8005697: Add StampedLock - JEP 155 (original) (raw)

Martin Buchholz martinrb at google.com
Tue Jan 29 08:04:45 UTC 2013

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On Mon, Jan 28, 2013 at 4:01 PM, Doug Lea <dl at cs.oswego.edu> wrote:

I also noticed that I had failed to include the simple toString-based informal debug/monitoring aids that we've been doing for synchronizers.

Which suggests looking for other missing methods by comparing lock-like classes. Looking at the implementation of toString and comparing with RRWL suggests (untested):

Index: src/main/java/util/concurrent/locks/StampedLock.java

RCS file: /export/home/jsr166/jsr166/jsr166/src/main/java/util/concurrent/locks/StampedLock.java,v retrieving revision 1.16 diff -u -r1.16 StampedLock.java --- src/main/java/util/concurrent/locks/StampedLock.java 28 Jan 2013 23:54:42 -0000 1.16 +++ src/main/java/util/concurrent/locks/StampedLock.java 29 Jan 2013 07:56:20 -0000 @@ -886,6 +886,23 @@ } }

• private int getReadLockCount(long s) {

•    long readers;

•    if ((readers = s & RBITS) >= RFULL)

•        readers = RFULL + readerOverflow;

•    return (int) readers;

• }
• /**

• * Queries the number of read locks held for this lock. This

• * method is designed for use in monitoring system state, not for

• * synchronization control.

• * @return the number of read locks held

• */

• public int getReadLockCount() {

•    return getReadLockCount(state);

• }

• /**
   * Returns a string identifying this lock, as well as its lock
   * state.  The state, in brackets, includes the String {@code

@@ -896,15 +913,11 @@ * @return a string identifying this lock, as well as its lock state */ public String toString() {

•    long readers;
     long s = state;

•    if ((readers = s & RBITS) >= RFULL)

•        readers = RFULL + readerOverflow;

•    return super.toString() + ((s & WBIT) != 0L ?

•                               "[Write-locked]" :

•                               readers == 0 ?

•                               "[Unlocked]" :

•                               "[Read-locks:" + readers + "]");

•    return super.toString() +

•        ((s & ABITS) == 0L ? "[Unlocked]" :

•         (s & WBIT) != 0L ? "[Write-locked]" :

•         "[Read-locks:" + getReadLockCount(s) + "]");

  }

  // internals

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