64 lines
2.5 KiB
Go
64 lines
2.5 KiB
Go
package experimental
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import (
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"context"
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"github.com/tetratelabs/wazero/internal/expctxkeys"
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)
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// CloseNotifier is a notification hook, invoked when a module is closed.
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//
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// Note: This is experimental progress towards #1197, and likely to change. Do
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// not expose this in shared libraries as it can cause version locks.
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type CloseNotifier interface {
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// CloseNotify is a notification that occurs *before* an api.Module is
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// closed. `exitCode` is zero on success or in the case there was no exit
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// code.
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//
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// Notes:
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// - This does not return an error because the module will be closed
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// unconditionally.
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// - Do not panic from this function as it doing so could cause resource
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// leaks.
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// - While this is only called once per module, if configured for
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// multiple modules, it will be called for each, e.g. on runtime close.
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CloseNotify(ctx context.Context, exitCode uint32)
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}
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// ^-- Note: This might need to be a part of the listener or become a part of
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// host state implementation. For example, if this is used to implement state
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// cleanup for host modules, possibly something like below would be better, as
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// it could be implemented in a way that allows concurrent module use.
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//
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// // key is like a context key, stateFactory is invoked per instantiate and
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// // is associated with the key (exposed as `Module.State` similar to go
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// // context). Using a key is better than the module name because we can
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// // de-dupe it for host modules that can be instantiated into different
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// // names. Also, you can make the key package private.
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// HostModuleBuilder.WithState(key any, stateFactory func() Cleanup)`
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//
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// Such a design could work to isolate state only needed for wasip1, for
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// example the dirent cache. However, if end users use this for different
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// things, we may need separate designs.
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//
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// In summary, the purpose of this iteration is to identify projects that
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// would use something like this, and then we can figure out which way it
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// should go.
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// CloseNotifyFunc is a convenience for defining inlining a CloseNotifier.
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type CloseNotifyFunc func(ctx context.Context, exitCode uint32)
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// CloseNotify implements CloseNotifier.CloseNotify.
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func (f CloseNotifyFunc) CloseNotify(ctx context.Context, exitCode uint32) {
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f(ctx, exitCode)
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}
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// WithCloseNotifier registers the given CloseNotifier into the given
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// context.Context.
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func WithCloseNotifier(ctx context.Context, notifier CloseNotifier) context.Context {
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if notifier != nil {
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return context.WithValue(ctx, expctxkeys.CloseNotifierKey{}, notifier)
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}
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return ctx
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}
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