Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2001, 2009, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 /* jvmstat global and subsystem counter name space - enumeration value

  * serve as an index into the PerfDataManager::_name_space[] array

  * containing the corresponding name space string. Only the top level

  * subsystem name spaces are represented here.

  */

 enum CounterNS {

   // top level name spaces

   JAVA_NS,

   COM_NS,

   SUN_NS,

   // subsystem name spaces

   JAVA_GC,              // Garbage Collection name spaces

   COM_GC,

   SUN_GC,

   JAVA_CI,              // Compiler name spaces

   COM_CI,

   SUN_CI,

   JAVA_CLS,             // Class Loader name spaces

   COM_CLS,

   SUN_CLS,

   JAVA_RT,              // Runtime name spaces

   COM_RT,

   SUN_RT,

   JAVA_OS,              // Operating System name spaces

   COM_OS,

   SUN_OS,

   JAVA_THREADS,         // Threads System name spaces

   COM_THREADS,

   SUN_THREADS,

   JAVA_PROPERTY,        // Java Property name spaces

   COM_PROPERTY,

   SUN_PROPERTY,

   NULL_NS,

   COUNTERNS_LAST = NULL_NS

 };

 /*

  * Classes to support access to production performance data

  *

  * The PerfData class structure is provided for creation, access, and update

  * of performance data (a.k.a. instrumentation) in a specific memory region

  * which is possibly accessible as shared memory. Although not explicitly

  * prevented from doing so, developers should not use the values returned

  * by accessor methods to make algorithmic decisions as they are potentially

  * extracted from a shared memory region. Although any shared memory region

  * created is with appropriate access restrictions, allowing read-write access

  * only to the principal that created the JVM, it is believed that a the

  * shared memory region facilitates an easier attack path than attacks

  * launched through mechanisms such as /proc. For this reason, it is

  * recommended that data returned by PerfData accessor methods be used

  * cautiously.

  *

  * There are three variability classifications of performance data

  *   Constants  -  value is written to the PerfData memory once, on creation

  *   Variables  -  value is modifiable, with no particular restrictions

  *   Counters   -  value is monotonically changing (increasing or decreasing)

  *

  * The performance data items can also have various types. The class

  * hierarchy and the structure of the memory region are designed to

  * accommodate new types as they are needed. Types are specified in

  * terms of Java basic types, which accommodates client applications

  * written in the Java programming language. The class hierarchy is:

  *

  * - PerfData (Abstract)

  *     - PerfLong (Abstract)

  *         - PerfLongConstant        (alias: PerfConstant)

  *         - PerfLongVariant (Abstract)

  *             - PerfLongVariable    (alias: PerfVariable)

  *             - PerfLongCounter     (alias: PerfCounter)

  *

  *     - PerfByteArray (Abstract)

  *         - PerfString (Abstract)

  *             - PerfStringVariable

  *             - PerfStringConstant

  *

  *

  * As seen in the class hierarchy, the initially supported types are:

  *

  *    Long      - performance data holds a Java long type

  *    ByteArray - performance data holds an array of Java bytes

  *                used for holding C++ char arrays.

  *

  * The String type is derived from the ByteArray type.

  *

  * A PerfData subtype is not required to provide an implementation for

  * each variability classification. For example, the String type provides

  * Variable and Constant variablility classifications in the PerfStringVariable

  * and PerfStringConstant classes, but does not provide a counter type.

  *

  * Performance data are also described by a unit of measure. Units allow

  * client applications to make reasonable decisions on how to treat

  * performance data generically, preventing the need to hard-code the

  * specifics of a particular data item in client applications. The current

  * set of units are:

  *

  *   None        - the data has no units of measure

  *   Bytes       - data is measured in bytes

  *   Ticks       - data is measured in clock ticks

  *   Events      - data is measured in events. For example,

  *                 the number of garbage collection events or the

  *                 number of methods compiled.

