117 lines
3.7 KiB
Go
117 lines
3.7 KiB
Go
package wazero
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import (
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"context"
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"errors"
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"fmt"
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"os"
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"path"
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"path/filepath"
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goruntime "runtime"
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"sync"
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"github.com/tetratelabs/wazero/api"
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"github.com/tetratelabs/wazero/internal/filecache"
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"github.com/tetratelabs/wazero/internal/version"
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"github.com/tetratelabs/wazero/internal/wasm"
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)
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// CompilationCache reduces time spent compiling (Runtime.CompileModule) the same wasm module.
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//
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// # Notes
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//
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// - This is an interface for decoupling, not third-party implementations.
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// All implementations are in wazero.
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// - Instances of this can be reused across multiple runtimes, if configured
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// via RuntimeConfig.
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type CompilationCache interface{ api.Closer }
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// NewCompilationCache returns a new CompilationCache to be passed to RuntimeConfig.
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// This configures only in-memory cache, and doesn't persist to the file system. See wazero.NewCompilationCacheWithDir for detail.
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//
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// The returned CompilationCache can be used to share the in-memory compilation results across multiple instances of wazero.Runtime.
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func NewCompilationCache() CompilationCache {
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return &cache{}
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}
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// NewCompilationCacheWithDir is like wazero.NewCompilationCache except the result also writes
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// state into the directory specified by `dirname` parameter.
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//
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// If the dirname doesn't exist, this creates it or returns an error.
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//
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// Those running wazero as a CLI or frequently restarting a process using the same wasm should
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// use this feature to reduce time waiting to compile the same module a second time.
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//
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// The contents written into dirname are wazero-version specific, meaning different versions of
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// wazero will duplicate entries for the same input wasm.
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//
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// Note: The embedder must safeguard this directory from external changes.
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func NewCompilationCacheWithDir(dirname string) (CompilationCache, error) {
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c := &cache{}
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err := c.ensuresFileCache(dirname, version.GetWazeroVersion())
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return c, err
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}
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// cache implements Cache interface.
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type cache struct {
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// eng is the engine for this cache. If the cache is configured, the engine is shared across multiple instances of
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// Runtime, and its lifetime is not bound to them. Instead, the engine is alive until Cache.Close is called.
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engs [engineKindCount]wasm.Engine
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fileCache filecache.Cache
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initOnces [engineKindCount]sync.Once
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}
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func (c *cache) initEngine(ek engineKind, ne newEngine, ctx context.Context, features api.CoreFeatures) wasm.Engine {
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c.initOnces[ek].Do(func() { c.engs[ek] = ne(ctx, features, c.fileCache) })
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return c.engs[ek]
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}
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// Close implements the same method on the Cache interface.
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func (c *cache) Close(_ context.Context) (err error) {
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for _, eng := range c.engs {
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if eng != nil {
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if err = eng.Close(); err != nil {
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return
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}
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}
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}
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return
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}
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func (c *cache) ensuresFileCache(dir string, wazeroVersion string) error {
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// Resolve a potentially relative directory into an absolute one.
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var err error
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dir, err = filepath.Abs(dir)
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if err != nil {
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return err
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}
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// Ensure the user-supplied directory.
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if err = mkdir(dir); err != nil {
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return err
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}
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// Create a version-specific directory to avoid conflicts.
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dirname := path.Join(dir, "wazero-"+wazeroVersion+"-"+goruntime.GOARCH+"-"+goruntime.GOOS)
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if err = mkdir(dirname); err != nil {
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return err
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}
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c.fileCache = filecache.New(dirname)
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return nil
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}
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func mkdir(dirname string) error {
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if st, err := os.Stat(dirname); errors.Is(err, os.ErrNotExist) {
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// If the directory not found, create the cache dir.
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if err = os.MkdirAll(dirname, 0o700); err != nil {
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return fmt.Errorf("create directory %s: %v", dirname, err)
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}
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} else if err != nil {
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return err
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} else if !st.IsDir() {
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return fmt.Errorf("%s is not dir", dirname)
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}
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return nil
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}
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