rev 50556 : [mq]: jcmd-cleanups

   1 /*
   2  * Copyright (c) 2011, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_SERVICES_DIAGNOSTICFRAMEWORK_HPP
  26 #define SHARE_VM_SERVICES_DIAGNOSTICFRAMEWORK_HPP
  27 
  28 #include "classfile/vmSymbols.hpp"
  29 #include "memory/allocation.hpp"
  30 #include "runtime/arguments.hpp"
  31 #include "runtime/os.hpp"
  32 #include "runtime/vmThread.hpp"
  33 #include "utilities/ostream.hpp"
  34 
  35 
  36 enum DCmdSource {
  37   DCmd_Source_Internal  = 0x01U,  // invocation from the JVM
  38   DCmd_Source_AttachAPI = 0x02U,  // invocation via the attachAPI
  39   DCmd_Source_MBean     = 0x04U   // invocation via a MBean
  40 };
  41 
  42 // Warning: strings referenced by the JavaPermission struct are passed to
  43 // the native part of the JDK. Avoid use of dynamically allocated strings
  44 // that could be de-allocated before the JDK native code had time to
  45 // convert them into Java Strings.
  46 struct JavaPermission {
  47   const char* _class;
  48   const char* _name;
  49   const char* _action;
  50 };
  51 
  52 // CmdLine is the class used to handle a command line containing a single
  53 // diagnostic command and its arguments. It provides methods to access the
  54 // command name and the beginning of the arguments. The class is also
  55 // able to identify commented command lines and the "stop" keyword
  56 class CmdLine : public StackObj {
  57 private:
  58   const char* _cmd;
  59   size_t      _cmd_len;
  60   const char* _args;
  61   size_t      _args_len;
  62 public:
  63   CmdLine(const char* line, size_t len, bool no_command_name);
  64   const char* args_addr() const   { return _args; }
  65   size_t args_len() const         { return _args_len; }
  66   const char* cmd_addr() const    { return _cmd; }
  67   size_t cmd_len() const          { return _cmd_len; }
  68   bool is_empty() const           { return _cmd_len == 0; }
  69   bool is_executable() const      { return is_empty() || _cmd[0] != '#'; }
  70   bool is_stop() const            { return !is_empty() && strncmp("stop", _cmd, _cmd_len) == 0; }
  71 };
  72 
  73 // Iterator class taking a character string in input and returning a CmdLine
  74 // instance for each command line. The argument delimiter has to be specified.
  75 class DCmdIter : public StackObj {
  76   friend class DCmd;
  77 private:
  78   const char* const _str;
  79   const char        _delim;
  80   const size_t      _len;
  81   size_t      _cursor;
  82 public:
  83 
  84   DCmdIter(const char* str, char delim)
  85    : _str(str)
  86    , _delim(delim)
  87    , _len(::strlen(str))
  88    , _cursor(0) {}
  89   bool has_next() const { return _cursor < _len; }

