For each signal handler that is changed, save its state, and restore
the state in a child process after a `fork` and before an `execve`.
Also save and restore the signal mask.
This change requires cooperation from various subsystems, which often
takes the form of a callback registered with the subsystem to be
called before adjusts a signal handler.
Closes#3609
Forbidden set operations on weak sets produced slightly confusing error
messages:
> (define s (weak-set))
> (set-add s 42)
; set-add:
; expected: (not/c set-mutable?)
; given mutable set: (weak-set)
; argument position: 1st
> (set-mutable? s)
#f
Invoking an operation that required an immutable set gave a message
saying that a `(not/c set-mutable?)` was expected, but a `weak-set` is
not recognized by `set-mutable?`, which only recognizes mutable sets
with strongly-held keys. Changing `set-mutable?` to recognize weak sets
seems undesirable.
This patch changes the error message so that the above example produces
the following error:
> (define s (weak-set))
> (set-add s 42)
; set-add:
; expected: (not/c (or/c set-mutable? set-weak?))
; given mutable set: (weak-set)
; argument position: 1st
Instead of keeping a rectord type's ancestry in a vector ordered from
subtype to supertype, keep the vector the other way around, and
include a record type at the end of its own vector. This order makes a
more direct test possible when checking for a known record type,
especially one without a supertype, and it's generally easier to
reason about.
The revised compilation of record predicates trades some speed in one
case for smaller generated code and speed in other cases. The case
that becomes slower is when a predicate succeeds because the record is
an immediate instance of the record type. The cases that go faster are
when a predicate fails for a non-instance record or when a predicate
succeeds for a non-immediate instance. It's possible that an
immediate-instance shortcut is worthwhile on the grounds that it's a
common case for a predicate used as contract, but we opt for simpler
and less code for now, because the difference is small.
Also, add `record-instance?`, which in unsafe mode can skip the check
that its first argument is a record, and cptypes can substitute
`record-instance?` for `record?` in some cases. This change was worked
out independently and earlier by @yjqww6, especially the cptypes part.
Related to #3679
As documented, `define-struct` "is provided for backwards compatibility;
struct is preferred". This PR changes uses of `define-struct` to
`struct` whenever possible in the docs.
On an Apple M1, an example like
(let ([v (make-vector 1000000)])
(for* ([_ (in-range 100)]
[i (in-range 1000000)])
(vector-set! v i (+ 1 i))))
would generate tightly interleaved fence and store operations, which
seems to make the processor unhappy so that the code run 40x slower
than it should.
A key part of the example is that `(+ 1 i)` defeats cp0-level
inference that the result will be a fixnum. A dynamic fixnum test
avoids adding the update to a remembered set as part of the write
barrier, but the memory fence needed for ARM must be before the store,
while the fixnum test was after the store. This change bundles the
write fence and remember-set update under a `fixnum?` guard, so they
happen to gether or not at all --- at the small cost of generating the
store instruction(s) in two branches. In the example above, neither
the fence nor remember-set update happen, but changing `(+ 1 i)` to
`(quote x)` triggers both, and performance is still ok.
Remove a `with-continuation-mark` that is redundant because its both
is another `with-continuation-mark` with the same key. That's useful
for reducing a pattern that appears after some `if`-removing
optimizations on code with errortrace-generated annotations.
Use a comment trick to make `nmake` see a different default target
than `make`, which will save a small amount of hassle from forgetting
to type `nmake win`.
This change allows a query that is run in an OS thread to succeed even
when the connection is custodian-disconnected. Previously, the part in
the OS thread would complete, and then the operations needed to
package the result would fail. This fix moves some of those operations
to the OS thread and makes read-tx-status work when disconnected.
Replace "3m and/or CGC" with "BC", use "implementation" instead of
"variant", add a section on implementations to the reference,
update corners where the documentation suggests that BC/3m is the
default, and generally order CS first.
Clean up the implementation. For example predicate-union was
calling predicate-implies? like 20 times. With the new
implementation this can be done in a single pass.
Also, this changes the results of the functions for 'bottom and
#f so they behave like sets. So this removes some special cases
and makes the functions more consistent.
Relative-path handling for `fasl->s-exp` was meant to be like code
unmarshaling, but it did not fall back to `(current-directory)` when
`(current-load-relative-directory)` is #f. There's some risk to
changing the behavior of `fasl->s-exp`, but better matching the intent
seems at least as likely to fix problems as create them. One problem
it fixes is in CS code marshaling.
Closesracket/drracket#421 (again)
As described in #3635, there isn’t currently any good way to use
first-class definition contexts without evaluating define-syntaxes RHSs
multiple times. For macros like `class` and `unit`, it’s unclear if that
can be avoided, but for `block`, the first-class definition context
turns out to not be necessary.
This commit changes the implementation strategy used by `block` to a
trampolining macro rather than a first-class definition context. This
has the nice side-effect of avoiding the issue described in #3198, too.
Visual Studio 2015 duplicates the "Replace me for EXE hack" string in
the GRacket executable, which breaks the hack. Adding the /GF compiler
flag counteracts that duplication, and it's consistent with
`<StringPooling>true</StringPooling>` in the BC projects.
For CS, the default error display handler was not using `prop:exn:srcloc`.
For BC, a bad `prop:exn:srcloc` that returned a value other than a
list of srclocs coudl cause a crash.
Related to #3645
