forked from mirrors/gotosocial
66 lines
2 KiB
Go
66 lines
2 KiB
Go
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/*
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*
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* Copyright 2022 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package grpcsync
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import (
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"context"
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"google.golang.org/grpc/internal/buffer"
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)
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// CallbackSerializer provides a mechanism to schedule callbacks in a
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// synchronized manner. It provides a FIFO guarantee on the order of execution
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// of scheduled callbacks. New callbacks can be scheduled by invoking the
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// Schedule() method.
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//
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// This type is safe for concurrent access.
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type CallbackSerializer struct {
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callbacks *buffer.Unbounded
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}
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// NewCallbackSerializer returns a new CallbackSerializer instance. The provided
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// context will be passed to the scheduled callbacks. Users should cancel the
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// provided context to shutdown the CallbackSerializer. It is guaranteed that no
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// callbacks will be executed once this context is canceled.
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func NewCallbackSerializer(ctx context.Context) *CallbackSerializer {
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t := &CallbackSerializer{callbacks: buffer.NewUnbounded()}
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go t.run(ctx)
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return t
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}
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// Schedule adds a callback to be scheduled after existing callbacks are run.
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//
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// Callbacks are expected to honor the context when performing any blocking
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// operations, and should return early when the context is canceled.
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func (t *CallbackSerializer) Schedule(f func(ctx context.Context)) {
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t.callbacks.Put(f)
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}
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func (t *CallbackSerializer) run(ctx context.Context) {
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for ctx.Err() == nil {
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select {
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case <-ctx.Done():
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return
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case callback := <-t.callbacks.Get():
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t.callbacks.Load()
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callback.(func(ctx context.Context))(ctx)
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}
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}
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}
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