In order to be able to reasonably debug error results from things like
JSWindowActor.sendQuery, we need to be able to clone errors across process
boundaries, so that they can be propagated to the caller that initiated a
query. The standard for the structured clone algorithm does not allow cloning
errors directly, so this patch instead adds a chrome-only wrapper object which
supports structured clone writing, and on reading, automatically decodes to
the error object it wraps. Callers who wish to clone an Error or Exception
object simply need to wrap it in a ClonedErrorHolder before sending.
Differential Revision: https://phabricator.services.mozilla.com/D50881
In order to be able to reasonably debug error results from things like
JSWindowActor.sendQuery, we need to be able to clone errors across process
boundaries, so that they can be propagated to the caller that initiated a
query. The standard for the structured clone algorithm does not allow cloning
errors directly, so this patch instead adds a chrome-only wrapper object which
supports structured clone writing, and on reading, automatically decodes to
the error object it wraps. Callers who wish to clone an Error or Exception
object simply need to wrap it in a ClonedErrorHolder before sending.
Differential Revision: https://phabricator.services.mozilla.com/D50881
Summary: Really sorry for the size of the patch. It's mostly automatic
s/nsIDocument/Document/ but I had to fix up in a bunch of places manually to
add the right namespacing and such.
Overall it's not a very interesting patch I think.
nsDocument.cpp turns into Document.cpp, nsIDocument.h into Document.h and
nsIDocumentInlines.h into DocumentInlines.h.
I also changed a bunch of nsCOMPtr usage to RefPtr, but not all of it.
While fixing up some of the bits I also removed some unneeded OwnerDoc() null
checks and such, but I didn't do anything riskier than that.
Correctness improvements:
* UTF errors are handled safely per spec instead of dangerously truncating
strings.
* There are fewer converter implementations.
Performance improvements:
* The old code did exact buffer length math, which meant doing UTF math twice
on each input string (once for length calculation and another time for
conversion). Exact length math is more complicated when handling errors
properly, which the old code didn't do. The new code does UTF math on the
string content only once (when converting) but risks allocating more than
once. There are heuristics in place to lower the probability of
reallocation in cases where the double math avoidance isn't enough of a
saving to absorb an allocation and memcpy.
* Previously, in UTF-16 <-> UTF-8 conversions, an ASCII prefix was optimized
but a single non-ASCII code point pessimized the rest of the string. The
new code tries to get back on the fast ASCII path.
* UTF-16 to Latin1 conversion guarantees less about handling of out-of-range
input to eliminate an operation from the inner loop on x86/x86_64.
* When assigning to a pre-existing string, the new code tries to reuse the
old buffer instead of first releasing the old buffer and then allocating a
new one.
* When reallocating from the new code, the memcpy covers only the data that
is part of the logical length of the old string instead of memcpying the
whole capacity. (For old callers old excess memcpy behavior is preserved
due to bogus callers. See bug 1472113.)
* UTF-8 strings in XPConnect that are in the Latin1 range are passed to
SpiderMonkey as Latin1.
New features:
* Conversion between UTF-8 and Latin1 is added in order to enable faster
future interop between Rust code (or otherwise UTF-8-using code) and text
node and SpiderMonkey code that uses Latin1.
MozReview-Commit-ID: JaJuExfILM9
This interface is not usable from JS, because we don't expose initialize() in
the WebIDL bindings for Exception. And C++ doesn't use it.
MozReview-Commit-ID: LsIm4YA0YZE
