ZOOKEEPER-4966: Decouple ZKConfig from QuorumPeerConfig.ConfigException

`ZKConfig` is client accessible, it should avoid accessing server side
`QuorumPeerConfig`.

Changes:
1. Change method and constructor signatures of `ZKConfig` and
   `ZKClientConfig` to throw `o.a.zookeeper.common.ConfigException`.
3. Throw `QuorumPeerConfig.ConfigException` if it is in classpath.

Given above changes, this pr maintain abi compatibility with old
releases.

**Breaking change**: methods and constructors of `ZKConfig` and
`ZKClientConfig` throw `org.apache.zookeeper.common.ConfigException`
now but not `QuorumPeerConfig.ConfigException`, so developers have to
fix it to compile.

This is a small step towards ZOOKEEPER-233.

Refs: ZOOKEEPER-233, ZOOKEEPER-835, ZOOKEEPER-842, ZOOKEEPER-4970,
ZOOKEEPER-4966.

Author: kezhuw

zookeeper-server/src/main/java/org/apache/zookeeper/client/ZKClientConfig.java

@@ -23,7 +23,6 @@
 import org.apache.yetus.audience.InterfaceAudience;
 import org.apache.zookeeper.common.ConfigException;
 import org.apache.zookeeper.common.ZKConfig;
-import org.apache.zookeeper.server.quorum.QuorumPeerConfig;
 
 /**
  * Handles client specific properties
@@ -69,22 +68,22 @@ public ZKClientConfig() {
     /**
      * <p><b>Use {@link ZKClientConfig#ZKClientConfig(Path configPath)} instead.</b>
      *
-     * <p><b>The signature of this method will be changed to throw {@link ConfigException}
-     * instead of {@link QuorumPeerConfig.ConfigException} in future release.</b>
+     * <p><b>The signature of this method has been changed to throw {@link ConfigException}
+     * instead of {@code QuorumPeerConfig.ConfigException}.</b>
      */
     @Deprecated
-    public ZKClientConfig(File configFile) throws QuorumPeerConfig.ConfigException {
+    public ZKClientConfig(File configFile) throws ConfigException {
         super(configFile);
     }
 
     /**
      * <p><b>Use {@link ZKClientConfig#ZKClientConfig(Path configPath)} instead.</b>
      *
-     * <p><b>The signature of this method will be changed to throw {@link ConfigException}
-     * instead of {@link QuorumPeerConfig.ConfigException} in future release.</b>
+     * <p><b>The signature of this method has been changed to throw {@link ConfigException}
+     * instead of {@code QuorumPeerConfig.ConfigException}.</b>
      */
     @Deprecated
-    public ZKClientConfig(String configPath) throws QuorumPeerConfig.ConfigException {
+    public ZKClientConfig(String configPath) throws ConfigException {
         super(configPath);
     }
 

zookeeper-server/src/main/java/org/apache/zookeeper/common/ZKConfig.java

@@ -21,13 +21,14 @@
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
+import java.lang.reflect.Constructor;
 import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Properties;
 import org.apache.zookeeper.Environment;
-import org.apache.zookeeper.server.quorum.QuorumPeerConfig;
 import org.apache.zookeeper.server.util.VerifyingFileFactory;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -65,35 +66,33 @@ public ZKConfig() {
     /**
      * <p><b>Use {@link ZKConfig#ZKConfig(Path configPath)} instead.</b>
      *
-     * <p><b>The signature of this method will be changed to throw {@link ConfigException}
-     * instead of {@link QuorumPeerConfig.ConfigException} in future release.</b>
+     * <p><b>The signature of this method has been changed to throw {@link ConfigException}
+     * instead of {@code QuorumPeerConfig.ConfigException}.</b>
      *
      * @param configPath
      *            Configuration file path
      * @throws ConfigException
      *             if failed to load configuration properties
      */
     @Deprecated
-    public ZKConfig(String configPath) throws QuorumPeerConfig.ConfigException {
-        this(new File(configPath));
+    public ZKConfig(String configPath) throws ConfigException {
+        this(Paths.get(configPath));
     }
 
     /**
      * <p><b>Use {@link ZKConfig#ZKConfig(Path configPath)} instead.</b>
      *
-     * <p><b>The signature of this method will be changed to throw {@link ConfigException}
-     * instead of {@link QuorumPeerConfig.ConfigException} in future release.</b>
+     * <p><b>The signature of this method has been changed to throw {@link ConfigException}
+     * instead of {@code QuorumPeerConfig.ConfigException}.</b>
      *
      * @param configFile
      *            Configuration file
      * @throws ConfigException
      *             if failed to load configuration properties
      */
     @Deprecated
-    public ZKConfig(File configFile) throws QuorumPeerConfig.ConfigException {
-        this();
-        addConfiguration(configFile);
-        LOG.info("ZK Config {}", this.properties);
+    public ZKConfig(File configFile) throws ConfigException {
+        this(configFile.toPath());
     }
 
