/
engine_cache.go
296 lines (264 loc) · 9.72 KB
/
engine_cache.go
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package wazevo
import (
"bytes"
"context"
"crypto/sha256"
"encoding/binary"
"fmt"
"hash/crc32"
"io"
"runtime"
"unsafe"
"github.com/tetratelabs/wazero/experimental"
"github.com/tetratelabs/wazero/internal/engine/wazevo/backend"
"github.com/tetratelabs/wazero/internal/engine/wazevo/ssa"
"github.com/tetratelabs/wazero/internal/engine/wazevo/wazevoapi"
"github.com/tetratelabs/wazero/internal/filecache"
"github.com/tetratelabs/wazero/internal/platform"
"github.com/tetratelabs/wazero/internal/u32"
"github.com/tetratelabs/wazero/internal/u64"
"github.com/tetratelabs/wazero/internal/wasm"
)
var crc = crc32.MakeTable(crc32.Castagnoli)
// fileCacheKey returns a key for the file cache.
// In order to avoid collisions with the existing compiler, we do not use m.ID directly,
// but instead we rehash it with magic.
func fileCacheKey(m *wasm.Module) (ret filecache.Key) {
s := sha256.New()
s.Write(m.ID[:])
s.Write(magic)
s.Sum(ret[:0])
return
}
func (e *engine) addCompiledModule(module *wasm.Module, cm *compiledModule) (err error) {
e.addCompiledModuleToMemory(module, cm)
if !module.IsHostModule && e.fileCache != nil {
err = e.addCompiledModuleToCache(module, cm)
}
return
}
func (e *engine) getCompiledModule(module *wasm.Module, listeners []experimental.FunctionListener, ensureTermination bool) (cm *compiledModule, ok bool, err error) {
cm, ok = e.getCompiledModuleFromMemory(module)
if ok {
return
}
cm, ok, err = e.getCompiledModuleFromCache(module)
if ok {
cm.parent = e
cm.module = module
cm.sharedFunctions = e.sharedFunctions
cm.ensureTermination = ensureTermination
cm.offsets = wazevoapi.NewModuleContextOffsetData(module, len(listeners) > 0)
if len(listeners) > 0 {
cm.listeners = listeners
cm.listenerBeforeTrampolines = make([]*byte, len(module.TypeSection))
cm.listenerAfterTrampolines = make([]*byte, len(module.TypeSection))
for i := range module.TypeSection {
typ := &module.TypeSection[i]
before, after := e.getListenerTrampolineForType(typ)
cm.listenerBeforeTrampolines[i] = before
cm.listenerAfterTrampolines[i] = after
}
}
e.addCompiledModuleToMemory(module, cm)
ssaBuilder := ssa.NewBuilder()
machine := newMachine()
be := backend.NewCompiler(context.Background(), machine, ssaBuilder)
cm.executables.compileEntryPreambles(module, machine, be)
// Set the finalizer.
e.setFinalizer(cm.executables, executablesFinalizer)
}
return
}
func (e *engine) addCompiledModuleToMemory(m *wasm.Module, cm *compiledModule) {
e.mux.Lock()
defer e.mux.Unlock()
e.compiledModules[m.ID] = cm
if len(cm.executable) > 0 {
e.addCompiledModuleToSortedList(cm)
}
}
func (e *engine) getCompiledModuleFromMemory(module *wasm.Module) (cm *compiledModule, ok bool) {
e.mux.RLock()
defer e.mux.RUnlock()
cm, ok = e.compiledModules[module.ID]
return
}
func (e *engine) addCompiledModuleToCache(module *wasm.Module, cm *compiledModule) (err error) {
if e.fileCache == nil || module.IsHostModule {
return
}
err = e.fileCache.Add(fileCacheKey(module), serializeCompiledModule(e.wazeroVersion, cm))
return
}
func (e *engine) getCompiledModuleFromCache(module *wasm.Module) (cm *compiledModule, hit bool, err error) {
if e.fileCache == nil || module.IsHostModule {
return
}
// Check if the entries exist in the external cache.
var cached io.ReadCloser
cached, hit, err = e.fileCache.Get(fileCacheKey(module))
if !hit || err != nil {
return
}
// Otherwise, we hit the cache on external cache.
// We retrieve *code structures from `cached`.
var staleCache bool
// Note: cached.Close is ensured to be called in deserializeCodes.
cm, staleCache, err = deserializeCompiledModule(e.wazeroVersion, cached)
if err != nil {
hit = false
return
} else if staleCache {
return nil, false, e.fileCache.Delete(fileCacheKey(module))
}
return
}
var magic = []byte{'W', 'A', 'Z', 'E', 'V', 'O'}
func serializeCompiledModule(wazeroVersion string, cm *compiledModule) io.Reader {
buf := bytes.NewBuffer(nil)
// First 6 byte: WAZEVO header.
buf.Write(magic)
// Next 1 byte: length of version:
buf.WriteByte(byte(len(wazeroVersion)))
// Version of wazero.
buf.WriteString(wazeroVersion)
// Number of *code (== locally defined functions in the module): 4 bytes.
buf.Write(u32.LeBytes(uint32(len(cm.functionOffsets))))
for _, offset := range cm.functionOffsets {
// The offset of this function in the executable (8 bytes).
buf.Write(u64.LeBytes(uint64(offset)))
}
// The length of code segment (8 bytes).
buf.Write(u64.LeBytes(uint64(len(cm.executable))))
// Append the native code.
buf.Write(cm.executable)
// Append checksum.
checksum := crc32.Checksum(cm.executable, crc)
buf.Write(u32.LeBytes(checksum))
if sm := cm.sourceMap; len(sm.executableOffsets) > 0 {
buf.WriteByte(1) // indicates that source map is present.
l := len(sm.wasmBinaryOffsets)
buf.Write(u64.LeBytes(uint64(l)))
executableAddr := uintptr(unsafe.Pointer(&cm.executable[0]))
for i := 0; i < l; i++ {
buf.Write(u64.LeBytes(sm.wasmBinaryOffsets[i]))
// executableOffsets is absolute address, so we need to subtract executableAddr.
buf.Write(u64.LeBytes(uint64(sm.executableOffsets[i] - executableAddr)))
}
} else {
buf.WriteByte(0) // indicates that source map is not present.