  *   String      - data is not numerical. For example,

  *                 the java command line options

  *   Hertz       - data is a frequency

  *

  * The performance counters also provide a support attribute, indicating

  * the stability of the counter as a programmatic interface. The support

  * level is also implied by the name space in which the counter is created.

  * The counter name space support conventions follow the Java package, class,

  * and property support conventions:

  *

  *    java.*          - stable, supported interface

  *    com.sun.*       - unstable, supported interface

  *    sun.*           - unstable, unsupported interface

  *

  * In the above context, unstable is a measure of the interface support

  * level, not the implementation stability level.

  *

  * Currently, instances of PerfData subtypes are considered to have

  * a life time equal to that of the VM and are managed by the

  * PerfDataManager class. All constructors for the PerfData class and

  * its subtypes have protected constructors. Creation of PerfData

  * instances is performed by invoking various create methods on the

  * PerfDataManager class. Users should not attempt to delete these

  * instances as the PerfDataManager class expects to perform deletion

  * operations on exit of the VM.

  *

  * Examples:

  *

  * Creating performance counter that holds a monotonically increasing

  * long data value with units specified in U_Bytes in the "java.gc.*"

  * name space.

  *

  *   PerfLongCounter* foo_counter;

  *

  *   foo_counter = PerfDataManager::create_long_counter(JAVA_GC, "foo",

  *                                                       PerfData::U_Bytes,

  *                                                       optionalInitialValue,

  *                                                       CHECK);

  *   foo_counter->inc();

  *

  * Creating a performance counter that holds a variably change long

  * data value with untis specified in U_Bytes in the "com.sun.ci

  * name space.

  *

  *   PerfLongVariable* bar_varible;

  *   bar_variable = PerfDataManager::create_long_variable(COM_CI, "bar",

 .*                                                        PerfData::U_Bytes,

  *                                                        optionalInitialValue,

  *                                                        CHECK);

  *

  *   bar_variable->inc();

  *   bar_variable->set_value(0);

  *

  * Creating a performance counter that holds a constant string value in

  * the "sun.cls.*" name space.

  *

  *   PerfDataManager::create_string_constant(SUN_CLS, "foo", string, CHECK);

  *

  *   Although the create_string_constant() factory method returns a pointer

  *   to the PerfStringConstant object, it can safely be ignored. Developers

  *   are not encouraged to access the string constant's value via this

  *   pointer at this time due to security concerns.

  *

  * Creating a performance counter in an arbitrary name space that holds a

  * value that is sampled by the StatSampler periodic task.

  *

  *    PerfDataManager::create_counter("foo.sampled", PerfData::U_Events,

  *                                    &my_jlong, CHECK);

  *

  *    In this example, the PerfData pointer can be ignored as the caller

  *    is relying on the StatSampler PeriodicTask to sample the given

  *    address at a regular interval. The interval is defined by the

  *    PerfDataSamplingInterval global variable, and is applyied on

  *    a system wide basis, not on an per-counter basis.

  *

  * Creating a performance counter in an arbitrary name space that utilizes

  * a helper object to return a value to the StatSampler via the take_sample()

  * method.

  *

  *     class MyTimeSampler : public PerfLongSampleHelper {

  *       public:

  *         jlong take_sample() { return os::elapsed_counter(); }

  *     };

  *

  *     PerfDataManager::create_counter(SUN_RT, "helped",

  *                                     PerfData::U_Ticks,

  *                                     new MyTimeSampler(), CHECK);

  *

  *     In this example, a subtype of PerfLongSampleHelper is instantiated

  *     and its take_sample() method is overridden to perform whatever

  *     operation is necessary to generate the data sample. This method

  *     will be called by the StatSampler at a regular interval, defined

  *     by the PerfDataSamplingInterval global variable.

  *

  *     As before, PerfSampleHelper is an alias for PerfLongSampleHelper.

  *

  * For additional uses of PerfData subtypes, see the utility classes

  * PerfTraceTime and PerfTraceTimedEvent below.

  *

  * Always-on non-sampled counters can be created independent of

  * the UsePerfData flag. Counters will be created on the c-heap

  * if UsePerfData is false.

