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--- !ditz.rubyforge.org,2008-03-06/issue
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title: force specific key slots for internal non-configurable properties where it matters
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desc: |-
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For instance:
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* Proxy target/handler should reside in a specific slot to make the
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lookup fast. In other words, if DUK_HOBJECT_FLAG_SPECIAL_PROXYOBJ
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is set, one can be certain that target/handler are in specific slots
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without a scan.
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* Internal values for Buffer, String, etc, should reside in a known slot.
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* Typed array internal properties (byte offset, byte length, underlying
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buffer).
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* Enumerator.
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Putting values in specific slots is safe provided that:
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* Each "trusted slot" contains a non-configurable property that is never
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deleted (even internally, with raw operations).
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* Each property preceding a "trusted slot" is also trusted (i.e.
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non-deletable).
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If this is the case, the properties never change their slot because they
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are never affected by object compaction.
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If trusted slots are used, they should be asserted both during creation
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and usage, and defines should be used for the slots.
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Without trusted slots it will be difficult to support e.g. typed arrays
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efficiently without creating a new struct subtype with more fields or
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increasing the object footprint for all objects.
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type: :task
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component: duk
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release:
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reporter: Sami Vaarala <sami.vaarala@iki.fi>
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status: :unstarted
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disposition:
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creation_time: 2014-04-28 13:05:31.860401 Z
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references: []
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id: 6c9b8a83de00e6d6eb2c4ded8ac0a0ef52ab054b
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log_events:
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- - 2014-04-28 13:05:32.068368 Z
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- Sami Vaarala <sami.vaarala@iki.fi>
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- created
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- ""
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- - 2014-07-24 13:10:09.781408 Z
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- Sami Vaarala <sami.vaarala@iki.fi>
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- unassigned from release v0.12
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- ""
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