}
return bytes.NewReader(buf.Bytes())
}
func deserializeCompiledModule(wazeroVersion string, reader io.ReadCloser) (cm *compiledModule, staleCache bool, err error) {
defer reader.Close()
cacheHeaderSize := len(magic) + 1 /* version size */ + len(wazeroVersion) + 4 /* number of functions */
// Read the header before the native code.
header := make([]byte, cacheHeaderSize)
n, err := reader.Read(header)
if err != nil {
return nil, false, fmt.Errorf("compilationcache: error reading header: %v", err)
}
if n != cacheHeaderSize {
return nil, false, fmt.Errorf("compilationcache: invalid header length: %d", n)
}
if !bytes.Equal(header[:len(magic)], magic) {
return nil, false, fmt.Errorf(
"compilationcache: invalid magic number: got %s but want %s", magic, header[:len(magic)])
}
// Check the version compatibility.
versionSize := int(header[len(magic)])
cachedVersionBegin, cachedVersionEnd := len(magic)+1, len(magic)+1+versionSize
if cachedVersionEnd >= len(header) {
staleCache = true
return
} else if cachedVersion := string(header[cachedVersionBegin:cachedVersionEnd]); cachedVersion != wazeroVersion {
staleCache = true
return
}
functionsNum := binary.LittleEndian.Uint32(header[len(header)-4:])
cm = &compiledModule{functionOffsets: make([]int, functionsNum), executables: &executables{}}
var eightBytes [8]byte
for i := uint32(0); i < functionsNum; i++ {
// Read the offset of each function in the executable.
var offset uint64
if offset, err = readUint64(reader, &eightBytes); err != nil {
err = fmt.Errorf("compilationcache: error reading func[%d] executable offset: %v", i, err)
return
}
cm.functionOffsets[i] = int(offset)
}
executableLen, err := readUint64(reader, &eightBytes)
if err != nil {
err = fmt.Errorf("compilationcache: error reading executable size: %v", err)
return
}
if executableLen > 0 {
executable, err := platform.MmapCodeSegment(int(executableLen))
if err != nil {
err = fmt.Errorf("compilationcache: error mmapping executable (len=%d): %v", executableLen, err)
return nil, false, err
}
_, err = io.ReadFull(reader, executable)
if err != nil {
err = fmt.Errorf("compilationcache: error reading executable (len=%d): %v", executableLen, err)
return nil, false, err
}
expected := crc32.Checksum(executable, crc)
if _, err = io.ReadFull(reader, eightBytes[:4]); err != nil {
return nil, false, fmt.Errorf("compilationcache: could not read checksum: %v", err)
} else if checksum := binary.LittleEndian.Uint32(eightBytes[:4]); expected != checksum {
return nil, false, fmt.Errorf("compilationcache: checksum mismatch (expected %d, got %d)", expected, checksum)
}
if runtime.GOARCH == "arm64" {
// On arm64, we cannot give all of rwx at the same time, so we change it to exec.
if err = platform.MprotectRX(executable); err != nil {
return nil, false, err
}
}
cm.executable = executable
}
if _, err := io.ReadFull(reader, eightBytes[:1]); err != nil {
return nil, false, fmt.Errorf("compilationcache: error reading source map presence: %v", err)
}
if eightBytes[0] == 1 {
sm := &cm.sourceMap
sourceMapLen, err := readUint64(reader, &eightBytes)
if err != nil {
err = fmt.Errorf("compilationcache: error reading source map length: %v", err)
return nil, false, err
}
executableOffset := uintptr(unsafe.Pointer(&cm.executable[0]))
for i := uint64(0); i < sourceMapLen; i++ {
wasmBinaryOffset, err := readUint64(reader, &eightBytes)
if err != nil {
err = fmt.Errorf("compilationcache: error reading source map[%d] wasm binary offset: %v", i, err)
return nil, false, err
}
executableRelativeOffset, err := readUint64(reader, &eightBytes)
if err != nil {
err = fmt.Errorf("compilationcache: error reading source map[%d] executable offset: %v", i, err)
return nil, false, err
}
sm.wasmBinaryOffsets = append(sm.wasmBinaryOffsets, wasmBinaryOffset)
// executableOffsets is absolute address, so we need to add executableOffset.
sm.executableOffsets = append(sm.executableOffsets, uintptr(executableRelativeOffset)+executableOffset)
}
}
return
}
// readUint64 strictly reads an uint64 in little-endian byte order, using the
// given array as a buffer. This returns io.EOF if less than 8 bytes were read.
func readUint64(reader io.Reader, b *[8]byte) (uint64, error) {
s := b[0:8]
n, err := reader.Read(s)
if err != nil {
return 0, err
} else if n < 8 { // more strict than reader.Read
return 0, io.EOF
}
// Read the u64 from the underlying buffer.
ret := binary.LittleEndian.Uint64(s)
return ret, nil
}