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feat(Context): provides context integration
I arrived on a solution to provide context support that I was happy to include in the core implementation. Peripheral, and entirely optional extra functionality, as usual. The new Context type simplifies context utilisation, via composition of basic building blocks.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,101 @@ | ||
| /* | ||
| Copyright 2020 Joseph Cumines | ||
| Licensed under the Apache License, Version 2.0 (the "License"); | ||
| you may not use this file except in compliance with the License. | ||
| You may obtain a copy of the License at | ||
| http://www.apache.org/licenses/LICENSE-2.0 | ||
| Unless required by applicable law or agreed to in writing, software | ||
| distributed under the License is distributed on an "AS IS" BASIS, | ||
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| See the License for the specific language governing permissions and | ||
| limitations under the License. | ||
| */ | ||
|
|
||
| package behaviortree | ||
|
|
||
| import ( | ||
| "context" | ||
| "time" | ||
| ) | ||
|
|
||
| // Context provides support for tick(s) utilising context as a means of cancelation, with cancelation triggered by | ||
| // either BT-driven logic or the normal means (parent cancelation, deadline / timeout). | ||
| // | ||
| // Note that it must be initialised by means of it's Init method (implements a tick) prior to use (Context.Tick tick). | ||
| // Init may be ticked any number of times (each time triggering cancelation of any prior context). | ||
| type Context struct { | ||
| parent func() (context.Context, context.CancelFunc) | ||
| ctx context.Context | ||
| cancel context.CancelFunc | ||
| } | ||
|
|
||
| // WithCancel configures the receiver to initialise context like context.WithCancel(parent), returning the receiver | ||
| func (c *Context) WithCancel(parent context.Context) *Context { | ||
| c.parent = func() (context.Context, context.CancelFunc) { return context.WithCancel(parent) } | ||
| return c | ||
| } | ||
|
|
||
| // WithDeadline configures the receiver to initialise context like context.WithDeadline(parent, deadline), returning | ||
| // the receiver | ||
| func (c *Context) WithDeadline(parent context.Context, deadline time.Time) *Context { | ||
| c.parent = func() (context.Context, context.CancelFunc) { return context.WithDeadline(parent, deadline) } | ||
| return c | ||
| } | ||
|
|
||
| // WithTimeout configures the receiver to initialise context like context.WithTimeout(parent, timeout), returning | ||
| // the receiver | ||
| func (c *Context) WithTimeout(parent context.Context, timeout time.Duration) *Context { | ||
| c.parent = func() (context.Context, context.CancelFunc) { return context.WithTimeout(parent, timeout) } | ||
| return c | ||
| } | ||
|
|
||
| // Init implements a tick that will cancel existing context, (re)initialise the context, then succeed, note that it | ||
| // must not be called concurrently with any other method, and it must be ticked prior to any Context.Tick tick | ||
| func (c *Context) Init([]Node) (Status, error) { | ||
| if c.cancel != nil { | ||
| c.cancel() | ||
| } | ||
| if c.parent != nil { | ||
| c.ctx, c.cancel = c.parent() | ||
| } else { | ||
| c.ctx, c.cancel = context.WithCancel(context.Background()) | ||
| } | ||
| return Success, nil | ||
| } | ||
|
|
||
| // Tick returns a tick that will call fn with the receiver's context, returning nil if fn is nil (for consistency | ||
| // with other implementations in this package), note that a Init node must have already been ticked on all possible | ||
| // execution paths, or a panic may occur, due to fn being passed a nil context.Context | ||
| func (c *Context) Tick(fn func(ctx context.Context, children []Node) (Status, error)) Tick { | ||
| if fn != nil { | ||
| return func(children []Node) (Status, error) { return fn(c.ctx, children) } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // Cancel implements a tick that will cancel the receiver's context (noop if it has none) then succeed | ||
