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HADOOP-17009: Embrace Immutability of Java Collections

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belugabehr 2020-06-19 13:23:43 -04:00 committed by GitHub
parent 3472c3efc0
commit 100ec8e870
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20 changed files with 55 additions and 65 deletions
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3
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/AbstractFileSystem.java
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@ -23,7 +23,6 @@
import java.lang.reflect.InvocationTargetException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumSet;
@ -1032,7 +1031,7 @@ public String getCanonicalServiceName() {
*/
@InterfaceAudience.LimitedPrivate( { "HDFS", "MapReduce" })
public List<Token<?>> getDelegationTokens(String renewer) throws IOException {
return new ArrayList<Token<?>>(0);
return Collections.emptyList();
}
/**

7
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/Stat.java
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@ -20,8 +20,7 @@
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Collections;
import java.util.NoSuchElementException;
import java.util.StringTokenizer;
@ -65,9 +64,7 @@ public Stat(Path path, long blockSize, boolean deref, FileSystem fs)
this.blockSize = blockSize;
this.dereference = deref;
// LANG = C setting
Map<String, String> env = new HashMap<String, String>();
env.put("LANG", "C");
setEnvironment(env);
setEnvironment(Collections.singletonMap("LANG", "C"));
}
public FileStatus getFileStatus() throws IOException {

3
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/Delete.java
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@ -20,6 +20,7 @@
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
@ -97,7 +98,7 @@ protected List<PathData> expandArgument(String arg) throws IOException {
throw e;
}
// prevent -f on a non-existent glob from failing
return new LinkedList<PathData>();
return Collections.emptyList();
}
}

11
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ha/HAAdmin.java
View File

@ -19,9 +19,9 @@
import java.io.IOException;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import org.apache.commons.cli.Options;
@ -107,8 +107,7 @@ protected HAAdmin(Configuration conf) {
protected abstract HAServiceTarget resolveTarget(String string);
protected Collection<String> getTargetIds(String targetNodeToActivate) {
return new ArrayList<String>(
Arrays.asList(new String[]{targetNodeToActivate}));
return Collections.singleton(targetNodeToActivate);
}
protected String getUsageString() {
@ -188,8 +187,10 @@ private int transitionToActive(final CommandLine cmd)
private boolean isOtherTargetNodeActive(String targetNodeToActivate, boolean forceActive)
throws IOException {
Collection<String> targetIds = getTargetIds(targetNodeToActivate);
targetIds.remove(targetNodeToActivate);
for(String targetId : targetIds) {
for (String targetId : targetIds) {
if (targetNodeToActivate.equals(targetId)) {
continue;
}
HAServiceTarget target = resolveTarget(targetId);
if (!checkManualStateManagementOK(target)) {
return true;

10
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/http/lib/StaticUserWebFilter.java
View File

@ -19,7 +19,7 @@
import java.io.IOException;
import java.security.Principal;
import java.util.HashMap;
import java.util.Collections;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
@ -121,14 +121,10 @@ public void init(FilterConfig conf) throws ServletException {
@Override
public void initFilter(FilterContainer container, Configuration conf) {
HashMap<String, String> options = new HashMap<String, String>();
String username = getUsernameFromConf(conf);
options.put(HADOOP_HTTP_STATIC_USER, username);
container.addFilter("static_user_filter",
StaticUserFilter.class.getName(),
options);
container.addFilter("static_user_filter", StaticUserFilter.class.getName(),
Collections.singletonMap(HADOOP_HTTP_STATIC_USER, username));
}
/**

5
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics2/util/MBeans.java
View File

@ -18,7 +18,7 @@
package org.apache.hadoop.metrics2.util;
import java.lang.management.ManagementFactory;
import java.util.HashMap;
import java.util.Collections;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
@ -70,8 +70,7 @@ private MBeans() {
*/
static public ObjectName register(String serviceName, String nameName,
Object theMbean) {
return register(serviceName, nameName, new HashMap<String, String>(),
theMbean);
return register(serviceName, nameName, Collections.emptyMap(), theMbean);
}
/**

3
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/net/CachedDNSToSwitchMapping.java
View File

@ -130,8 +130,7 @@ public List<String> resolve(List<String> names) {
*/
@Override
public Map<String, String> getSwitchMap() {
Map<String, String > switchMap = new HashMap<String, String>(cache);
return switchMap;
return new HashMap<>(cache);
}

6
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/net/NetworkTopology.java
View File