  *

  * Until further noice, all PerfData objects should be created and

  * manipulated within a guarded block. The guard variable is

  * UsePerfData, a product flag set to true by default. This flag may

  * be removed from the product in the future.

  *

  */

 class PerfData : public CHeapObj {

   friend class StatSampler;      // for access to protected void sample()

   friend class PerfDataManager;  // for access to protected destructor

   public:

     // the Variability enum must be kept in synchronization with the

     // the com.sun.hotspot.perfdata.Variability class

     enum Variability {

       V_Constant = 1,

       V_Monotonic = 2,

       V_Variable = 3,

       V_last = V_Variable

     };

     // the Units enum must be kept in synchronization with the

     // the com.sun.hotspot.perfdata.Units class

     enum Units {

       U_None = 1,

       U_Bytes = 2,

       U_Ticks = 3,

       U_Events = 4,

       U_String = 5,

       U_Hertz = 6,

       U_Last = U_Hertz

     };

     // Miscellaneous flags

     enum Flags {

       F_None = 0x0,

       F_Supported = 0x1    // interface is supported - java.* and com.sun.*

     };

   private:

     char* _name;

     Variability _v;

     Units _u;

     bool _on_c_heap;

     Flags _flags;

     PerfDataEntry* _pdep;

   protected:

     void *_valuep;

     PerfData(CounterNS ns, const char* name, Units u, Variability v);

     ~PerfData();

     // create the entry for the PerfData item in the PerfData memory region.

     // this region is maintained separately from the PerfData objects to

     // facilitate its use by external processes.

     void create_entry(BasicType dtype, size_t dsize, size_t dlen = 0);

     // sample the data item given at creation time and write its value

     // into the its corresponding PerfMemory location.

     virtual void sample() = 0;

   public:

     // returns a boolean indicating the validity of this object.

     // the object is valid if and only if memory in PerfMemory

     // region was successfully allocated.

     inline bool is_valid() { return _valuep != NULL; }

     // returns a boolean indicating whether the underlying object

     // was allocated in the PerfMemory region or on the C heap.

     inline bool is_on_c_heap() { return _on_c_heap; }

     // returns a pointer to a char* containing the name of the item.

     // The pointer returned is the pointer to a copy of the name

     // passed to the constructor, not the pointer to the name in the

     // PerfData memory region. This redundancy is maintained for

     // security reasons as the PerfMemory region may be in shared

     // memory.

     const char* name() { return _name; }

     // returns the variability classification associated with this item

     Variability variability() { return _v; }

     // returns the units associated with this item.

     Units units() { return _u; }

     // returns the flags associated with this item.

     Flags flags() { return _flags; }

     // returns the address of the data portion of the item in the

     // PerfData memory region.

     inline void* get_address() { return _valuep; }

     // returns the value of the data portion of the item in the

     // PerfData memory region formatted as a string.

     virtual int format(char* cp, int length) = 0;

 };

 /*

  * PerfLongSampleHelper, and its alias PerfSamplerHelper, is a base class

  * for helper classes that rely upon the StatSampler periodic task to

  * invoke the take_sample() method and write the value returned to its

  * appropriate location in the PerfData memory region.

  */

 class PerfLongSampleHelper : public CHeapObj {

   public:

     virtual jlong take_sample() = 0;

 };

 typedef PerfLongSampleHelper PerfSampleHelper;

 /*

  * PerfLong is the base class for the various Long PerfData subtypes.

  * it contains implementation details that are common among its derived

  * types.

  */

 class PerfLong : public PerfData {

   protected:

     PerfLong(CounterNS ns, const char* namep, Units u, Variability v);

   public:

     int format(char* buffer, int length);

     // returns the value of the data portion of the item in the

     // PerfData memory region.

     inline jlong get_value() { return *(jlong*)_valuep; }

 };

 /*

  * The PerfLongConstant class, and its alias PerfConstant, implement

  * a PerfData subtype that holds a jlong data value that is set upon

  * creation of an instance of this class. This class provides no

  * methods for changing the data value stored in PerfData memory region.

