Github user arina-ielchiieva commented on a diff in the pull request: https://github.com/apache/drill/pull/701#discussion_r102921712 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/FunctionImplementationRegistry.java --- @@ -260,76 +293,101 @@ public RemoteFunctionRegistry getRemoteFunctionRegistry() { } /** - * Attempts to load and register functions from remote function registry. - * First checks if there is no missing jars. - * If yes, enters synchronized block to prevent other loading the same jars. - * Again re-checks if there are no missing jars in case someone has already loaded them (double-check lock). - * If there are still missing jars, first copies jars to local udf area and prepares {@link JarScan} for each jar. - * Jar registration timestamp represented in milliseconds is used as suffix. - * Then registers all jars at the same time. Returns true when finished. - * In case if any errors during jars coping or registration, logs errors and proceeds. + * Purpose of this method is to synchronize remote and local function registries if needed + * and to inform if function registry was changed after given version. * - * If no missing jars are found, checks current local registry version. - * Returns false if versions match, true otherwise. + * To make synchronization as much light-weigh as possible, first only versions of both registries are checked + * without any locking. If synchronization is needed, enters synchronized block to prevent others loading the same jars. + * The need of synchronization is checked again (double-check lock) before comparing jars. + * If any missing jars are found, they are downloaded to local udf area, each is wrapped into {@link JarScan}. + * Once jar download is finished, all missing jars are registered in one batch. + * In case if any errors during jars download / registration, these errors are logged. * - * @param version local function registry version - * @return true if new jars were registered or local function registry version is different, false otherwise + * During registration local function registry is updated with remote function registry version it is synced with. + * When at least one jar of the missing jars failed to download / register, + * local function registry version are not updated but jars that where successfully downloaded / registered + * are added to local function registry. + * + * If synchronization between remote and local function registry was not needed, + * checks if given registry version matches latest sync version + * to inform if function registry was changed after given version. + * + * @param version remote function registry local function registry was based on + * @return true if remote and local function registries were synchronized after given version */ - public boolean loadRemoteFunctions(long version) { - List<String> missingJars = getMissingJars(remoteFunctionRegistry, localFunctionRegistry); - if (!missingJars.isEmpty()) { + public boolean syncWithRemoteRegistry(long version) { + if (doSyncFunctionRegistries(remoteFunctionRegistry.getRegistryVersion(), localFunctionRegistry.getVersion())) { synchronized (this) { - missingJars = getMissingJars(remoteFunctionRegistry, localFunctionRegistry); - if (!missingJars.isEmpty()) { - logger.info("Starting dynamic UDFs lazy-init process.\n" + - "The following jars are going to be downloaded and registered locally: " + missingJars); + long localRegistryVersion = localFunctionRegistry.getVersion(); + if (doSyncFunctionRegistries(remoteFunctionRegistry.getRegistryVersion(), localRegistryVersion)) { + DataChangeVersion remoteVersion = new DataChangeVersion(); + List<String> missingJars = getMissingJars(this.remoteFunctionRegistry, localFunctionRegistry, remoteVersion); List<JarScan> jars = Lists.newArrayList(); - for (String jarName : missingJars) { - Path binary = null; - Path source = null; - URLClassLoader classLoader = null; - try { - binary = copyJarToLocal(jarName, remoteFunctionRegistry); - source = copyJarToLocal(JarUtil.getSourceName(jarName), remoteFunctionRegistry); - URL[] urls = {binary.toUri().toURL(), source.toUri().toURL()}; - classLoader = new URLClassLoader(urls); - ScanResult scanResult = scan(classLoader, binary, urls); - localFunctionRegistry.validate(jarName, scanResult); - jars.add(new JarScan(jarName, scanResult, classLoader)); - } catch (Exception e) { - deleteQuietlyLocalJar(binary); - deleteQuietlyLocalJar(source); - if (classLoader != null) { - try { - classLoader.close(); - } catch (Exception ex) { - logger.warn("Problem during closing class loader for {}", jarName, e); + if (!missingJars.isEmpty()) { + logger.info("Starting dynamic UDFs lazy-init process.\n" + + "The following jars are going to be downloaded and registered locally: " + missingJars); + for (String jarName : missingJars) { + Path binary = null; + Path source = null; + URLClassLoader classLoader = null; + try { + binary = copyJarToLocal(jarName, this.remoteFunctionRegistry); + source = copyJarToLocal(JarUtil.getSourceName(jarName), this.remoteFunctionRegistry); + URL[] urls = {binary.toUri().toURL(), source.toUri().toURL()}; + classLoader = new URLClassLoader(urls); + ScanResult scanResult = scan(classLoader, binary, urls); + localFunctionRegistry.validate(jarName, scanResult); + jars.add(new JarScan(jarName, scanResult, classLoader)); + } catch (Exception e) { + deleteQuietlyLocalJar(binary); --- End diff -- Makes sense. As agreed we'll leave current implementation as is till MVCC will be implemented. MVCC will ensure that query will be run across the same function registry version across different drillbits.
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