43 lines
1.9 KiB
Go
43 lines
1.9 KiB
Go
package filecache
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import (
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"crypto/sha256"
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"io"
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)
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// Cache allows the compiler engine to skip compilation of wasm to machine code
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// where doing so is redundant for the same wasm binary and version of wazero.
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//
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// This augments the default in-memory cache of compiled functions, by
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// decoupling it from a wazero.Runtime instance. Concretely, a runtime loses
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// its cache once closed. This cache allows the runtime to rebuild its
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// in-memory cache quicker, significantly reducing first-hit penalty on a hit.
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//
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// See New for the example implementation.
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type Cache interface {
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// Get is called when the runtime is trying to get the cached compiled functions.
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// Implementations are supposed to return compiled function in io.Reader with ok=true
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// if the key exists on the cache. In the case of not-found, this should return
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// ok=false with err=nil. content.Close() is automatically called by
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// the caller of this Get.
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//
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// Note: the returned content won't go through the validation pass of Wasm binary
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// which is applied when the binary is compiled from scratch without cache hit.
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Get(key Key) (content io.ReadCloser, ok bool, err error)
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//
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// Add is called when the runtime is trying to add the new cache entry.
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// The given `content` must be un-modified, and returned as-is in Get method.
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//
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// Note: the `content` is ensured to be safe through the validation phase applied on the Wasm binary.
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Add(key Key, content io.Reader) (err error)
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//
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// Delete is called when the cache on the `key` returned by Get is no longer usable, and
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// must be purged. Specifically, this is called happens when the wazero's version has been changed.
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// For example, that is when there's a difference between the version of compiling wazero and the
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// version of the currently used wazero.
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Delete(key Key) (err error)
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}
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// Key represents the 256-bit unique identifier assigned to each cache entry.
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type Key = [sha256.Size]byte
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