  */

 class PerfLongConstant : public PerfLong {

   friend class PerfDataManager; // for access to protected constructor

   private:

     // hide sample() - no need to sample constants

     void sample() { }

   protected:

     PerfLongConstant(CounterNS ns, const char* namep, Units u,

                      jlong initial_value=0)

                     : PerfLong(ns, namep, u, V_Constant) {

        if (is_valid()) *(jlong*)_valuep = initial_value;

     }

 };

 typedef PerfLongConstant PerfConstant;

 /*

  * The PerfLongVariant class, and its alias PerfVariant, implement

  * a PerfData subtype that holds a jlong data value that can be modified

  * in an unrestricted manner. This class provides the implementation details

  * for common functionality among its derived types.

  */

 class PerfLongVariant : public PerfLong {

   protected:

     jlong* _sampled;

     PerfLongSampleHelper* _sample_helper;

     PerfLongVariant(CounterNS ns, const char* namep, Units u, Variability v,

                     jlong initial_value=0)

                    : PerfLong(ns, namep, u, v) {

       if (is_valid()) *(jlong*)_valuep = initial_value;

     }

     PerfLongVariant(CounterNS ns, const char* namep, Units u, Variability v,

                     jlong* sampled);

     PerfLongVariant(CounterNS ns, const char* namep, Units u, Variability v,

                     PerfLongSampleHelper* sample_helper);

     void sample();

   public:

     inline void inc() { (*(jlong*)_valuep)++; }

     inline void inc(jlong val) { (*(jlong*)_valuep) += val; }

     inline void add(jlong val) { (*(jlong*)_valuep) += val; }

 };

 /*

  * The PerfLongCounter class, and its alias PerfCounter, implement

  * a PerfData subtype that holds a jlong data value that can (should)

  * be modified in a monotonic manner. The inc(jlong) and add(jlong)

  * methods can be passed negative values to implement a monotonically

  * decreasing value. However, we rely upon the programmer to honor

  * the notion that this counter always moves in the same direction -

  * either increasing or decreasing.

  */

 class PerfLongCounter : public PerfLongVariant {

   friend class PerfDataManager; // for access to protected constructor

   protected:

     PerfLongCounter(CounterNS ns, const char* namep, Units u,

                     jlong initial_value=0)

                    : PerfLongVariant(ns, namep, u, V_Monotonic,

                                      initial_value) { }

     PerfLongCounter(CounterNS ns, const char* namep, Units u, jlong* sampled)

                   : PerfLongVariant(ns, namep, u, V_Monotonic, sampled) { }

     PerfLongCounter(CounterNS ns, const char* namep, Units u,

                     PerfLongSampleHelper* sample_helper)

                    : PerfLongVariant(ns, namep, u, V_Monotonic,

                                      sample_helper) { }

 };

 typedef PerfLongCounter PerfCounter;

 /*

  * The PerfLongVariable class, and its alias PerfVariable, implement

  * a PerfData subtype that holds a jlong data value that can

  * be modified in an unrestricted manner.

  */

 class PerfLongVariable : public PerfLongVariant {

   friend class PerfDataManager; // for access to protected constructor

   protected:

     PerfLongVariable(CounterNS ns, const char* namep, Units u,

                      jlong initial_value=0)

                     : PerfLongVariant(ns, namep, u, V_Variable,

                                       initial_value) { }

     PerfLongVariable(CounterNS ns, const char* namep, Units u, jlong* sampled)

                     : PerfLongVariant(ns, namep, u, V_Variable, sampled) { }

     PerfLongVariable(CounterNS ns, const char* namep, Units u,

                      PerfLongSampleHelper* sample_helper)

                     : PerfLongVariant(ns, namep, u, V_Variable,

                                       sample_helper) { }

   public:

     inline void set_value(jlong val) { (*(jlong*)_valuep) = val; }

 };

 typedef PerfLongVariable PerfVariable;

 /*

  * The PerfByteArray provides a PerfData subtype that allows the creation

  * of a contiguous region of the PerfData memory region for storing a vector

  * of bytes. This class is currently intended to be a base class for

  * the PerfString class, and cannot be instantiated directly.

