Propagates context to all api interface methods that aren't constant (#502)

This prepares for exposing operations like Memory.Grow while keeping the
ability to trace what did that, by adding a `context.Context` initial
parameter. This adds this to all API methods that mutate or return
mutated data.

Before, we made a change to trace functions and general lifecycle
commands, but we missed this part. Ex. We track functions, but can't
track what closed the module, changed memory or a mutable constant.
Changing to do this now is not only more consistent, but helps us
optimize at least the interpreter to help users identify otherwise
opaque code that can cause harm. This is critical before we add more
functions that can cause harm, such as Memory.Grow.

Signed-off-by: Adrian Cole <adrian@tetrate.io>

api/wasm.go

@@ -70,8 +70,8 @@ type Module interface {
 	Name() string
 
 	// Close is a convenience that invokes CloseWithExitCode with zero.
-	Close() error
-	// ^^ not io.Closer as the rationale (static analysis of leaks) is invalid when there are multiple close methods.
+	// Note: When the context is nil, it defaults to context.Background.
+	Close(context.Context) error
 
 	// CloseWithExitCode releases resources allocated for this Module. Use a non-zero exitCode parameter to indicate a
 	// failure to ExportedFunction callers.
@@ -82,7 +82,8 @@ type Module interface {
 	//
 	// Calling this inside a host function is safe, and may cause ExportedFunction callers to receive a sys.ExitError
 	// with the exitCode.
-	CloseWithExitCode(exitCode uint32) error
+	// Note: When the context is nil, it defaults to context.Background.
+	CloseWithExitCode(ctx context.Context, exitCode uint32) error
 
 	// Memory returns a memory defined in this module or nil if there are none wasn't.
 	Memory() Memory
@@ -121,7 +122,7 @@ type Function interface {
 	// encoded according to ResultTypes. An error is returned for any failure looking up or invoking the function
 	// including signature mismatch.
 	//
-	// Note: when `ctx` is nil, it defaults to context.Background.
+	// Note: When the context is nil, it defaults to context.Background.
 	// Note: If Module.Close or Module.CloseWithExitCode were invoked during this call, the error returned may be a
 	// sys.ExitError. Interpreting this is specific to the module. For example, some "main" functions always call a
 	// function that exits.
@@ -153,7 +154,9 @@ type Global interface {
 
 	// Get returns the last known value of this global.
 	// See Type for how to encode this value from a Go type.
-	Get() uint64
+	//
+	// Note: When the context is nil, it defaults to context.Background.
+	Get(context.Context) uint64
 }
 
 // MutableGlobal is a Global whose value can be updated at runtime (variable).
@@ -162,11 +165,14 @@ type MutableGlobal interface {
 
 	// Set updates the value of this global.
 	// See Global.Type for how to decode this value to a Go type.
-	Set(v uint64)
+	//
+	// Note: When the context is nil, it defaults to context.Background.
+	Set(ctx context.Context, v uint64)
 }
 
 // Memory allows restricted access to a module's memory. Notably, this does not allow growing.
 //
+// Note: All functions accept a context.Context, which when nil, default to context.Background.
 // Note: This is an interface for decoupling, not third-party implementations. All implementations are in wazero.
 // Note: This includes all value types available in WebAssembly 1.0 (20191205) and all are encoded little-endian.
 // See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#storage%E2%91%A0
@@ -177,59 +183,67 @@ type Memory interface {
 	// memory has min 0 and max 2 pages, this returns zero.
 	//
 	// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#-hrefsyntax-instr-memorymathsfmemorysize%E2%91%A0
-	Size() uint32
+	Size(context.Context) uint32
 
 	// IndexByte returns the index of the first instance of c in the underlying buffer at the offset or returns false if
 	// not found or out of range.
-	IndexByte(offset uint32, c byte) (uint32, bool)
+	IndexByte(ctx context.Context, offset uint32, c byte) (uint32, bool)
 
