

Mikael Vidstedt

Wayne C Gramlich

David L Weaver

Paul Sandoz

David Colin Holmes

David Dice

Lawrence Spracklen

Victor M Luchangco

Dean R E Long

Joseph D Darcy

Alan Bateman

Zoran Radovic

Stefan Mats Rikard Karlsson

Timothy Quinn

Richard D Tuck

Clifford N Click

Roland Westrelin

Guy Steele

Patrick McGehearty

Paul Govereau

Frederic Parain

A parametric constant resolves to different values in different contexts, but a single value within a particular context. An anchor constant is a parametric constant that allows for a degree of parametricity for an API point. The context for the anchor constant is provided by a caller to the API point. The anchor constant resolves to an anchor value that records specialization decisions for the API point within the provided context. Specialization decisions may include type restrictions, memory layout, and/or memory size. The anchor value together with an unspecialized type of the API point result in a specialized type of the API point. A class object representing the specialized type is created. The class object may be accessible to the caller, but the full value of the anchor value is not accessible to the caller. The API point is executed based on the specialization decisions embodied in the anchor value.

Determining a resolution state of an anchor constant associated with an application programming interface (API) point

Techniques are described herein for performing thread-local garbage collection. The techniques include automatic profiling and separation of private and shared objects, allowing for efficient reclamation of memory local to threads. In some embodiments, threads are assigned speculatively-private heaps within memory. Unless there is a prior indication that an allocation site yields shared objects, then a garbage collection system may assume and operate as if such allocations are private until proven otherwise. Object allocations in a private heap may violate the speculative state of the heap when reachable outside of the thread. When violations to the speculative state are detected, an indication may be generated to notify the garbage collection system, which may prevent thread-local memory reclamation operations until the speculative state is restored. The garbage collection system may learn from the violations to reduce the allocation of invalidly private objects and increase the efficiency of the garbage collection system.

Thread-local garbage collection

Techniques for determining and displaying error messages including a cause of an error generated because two types are not members of the same nest are disclosed. The system detects, at runtime, an instruction in a first type that attempts to access a private member of a second type. The system evaluates one or more nestmate criteria to determine whether the first type and the second type are within a same nest. A nest host corresponding to the nest specifies each nest member of the nest, and each nest member specifies an association with the nest. Responsive to determining that a particular nestmate criterion is not met, the system determines that the first type and the second type are not within the same nest and records or displays data identifying the particular nestmate criterion that has not been met, and throws an access error.

Distinguished nest-based access control

Accessing a parametric field within a specialized context

Techniques for performing type-constrained operations for plug-in types are disclosed. A runtime environment encounters a request to perform a type-constrained operation that requires evaluating a type constraint associated with a particular plug-in type. The runtime environment lacks sufficient native instructions to evaluate type constraints associated with plug-in types. The runtime environment accesses a plug-in type framework to obtain a particular type descriptor instance associated with the particular plug-in type. The plug-in type framework is designated, prior to encountering any request to perform the type-constrained operation, for obtaining type descriptor instances which define constraints on plug-in types, to an extent that any such constraints exist. The particular type descriptor instance defines a particular type constraint that does not match any single built-in type. The runtime environment performs the type-constrained operation, which comprises using the particular type descriptor instance to evaluate the particular type constraint associated with the particular plug-in type.

Type-constrained operations for plug-in types

Determining different resolution states for a parametric constant in different contexts

A type restriction contextually modifies an existing type descriptor. The type restriction is imposed on a data structure to restrict the values that are assumable by the data structure. The type restriction does not cancel or otherwise override the effect of the existing type descriptor on the data structure. Rather the type restriction may declare that a value of the data structure's type is forbidden for the data structure. Additionally or alternatively, the type restriction may declare that an element count allowable for a data structure's type is forbidden for the data structure. Type restriction allows optionality (where only a singleton value for a data structure is allowed), empty sets (where no value for a data structure is allowed), and multiplicity (where only a limited element count for a data structure) to be injected into a code set independent of data type. Type restriction allows certain optimizations to be performed.

Implementing a type restriction that restricts to a singleton value or zero values

Implementing a type restriction that restricts to a maximum or specific element count

Instantiating a parametric class within a specialized context

A compiler is capable of compiling instructions that do or do not supply specialization information for a generic type. The generic type is compiled into an unspecialized type. If specialization information was supplied, the unspecialized type is adorned with information indicating type restrictions for application programming interface (API) points associated with the unspecialized type, which becomes a specialized type. A runtime environment is capable of executing calls to a same API point that do or do not indicate a specialized type, and is capable of executing calls to a same API point of objects of an unspecialized type or of objects of a specialized type. When the call to an API point indicates a specialized type, and the specialized type matches that of the object (if the API point belongs to an object), then a runtime environment may perform optimized accesses based on type restrictions derived from the specialized type.

Implementing optional specialization when compiling code

Techniques for computing and storing object identity hash values are disclosed. In some embodiments, a runtime system generates a value, such as a nonce, that is unique to a particular allocation region within memory. The runtime system may mix the value with one or more seed values that are associated with one or more respective objects stored in the allocation region. The runtime system may obtain object identifiers for the respective objects by applying a hash function to the result of mixing the seed value with at least the value associated with the allocation region. Conditioning operations may also be applied before, during or after the mixing operations to make the values appear more random. The nonce value may be changed from time to time, such as when memory is recycled in the allocation region, to reduce the risk of hash collisions.

Computation and storage of object identity hash values

Techniques for accessing a migrated method include: identifying a request to invoke a method defined by a particular type; identifying, in the particular type: an older version of the method that is (a) associated with a method name and (b) configured to return values of a first return type, and a current version of the method that is (a) associated with the method name and (b) configured to return values of a second return type; determining that the first request specifies the first return type; responsive to determining that the first request specifies the first return type: executing the current version of the method to obtain a value of the second return type; applying one or more conversion functions to convert the value of the second return type to a value of the first return type; returning the value of the first return type responsive to the first request.

Accessing a migrated member in an updated type

Executing a parametric method within a specialized context

Implementing a type restriction that restricts to a non-polymorphic layout type or a maximum value

Growing community of inventors

San Jose, CA, United States of America

John Robert Rose