  */

 class PerfByteArray : public PerfData {

   protected:

     jint _length;

     PerfByteArray(CounterNS ns, const char* namep, Units u, Variability v,

                   jint length);

 };

 class PerfString : public PerfByteArray {

   protected:

     void set_string(const char* s2);

     PerfString(CounterNS ns, const char* namep, Variability v, jint length,

                const char* initial_value)

               : PerfByteArray(ns, namep, U_String, v, length) {

        if (is_valid()) set_string(initial_value);

     }

   public:

     int format(char* buffer, int length);

 };

 /*

  * The PerfStringConstant class provides a PerfData sub class that

  * allows a null terminated string of single byte characters to be

  * stored in the PerfData memory region.

  */

 class PerfStringConstant : public PerfString {

   friend class PerfDataManager; // for access to protected constructor

   private:

     // hide sample() - no need to sample constants

     void sample() { }

   protected:

     // Restrict string constant lengths to be <= PerfMaxStringConstLength.

     // This prevents long string constants, as can occur with very

     // long classpaths or java command lines, from consuming too much

     // PerfData memory.

     PerfStringConstant(CounterNS ns, const char* namep,

                        const char* initial_value);

 };

 /*

  * The PerfStringVariable class provides a PerfData sub class that

  * allows a null terminated string of single byte character data

  * to be stored in PerfData memory region. The string value can be reset

  * after initialization. If the string value is >= max_length, then

  * it will be truncated to max_length characters. The copied string

  * is always null terminated.

  */

 class PerfStringVariable : public PerfString {

   friend class PerfDataManager; // for access to protected constructor

   protected:

     // sampling of string variables are not yet supported

     void sample() { }

     PerfStringVariable(CounterNS ns, const char* namep, jint max_length,

                        const char* initial_value)

                       : PerfString(ns, namep, V_Variable, max_length+1,

                                    initial_value) { }

   public:

     inline void set_value(const char* val) { set_string(val); }

 };

 /*

  * The PerfDataList class is a container class for managing lists

  * of PerfData items. The intention of this class is to allow for

  * alternative implementations for management of list of PerfData

  * items without impacting the code that uses the lists.

  *

  * The initial implementation is based upon GrowableArray. Searches

  * on GrowableArray types is linear in nature and this may become

  * a performance issue for creation of PerfData items, particularly

  * from Java code where a test for existence is implemented as a

  * search over all existing PerfData items.

  *

  * The abstraction is not complete. A more general container class

  * would provide an Iterator abstraction that could be used to

  * traverse the lists. This implementation still relys upon integer

  * iterators and the at(int index) method. However, the GrowableArray

  * is not directly visible outside this class and can be replaced by

  * some other implementation, as long as that implementation provides

  * a mechanism to iterate over the container by index.

  */

 class PerfDataList : public CHeapObj {

   private:

     // GrowableArray implementation

     typedef GrowableArray<PerfData*> PerfDataArray;

     PerfDataArray* _set;

     // method to search for a instrumentation object by name

     static bool by_name(void* name, PerfData* pd);

   protected:

     // we expose the implementation here to facilitate the clone

     // method.

     PerfDataArray* get_impl() { return _set; }

   public:

     // create a PerfDataList with the given initial length

     PerfDataList(int length);

     // create a PerfDataList as a shallow copy of the given PerfDataList

     PerfDataList(PerfDataList* p);

     ~PerfDataList();

     // return the PerfData item indicated by name,

     // or NULL if it doesn't exist.