 	// ReadByte reads a single byte from the underlying buffer at the offset or returns false if out of range.
-	ReadByte(offset uint32) (byte, bool)
+	ReadByte(ctx context.Context, offset uint32) (byte, bool)
+
+	// ReadUint16Le reads a uint16 in little-endian encoding from the underlying buffer at the offset in or returns
+	// false if out of range.
+	ReadUint16Le(ctx context.Context, offset uint32) (uint16, bool)
 
 	// ReadUint32Le reads a uint32 in little-endian encoding from the underlying buffer at the offset in or returns
 	// false if out of range.
-	ReadUint32Le(offset uint32) (uint32, bool)
+	ReadUint32Le(ctx context.Context, offset uint32) (uint32, bool)
 
 	// ReadFloat32Le reads a float32 from 32 IEEE 754 little-endian encoded bits in the underlying buffer at the offset
 	// or returns false if out of range.
 	// See math.Float32bits
-	ReadFloat32Le(offset uint32) (float32, bool)
+	ReadFloat32Le(ctx context.Context, offset uint32) (float32, bool)
 
 	// ReadUint64Le reads a uint64 in little-endian encoding from the underlying buffer at the offset or returns false
 	// if out of range.
-	ReadUint64Le(offset uint32) (uint64, bool)
+	ReadUint64Le(ctx context.Context, offset uint32) (uint64, bool)
 
 	// ReadFloat64Le reads a float64 from 64 IEEE 754 little-endian encoded bits in the underlying buffer at the offset
 	// or returns false if out of range.
 	// See math.Float64bits
-	ReadFloat64Le(offset uint32) (float64, bool)
+	ReadFloat64Le(ctx context.Context, offset uint32) (float64, bool)
 
 	// Read reads byteCount bytes from the underlying buffer at the offset or returns false if out of range.
-	Read(offset, byteCount uint32) ([]byte, bool)
+	Read(ctx context.Context, offset, byteCount uint32) ([]byte, bool)
 
 	// WriteByte writes a single byte to the underlying buffer at the offset in or returns false if out of range.
-	WriteByte(offset uint32, v byte) bool
+	WriteByte(ctx context.Context, offset uint32, v byte) bool
+
+	// WriteUint16Le writes the value in little-endian encoding to the underlying buffer at the offset in or returns
+	// false if out of range.
+	WriteUint16Le(ctx context.Context, offset uint32, v uint16) bool
 
 	// WriteUint32Le writes the value in little-endian encoding to the underlying buffer at the offset in or returns
 	// false if out of range.
-	WriteUint32Le(offset, v uint32) bool
+	WriteUint32Le(ctx context.Context, offset, v uint32) bool
 
 	// WriteFloat32Le writes the value in 32 IEEE 754 little-endian encoded bits to the underlying buffer at the offset
 	// or returns false if out of range.
 	// See math.Float32bits
-	WriteFloat32Le(offset uint32, v float32) bool
+	WriteFloat32Le(ctx context.Context, offset uint32, v float32) bool
 
 	// WriteUint64Le writes the value in little-endian encoding to the underlying buffer at the offset in or returns
 	// false if out of range.
-	WriteUint64Le(offset uint32, v uint64) bool
+	WriteUint64Le(ctx context.Context, offset uint32, v uint64) bool
 
 	// WriteFloat64Le writes the value in 64 IEEE 754 little-endian encoded bits to the underlying buffer at the offset
 	// or returns false if out of range.
 	// See math.Float64bits
-	WriteFloat64Le(offset uint32, v float64) bool
+	WriteFloat64Le(ctx context.Context, offset uint32, v float64) bool
 
 	// Write writes the slice to the underlying buffer at the offset or returns false if out of range.
-	Write(offset uint32, v []byte) bool
+	Write(ctx context.Context, offset uint32, v []byte) bool
 }
 
 // EncodeI32 encodes the input as a ValueTypeI32.