On 26/10/2009, [email protected] <[email protected]> wrote:
> Author: scolebourne
> Date: Mon Oct 26 21:56:46 2009
> New Revision: 829991
>
> URL: http://svn.apache.org/viewvc?rev=829991&view=rev
> Log:
> LANG-487 - Make default style thread-safe
>
> Modified:
>
> commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/ToStringBuilder.java
>
> Modified:
> commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/ToStringBuilder.java
> URL:
> http://svn.apache.org/viewvc/commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/ToStringBuilder.java?rev=829991&r1=829990&r2=829991&view=diff
>
> ==============================================================================
> ---
> commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/ToStringBuilder.java
> (original)
> +++
> commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/ToStringBuilder.java
> Mon Oct 26 21:56:46 2009
> @@ -94,27 +94,51 @@
> /**
> * The default style of output to use.
> */
> - private static ToStringStyle defaultStyle = ToStringStyle.DEFAULT_STYLE;
> + private static volatile ToStringStyle defaultStyle =
> ToStringStyle.DEFAULT_STYLE;
>
>
> //----------------------------------------------------------------------------
>
> /**
> * <p>Gets the default <code>ToStringStyle</code> to use.</p>
> - *
> - * <p>This could allow the <code>ToStringStyle</code> to be
> - * controlled for an entire application with one call.</p>
> - *
> - * <p>This might be used to have a verbose
> - * <code>ToStringStyle</code> during development and a compact
> - * <code>ToStringStyle</code> in production.</p>
> *
> - * @return the default <code>ToStringStyle</code>
> + * <p>This method gets a singleton default value, typically for the
> whole JVM.
> + * Changing this default should generally only be done during
> application startup.
> + * It is recommended to pass a <code>ToStringStyle</code> to the
> constructor instead
> + * of using this global default.</p>
> + *
Agreed.
> + * <p>This method is thread-safe, as a <code>volatile</code variable is
> used internally.</p>
I think it's misleading to call the method thread-safe.
Adding volatile/synch. merely ensures that the new value is published correctly.
The use of a mutable static variable means that the method cannot
really be considered thread-safe. Two independent threads cannot - in
general - both use the set method and still be assured of predictable
behaviour.
> + *
> + * <p>One reason for changing the default could be to have a verbose
> style during
> + * development and a compact style in production.</p>
> + *
> + * @return the default <code>ToStringStyle</code>, never null
> */
> public static ToStringStyle getDefaultStyle() {
> return defaultStyle;
> }
>
> /**
> + * <p>Sets the default <code>ToStringStyle</code> to use.</p>
> + *
> + * <p>This method sets a singleton default value, typically for the
> whole JVM.
> + * Changing this default should generally only be done during
> application startup.
> + * It is recommended to pass a <code>ToStringStyle</code> to the
> constructor instead
> + * of changing this global default.</p>
> + *
> + * <p>This method is thread-safe, as a <code>volatile</code variable is
> used internally.</p>
DItto.
> + *
> + * @param style the default <code>ToStringStyle</code>
> + * @throws IllegalArgumentException if the style is <code>null</code>
> + */
> + public static void setDefaultStyle(ToStringStyle style) {
> + if (style == null) {
> + throw new IllegalArgumentException("The style must not be
> null");
> + }
> + defaultStyle = style;
> + }
> +
> +
> //----------------------------------------------------------------------------
> + /**
> * <p>Forwards to <code>ReflectionToStringBuilder</code>.</p>
> *
> * @param object the Object to be output
> @@ -169,18 +193,7 @@
> return ReflectionToStringBuilder.toString(object, style,
> outputTransients, false, reflectUpToClass);
> }
>
> - /**
> - * <p>Sets the default <code>ToStringStyle</code> to use.</p>
> - *
> - * @param style the default <code>ToStringStyle</code>
> - * @throws IllegalArgumentException if the style is <code>null</code>
> - */
> - public static void setDefaultStyle(ToStringStyle style) {
> - if (style == null) {
> - throw new IllegalArgumentException("The style must not be
> null");
> - }
> - defaultStyle = style;
> - }
> +
> //----------------------------------------------------------------------------
>
> /**
> * Current toString buffer.
> @@ -208,7 +221,7 @@
> * <code>null</code>
> */
> public ToStringBuilder(Object object) {
> - this(object, getDefaultStyle(), null);
> + this(object, null, null);
> }
>
> /**
>
>
>
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