     PerfData* find_by_name(const char* name);

     // return true if a PerfData item with the name specified in the

     // argument exists, otherwise return false.

     bool contains(const char* name) { return find_by_name(name) != NULL; }

     // return the number of PerfData items in this list

     int length() { return _set->length(); }

     // add a PerfData item to this list

     void append(PerfData *p) { _set->append(p); }

     // remove the given PerfData item from this list. When called

     // while iterating over the list, this method will result in a

     // change in the length of the container. The at(int index)

     // method is also impacted by this method as elements with an

     // index greater than the index of the element removed by this

     // method will be shifted down by one.

     void remove(PerfData *p) { _set->remove(p); }

     // create a new PerfDataList from this list. The new list is

     // a shallow copy of the original list and care should be taken

     // with respect to delete operations on the elements of the list

     // as the are likely in use by another copy of the list.

     PerfDataList* clone();

     // for backward compatibility with GrowableArray - need to implement

     // some form of iterator to provide a cleaner abstraction for

     // iteration over the container.

     PerfData* at(int index) { return _set->at(index); }

 };

 /*

  * The PerfDataManager class is responsible for creating PerfData

  * subtypes via a set a factory methods and for managing lists

  * of the various PerfData types.

  */

 class PerfDataManager : AllStatic {

   friend class StatSampler;   // for access to protected PerfDataList methods

   private:

     static PerfDataList* _all;

     static PerfDataList* _sampled;

     static PerfDataList* _constants;

     static const char* _name_spaces[];

     // add a PerfData item to the list(s) of know PerfData objects

     static void add_item(PerfData* p, bool sampled);

   protected:

     // return the list of all known PerfData items

     static PerfDataList* all();

     static int count() { return _all->length(); }

     // return the list of all known PerfData items that are to be

     // sampled by the StatSampler.

     static PerfDataList* sampled();

     static int sampled_count() { return _sampled->length(); }

     // return the list of all known PerfData items that have a

     // variability classification of type Constant

     static PerfDataList* constants();

     static int constants_count() { return _constants->length(); }

   public:

     // method to check for the existence of a PerfData item with

     // the given name.

     static bool exists(const char* name) { return _all->contains(name); }

     // method to map a CounterNS enumeration to a namespace string

     static const char* ns_to_string(CounterNS ns) {

       return _name_spaces[ns];

     }

     // methods to test the interface stability of a given counter namespace

     //

     static bool is_stable_supported(CounterNS ns) {

       return (ns != NULL_NS) && ((ns % 3) == JAVA_NS);

     }

     static bool is_unstable_supported(CounterNS ns) {

       return (ns != NULL_NS) && ((ns % 3) == COM_NS);

     }

     static bool is_unstable_unsupported(CounterNS ns) {

       return (ns == NULL_NS) || ((ns % 3) == SUN_NS);

     }

     // methods to test the interface stability of a given counter name

     //

     static bool is_stable_supported(const char* name) {

       const char* javadot = "java.";

       return strncmp(name, javadot, strlen(javadot)) == 0;

     }

     static bool is_unstable_supported(const char* name) {

       const char* comdot = "com.sun.";

       return strncmp(name, comdot, strlen(comdot)) == 0;

     }

     static bool is_unstable_unsupported(const char* name) {

       return !(is_stable_supported(name) && is_unstable_supported(name));

     }

     // method to construct counter name strings in a given name space.

     // The string object is allocated from the Resource Area and calls

     // to this method must be made within a ResourceMark.

     //

     static char* counter_name(const char* name_space, const char* name);

     // method to construct name space strings in a given name space.

     // The string object is allocated from the Resource Area and calls

     // to this method must be made within a ResourceMark.

     //

     static char* name_space(const char* name_space, const char* sub_space) {

       return counter_name(name_space, sub_space);

     }

     // same as above, but appends the instance number to the name space

     //

     static char* name_space(const char* name_space, const char* sub_space,

                             int instance);

     static char* name_space(const char* name_space, int instance);

     // these methods provide the general interface for creating

     // performance data resources. The types of performance data

     // resources can be extended by adding additional create<type>

     // methods.