     /**
@@ -102,9 +101,10 @@ public ZKConfig(File configFile) throws QuorumPeerConfig.ConfigException {
      * @param configPath path to configuration file
      * @throws ConfigException
      */
-    @SuppressWarnings("deprecation")
     public ZKConfig(Path configPath) throws ConfigException {
-        this(configPath.toFile());
+        this();
+        addConfiguration(configPath);
+        LOG.info("ZK Config {}", this.properties);
     }
 
     private void init() {
@@ -215,16 +215,39 @@ public void setProperty(String key, String value) {
      *
      * @param configPath path to Configuration file.
      */
-    @SuppressWarnings("deprecation")
     public void addConfiguration(Path configPath) throws ConfigException {
-        addConfiguration(configPath.toFile());
+        Path absoluteConfigPath = configPath.toAbsolutePath();
+        LOG.info("Reading configuration from: {}", absoluteConfigPath);
+        try {
+            File configFile = (new VerifyingFileFactory.Builder(LOG).warnForRelativePath()
+                                                               .failForNonExistingPath()
+                                                               .build()).validate(configPath.toFile());
+            Properties cfg = new Properties();
+            try (FileInputStream in = new FileInputStream(configFile)) {
+                cfg.load(in);
+            }
+            parseProperties(cfg);
+        } catch (IOException | IllegalArgumentException e) {
+            LOG.error("Error while configuration from: {}", absoluteConfigPath, e);
+            String msg = "Error while processing " + absoluteConfigPath;
+            try {
+                Class<?> clazz = Class.forName("org.apache.zookeeper.server.quorum.QuorumPeerConfig.ConfigException");
+                Class<? extends ConfigException> exceptionClass = clazz.asSubclass(ConfigException.class);
+                Constructor<? extends ConfigException> constructor = exceptionClass.getDeclaredConstructor(String.class, Exception.class);
+                throw constructor.newInstance(msg, e);
+            } catch (ClassNotFoundException ignored) {
+            } catch (Exception ignored) {
+                LOG.warn("Fail to construct QuorumPeerConfig.ConfigException", e);
+            }
+            throw new ConfigException(msg, e);
+        }
     }
 
     /**
      * <p><b>Use {@link #addConfiguration(Path)} instead.</b></p>
      *
-     * <p><b>The signature of this method will be changed to throw {@link ConfigException}
-     * instead of {@link QuorumPeerConfig.ConfigException} in future release.</b>
+     * <p><b>The signature of this method has been changed to throw {@link ConfigException}
+     * instead of {@code QuorumPeerConfig.ConfigException}.</b>
      *
      * <p>Add a configuration resource. The properties form this configuration will
      * overwrite corresponding already loaded property and system property
@@ -233,31 +256,15 @@ public void addConfiguration(Path configPath) throws ConfigException {
      *            Configuration file.
      */
     @Deprecated
-    public void addConfiguration(File configFile) throws QuorumPeerConfig.ConfigException {
-        LOG.info("Reading configuration from: {}", configFile.getAbsolutePath());
-        try {
-            configFile = (new VerifyingFileFactory.Builder(LOG).warnForRelativePath()
-                                                               .failForNonExistingPath()
-                                                               .build()).validate(configFile);
-            Properties cfg = new Properties();
-            FileInputStream in = new FileInputStream(configFile);
-            try {
-                cfg.load(in);
-            } finally {
-                in.close();
-            }
-            parseProperties(cfg);
-        } catch (IOException | IllegalArgumentException e) {
-            LOG.error("Error while configuration from: {}", configFile.getAbsolutePath(), e);
-            throw new QuorumPeerConfig.ConfigException("Error while processing " + configFile.getAbsolutePath(), e);
-        }
+    public void addConfiguration(File configFile) throws ConfigException {
+        addConfiguration(configFile.toPath());
     }
 
     /**
      * <p><b>Use {@link #addConfiguration(Path)} instead.</b></p>
      *
-     * <p><b>The signature of this method will be changed to throw {@link ConfigException}
-     * instead of {@link QuorumPeerConfig.ConfigException} in future release.</b>
+     * <p><b>The signature of this method has been changed to throw {@link ConfigException}
+     * instead of {@code QuorumPeerConfig.ConfigException}.</b>
      *
      * <p>Add a configuration resource. The properties form this configuration will
      * overwrite corresponding already loaded property and system property
@@ -266,8 +273,8 @@ public void addConfiguration(File configFile) throws QuorumPeerConfig.ConfigExce
      *            Configuration file path.
      */
     @Deprecated
-    public void addConfiguration(String configPath) throws QuorumPeerConfig.ConfigException {
-        addConfiguration(new File(configPath));
+    public void addConfiguration(String configPath) throws ConfigException {
+        addConfiguration(Paths.get(configPath));
     }
 
     private void parseProperties(Properties cfg) {