When 64-bit atomics are supported, use 32-bit queue indices. This
greatly improves resilience to ABA and has no impact on performance on
64-bit platforms.
Fixes: #5041
Functions that may panic can be annotated with `#[track_caller]` so that
in the event of a panic, the function where the user called the
panicking function is shown instead of the file and line within Tokio
source.
This change adds `#[track_caller]` to two public APIs in tokio task
module which weren't added in #4848.
* `tokio::task::block_in_place`
* `tokio::task::spawn_local`
These APIs had call stacks that went through closures, which is a use
case not supported by `#[track_caller]`. These two cases have been
refactored so that the `panic!` call is no longer inside a closure.
Tests have been added for these two new cases.
Refs: #4413
This patch removes all internal `Unpark` runtime types. The runtime now
uses the `Handle` types (`runtime::io::Handle` and
`runtime::time::Handle`) to signal threads to unpark.
Without separate `Unpark` types, future patches will be able to remove
more `Arc`s used inside various drivers.
This patch removes the driver Unpark handle out of the multi-thread
parker and passes a reference in when it is needed. This is a first step
towards getting rid of the separate driver unpark handle in favor of
just using the regular driver handle. Because the regular driver handle
is owned at a higher level (at the top of the worker struct).
This is the equivalent as tokio-rs/tokio#5023, but for the MultiThread
scheduler. This patch updates `MultiThread` to use `Arc<Handle>` for all
of its cross-thread needs instead of `Arc<Shared>`.
The effect of this change is that the multi-thread scheduler only has a
single `Arc` type, which includes the driver handles, keeping all
"shared state" together.
This is the next step in the internal runtime refactoring. This patch
updates `CurrentThread` to use `Arc<Handle>` for all of its cross-thread
needs instead of `Arc<Shared>`.
The effect of this change is that the current-thread scheduler only has
a single `Arc` type, which includes the driver handles, keeping all
"shared state" together.
The `runtime::Handle` struct is part of the public API but is also used
internally. This has created a bit of tension. An earlier patch made
defined Handle as a private struct in some cases when `rt` is not
enabled.
This patch splits out internal handle concerns into a new
`scheduler::Handle` type, which will only be internal. This also defines
a `Handle` type for each scheduler variant. Eventually, the
per-scheduler `Handle` types will replace the per-scheduler `Spawner`
types, but more work is needed before we can make that change.
The `tokio::select!` macro polls branches in a random order. While this
is desirable in production, for testing purposes a more deterministic
approach can be useul.
This change adds an additional parameter `rng_seed` to the runtime
`Builder` to set the random number generator seed. This value is then
used to reset the seed on the current thread when the runtime is entered
into (restoring the previous value when the thread leaves the runtime). All
threads created explicitly by the runtime also have a seed set as the
runtime is built. Each thread is set with a seed from a deterministic
sequence.
This guarantees that calls to the `tokio::select!` macro which are
performed in the same order on the same thread will poll branches in the
same order.
Additionally, the peer chosen to attempt to steal work from also uses a
deterministic sequence if `rng_seed` is set.
Both the builder parameter as well as the `RngSeed` struct are marked
unstable initially.
The `runtime::Kind` enum doesn't really represent the runtime flavor,
but is an enumeration of the different scheduler types. This patch
renames the enum to reflect this.
At a later time, it is likely the `Scheduler` enum will be moved to
`tokio::runtime::scheduler`, but that is punted to a later PR.
This rename is to make space for other enums
This patch removes println statements from tests. Some of these were
used to test that types implement `fmt::Debug`. These println statements
have been replaced with an equivalent test that does not output to
STDOUT. The rest of the println statements are most likely left over
from debugging sessions.
Currently, drivers are responsible for clean up when they are dropped.
This is possible today because each driver struct holds a reference to
its internal handle.
As part of an effort to decouple drivers from their handles, this patch
removes the drop implementations for the time and IO driver in favor of
having the scheduler explicitly call `shutdown()` as part of its
shutdown process. The scheduler will hold a reference to both the driver
and the driver handles, so in the future, it will be able to pass in the
driver handles as part of the shutdown process.
Currently, the various resource drivers use a layered approach where
each driver contains the next one. When the scheduler calls park on the
top-most driver, it does work then calls park on the inner driver it
holds. The handles do the same with unparking.
This patch is a step towards refactoring the runtime to move away from
the nested approach towards keeping all drivers and handles together in
a single runtime driver/handle. The unparker is removed from the time
handle and placed in the runtime handle and is passed into the time
driver as needed.
The `TimerEntry` struct is the internal integration point for public
time APIs (`sleep`, `interval`, ...) with the time driver. Currently,
`TimerEntry` holds an ref-counted reference to the time driver handle.
This patch replaces the reference to the time driver handle with a
reference to the runtime handle. This is part of a larger effort to
consolate internal handles across the runtime.
In an earlier PR (#4629), driver handles were moved into the scheduler
handle (`Spawner`). This was done to let the multi-threaded scheduler
have direct access to the thread pool spawner.
However, we are now working on a greater decoupling of the runtime
internals. All drivers and schedulers will be peers, stored in a single
thread-local variable, and the scheduler will be passed the full
runtime::Handle. This will achieve the original goal of giving the
scheduler access to the thread-pool while also (hopefully) simplifying
other aspects of the code.
As has been pointed out a few times in the past (e.g., #4036 (comment)), each-feature
is not sufficient for features check.
Ideally, we'd like to check all combinations of features, but there are too many
combinations. So limit the max number of simultaneous feature flags to 2 by --depth
option. I think this should be sufficient in most cases as @carllerche said in
taiki-e/cargo-hack#58.
The docs for `Registration::new_with_interest_and_handle` (internal
function) included a reference to two old functions `new_with_interest`
and `new` on the same struct. These functions no longer exist, which
could be confusing.
Since there is currently only a single constructor function on
`Registration`, the misleading text has simply been removed.
A few spawn_blocking methods were implemented on a Handle struct that is
intended to hold all runtime driver handles. These methods make more
sense in the blocking module.
A step towards the goal of consolidating thread-local variables, this
patch removes the `time::Handle` reference from the time driver struct.
The reference is moved a level up and passed into methods that need it.
The end goal is to have a single `Driver` struct that holds each
sub-driver and a single `Handle` ref-counted struct that holds all the
misc handles. Further work on the time driver is blocked by some other
refactoring that will happen in follow-up patches.
Years ago, Tokio was organized as a cluster of separate crates. This
architecture required a trait to represent "park the thread and do
work.". When all crates were combined into a single crate, the `Park`
and `Unpark` traits remained as internal details.
This patch removes these traits as they are no longer needed. This is in
service of a future refactor that will decouple the various resource
drivers and store them in a single struct instead of nesting them.
However, in the mean time, removing the Park/Unpark traits adds a bit of
messy code to make the conditional compilation work. This code will
(hopefully) be short-lived.
This patch makes some minor refactors. It renames `ClockTime` to
`TimeSource` since that is how all variables refer to it. It also moves
the type into a new file.
Finally, it moves the `unpark` handle out of the mutex as it does not
need to be there. Note, the call to `unpark` is still called while the
mutex is held, so there is no functional change. Moving it out of the
mutex is in preparation for moving the unpark handle completely out of
the time driver.
