When repeatedly enqueing and dequeing a single item in a Queue we end
up faulting in all the pages for the underlying Vector. This is a
performance issue - especially where the element type is large.
Previously the Queue class used a SinglyLinkedList to manage its queue
segments. This changes the Queue class to use the IntrusiveList class
instead which saves us one allocation per segment.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
Problem:
- Using regular functions rather than function templates results in
the arguments not being deduced. This then requires the same
function to be written multiple times and for `move` to be used
rather than `forward`.
Solution:
- Collapse multiple function overloads to a single function template
with a deduced argument. This allows the argument to be a forwarding
reference and bind to either an l-value or r-value and forward the
value.
Problem:
- Many constructors are defined as `{}` rather than using the ` =
default` compiler-provided constructor.
- Some types provide an implicit conversion operator from `nullptr_t`
instead of requiring the caller to default construct. This violates
the C++ Core Guidelines suggestion to declare single-argument
constructors explicit
(https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c46-by-default-declare-single-argument-constructors-explicit).
Solution:
- Change default constructors to use the compiler-provided default
constructor.
- Remove implicit conversion operators from `nullptr_t` and change
usage to enforce type consistency without conversion.
As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
The underlying data structure is a singly-linked list of Vector<T>.
We never shift any of the vector contents around, but we batch the memory
allocations into 1000-element segments.
