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hotspot/src/share/vm/runtime/perfData.hpp

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+/*
+ * Copyright 2001-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.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);}
+
+// 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();
+    }
+};