@ -196,10 +196,8 @@ public List<Node> getDatanodesInRack(String loc) {
loc = loc.substring(1);
}
InnerNode rack = (InnerNode) clusterMap.getLoc(loc);
if (rack == null) {
return null;
}
return new ArrayList<Node>(rack.getChildren());
return (rack == null) ? new ArrayList<>(0)
: new ArrayList<>(rack.getChildren());
} finally {
netlock.readLock().unlock();
}

3
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/net/TableMapping.java
View File

@ -25,6 +25,7 @@
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@ -130,7 +131,7 @@ public synchronized List<String> resolve(List<String> names) {
if (map == null) {
LOG.warn("Failed to read topology table. " +
NetworkTopology.DEFAULT_RACK + " will be used for all nodes.");
map = new HashMap<String, String>();
map = Collections.emptyMap();
}
}
List<String> results = new ArrayList<String>(names.size());

11
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/CompositeGroupsMapping.java
View File

@ -19,6 +19,7 @@
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
@ -69,8 +70,8 @@ public class CompositeGroupsMapping
public synchronized List<String> getGroups(String user) throws IOException {
Set<String> groupSet = new TreeSet<String>();
List<String> groups = null;
for (GroupMappingServiceProvider provider : providersList) {
List<String> groups = Collections.emptyList();
try {
groups = provider.getGroups(user);
} catch (Exception e) {
@ -78,17 +79,15 @@ public synchronized List<String> getGroups(String user) throws IOException {
user, provider.getClass().getSimpleName(), e.toString());
LOG.debug("Stacktrace: ", e);
}
if (groups != null && ! groups.isEmpty()) {
if (!groups.isEmpty()) {
groupSet.addAll(groups);
if (!combined) break;
}
}
List<String> results = new ArrayList<String>(groupSet.size());
results.addAll(groupSet);
return results;
return new ArrayList<>(groupSet);
}
/**
* Caches groups, no need to do that for this provider
*/

3
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/JniBasedUnixGroupsNetgroupMapping.java
View File

@ -20,6 +20,7 @@
import java.io.IOException;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.LinkedList;
@ -125,6 +126,6 @@ protected synchronized List<String> getUsersForNetgroup(String netgroup) {
if (users != null && users.length != 0) {
return Arrays.asList(users);
}
return new LinkedList<String>();
return Collections.emptyList();
}
}

6
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/LdapGroupsMapping.java
View File

@ -518,11 +518,11 @@ List<String> doGetGroups(String user, int goUpHierarchy)
if (!results.hasMoreElements()) {
LOG.debug("doGetGroups({}) returned no groups because the " +
"user is not found.", user);
return new ArrayList<>();
return Collections.emptyList();
}
SearchResult result = results.nextElement();
List<String> groups = null;
List<String> groups = Collections.emptyList();
if (useOneQuery) {
try {
/**
@ -548,7 +548,7 @@ List<String> doGetGroups(String user, int goUpHierarchy)
"the second LDAP query using the user's DN.", e);
}
}
if (groups == null || groups.isEmpty() || goUpHierarchy > 0) {
if (groups.isEmpty() || goUpHierarchy > 0) {
groups = lookupGroup(result, c, goUpHierarchy);
}
LOG.debug("doGetGroups({}) returned {}", user, groups);

4
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/NetgroupCache.java
View File

@ -17,9 +17,9 @@
*/
package org.apache.hadoop.security;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
@ -61,7 +61,7 @@ public static void getNetgroups(final String user,
* @return list of cached groups
*/
public static List<String> getNetgroupNames() {
return new LinkedList<String>(getGroups());
return new ArrayList<>(getGroups());
}
private static Set<String> getGroups() {

3
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/ShellBasedIdMapping.java
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@ -24,6 +24,7 @@
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
@ -534,7 +535,7 @@ synchronized private void updateMapIncr(final int id,
static final class PassThroughMap<K> extends HashMap<K, K> {
public PassThroughMap() {
this(new HashMap<K, K>());
this(Collections.emptyMap());
}
public PassThroughMap(Map<K, K> mapping) {

14
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/token/delegation/web/DelegationTokenAuthenticationHandler.java
View File

@ -20,9 +20,8 @@
import java.io.IOException;
import java.io.Writer;
import java.text.MessageFormat;
import java.util.HashMap;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
@ -301,8 +300,7 @@ public boolean managementOperation(AuthenticationToken token,
dt.decodeFromUrlString(tokenToRenew);
long expirationTime = tokenManager.renewToken(dt,
requestUgi.getShortUserName());
map = new HashMap();
map.put("long", expirationTime);
map = Collections.singletonMap("long", expirationTime);
} catch (IOException ex) {
throw new AuthenticationException(ex.toString(), ex);
}
@ -358,13 +356,11 @@ public boolean managementOperation(AuthenticationToken token,
@SuppressWarnings("unchecked")
private static Map delegationTokenToJSON(Token token) throws IOException {
Map json = new LinkedHashMap();
json.put(
Map json = Collections.singletonMap(
KerberosDelegationTokenAuthenticator.DELEGATION_TOKEN_URL_STRING_JSON,
token.encodeToUrlString());
Map response = new LinkedHashMap();
response.put(KerberosDelegationTokenAuthenticator.DELEGATION_TOKEN_JSON,
json);
Map response = Collections.singletonMap(
KerberosDelegationTokenAuthenticator.DELEGATION_TOKEN_JSON, json);
return response;
}

