github.com/google/osv-scalibr@v0.4.1/clients/datasource/npm_registry_cache.go (about)

     1  // Copyright 2025 Google LLC
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package datasource
    16  
    17  import (
    18  	"maps"
    19  	"strings"
    20  	"time"
    21  )
    22  
    23  type npmRegistryCache struct {
    24  	Timestamp *time.Time                           // Timestamp of when this cache was made
    25  	Details   map[string]npmRegistryPackageDetails // For a package name, the versions & their dependencies, and the list of tags
    26  	ScopeURLs map[string]string                    // The URL of the registry used for a given package @scope. Used to invalidate cache if registry has changed.
    27  }
    28  
    29  // GobEncode encodes the cache to bytes.
    30  func (c *NPMRegistryAPIClient) GobEncode() ([]byte, error) {
    31  	c.mu.Lock()
    32  	defer c.mu.Unlock()
    33  
    34  	if c.cacheTimestamp == nil {
    35  		now := time.Now().UTC()
    36  		c.cacheTimestamp = &now
    37  	}
    38  
    39  	cache := npmRegistryCache{
    40  		Timestamp: c.cacheTimestamp,
    41  		Details:   c.details.GetMap(),
    42  		ScopeURLs: make(map[string]string),
    43  	}
    44  
    45  	// store the registry URL for each scope (but not the auth info)
    46  	cache.ScopeURLs = c.registries.ScopeURLs
    47  
    48  	return gobMarshal(&cache)
    49  }
    50  
    51  // GobDecode decodes the cache from bytes.
    52  func (c *NPMRegistryAPIClient) GobDecode(b []byte) error {
    53  	// decode the cached data
    54  	var cache npmRegistryCache
    55  	if err := gobUnmarshal(b, &cache); err != nil {
    56  		return err
    57  	}
    58  
    59  	if cache.Timestamp != nil && time.Since(*cache.Timestamp) >= cacheExpiry {
    60  		// Cache expired
    61  		return nil
    62  	}
    63  
    64  	c.mu.Lock()
    65  	defer c.mu.Unlock()
    66  
    67  	// remove any cache entries whose registry has changed
    68  	maps.DeleteFunc(cache.Details, func(pkg string, _ npmRegistryPackageDetails) bool {
    69  		scope := ""
    70  		if strings.HasPrefix(pkg, "@") {
    71  			scope, _, _ = strings.Cut(pkg, "/")
    72  		}
    73  
    74  		return cache.ScopeURLs[scope] != c.registries.ScopeURLs[scope]
    75  	})
    76  
    77  	c.cacheTimestamp = cache.Timestamp
    78  	c.details.SetMap(cache.Details)
    79  
    80  	return nil
    81  }