Problem:
- There is no test which guarantees the CircularQueue does not
construct any objects of the value type. The goal is to have
uninitialized memory which can be used.
Solution:
- Add a test requiring that the constructor of the value type is never
called.
This commit also removes a few functions like raw_out and vwarn. If we
want to write raw output, we can do this as follows:
out("{}", "Hello, World!");
The vout stuff isn't really public API anyways, so no need for another
vwarn.
Problem:
- It is not possible to perform a binary search at compile-time
because `binary_search` is not `constexpr`-aware.
Solution:
- Add `constexpr` support.
This implements the transmit time suggestion in (abandoned?)
draft-ietf-ntp-data-minimization. (The other suggestions were already
implemented as far as I can tell.)
Problem:
- `Span` is not `constexpr` aware.
Solution:
- Add `constexpr` support for all parts that do not require
`reinterpret_cast`.
- Modify tests which use the `constexpr` functions.
Double the capacity when used+deleted buckets crosses 60% of capacity.
This appears to be a sweet spot for performance based on some ad-hoc
testing with test-js. :^)
Instead of each hash bucket being a SinglyLinkedList, switch to using
closed hashing (open addressing). Buckets are chained together via
double hashing (hashing the hash until we find an unused bucket.)
This greatly reduces malloc traffic, since each added element no longer
allocates a new linked list node.
Appears performance neutral on test-js. Can definitely be tuned and
could use proper management of load factor, etc.
There is no portable way to forward declare abort because the libc
implementations disagree on the signature.
Originally, I added a __portable_abort function with a "portable"
signature which just called abort. But I really don't like it and just
including <stdlib.h> is simpler.
Note that the headers we include in <AK/TestSuite.h> are no longer
commutative now, we have to include <stdlib.h> before anything else.
Problem:
- Output of decode and encode grow as the decode and encode
happen. This is inefficient because a large size will require many
reallocations.
- `const` qualifiers are missing on variables which are not intended
to change.
Solution:
- Since the size of the decoded or encoded message is known prior to
starting, calculate the size and set the output to that size
immediately. All appends will not incur the reallocation overhead.
- Add `const` qualifiers to show intent.
* AK: Add formatter for JsonValue.
* Inspector: Use new format functions.
* Profiler: Use new format functions.
* UserspaceEmulator: Use new format functions.
Problem:
- The Base64 alphabet and lookup table are initialized at
run-time. This results in an initial start-up cost as well as a
boolean evaluation and branch every time the function is called.
Solution:
- Provide `constexpr` functions which initialize the alphabet and
lookup table at compile-time. These can be called and assigned to a
`constexpr` variable so that there is no run-time cost associated
with the initialization or lookup.
We are adding the process name as prefix and a newline as suffix to any
message written to debug. Thus, the following doesn't make any sense:
for (u8 byte : bytes)
dbg("{:02x} ", byte);
dbgln();
Which function call would put the prefix? This doesn't make any sense,
thus these functions must go.
The example above could be converted to:
StringBuilder builder;
for (u8 byte : bytes)
builder.appendff("{:02x} ", byte);
dbgln("{}", builder.build());
Problem:
- Constructors and conversion operators are not `constexpr`,
but they can be.
- `constexpr` is needed here so that other classes can add `constexpr`
evaluation.
Solution:
- Add the `constexpr` keyword to the constructors and
conversion operators.
- Add `static_assert` tests which ensure the capability works.
Problem:
- m_data is being passed to the constructor of the parent class before
it is initialized. This is not really a problem because the compiler
knows the location and it is only a span being constructed, but it
triggers a warning in clang for use-before-init.
Solution:
- Initialize using a default constructed array and then overwrite it
inside the constructor after the member is initialized.
Formatter is specialized in the header file. The definition in the
implementation file is extraneous and has no effect. Simply removing
it so that there is no confusion.
String literals are just pointers to a constant character. It should be
possible to format them as such. (The default is to print them as
strings still.)
When we write the format specifier '{:#08x}' we are asking for eight
significant digits, zero padding and the prefix '0x'.
However, previously we got only six significant digits because the
prefix counted towards the width. (The number '8' here is the total
width and not the number of significant digits.)
Both fmtlib and printf shared this behaviour. However, I am introducing
a special case here because when we do zero padding we really only care
about the digits and not the width.
Notice that zero padding is a special case anyways, because zero padding
goes after the prefix as opposed to any other padding which goes before
it.
This would previously fail at runtime, and it would have zero indication
of what exactly went wrong.
Also adds `AK::DependentFalse<Ts...>', which is a...dependent false.
In the future all (normal) output should be written by any of the
following functions:
out (currently called new_out)
outln
dbg (currently called new_dbg)
dbgln
warn (currently called new_warn)
warnln
However, there are still a ton of uses of the old out/warn/dbg in the
code base so the new functions are called new_out/new_warn/new_dbg. I am
going to rename them as soon as all the other usages are gone (this
might take a while.)
I also added raw_out/raw_dbg/raw_warn which don't do any escaping,
this should be useful if no formatting is required and if the input
contains tons of curly braces. (I am not entirely sure if this function
will stay, but I am adding it for now.)
