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8129344: (process) ProcessHandle instances should define equals and be value-based

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Add equals(), hashCode() and value-based spec

Reviewed-by: psandoz
This commit is contained in:
Roger Riggs 2015-07-14 15:29:16 -04:00
parent f570f46d3b
commit 7b58767f2b
1 changed files with 50 additions and 1 deletions
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51
jdk/src/java.base/share/classes/java/lang/ProcessHandle.java
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@ -78,6 +78,16 @@ import java.util.stream.Stream;
* The methods of this class throw {@link java.lang.UnsupportedOperationException}
* if the operating system does not allow access to query or kill a process.
*
* <p>
* The {@code ProcessHandle} static factory methods return instances that are
* <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>,
* immutable and thread-safe.
* Use of identity-sensitive operations (including reference equality
* ({@code ==}), identity hash code, or synchronization) on these instances of
* {@code ProcessHandle} may have unpredictable results and should be avoided.
* Use {@link #equals(Object) equals} or
* {@link #compareTo(ProcessHandle) compareTo} methods to compare ProcessHandles.
*
* @see Process
* @since 1.9
*/
@ -86,6 +96,9 @@ public interface ProcessHandle extends Comparable<ProcessHandle> {
/**
* Returns the native process ID of the process. The native process ID is an
* identification number that the operating system assigns to the process.
* The operating system may reuse the process ID after a process terminates.
* Use {@link #equals(Object) equals} or
* {@link #compareTo(ProcessHandle) compareTo} to compare ProcessHandles.
*
* @return the native process ID of the process
* @throws UnsupportedOperationException if the implementation
@ -337,7 +350,43 @@ public interface ProcessHandle extends Comparable<ProcessHandle> {
* @return {@code true} if the process represented by this
* {@code ProcessHandle} object has not yet terminated
*/
boolean isAlive();
boolean isAlive();
/**
* Returns a hash code value for this ProcessHandle.
* The hashcode value follows the general contract for {@link Object#hashCode()}.
* The value is a function of the {@link #getPid getPid()} value and
* may be a function of additional information to uniquely identify the process.
* If two ProcessHandles are equal according to the {@link #equals(Object) equals}
* method, then calling the hashCode method on each of the two objects
* must produce the same integer result.
*
* @return a hash code value for this object
*/
@Override
int hashCode();
/**
* Returns {@code true} if {@code other} object is non-null, is of the
* same implementation, and represents the same system process;
* otherwise it returns {@code false}.
* @implNote
* It is implementation specific whether ProcessHandles with the same PID
* represent the same system process. ProcessHandle implementations
* should contain additional information to uniquely identify the process.
* For example, the start time of the process could be used
* to determine if the PID has been re-used.
* The implementation of {@code equals} should return {@code true} for two
* ProcessHandles with the same PID unless there is information to
* distinguish them.
*
* @param other another object
* @return {@code true} if the {@code other} object is non-null,
* is of the same implementation class and represents
* the same system process; otherwise returns {@code false}
*/
@Override
boolean equals(Object other);
/**
* Compares this ProcessHandle with the specified ProcessHandle for order.