Fix CABI definition of coop thread promotability and add tests - #696
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Fix CABI definition of coop thread promotability and add tests#696lukewagner wants to merge 2 commits into
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Now that the spec requires runtimes to enforce trapping lazily for subtask and intrinsic calls that block sync-typed tasks, several existing tests which previously relied on eager enforcement need to be updated.
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This updates Wasmtime's Component Model async and cooperative multithreading support to match the current specification, including: - Refined rules for trapping when a sync-typed function blocks. We now enforce this "lazily" rather than "eagerly", mwaning a sync-typed function is allowed to call an async-typed function or blocking intrinsic, and if it doesn't actually block, we won't trap. And if the call _does_ block, we will look for any eligible threads to run and run them until no such threads remain, only trapping if and when we still need to block and have no more threads to run. - Ensure that the predicate for determining which threads can be run when a sync-typed function is executing in an instance matches the spec. - Remove the previous "may block" bookkeeping at the task and root instance level, replacing it with (sub-)instance level tracking of whether any sync-typed function is running in that instance. - Run the event loop during start function calls since they are now allowed to call async-typed functions, create and resume threads, etc. Note that this includes `test/component-model` submodule updates which haven't yet been merged to the main branch of the upstream repo, but should be merged soon. See WebAssembly/component-model#696 Fixes bytecodealliance#14117 Co-authored-by: Alex Crichton <alex@alexcrichton.com>
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| ;; TODO: also test sync calls to `{stream,future}.cancel-{read,write}`. As of | ||
| ;; this writing, such calls can only ever block if the host has the other end, | ||
| ;; meaning we can't currently test that case in pure WAST; we'd need custom host | ||
| ;; code. In the future, additional intrinsics (e.g. `stream.read-complete`) may | ||
| ;; enable us to test those cases in pure WAST. |
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For this Wasmtime has a psuedo-host-world of sorts which is intended to be simple-to-define here -- https://github.com/bytecodealliance/wasmtime/blob/bc2f967927f9f0e839095a752bf554c4a09fdd13/crates/wast/src/spectest.rs#L91. I think it'd be reasonable to have a world spectest { ... } or similar with some canonical WIT that has comments for how the functions are expected to be implemented, and that could exercise some host-related functionality too without too much of an increase in complexity on the host side.
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This updates Wasmtime's Component Model async and cooperative multithreading support to match the current specification, including: - Refined rules for trapping when a sync-typed function blocks. We now enforce this "lazily" rather than "eagerly", mwaning a sync-typed function is allowed to call an async-typed function or blocking intrinsic, and if it doesn't actually block, we won't trap. And if the call _does_ block, we will look for any eligible threads to run and run them until no such threads remain, only trapping if and when we still need to block and have no more threads to run. - Ensure that the predicate for determining which threads can be run when a sync-typed function is executing in an instance matches the spec. - Remove the previous "may block" bookkeeping at the task and root instance level, replacing it with (sub-)instance level tracking of whether any sync-typed function is running in that instance. - Run the event loop during start function calls since they are now allowed to call async-typed functions, create and resume threads, etc. Note that this includes `test/component-model` submodule updates which haven't yet been merged to the main branch of the upstream repo, but should be merged soon. See WebAssembly/component-model#696 Fixes bytecodealliance#14117 Co-authored-by: Alex Crichton <alex@alexcrichton.com>
dicej
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This updates Wasmtime's Component Model async and cooperative multithreading support to match the current specification, including: - Refined rules for trapping when a sync-typed function blocks. We now enforce this "lazily" rather than "eagerly", mwaning a sync-typed function is allowed to call an async-typed function or blocking intrinsic, and if it doesn't actually block, we won't trap. And if the call _does_ block, we will look for any eligible threads to run and run them until no such threads remain, only trapping if and when we still need to block and have no more threads to run. - Ensure that the predicate for determining which threads can be run when a sync-typed function is executing in an instance matches the spec. - Remove the previous "may block" bookkeeping at the task and root instance level, replacing it with (sub-)instance level tracking of whether any sync-typed function is running in that instance. - Run the event loop during start function calls since they are now allowed to call async-typed functions, create and resume threads, etc. Note that this includes `test/component-model` submodule updates which haven't yet been merged to the main branch of the upstream repo, but should be merged soon. See WebAssembly/component-model#696 Fixes bytecodealliance#14117 Co-authored-by: Alex Crichton <alex@alexcrichton.com>
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Currently, there is some divergence between Wasmtime and the spec for which coop threads can be switched-to during a synchronous call (when one thread blocks but others can be run). Digging into it, I realized that the spec is buggy (at ensuring the stated Component Invariant #3), so this PR fixes the spec to match what Wasmtime is already correctly doing. However, testing revealed other cases where I expect it's Wasmtime that we want to change to match the (fixed) spec.
(The WASTs added here assume #687 and its WAST tests pass (regarding
thread.*-then-promote) and also probably dovetail with the WASTs merged in #691 discussed in wasmtime/#14117, so cc @alexcrichton and @dicej)