Library avoids blocking on pending yardoc caches

lib/solargraph/doc_map.rb

@@ -21,8 +21,9 @@ class DocMap
 
     # @return [Array<Gem::Specification>]
     def uncached_gemspecs
-      (uncached_yard_gemspecs + uncached_rbs_collection_gemspecs).sort.
-        uniq { |gemspec| "#{gemspec.name}:#{gemspec.version}" }
+      uncached_yard_gemspecs.concat(uncached_rbs_collection_gemspecs)
+                            .sort
+                            .uniq { |gemspec| "#{gemspec.name}:#{gemspec.version}" }
     end
 
     # @return [Array<Gem::Specification>]

lib/solargraph/library.rb

@@ -588,29 +588,53 @@ def cache_errors
     # @return [void]
     def cache_next_gemspec
       return if @cache_progress
-      spec = (api_map.uncached_yard_gemspecs + api_map.uncached_rbs_collection_gemspecs).
-               find { |spec| !cache_errors.include?(spec) }
+
+      spec = cacheable_specs.first
       return end_cache_progress unless spec
 
       pending = api_map.uncached_gemspecs.length - cache_errors.length - 1
-      logger.info "Caching #{spec.name} #{spec.version}"
-      Thread.new do
-        cache_pid = Process.spawn(workspace.command_path, 'cache', spec.name, spec.version.to_s)
-        report_cache_progress spec.name, pending
-        Process.wait(cache_pid)
-        logger.info "Cached #{spec.name} #{spec.version}"
-      rescue Errno::EINVAL => _e
-        logger.info "Cached #{spec.name} #{spec.version} with EINVAL"
-      rescue StandardError => e
-        cache_errors.add spec
-        Solargraph.logger.warn "Error caching gemspec #{spec.name} #{spec.version}: [#{e.class}] #{e.message}"
-      ensure
-        end_cache_progress
+
+      if Yardoc.processing?(spec)
+        logger.info "Enqueuing cache of #{spec.name} #{spec.version} (already being processed)"
+        queued_gemspec_cache.push(spec)
+        return if pending - queued_gemspec_cache.length < 1
+
         catalog
         sync_catalog
+      else
+        logger.info "Caching #{spec.name} #{spec.version}"
+        Thread.new do
+          cache_pid = Process.spawn(workspace.command_path, 'cache', spec.name, spec.version.to_s)
+          report_cache_progress spec.name, pending
+          Process.wait(cache_pid)
+          logger.info "Cached #{spec.name} #{spec.version}"
+        rescue Errno::EINVAL => _e
+          logger.info "Cached #{spec.name} #{spec.version} with EINVAL"
+        rescue StandardError => e
+          cache_errors.add spec
+          Solargraph.logger.warn "Error caching gemspec #{spec.name} #{spec.version}: [#{e.class}] #{e.message}"
+        ensure
+          end_cache_progress
+          catalog
+          sync_catalog
+        end
       end
     end
 
+    def cacheable_specs
+      cacheable = api_map.uncached_yard_gemspecs +
+                  api_map.uncached_rbs_collection_gemspecs -
+                  queued_gemspec_cache -
+                  cache_errors.to_a
+      return cacheable unless cacheable.empty?
+
+      queued_gemspec_cache
+    end
+
+    def queued_gemspec_cache
+      @queued_gemspec_cache ||= []
+    end
+
     # @param gem_name [String]
     # @param pending [Integer]
     # @return [void]

lib/solargraph/yardoc.rb

@@ -30,6 +30,13 @@ def cached?(gemspec)
       File.exist?(yardoc)
     end
 
+    # True if another process is currently building the yardoc cache.
+    #
+    def processing?(gemspec)
+      yardoc = File.join(PinCache.yardoc_path(gemspec), 'processing')
+      File.exist?(yardoc)
+    end
+
     # Load a gem's yardoc and return its code objects.
     #
     # @note This method modifies the global YARD registry.