92 lines
1.9 KiB
Go
92 lines
1.9 KiB
Go
// Copyright 2024 PingCAP, Inc.
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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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package cursor
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import (
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"sync"
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"sync/atomic"
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)
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// Tracker is used to track the state of cursor inside a session
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type Tracker interface {
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NewCursor(state State) Handle
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GetCursor(id int) Handle
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RangeCursor(f func(cursor Handle) bool)
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}
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var _ Tracker = &cursorTracker{}
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type cursorTracker struct {
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cursors *sync.Map
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idAlloc atomic.Int64
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}
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// NewTracker creates a new cursor tracker
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func NewTracker() Tracker {
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return &cursorTracker{cursors: &sync.Map{}}
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}
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func (c *cursorTracker) NewCursor(state State) Handle {
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id := int(c.idAlloc.Add(1))
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cursor := &cursorHandle{id: id, state: state, tracker: c}
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c.cursors.Store(id, cursor)
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return cursor
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}
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func (c *cursorTracker) GetCursor(id int) Handle {
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cursor, ok := c.cursors.Load(id)
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if !ok {
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return nil
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}
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return cursor.(Handle)
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}
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func (c *cursorTracker) RangeCursor(f func(cursor Handle) bool) {
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c.cursors.Range(func(_, value any) bool {
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return f(value.(Handle))
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})
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}
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func (c *cursorTracker) remove(id int) {
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c.cursors.Delete(id)
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}
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// Handle is used to update/close the cursor.
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type Handle interface {
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ID() int
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GetState() State
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Close()
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}
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var _ Handle = &cursorHandle{}
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type cursorHandle struct {
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id int
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state State
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tracker *cursorTracker
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}
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func (c *cursorHandle) ID() int {
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return c.id
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}
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func (c *cursorHandle) Close() {
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c.tracker.remove(c.id)
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}
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func (c *cursorHandle) GetState() State {
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return c.state
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}
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