vitess.io/vitess@v0.16.2/go/vt/srvtopo/watch_srvvschema.go (about)

     1  /*
     2  Copyright 2021 The Vitess Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package srvtopo
    18  
    19  import (
    20  	"context"
    21  	"time"
    22  
    23  	"vitess.io/vitess/go/stats"
    24  	vschemapb "vitess.io/vitess/go/vt/proto/vschema"
    25  	"vitess.io/vitess/go/vt/topo"
    26  )
    27  
    28  type SrvVSchemaWatcher struct {
    29  	rw *resilientWatcher
    30  }
    31  
    32  type cellName string
    33  
    34  func (k cellName) String() string {
    35  	return string(k)
    36  }
    37  
    38  func NewSrvVSchemaWatcher(topoServer *topo.Server, counts *stats.CountersWithSingleLabel, cacheRefresh, cacheTTL time.Duration) *SrvVSchemaWatcher {
    39  	watch := func(entry *watchEntry) {
    40  		key := entry.key.(cellName)
    41  		ctx, cancel := context.WithCancel(context.Background())
    42  		defer cancel()
    43  
    44  		current, changes, err := topoServer.WatchSrvVSchema(ctx, key.String())
    45  		if err != nil {
    46  			entry.update(nil, err, true)
    47  			return
    48  		}
    49  
    50  		entry.update(current.Value, current.Err, true)
    51  		if current.Err != nil {
    52  			return
    53  		}
    54  
    55  		defer cancel()
    56  		for c := range changes {
    57  			entry.update(c.Value, c.Err, false)
    58  			if c.Err != nil {
    59  				return
    60  			}
    61  		}
    62  	}
    63  
    64  	rw := &resilientWatcher{
    65  		watcher:              watch,
    66  		counts:               counts,
    67  		cacheRefreshInterval: cacheRefresh,
    68  		cacheTTL:             cacheTTL,
    69  		entries:              make(map[string]*watchEntry),
    70  	}
    71  
    72  	return &SrvVSchemaWatcher{rw}
    73  }
    74  
    75  func (w *SrvVSchemaWatcher) GetSrvVSchema(ctx context.Context, cell string) (*vschemapb.SrvVSchema, error) {
    76  	v, err := w.rw.getValue(ctx, cellName(cell))
    77  	vschema, _ := v.(*vschemapb.SrvVSchema)
    78  	return vschema, err
    79  }
    80  
    81  func (w *SrvVSchemaWatcher) WatchSrvVSchema(ctx context.Context, cell string, callback func(*vschemapb.SrvVSchema, error) bool) {
    82  	entry := w.rw.getEntry(cellName(cell))
    83  	entry.addListener(ctx, func(v any, err error) bool {
    84  		vschema, _ := v.(*vschemapb.SrvVSchema)
    85  		return callback(vschema, err)
    86  	})
    87  }