     // Constant Types

     static PerfStringConstant* create_string_constant(CounterNS ns,

                                                       const char* name,

                                                       const char *s, TRAPS);

     static PerfLongConstant* create_long_constant(CounterNS ns,

                                                   const char* name,

                                                   PerfData::Units u,

                                                   jlong val, TRAPS);

     // Variable Types

     static PerfStringVariable* create_string_variable(CounterNS ns,

                                                       const char* name,

                                                       int max_length,

                                                       const char *s, TRAPS);

     static PerfStringVariable* create_string_variable(CounterNS ns,

                                                       const char* name,

                                                       const char *s, TRAPS) {

       return create_string_variable(ns, name, 0, s, CHECK_NULL);

     };

     static PerfLongVariable* create_long_variable(CounterNS ns,

                                                   const char* name,

                                                   PerfData::Units u,

                                                   jlong ival, TRAPS);

     static PerfLongVariable* create_long_variable(CounterNS ns,

                                                   const char* name,

                                                   PerfData::Units u, TRAPS) {

       return create_long_variable(ns, name, u, (jlong)0, CHECK_NULL);

     };

     static PerfLongVariable* create_long_variable(CounterNS, const char* name,

                                                   PerfData::Units u,

                                                   jlong* sp, TRAPS);

     static PerfLongVariable* create_long_variable(CounterNS ns,

                                                   const char* name,

                                                   PerfData::Units u,

                                                   PerfLongSampleHelper* sh,

                                                   TRAPS);

     // Counter Types

     static PerfLongCounter* create_long_counter(CounterNS ns, const char* name,

                                                 PerfData::Units u,

                                                 jlong ival, TRAPS);

     static PerfLongCounter* create_long_counter(CounterNS ns, const char* name,

                                                 PerfData::Units u, TRAPS) {

       return create_long_counter(ns, name, u, (jlong)0, CHECK_NULL);

     };

     static PerfLongCounter* create_long_counter(CounterNS ns, const char* name,

                                                 PerfData::Units u, jlong* sp,

                                                 TRAPS);

     static PerfLongCounter* create_long_counter(CounterNS ns, const char* name,

                                                 PerfData::Units u,

                                                 PerfLongSampleHelper* sh,

                                                 TRAPS);

     // these creation methods are provided for ease of use. These allow

     // Long performance data types to be created with a shorthand syntax.

     static PerfConstant* create_constant(CounterNS ns, const char* name,

                                          PerfData::Units u, jlong val, TRAPS) {

       return create_long_constant(ns, name, u, val, CHECK_NULL);

     }

     static PerfVariable* create_variable(CounterNS ns, const char* name,

                                          PerfData::Units u, jlong ival, TRAPS) {

       return create_long_variable(ns, name, u, ival, CHECK_NULL);

     }

     static PerfVariable* create_variable(CounterNS ns, const char* name,

                                          PerfData::Units u, TRAPS) {

       return create_long_variable(ns, name, u, (jlong)0, CHECK_NULL);

     }

     static PerfVariable* create_variable(CounterNS ns, const char* name,

                                          PerfData::Units u, jlong* sp, TRAPS) {

       return create_long_variable(ns, name, u, sp, CHECK_NULL);

     }

     static PerfVariable* create_variable(CounterNS ns, const char* name,

                                          PerfData::Units u,

                                          PerfSampleHelper* sh, TRAPS) {

       return create_long_variable(ns, name, u, sh, CHECK_NULL);

     }

     static PerfCounter* create_counter(CounterNS ns, const char* name,

                                        PerfData::Units u, jlong ival, TRAPS) {

       return create_long_counter(ns, name, u, ival, CHECK_NULL);

     }

     static PerfCounter* create_counter(CounterNS ns, const char* name,

                                        PerfData::Units u, TRAPS) {

       return create_long_counter(ns, name, u, (jlong)0, CHECK_NULL);

     }

     static PerfCounter* create_counter(CounterNS ns, const char* name,

                                        PerfData::Units u, jlong* sp, TRAPS) {

       return create_long_counter(ns, name, u, sp, CHECK_NULL);

