github.com/meulengracht/snapd@v0.0.0-20210719210640-8bde69bcc84e/overlord/hookstate/repository.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2016 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package hookstate
    21  
    22  import (
    23  	"regexp"
    24  	"sync"
    25  )
    26  
    27  // repository stores all registered handler generators, and generates registered
    28  // handlers.
    29  type repository struct {
    30  	mutex      sync.RWMutex
    31  	generators []patternGeneratorPair
    32  }
    33  
    34  // patternGeneratorPair contains a hook handler generator and its corresponding
    35  // regex pattern for what hook name should cause it to be called.
    36  type patternGeneratorPair struct {
    37  	pattern   *regexp.Regexp
    38  	generator HandlerGenerator
    39  }
    40  
    41  // NewRepository creates an empty handler generator repository.
    42  func newRepository() *repository {
    43  	return &repository{}
    44  }
    45  
    46  // AddHandler adds the provided handler generator to the repository.
    47  func (r *repository) addHandlerGenerator(pattern *regexp.Regexp, generator HandlerGenerator) {
    48  	r.mutex.Lock()
    49  	defer r.mutex.Unlock()
    50  
    51  	r.generators = append(r.generators, patternGeneratorPair{
    52  		pattern:   pattern,
    53  		generator: generator,
    54  	})
    55  }
    56  
    57  // GenerateHandlers calls the handler generators whose patterns match the
    58  // hook name contained within the provided context, and returns the resulting
    59  // handlers.
    60  func (r *repository) generateHandlers(context *Context) []Handler {
    61  	hookName := context.HookName()
    62  	var handlers []Handler
    63  
    64  	r.mutex.RLock()
    65  	defer r.mutex.RUnlock()
    66  
    67  	for _, pair := range r.generators {
    68  		if pair.pattern.MatchString(hookName) {
    69  			handlers = append(handlers, pair.generator(context))
    70  		}
    71  	}
    72  
    73  	return handlers
    74  }