| func (c *Context) Cancel([]Node) (Status, error) { | ||
| if c.cancel != nil { | ||
| c.cancel() | ||
| } | ||
| return Success, nil | ||
| } | ||
|
|
||
| // Err implements a tick that will succeed if the receiver does not have a context or it has been canceled | ||
| func (c *Context) Err([]Node) (Status, error) { | ||
| if c.ctx == nil || c.ctx.Err() != nil { | ||
| return Success, nil | ||
| } | ||
| return Failure, nil | ||
| } | ||
|
|
||
| // Done implements a tick that will block on the receiver's context being canceled (noop if it has none) then succeed | ||
| func (c *Context) Done([]Node) (Status, error) { | ||
| if c.ctx != nil { | ||
| <-c.ctx.Done() | ||
| } | ||
| return Success, nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,103 @@ | ||
| /* | ||
| Copyright 2020 Joseph Cumines | ||
| Licensed under the Apache License, Version 2.0 (the "License"); | ||
| you may not use this file except in compliance with the License. | ||
| You may obtain a copy of the License at | ||
| http://www.apache.org/licenses/LICENSE-2.0 | ||
| Unless required by applicable law or agreed to in writing, software | ||
| distributed under the License is distributed on an "AS IS" BASIS, | ||
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| See the License for the specific language governing permissions and | ||
| limitations under the License. | ||
| */ | ||
|
|
||
| package behaviortree | ||
|
|
||
| import ( | ||
| "context" | ||
| "testing" | ||
| "time" | ||
| ) | ||
|
|
||
| func TestContext_Tick_nilFn(t *testing.T) { | ||
| if v := new(Context).Tick(nil); v != nil { | ||
| t.Error(`expected nil`) | ||
| } | ||
| } | ||
|
|
||
| func TestContext_Cancel_noContext(t *testing.T) { | ||
| if status, err := new(Context).Cancel(nil); err != nil || status != Success { | ||
| t.Error(status, err) | ||
| } | ||
| } | ||
|
|
||
| func TestContext_Done_noContext(t *testing.T) { | ||
| if status, err := new(Context).Done(nil); err != nil || status != Success { | ||
| t.Error(status, err) | ||
| } | ||
| } | ||
|
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||
| func TestContext_Init_default(t *testing.T) { | ||
| c := new(Context) | ||
| if status, err := c.Init(nil); err != nil || status != Success { | ||
| t.Fatal(status, err) | ||
| } | ||
| ctx := c.ctx | ||
| if err := ctx.Err(); err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| if status, err := c.Init(nil); err != nil || status != Success { | ||
| t.Fatal(status, err) | ||
| } | ||
| if err := ctx.Err(); err == nil { | ||
| t.Error(c) | ||
| } | ||
| if c.ctx == nil || c.cancel == nil || c.ctx.Err() != nil { | ||
| t.Fatal(c) | ||
| } | ||
| c.cancel() | ||
| if c.ctx.Err() == nil { | ||
| t.Fatal(c) | ||
| } | ||
| } | ||
|
|
||
| func TestContext_WithCancel(t *testing.T) { | ||
| ctx, cancel := context.WithCancel(context.Background()) | ||
| defer cancel() | ||
| c := new(Context) | ||
| if v := c.WithCancel(ctx); v != c { | ||
| t.Error(v) | ||
| } | ||
| if c.ctx != nil || c.cancel != nil || c.parent == nil { | ||
| t.Fatal(c) | ||
| } | ||
| if status, err := c.Init(nil); err != nil || status != Success { | ||
| t.Fatal(status, err) | ||
| } | ||
| if c.ctx == nil || c.cancel == nil || c.ctx.Err() != nil { | ||
| t.Fatal(c) | ||
| } | ||
| cancel() | ||
| if err := c.ctx.Err(); err != context.Canceled { | ||
| t.Fatal(err) | ||
| } | ||
| } | ||
|
|
||
| func TestContext_WithDeadline(t *testing.T) { | ||
| c := new(Context) | ||
| if v := c.WithDeadline(context.Background(), time.Now().Add(-time.Second)); v != c { | ||
| t.Error(v) | ||
| } | ||
| if c.ctx != nil || c.cancel != nil || c.parent == nil { | ||
| t.Fatal(c) | ||
| } | ||
| if status, err := c.Init(nil); err != nil || status != Success { | ||
| t.Fatal(status, err) | ||
| } | ||
| if err := c.ctx.Err(); err != context.DeadlineExceeded { | ||
| t.Fatal(err) | ||
| } | ||
| } |
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