     }

     static PerfCounter* create_counter(CounterNS ns, const char* name,

                                        PerfData::Units u,

                                        PerfSampleHelper* sh, TRAPS) {

       return create_long_counter(ns, name, u, sh, CHECK_NULL);

     }

     static void destroy();

 };

 // Useful macros to create the performance counters

 #define NEWPERFTICKCOUNTER(counter, counter_ns, counter_name)  \

   {counter = PerfDataManager::create_counter(counter_ns, counter_name, \

                                              PerfData::U_Ticks,CHECK);}

 #define NEWPERFEVENTCOUNTER(counter, counter_ns, counter_name)  \

   {counter = PerfDataManager::create_counter(counter_ns, counter_name, \

                                              PerfData::U_Events,CHECK);}

 #define NEWPERFBYTECOUNTER(counter, counter_ns, counter_name)  \

   {counter = PerfDataManager::create_counter(counter_ns, counter_name, \

                                              PerfData::U_Bytes,CHECK);}

 // Utility Classes

 /*

  * this class will administer a PerfCounter used as a time accumulator

  * for a basic block much like the TraceTime class.

  *

  * Example:

  *

  *    static PerfCounter* my_time_counter = PerfDataManager::create_counter("my.time.counter", PerfData::U_Ticks, 0LL, CHECK);

  *

  *    {

  *      PerfTraceTime ptt(my_time_counter);

  *      // perform the operation you want to measure

  *    }

  *

  * Note: use of this class does not need to occur within a guarded

  * block. The UsePerfData guard is used with the implementation

  * of this class.

  */

 class PerfTraceTime : public StackObj {

   protected:

     elapsedTimer _t;

     PerfLongCounter* _timerp;

     // pointer to thread-local or global recursion counter variable

     int* _recursion_counter;

   public:

     inline PerfTraceTime(PerfLongCounter* timerp) : _timerp(timerp), _recursion_counter(NULL) {

       if (!UsePerfData) return;

       _t.start();

     }

     inline PerfTraceTime(PerfLongCounter* timerp, int* recursion_counter) : _timerp(timerp), _recursion_counter(recursion_counter) {

       if (!UsePerfData || (_recursion_counter != NULL &&

                            (*_recursion_counter)++ > 0)) return;

       _t.start();

     }

     inline void suspend() { if (!UsePerfData) return; _t.stop(); }

     inline void resume() { if (!UsePerfData) return; _t.start(); }

     inline ~PerfTraceTime() {

       if (!UsePerfData || (_recursion_counter != NULL &&

                            --(*_recursion_counter) > 0)) return;

       _t.stop();

       _timerp->inc(_t.ticks());

     }

 };

 /* The PerfTraceTimedEvent class is responsible for counting the

  * occurrence of some event and measuring the the elapsed time of

  * the event in two separate PerfCounter instances.

  *

  * Example:

  *

  *    static PerfCounter* my_time_counter = PerfDataManager::create_counter("my.time.counter", PerfData::U_Ticks, CHECK);

  *    static PerfCounter* my_event_counter = PerfDataManager::create_counter("my.event.counter", PerfData::U_Events, CHECK);

  *

  *    {

  *      PerfTraceTimedEvent ptte(my_time_counter, my_event_counter);

  *      // perform the operation you want to count and measure

  *    }

  *

  * Note: use of this class does not need to occur within a guarded

  * block. The UsePerfData guard is used with the implementation

  * of this class.

  *

  */

 class PerfTraceTimedEvent : public PerfTraceTime {

   protected:

     PerfLongCounter* _eventp;

   public:

     inline PerfTraceTimedEvent(PerfLongCounter* timerp, PerfLongCounter* eventp): PerfTraceTime(timerp), _eventp(eventp) {

       if (!UsePerfData) return;

       _eventp->inc();

     }

     inline PerfTraceTimedEvent(PerfLongCounter* timerp, PerfLongCounter* eventp, int* recursion_counter): PerfTraceTime(timerp, recursion_counter), _eventp(eventp) {

       if (!UsePerfData) return;

       _eventp->inc();

     }

 };