Prepare Jira import for caching users mapping

- add bulk_write method to Gitlab::Cache::Import::Caching
- use that metthod for users mapping caching

lib/gitlab/cache/import/caching.rb

@@ -113,15 +113,18 @@ module Gitlab
           end
         end
 
-        # Sets multiple keys to a given value.
+        # Sets multiple keys to given values.
         #
         # mapping - A Hash mapping the cache keys to their values.
+        # key_prefix - prefix inserted before each key
         # timeout - The time after which the cache key should expire.
-        def self.write_multiple(mapping, timeout: TIMEOUT)
+        def self.write_multiple(mapping, key_prefix: nil, timeout: TIMEOUT)
           Redis::Cache.with do |redis|
-            redis.multi do |multi|
+            redis.pipelined do |multi|
               mapping.each do |raw_key, value|
-                multi.set(cache_key_for(raw_key), value, ex: timeout)
+                key = cache_key_for("#{key_prefix}#{raw_key}")
+
+                multi.set(key, value, ex: timeout)
               end
             end
           end

lib/gitlab/jira_import.rb

@@ -7,7 +7,8 @@ module Gitlab
     FAILED_ISSUES_COUNTER_KEY = 'jira-import/failed/%{project_id}/%{collection_type}'
     NEXT_ITEMS_START_AT_KEY = 'jira-import/paginator/%{project_id}/%{collection_type}'
     JIRA_IMPORT_LABEL = 'jira-import/import-label/%{project_id}'
-    ITEMS_MAPPER_CACHE_KEY = 'jira-import/items-mapper/%{project_id}/%{collection_type}/%{jira_isssue_id}'
+    ITEMS_MAPPER_CACHE_KEY = 'jira-import/items-mapper/%{project_id}/%{collection_type}/%{jira_item_id}'
+    USERS_MAPPER_KEY_PREFIX = 'jira-import/items-mapper/%{project_id}/users/'
     ALREADY_IMPORTED_ITEMS_CACHE_KEY = 'jira-importer/already-imported/%{project}/%{collection_type}'
 
     def self.validate_project_settings!(project, user: nil, configuration_check: true)
@@ -24,8 +25,12 @@ module Gitlab
       raise Projects::ImportService::Error, _('Unable to connect to the Jira instance. Please check your Jira integration configuration.') unless jira_service&.valid_connection?
     end
 
-    def self.jira_issue_cache_key(project_id, jira_issue_id)
-      ITEMS_MAPPER_CACHE_KEY % { project_id: project_id, collection_type: :issues, jira_isssue_id: jira_issue_id }
+    def self.jira_item_cache_key(project_id, jira_item_id, collection_type)
+      ITEMS_MAPPER_CACHE_KEY % { project_id: project_id, collection_type: collection_type, jira_item_id: jira_item_id }
+    end
+
+    def self.jira_user_key_prefix(project_id)
+      USERS_MAPPER_KEY_PREFIX % { project_id: project_id }
     end
 
     def self.already_imported_cache_key(collection_type, project_id)
@@ -62,7 +67,7 @@ module Gitlab
     end
 
     def self.cache_issue_mapping(issue_id, jira_issue_id, project_id)
-      cache_key = JiraImport.jira_issue_cache_key(project_id, jira_issue_id)
+      cache_key = JiraImport.jira_item_cache_key(project_id, jira_issue_id, :issues)
       cache_class.write(cache_key, issue_id)
     end
 
@@ -81,6 +86,19 @@ module Gitlab
       cache_class.expire(self.already_imported_cache_key(:issues, project_id), JIRA_IMPORT_CACHE_TIMEOUT)
     end
 
+    # Caches the mapping of jira_account_id -> gitlab user id
+    # project_id - id of a project
+    # mapping - hash in format of jira_account_id -> gitlab user id
+    def self.cache_users_mapping(project_id, mapping)
+      cache_class.write_multiple(mapping, key_prefix: jira_user_key_prefix(project_id))
+    end
+
+    def self.get_user_mapping(project_id, jira_account_id)
+      cache_key = JiraImport.jira_item_cache_key(project_id, jira_account_id, :users)
+
+      cache_class.read(cache_key)&.to_i
+    end
+
     def self.cache_class
       Gitlab::Cache::Import::Caching
     end

spec/lib/gitlab/cache/import/caching_spec.rb

@@ -89,7 +89,7 @@ describe Gitlab::Cache::Import::Caching, :clean_gitlab_redis_cache do
   end
 
   describe '.write_multiple' do
-    it 'sets multiple keys' do
+    it 'sets multiple keys when key_prefix not set' do
       mapping = { 'foo' => 10, 'bar' => 20 }
 
       described_class.write_multiple(mapping)
@@ -101,6 +101,19 @@ describe Gitlab::Cache::Import::Caching, :clean_gitlab_redis_cache do
         expect(found).to eq(value.to_s)
       end
     end
+
+    it 'sets multiple keys with correct prefix' do
+      mapping = { 'foo' => 10, 'bar' => 20 }
+
+      described_class.write_multiple(mapping, key_prefix: 'pref/')
+
+      mapping.each do |key, value|
+        full_key = described_class.cache_key_for("pref/#{key}")
+        found = Gitlab::Redis::Cache.with { |r| r.get(full_key) }
+
+        expect(found).to eq(value.to_s)
+      end
+    end
   end
 
   describe '.expire' do

spec/lib/gitlab/jira_import_spec.rb

@@ -107,7 +107,7 @@ describe Gitlab::JiraImport do
 
   describe '.jira_issue_cache_key' do
     it 'returns cache key for Jira issue imported to given project' do
-      expect(described_class.jira_issue_cache_key(project_id, 'DEMO-123')).to eq("jira-import/items-mapper/#{project_id}/issues/DEMO-123")
+      expect(described_class.jira_item_cache_key(project_id, 'DEMO-123', :issues)).to eq("jira-import/items-mapper/#{project_id}/issues/DEMO-123")
     end
   end
 
@@ -144,6 +144,29 @@ describe Gitlab::JiraImport do
     end
   end
 
+  describe '.cache_users_mapping', :clean_gitlab_redis_cache do
+    let(:data) { { 'user1' => '456', 'user234' => '23' } }
+
+    it 'stores the data correctly' do
+      described_class.cache_users_mapping(project_id, data)
+
+      expect(Gitlab::Cache::Import::Caching.read("jira-import/items-mapper/#{project_id}/users/user1")).to eq('456')
+      expect(Gitlab::Cache::Import::Caching.read("jira-import/items-mapper/#{project_id}/users/user234")).to eq('23')
+    end
+  end
+
+  describe '.get_user_mapping', :clean_gitlab_redis_cache do
+    it 'reads the data correctly' do
+      Gitlab::Cache::Import::Caching.write("jira-import/items-mapper/#{project_id}/users/user-123", '456')
+
+      expect(described_class.get_user_mapping(project_id, 'user-123')).to eq(456)
+    end
+
+    it 'returns nil if value not found' do
+      expect(described_class.get_user_mapping(project_id, 'user-123')).to be_nil
+    end
+  end
+
   describe '.store_issues_next_started_at', :clean_gitlab_redis_cache do
     it 'stores nil value' do
       described_class.store_issues_next_started_at(project_id, nil)