vitess.io/vitess@v0.16.2/go/vt/vtorc/inst/instance_topology_dao.go (about)

     1  /*
     2     Copyright 2015 Shlomi Noach, courtesy Booking.com
     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 inst
    18  
    19  // Max concurrency for bulk topology operations
    20  const topologyConcurrency = 128
    21  
    22  var topologyConcurrencyChan = make(chan bool, topologyConcurrency)
    23  
    24  // ExecuteOnTopology will execute given function while maintaining concurrency limit
    25  // on topology servers. It is safe in the sense that we will not leak tokens.
    26  func ExecuteOnTopology(f func()) {
    27  	topologyConcurrencyChan <- true
    28  	defer func() { _ = recover(); <-topologyConcurrencyChan }()
    29  	f()
    30  }