[jira] [Comment Edited] (SLING-913) Add a cache for pre-compiled scripts

["Chetan Mehrotra (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SLING-913?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14050491#comment-14050491 ] 

Chetan Mehrotra edited comment on SLING-913 at 7/2/14 6:17 PM:
---------------------------------------------------------------

[patch|^SLING-913.patch] which implements the above logic. 

Key points
* Introduced a new ScriptNameAware interface to enable passing scriptName via Reader instance. This was required in JS impl where the reader needs to be wrapped in ESPReader if the script is esp script
* Compiled scripts would be cached if possible 

Changes are also available at https://github.com/chetanmeh/sling/commits/SLING-913


was (Author: chetanm):
[patch|^SLING-913.patch] which implements the above logic. 

Key points
* Introduced a new ScriptNameAware interface to enable passing scriptName via Reader instance. This was required in JS impl where the reader needs to be wrapped in ESPReader if the script is esp script
* Compiled scripts would be cached if possible 

> Add a cache for pre-compiled scripts
> ------------------------------------
>
>                 Key: SLING-913
>                 URL: https://issues.apache.org/jira/browse/SLING-913
>             Project: Sling
>          Issue Type: New Feature
>          Components: Scripting
>    Affects Versions: Scripting Core 2.0.2
>            Reporter: Felix Meschberger
>         Attachments: SLING-913.patch
>
>
> The Java Scripting API provides support for scripting langugages which may precompile script source and reuse the precompiled scripts:
>   javax.script.Compilable: May be implemented by a ScriptEngine if precompilation is
>           supported
>   javax.script.CompiledScript: Result of calling the Compilable.compile method.
> The CompiledScript can be called to repeatedly execute the script without the need for recompilation and thus for improved performance.
> The Sling Core Scripting support should make use of this functionality by maintaining a cache compiled scripts with the following properties
>   * indexed by script path
>   * size limited (using LinkedHashMap overwriting the removeEldestEntry method)
>   * entries are weak or soft references ot cache entries
> A cache entry consists of the following information:
>   * The CompiledScript instance
>   * The time of last compilation. this is compared to the last modification time of the script to decide on whether to recompile
> We might probaly also try to add a reference to the script engine implementation bundle to only use the cache entry if the bundle has not been stopped since adding the cache entry
> Executing the script would then consist of the following steps:
>   1 Check the cache of precompiled scripts. if an entry exists and can be used, use it
>   2. if the ScriptEngine is Compilable:
>       2a. Compile the script and add it to the cache and use it
>       2b. Otherwise have the script engine execute the script



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