550
551 // -- Unsafe access --
552
553 private static final Unsafe unsafe = Unsafe.getUnsafe();
554
555 private static byte _get(long a) {
556 return unsafe.getByte(a);
557 }
558
559 private static void _put(long a, byte b) {
560 unsafe.putByte(a, b);
561 }
562
563 static Unsafe unsafe() {
564 return unsafe;
565 }
566
567
568 // -- Processor and memory-system properties --
569
570 private static final ByteOrder byteOrder;
571
572 static ByteOrder byteOrder() {
573 if (byteOrder == null)
574 throw new Error("Unknown byte order");
575 return byteOrder;
576 }
577
578 static {
579 long a = unsafe.allocateMemory(8);
580 try {
581 unsafe.putLong(a, 0x0102030405060708L);
582 byte b = unsafe.getByte(a);
583 switch (b) {
584 case 0x01: byteOrder = ByteOrder.BIG_ENDIAN; break;
585 case 0x08: byteOrder = ByteOrder.LITTLE_ENDIAN; break;
586 default:
587 assert false;
588 byteOrder = null;
589 }
590 } finally {
591 unsafe.freeMemory(a);
592 }
593 }
594
595
596 private static int pageSize = -1;
597
598 static int pageSize() {
599 if (pageSize == -1)
600 pageSize = unsafe().pageSize();
601 return pageSize;
602 }
603
604 static int pageCount(long size) {
605 return (int)(size + (long)pageSize() - 1L) / pageSize();
606 }
607
608 private static boolean unaligned;
609 private static boolean unalignedKnown = false;
610
611 static boolean unaligned() {
612 if (unalignedKnown)
613 return unaligned;
614 String arch = AccessController.doPrivileged(
615 new sun.security.action.GetPropertyAction("os.arch"));
616 unaligned = arch.equals("i386") || arch.equals("x86")
617 || arch.equals("amd64") || arch.equals("x86_64");
618 unalignedKnown = true;
619 return unaligned;
620 }
621
622
623 // -- Direct memory management --
624
625 // A user-settable upper limit on the maximum amount of allocatable
626 // direct buffer memory. This value may be changed during VM
627 // initialization if it is launched with "-XX:MaxDirectMemorySize=<size>".
628 private static volatile long maxMemory = VM.maxDirectMemory();
629 private static final AtomicLong reservedMemory = new AtomicLong();
630 private static final AtomicLong totalCapacity = new AtomicLong();
631 private static final AtomicLong count = new AtomicLong();
632 private static volatile boolean memoryLimitSet = false;
633 // max. number of sleeps during try-reserving with exponentially
634 // increasing delay before throwing OutOfMemoryError:
635 // 1, 2, 4, 8, 16, 32, 64, 128, 256 (total 511 ms ~ 0.5 s)
636 // which means that OOME will be thrown after 0.5 s of trying
637 private static final int MAX_SLEEPS = 9;
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550
551 // -- Unsafe access --
552
553 private static final Unsafe unsafe = Unsafe.getUnsafe();
554
555 private static byte _get(long a) {
556 return unsafe.getByte(a);
557 }
558
559 private static void _put(long a, byte b) {
560 unsafe.putByte(a, b);
561 }
562
563 static Unsafe unsafe() {
564 return unsafe;
565 }
566
567
568 // -- Processor and memory-system properties --
569
570 private static final ByteOrder byteOrder
571 = unsafe.getByteOrder() == Unsafe.LITTLE_ENDIAN ? ByteOrder.LITTLE_ENDIAN : ByteOrder.BIG_ENDIAN;
572
573 static ByteOrder byteOrder() {
574 if (byteOrder == null)
575 throw new Error("Unknown byte order");
576 return byteOrder;
577 }
578
579 private static int pageSize = -1;
580
581 static int pageSize() {
582 if (pageSize == -1)
583 pageSize = unsafe().pageSize();
584 return pageSize;
585 }
586
587 static int pageCount(long size) {
588 return (int)(size + (long)pageSize() - 1L) / pageSize();
589 }
590
591 private static boolean unaligned;
592 private static boolean unalignedKnown = false;
593
594 static boolean unaligned() {
595 if (unalignedKnown)
596 return unaligned;
597 String arch = AccessController.doPrivileged(
598 new sun.security.action.GetPropertyAction("os.arch"));
599 unaligned = unsafe.unalignedAccess();
600 unalignedKnown = true;
601 return unaligned;
602 }
603
604
605 // -- Direct memory management --
606
607 // A user-settable upper limit on the maximum amount of allocatable
608 // direct buffer memory. This value may be changed during VM
609 // initialization if it is launched with "-XX:MaxDirectMemorySize=<size>".
610 private static volatile long maxMemory = VM.maxDirectMemory();
611 private static final AtomicLong reservedMemory = new AtomicLong();
612 private static final AtomicLong totalCapacity = new AtomicLong();
613 private static final AtomicLong count = new AtomicLong();
614 private static volatile boolean memoryLimitSet = false;
615 // max. number of sleeps during try-reserving with exponentially
616 // increasing delay before throwing OutOfMemoryError:
617 // 1, 2, 4, 8, 16, 32, 64, 128, 256 (total 511 ms ~ 0.5 s)
618 // which means that OOME will be thrown after 0.5 s of trying
619 private static final int MAX_SLEEPS = 9;
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