/*

 * Copyright (c) 2001, 2017, 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.

 *

 */

#ifndef SHARE_VM_RUNTIME_PERFDATA_HPP

#define SHARE_VM_RUNTIME_PERFDATA_HPP

#include "runtime/perfMemory.hpp"

#include "runtime/timer.hpp"

/* 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 variability 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 units specified in U_Bytes in the "com.sun.ci

 * name space.

 *

 *   PerfLongVariable* bar_variable;

 *   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 applied 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 notice, 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<mtInternal> {

  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);

    virtual ~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<mtInternal> {

  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 dec(jlong val) { inc(-val); }

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

    void clear_sample_helper() { _sample_helper = NULL; }

};

/*

 * 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);

};