6
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/service/AbstractService.java
View File

@ -20,6 +20,7 @@
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@ -426,7 +427,7 @@ private void recordLifecycleEvent() {
@Override
public synchronized List<LifecycleEvent> getLifecycleHistory() {
return new ArrayList<LifecycleEvent>(lifecycleHistory);
return Collections.unmodifiableList(new ArrayList<>(lifecycleHistory));
}
/**
@ -483,8 +484,7 @@ public void removeBlocker(String name) {
@Override
public Map<String, String> getBlockers() {
synchronized (blockerMap) {
Map<String, String> map = new HashMap<String, String>(blockerMap);
return map;
return Collections.unmodifiableMap(new HashMap<>(blockerMap));
}
}
}

3
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/service/CompositeService.java
View File

@ -19,6 +19,7 @@
package org.apache.hadoop.service;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.apache.hadoop.classification.InterfaceAudience.Public;
@ -60,7 +61,7 @@ public CompositeService(String name) {
*/
public List<Service> getServices() {
synchronized (serviceList) {
return new ArrayList<Service>(serviceList);
return Collections.unmodifiableList(new ArrayList<>(serviceList));
}
}

3
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/service/launcher/ServiceLauncher.java
View File

@ -23,6 +23,7 @@
import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import com.google.common.annotations.VisibleForTesting;
@ -894,7 +895,7 @@ public List<String> extractCommandOptions(Configuration conf,
List<String> args) {
int size = args.size();
if (size <= 1) {
return new ArrayList<>(0);
return Collections.emptyList();
}
List<String> coreArgs = args.subList(1, size);

8
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/HttpExceptionUtils.java
View File

@ -28,6 +28,7 @@
import java.io.Writer;
import java.lang.reflect.Constructor;
import java.net.HttpURLConnection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
@ -71,8 +72,8 @@ public static void createServletExceptionResponse(
json.put(ERROR_MESSAGE_JSON, getOneLineMessage(ex));
json.put(ERROR_EXCEPTION_JSON, ex.getClass().getSimpleName());
json.put(ERROR_CLASSNAME_JSON, ex.getClass().getName());
Map<String, Object> jsonResponse = new LinkedHashMap<String, Object>();
jsonResponse.put(ERROR_JSON, json);
Map<String, Object> jsonResponse =
Collections.singletonMap(ERROR_JSON, json);
Writer writer = response.getWriter();
JsonSerialization.writer().writeValue(writer, jsonResponse);
writer.flush();
@ -91,8 +92,7 @@ public static Response createJerseyExceptionResponse(Response.Status status,
json.put(ERROR_MESSAGE_JSON, getOneLineMessage(ex));
json.put(ERROR_EXCEPTION_JSON, ex.getClass().getSimpleName());
json.put(ERROR_CLASSNAME_JSON, ex.getClass().getName());
Map<String, Object> response = new LinkedHashMap<String, Object>();
response.put(ERROR_JSON, json);
Map<String, Object> response = Collections.singletonMap(ERROR_JSON, json);
return Response.status(status).type(MediaType.APPLICATION_JSON).
entity(response).build();
}

8
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Shell.java
View File

@ -28,6 +28,7 @@
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;
@ -871,6 +872,7 @@ protected Shell(long interval, boolean redirectErrorStream) {
this.interval = interval;
this.lastTime = (interval < 0) ? 0 : -interval;
this.redirectErrorStream = redirectErrorStream;
this.environment = Collections.emptyMap();
}
/**
@ -878,7 +880,7 @@ protected Shell(long interval, boolean redirectErrorStream) {
* @param env Mapping of environment variables
*/
protected void setEnvironment(Map<String, String> env) {
this.environment = env;
this.environment = Objects.requireNonNull(env);
}
/**
@ -915,9 +917,7 @@ private void runCommand() throws IOException {
builder.environment().clear();
}
if (environment != null) {
builder.environment().putAll(this.environment);
}
builder.environment().putAll(this.environment);
if (dir != null) {
builder.directory(this.dir);