JavaScript engine

• US 20030110160A1
• Filed: 10/30/2002
• Published: 06/12/2003
• Est. Priority Date: 11/13/2001
• Status: Active Grant

• Current Assignee: Meta Platforms, Inc. (f/k/a Facebook, Inc.)
• Original Assignee: America Online Inc. (Warner Bros. Discovery, Inc.)
• Inventors: Eich, Brendan
• Granted Patent: US 6,892,200 B2
• Time in Patent Office: Days
• US Class Current: 707/2
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface

Abstract

A JavaScript enhancement is provided that increases performance of the JavaScript by avoiding the use of locking mechanisms in multi-threaded sessions. To do so, an object is deemed owned by a thread exclusively until the script is ended or suspended. Because scripts are typically short and complete quickly, the overhead to start and end a request containing a script is much less than the overhead of locking each and every object access done by the script, on average.

Claims

1. A method for avoiding using a locking mechanism when a thread having a context requests to use an object having a scope and having an owner of said scope, said method comprising:

determining if said owner is the same as said context;

if said owner is the same as said context, then avoiding using locking mechanism;

if said owner is not the same as said context, then promoting a lock on said object'"'"'s scope.

2. The method of claim 1, further comprising:

initially setting said object'"'"'s scope'"'"'s owner to a current context of a current thread when said object'"'"'s scope is created;

resetting said object'"'"'s scope'"'"'s owner to a second thread'"'"'s context when said second thread claims exclusive ownership of said scope; and

setting said object'"'"'s scope'"'"'s owner to null when said ownership is shared.

3. A method for locking an object having an ownership attribute, wherein a first thread having a first context makes a first request to a JavaScript engine at a first time, said first request comprising using said object, and a second thread having a second context makes a second request to the JavaScript engine at a second and later time, said second request comprising using said object, said method comprising:

said JavaScript engine determining if said first request is finished with said object;

if said first request is not finished with said object, then;

said JavaScript engine comparing said second context of said second thread with said ownership attribute of said object;

if said comparison is different, then suspending said second request until said first request is finished with said object;

said JavaScript engine setting said ownership attribute of said object to null;

said JavaScript engine resuming said second request;

otherwise, said JavaScript engine setting said ownership attribute of said object to said second context and processing said second request.

4. An apparatus for avoiding using a locking mechanism when a thread having a context requests to use an object having a scope and having an owner of said scope, said apparatus comprising:

means for determining if said owner is the same as said context;

if said owner is the same as said context, then means for avoiding using locking mechanism;

if said owner is not the same as said context, then means for promoting a lock on said object'"'"'s scope.

5. The apparatus of claim 4, further comprising:

means for initially setting said object'"'"'s scope'"'"'s owner to a current context of a current thread when said object'"'"'s scope is created;

means for resetting said object'"'"'s scope'"'"'s owner to a second thread'"'"'s context when said second thread claims exclusive ownership of said scope; and

means for setting said object'"'"'s scope'"'"'s owner to null when said ownership is shared.

6. An apparatus for locking an object having an ownership attribute, wherein a first thread having a first context makes a first request to a JavaScript engine at a first time, said first request comprising using said object, and a second thread having a second context makes a second request to the JavaScript engine at a second and later time, said second request comprising using said object, said method comprising:

means for said JavaScript engine determining if said first request is finished with said object;

if said first request is not finished with said object, then;

means for said JavaScript engine comparing said second context of said second thread with said ownership attribute of said object;

if said comparison is different, then means for suspending said second request until said first request is finished with said object;

means for said JavaScript engine setting said ownership attribute of said object to null;

means for said JavaScript engine resuming said second request;

otherwise, means for said JavaScript engine setting said ownership attribute of said object to said second context and processing said second request.