Author: markt
Date: Tue Sep 15 12:41:35 2015
New Revision: 1703174
URL: http://svn.apache.org/r1703174
Log:
Fix https://bz.apache.org/bugzilla/show_bug.cgi?id=58382
Use single object (membersLock) for all locking
Make members volatile so single reads are safe
Reduce scope of locks where possible
Expand scope of locks where necessary
Modified:
tomcat/trunk/java/org/apache/catalina/tribes/membership/Membership.java
Modified:
tomcat/trunk/java/org/apache/catalina/tribes/membership/Membership.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/tribes/membership/Membership.java?rev=1703174&r1=1703173&r2=1703174&view=diff
==============================================================================
--- tomcat/trunk/java/org/apache/catalina/tribes/membership/Membership.java
(original)
+++ tomcat/trunk/java/org/apache/catalina/tribes/membership/Membership.java Tue
Sep 15 12:41:35 2015
@@ -46,12 +46,12 @@ public class Membership implements Clone
/**
* A map of all the members in the cluster.
*/
- protected HashMap<Member, MbrEntry> map = new HashMap<>();
+ protected HashMap<Member, MbrEntry> map = new HashMap<>(); // Guarded by
membersLock
/**
* A list of all the members in the cluster.
*/
- protected Member[] members = EMPTY_MEMBERS;
+ protected volatile Member[] members = EMPTY_MEMBERS; // Guarded by
membersLock
/**
* Comparator for sorting members by alive time.
@@ -90,19 +90,21 @@ public class Membership implements Clone
public Membership(Member local, Comparator<Member> comp, boolean
includeLocal) {
this.local = local;
+ this.memberComparator = comp;
if (includeLocal) {
addMember(local);
}
- this.memberComparator = comp;
}
/**
* Reset the membership and start over fresh. i.e., delete all the members
* and wait for them to ping again and join this membership.
*/
- public synchronized void reset() {
- map.clear();
- members = EMPTY_MEMBERS ;
+ public void reset() {
+ synchronized (membersLock) {
+ map.clear();
+ members = EMPTY_MEMBERS ;
+ }
}
/**
@@ -112,29 +114,31 @@ public class Membership implements Clone
* @return - true if this member is new to the cluster, false
otherwise.<br>
* - false if this member is the local member or updated.
*/
- public synchronized boolean memberAlive(Member member) {
- //ignore ourselves
- if ( member.equals(local)) {
+ public boolean memberAlive(Member member) {
+ // Ignore ourselves
+ if (member.equals(local)) {
return false;
}
boolean result = false;
- MbrEntry entry = map.get(member);
- if (entry == null) {
- entry = addMember(member);
- result = true;
- } else {
- //update the member alive time
- Member updateMember = entry.getMember();
- if(updateMember.getMemberAliveTime() !=
member.getMemberAliveTime()) {
- //update fields that can change
- updateMember.setMemberAliveTime(member.getMemberAliveTime());
- updateMember.setPayload(member.getPayload());
- updateMember.setCommand(member.getCommand());
- Arrays.sort(members, memberComparator);
+ synchronized (membersLock) {
+ MbrEntry entry = map.get(member);
+ if (entry == null) {
+ entry = addMember(member);
+ result = true;
+ } else {
+ // Update the member alive time
+ Member updateMember = entry.getMember();
+ if (updateMember.getMemberAliveTime() !=
member.getMemberAliveTime()) {
+ // Update fields that can change
+
updateMember.setMemberAliveTime(member.getMemberAliveTime());
+ updateMember.setPayload(member.getPayload());
+ updateMember.setCommand(member.getCommand());
+ Arrays.sort(members, memberComparator);
+ }
}
+ entry.accessed();
}
- entry.accessed();
return result;
}
@@ -145,9 +149,9 @@ public class Membership implements Clone
*
* @return The member entry created for this new member.
*/
- public synchronized MbrEntry addMember(Member member) {
+ public MbrEntry addMember(Member member) {
+ MbrEntry entry = new MbrEntry(member);
synchronized (membersLock) {
- MbrEntry entry = new MbrEntry(member);
if (!map.containsKey(member) ) {
map.put(member, entry);
Member results[] = new Member[members.length + 1];
@@ -158,8 +162,8 @@ public class Membership implements Clone
members = results;
Arrays.sort(members, memberComparator);
}
- return entry;
}
+ return entry;
}
/**
@@ -168,8 +172,8 @@ public class Membership implements Clone
* @param member The member to remove
*/
public void removeMember(Member member) {
- map.remove(member);
synchronized (membersLock) {
+ map.remove(member);
int n = -1;
for (int i = 0; i < members.length; i++) {
if (members[i] == member || members[i].equals(member)) {
@@ -196,33 +200,35 @@ public class Membership implements Clone
* @param maxtime - the max time a member can remain unannounced before it
is considered dead.
* @return the list of expired members
*/
- public synchronized Member[] expire(long maxtime) {
- if (!hasMembers()) {
- return EMPTY_MEMBERS;
- }
+ public Member[] expire(long maxtime) {
+ synchronized (membersLock) {
+ if (!hasMembers()) {
+ return EMPTY_MEMBERS;
+ }
- ArrayList<Member> list = null;
- Iterator<MbrEntry> i = map.values().iterator();
- while (i.hasNext()) {
- MbrEntry entry = i.next();
- if (entry.hasExpired(maxtime)) {
- if (list == null) {
- // Only need a list when members are expired (smaller gc)
- list = new java.util.ArrayList<>();
+ ArrayList<Member> list = null;
+ Iterator<MbrEntry> i = map.values().iterator();
+ while (i.hasNext()) {
+ MbrEntry entry = i.next();
+ if (entry.hasExpired(maxtime)) {
+ if (list == null) {
+ // Only need a list when members are expired (smaller
gc)
+ list = new java.util.ArrayList<>();
+ }
+ list.add(entry.getMember());
}
- list.add(entry.getMember());
}
- }
- if (list != null) {
- Member[] result = new Member[list.size()];
- list.toArray(result);
- for (int j=0; j<result.length; j++) {
- removeMember(result[j]);
+ if (list != null) {
+ Member[] result = new Member[list.size()];
+ list.toArray(result);
+ for (int j=0; j<result.length; j++) {
+ removeMember(result[j]);
+ }
+ return result;
+ } else {
+ return EMPTY_MEMBERS ;
}
- return result;
- } else {
- return EMPTY_MEMBERS ;
}
}
@@ -233,14 +239,15 @@ public class Membership implements Clone
* <code>false</code>
*/
public boolean hasMembers() {
- return members.length > 0 ;
+ return members.length > 0;
}
public Member getMember(Member mbr) {
- if (hasMembers()) {
+ Member[] members = this.members;
+ if (members.length > 0) {
Member result = null;
- for (int i = 0; i < this.members.length && result == null; i++) {
+ for (int i = 0; i < members.length && result == null; i++) {
if (members[i].equals(mbr)) {
result = members[i];
}
@@ -262,11 +269,7 @@ public class Membership implements Clone
* @return An array of the current members
*/
public Member[] getMembers() {
- if (hasMembers()) {
- return members;
- } else {
- return EMPTY_MEMBERS;
- }
+ return members;
}
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