Chasm Interface (temporalio#6987)

## What changed?
<!-- Describe what has changed in this PR -->
- Chasm interface

## Why?
<!-- Tell your future self why have you made these changes -->
- For the new CHASM framework

## How did you test it?
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test? Checked in staging env? -->

## Potential risks
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change to production? -->

## Documentation
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stated in `docs/`? If significant
new behavior is added, have you described that in `docs/`? -->

## Is hotfix candidate?
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chasm/component.go

@@ -0,0 +1,100 @@
+// The MIT License
+//
+// Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
+//
+// Copyright (c) 2020 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package chasm
+
+import "context"
+
+type Component interface {
+	LifecycleState() LifecycleState
+
+	// TBD: the framework can just put the component in terminated state
+	// component lifecycle state can still be running when getting terminated
+	// but framework will use some rule to block incoming operations
+	// Terminate()
+
+	// we may not need this in the beginning
+	mustEmbedUnimplementedComponent()
+}
+
+// Embed UnimplementedComponent to get forward compatibility
+type UnimplementedComponent struct{}
+
+func (UnimplementedComponent) LifecycleState() LifecycleState {
+	return LifecycleStateUnspecified
+}
+
+// func (UnimplementedComponent) Terminate() {}
+
+func (UnimplementedComponent) mustEmbedUnimplementedComponent() {}
+
+// Shall it be named ComponentLifecycleState?
+type LifecycleState int
+
+const (
+	LifecycleStateCreated LifecycleState = 1 << iota
+	LifecycleStateRunning
+	// LifecycleStatePaused // <- this can also be a method of the engine: PauseComponent
+	LifecycleStateCompleted
+	LifecycleStateFailed
+	// LifecycleStateTerminated
+	// LifecycleStateReset
+
+	LifecycleStateUnspecified = LifecycleState(0)
+)
+
+type OperationIntent int
+
+const (
+	OperationIntentProgress OperationIntent = 1 << iota
+	OperationIntentObserve
+
+	OperationIntentUnspecified = OperationIntent(0)
+)
+
+// The operation intent must come from the context
+// as the handler may not pass the endpoint request as Input to,
+// say, the chasm.UpdateComponent method.
+// So similar to the chasm engine, handler needs to add the intent
+// to the context.
+type operationIntentCtxKeyType string
+
+const operationIntentCtxKey engineCtxKeyType = "chasmOperationIntent"
+
+func newContextWithOperationIntent(
+	ctx context.Context,
+	intent OperationIntent,
+) context.Context {
+	return context.WithValue(ctx, operationIntentCtxKey, intent)
+}
+
+func operationIntentFromContext(
+	ctx context.Context,
+) OperationIntent {
+	intent, ok := ctx.Value(engineCtxKey).(OperationIntent)
+	if !ok {
+		return OperationIntentUnspecified
+	}
+	return intent
+}

chasm/context.go

@@ -0,0 +1,63 @@
+// The MIT License
+//
+// Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
+//
+// Copyright (c) 2020 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package chasm
+
+import (
+	"context"
+	"time"
+)
+
+type Context interface {
+	// Context is not bound to any component,
+	// so all methods needs to take in component as a parameter
+
+	// NOTE: component created in the current transaction won't have a ref
+	// this is a Ref to the component state at the start of the transition
+	Ref(Component) (ComponentRef, bool)
+	Now(Component) time.Time
+
+	// Intent() OperationIntent
+	// ComponentOptions(Component) []ComponentOption
+
+	getContext() context.Context
+}
+
+type MutableContext interface {
+	Context
+
+	AddTask(Component, TaskAttributes, any) error
+
+	// Add more methods here for other storage commands/primitives.
+	// e.g. HistoryEvent
+
+	// Get a Ref for the component
+	// This ref to the component state at the end of the transition
+	// Same as Ref(Component) method in Context,
+	// this only works for components that already exists at the start of the transition
+	//
+	// If we provide this method, then the method on the engine doesn't need to
+	// return a Ref
+	// NewRef(Component) (ComponentRef, bool)
+}