* runtime: fix ticker not stopping when Stop races with its callback
On the threads and cores schedulers, timer callbacks run concurrently
with user goroutines.
If Stop (or Reset) was called in the window after the node was popped
but before its callback re-added it, removeTimer would not find the
timer in the queue, so it would be re-added to timer anyway.
Track timers whose callback is currently running in a firing list, and
have removeTimer mark a firing timer as stopped so its callback does not
re-add it.
Also make the timers test drain robust: allow a possible in-flight tick
delivered concurrently with Stop to settle before draining the channel.
Signed-off-by: deadprogram <ron@hybridgroup.com>
* runtime: fix Stop/Reset semantics when racing a firing timer callback
Address review feedback on the ticker Stop-race fix. On the threads and
cores schedulers a timer callback runs concurrently with user goroutines,
which left several problems:
- removeTimer reported a firing timer as successfully removed, so
Stop/Reset could return true even though the callback had already
started (wrong semantics, notably for AfterFunc). firingTimerStop now
returns a bool and removeTimer no longer hands the still-firing node
back to resetTimer.
- The periodic advance (when += period) ran in timerCallback outside the
scheduler timer lock. Move it into each scheduler's reAddTimer, under
the lock and after the stopped check, so a concurrent Reset can't have
its freshly-queued deadline corrupted.
- resetTimer now sets when/period after removeTimer for the same reason.
Add testdata/timer_stop_reset_race.go and TestTimerStopResetRace, which
reproduce the stop-while-firing and reset-while-firing races via the
runtime timer linkname hooks.
Signed-off-by: deadprogram <ron@hybridgroup.com>
* runtime: fix timer Stop/Reset race with firing periodic timers
Signed-off-by: deadprogram <ron@hybridgroup.com>
---------
Signed-off-by: deadprogram <ron@hybridgroup.com>
The reason is that allocating without a heap is usually more visible
than using an uninitialized random generator which is subtle and may
lead to security vulnerabilities.
Based on suggestion from @eliasnaur
Signed-off-by: deadprogram <ron@hybridgroup.com>
This commit adds support for a scheduler that runs a scheduler on all
available cores. It is meant to be used on baremetal systems with a
fixed number of cores, such as the RP2040.
The initial implementation adds support for multicore scheduling to the
riscv-qemu target as a convenient testing target. This means that this
new multicore scheduler is tested in CI, including a bunch of standard
library tests (`make tinygo-test-baremetal`). This should ensure the new
scheduler is reasonably well tested before trying to use it on
harder-to-debug targets like the RP2040.
The system stack is only needed when we're not on it. So we can directly
call task.SystemStack() without problems.
This also saves a tiny bit of binary size.
For the threads scheduler, it makes sense to have NumCPU available.
For all other schedulers, the number of available CPUs is practically
limited to one by the scheduler (even though the system might have more
CPUs).
This variable is only necessary on the cooperative and none scheduler.
It is not used on the threads scheduler.
The reason for moving is that the upcoming multicore baremetal scheduler
also needs mainExited but of a different type: an atomic variable
instead of a plain boolean.
This ensures:
1. The xorshift state is initialized during interp.
2. The xorshift state gets initialized to a real random number on
hardware that supports it at runtime.
This fixes a big binary size regression from the previous commit. It's
still not perfect: most programs increase binary size by a few bytes.
But it's not nearly as bad as before.
This moves all scheduler code into a separate file that is only compiled
when there's a scheduler in use (the tasks or asyncify scheduler, which
are both cooperative). The main goal of this change is to make it easier
to add a new "scheduler" based on OS threads.
It also fixes a few subtle issues with `-gc=none`:
- Gosched() panicked. This is now fixed to just return immediately
(the only logical thing to do when there's only one goroutine).
- Timers aren't supported without a scheduler, but the relevant code
was still present and would happily add a timer to the queue. It
just never ran. So now it exits with a runtime error, similar to any
blocking operation.
In the early days of TinyGo, the idea of `postinit` was to enable
interrupts only after initializers have run. Which kind of makes
sense... except that `time.Sleep` is allowed in init code and
`time.Sleep` requires interrupts to be enabled. Therefore, interrupts
must be enabled while initializers are being run.
This commit simply moves the enabling of interrupts to a point right
before running package initializers. It also removes `runtime.postinit`,
which is not necessary anymore (and was only used on AVR).
This change fixes the edge case where a negative sleep time is provided.
When this happens, the call now returns immediately (as specified by the docs for time.Sleep).
This commit refactors both determining the current time and sleeping for
a given time. It also improves precision for many chips.
* The nrf chips had a long-standing TODO comment about a slightly
inaccurate clock. This should now be fixed.
* The SAM D2x/D5x chips may have a slightly more accurate clock,
although probably within the error margin of the RTC. Also, by
working with RTC ticks and converting in the least number of places,
code size is often slightly reduced (usually just a few bytes, up to
around 1kB in some cases).
* I believe the HiFive1 rev B timer was slightly wrong (32768Hz vs
30517.6Hz). Because the datasheet says the clock runs at 32768Hz,
I've used the same conversion code here as in the nrf and sam cases.
* I couldn't test both stm32 timers, so I kept them as they currently
are. It may be possible to make them more efficient by using the
native tick frequency instead of using microseconds everywhere.
Ron Evans
Ayke van Laethem
Elias Naur
Yurii Soldak
Nia Waldvogel
Jaden Weiss