Avoid taking a write lock in RegisteredType::{root,clone,drop}
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By moving the registration count into the `Arc`, that is pulling the `Arc` outwards from containing just the `WasmFuncType` to the registration count as well, and turning it into an atomic, we can manipulate the registration count without a write lock. Once that is done, we have the following: * `RegisteredType::root` only needs a read lock, not a write lock. * `RegisteredType::clone`, which used to need a write lock, doesn't need any locking anymore. * `RegisteredType::drop` doesn't need any locking most of the time. The exception is when this is this drop that moves the refcount to zero, in which case grabbing a write lock is still necessary to remove the type from the registry.
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alexcrichton
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Feb 21, 2024
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By moving the registration count into the
Arc, that is pulling theArcoutwards from containing just theWasmFuncTypeto the registration count as well, and turning it into an atomic, we can manipulate the registration count without a write lock. Once that is done, we have the following:RegisteredType::rootonly needs a read lock, not a write lock.RegisteredType::clone, which used to need a write lock, doesn't need any locking anymore.RegisteredType::dropdoesn't need any locking most of the time. The exception is when this is this drop that moves the refcount to zero, in which case grabbing a write lock is still necessary to remove the type from the registry.