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From: ahgittin <git@git.apache.org>
To: dev@brooklyn.incubator.apache.org
Reply-To: dev@brooklyn.incubator.apache.org
References: <git-pr-617-incubator-brooklyn@git.apache.org>
In-Reply-To: <git-pr-617-incubator-brooklyn@git.apache.org>
Subject: [GitHub] incubator-brooklyn pull request: CLI commands for
 manipulating cat...
Content-Type: text/plain
Message-Id: <20150525082657.49C0BDFAF3@git1-us-west.apache.org>
Date: Mon, 25 May 2015 08:26:57 +0000 (UTC)

Github user ahgittin commented on a diff in the pull request:

    https://github.com/apache/incubator-brooklyn/pull/617#discussion_r30968526
  
    --- Diff: utils/common/src/main/java/brooklyn/util/javalang/AggregateClassLoader.java ---
    @@ -57,24 +61,65 @@ public static AggregateClassLoader newInstanceWithNoLoaders() {
     
         /** Add a loader to the first position in the search path. */
         public void addFirst(ClassLoader classLoader) {
    -        if (classLoader != null) classLoaders.add(0, classLoader);
    +        if (classLoader != null) {
    +            synchronized (classLoaders) {
    +                classLoaders.add(0, classLoader);
    +            }
    +        }
         }
         /** Add a loader to the last position in the search path. */
         public void addLast(ClassLoader classLoader) {
    -        if (classLoader != null) classLoaders.add(classLoader);
    +        if (classLoader != null) {
    +            synchronized (classLoaders) {
    +                classLoaders.add(classLoader);
    +            }
    +        }
         }
         /** Add a loader to the specific position in the search path. 
          * (It is callers responsibility to ensure that position is valid.) */
         public void add(int index, ClassLoader classLoader) {
    -        if (classLoader != null) classLoaders.add(index, classLoader);
    +        if (classLoader != null) {
    +            synchronized (classLoaders) {
    +                classLoaders.add(index, classLoader);
    +            }
    +        }
    +    }
    +    
    +    /** Resets the classloader shown here to be the given set */
    +    public void reset(Collection<? extends ClassLoader> newClassLoaders) {
    +        synchronized (classLoaders) {
    +            // synchronize:
    +            // * to prevent concurrent invocations
    +            // * so add(0, cl) doesn't interfere
    +            // * and for good measure we add before removing so that iterator always contains everything
    +            //   although since iterator access is synchronized that shouldn't be necessary
    +            int count = classLoaders.size();
    +            classLoaders.addAll(newClassLoaders);
    +            for (int i=0; i<count; i++) {
    +                classLoaders.remove(0);
    +            }
    +        }
    +    }
    +
    +    /** True if nothing is in the list here */
    +    public boolean isEmpty() {
    +        return classLoaders.isEmpty();
         }
         
    -    /** Returns the _live_ (and modifiable) list of classloaders 
    -     * @return */ 
    +    /** Returns the _live_ (and modifiable) list of classloaders; dangerous and discouraged. 
    +     * @deprecated since 0.7.0 */
    +    @Deprecated
         public List<ClassLoader> getList() {
             return classLoaders;
         }
     
    +    public Iterator<ClassLoader> iterator() {
    +        synchronized (classLoaders) {
    +            // provides iterator of snapshot
    +            return classLoaders.iterator();
    --- End diff --
    
    semantics of `CopyOnWriteList.iterator()` is to take a snapshot, with unmodifiable iterator; have expanded comment


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