  90   CmdLine next() {
  91     assert(_cursor <= _len, "Cannot iterate more");
  92     size_t n = _cursor;
  93     while (n < _len && _str[n] != _delim) n++;
  94     CmdLine line(&(_str[_cursor]), n - _cursor, false);
  95     _cursor = n + 1;
  96     // The default copy constructor of CmdLine is used to return a CmdLine
  97     // instance to the caller.
  98     return line;
  99   }
 100 };
 101 
 102 // Iterator class to iterate over diagnostic command arguments
 103 class DCmdArgIter : public ResourceObj {
 104   const char* const _buffer;
 105   const size_t      _len;
 106   size_t      _cursor;
 107   const char* _key_addr;
 108   size_t      _key_len;
 109   const char* _value_addr;
 110   size_t      _value_len;
 111   const char  _delim;
 112 public:
 113   DCmdArgIter(const char* buf, size_t len, char delim)
 114     : _buffer(buf)
 115     , _len(len)
 116     , _cursor(0)
 117     , _key_addr(NULL)
 118     , _key_len(0)
 119     , _value_addr(NULL)
 120     , _value_len(0)
 121     , _delim(delim)
 122   {}
 123 
 124   bool next(TRAPS);
 125   const char* key_addr() const    { return _key_addr; }
 126   size_t key_length() const       { return _key_len; }
 127   const char* value_addr() const  { return _value_addr; }
 128   size_t value_length() const     { return _value_len; }
 129 };
 130 
 131 // A DCmdInfo instance provides a description of a diagnostic command. It is
 132 // used to export the description to the JMX interface of the framework.
 133 class DCmdInfo : public ResourceObj {
 134 protected:
 135   const char* const _name;           /* Name of the diagnostic command */
 136   const char* const _description;    /* Short description */
 137   const char* const _impact;         /* Impact on the JVM */
 138   const JavaPermission _permission;  /* Java Permission required to execute this command if any */
 139   const int         _num_arguments;  /* Number of supported options or arguments */
 140   const bool        _is_enabled;     /* True if the diagnostic command can be invoked, false otherwise */
 141 public:
 142   DCmdInfo(const char* name,
 143           const char* description,
 144           const char* impact,
 145           JavaPermission permission,
 146           int num_arguments,
 147           bool enabled)
 148   : _name(name)
 149   , _description(description)
 150   , _impact(impact)
 151   , _permission(permission)
 152   , _num_arguments(num_arguments)
 153   , _is_enabled(enabled) {}

 154   const char* name() const          { return _name; }
 155   const char* description() const   { return _description; }
 156   const char* impact() const        { return _impact; }
 157   const JavaPermission& permission() const { return _permission; }
 158   int num_arguments() const         { return _num_arguments; }
 159   bool is_enabled() const           { return _is_enabled; }
 160 
 161   static bool by_name(void* name, DCmdInfo* info);
 162 };
 163 
 164 // A DCmdArgumentInfo instance provides a description of a diagnostic command
 165 // argument. It is used to export the description to the JMX interface of the
 166 // framework.
 167 class DCmdArgumentInfo : public ResourceObj {
 168 protected:
 169   const char* const _name;            /* Option/Argument name*/
 170   const char* const _description;     /* Short description */
 171   const char* const _type;            /* Type: STRING, BOOLEAN, etc. */
 172   const char* const _default_string;  /* Default value in a parsable string */
 173   const bool        _mandatory;       /* True if the option/argument is mandatory */
 174   const bool        _option;          /* True if it is an option, false if it is an argument */
 175                                 /* (see diagnosticFramework.hpp for option/argument definitions) */
 176   const bool        _multiple;        /* True is the option can be specified several time */
 177   const int         _position;        /* Expected position for this argument (this field is */
 178                                 /* meaningless for options) */
 179 public:
 180   DCmdArgumentInfo(const char* name, const char* description, const char* type,
 181                    const char* default_string, bool mandatory, bool option,
 182                    bool multiple, int position = -1)
 183     : _name(name)
 184     , _description(description)
 185     , _type(type)
 186     , _default_string(default_string)
 187     , _mandatory(mandatory)
 188     , _option(option)
 189     , _multiple(multiple)
 190     , _position(position) {}
 191 














 192   const char* name() const        { return _name; }
 193   const char* description() const { return _description; }
 194   const char* type() const        { return _type; }
 195   const char* default_string() const { return _default_string; }
 196   bool is_mandatory() const       { return _mandatory; }
 197   bool is_option() const          { return _option; }
 198   bool is_multiple() const        { return _multiple; }
 199   int position() const            { return _position; }
 200 };
 201 
 202 // The DCmdParser class can be used to create an argument parser for a
 203 // diagnostic command. It is not mandatory to use it to parse arguments.
 204 // The DCmdParser parses a CmdLine instance according to the parameters that
 205 // have been declared by its associated diagnostic command. A parameter can
 206 // either be an option or an argument. Options are identified by the option name
 207 // while arguments are identified by their position in the command line. The
 208 // position of an argument is defined relative to all arguments passed on the
 209 // command line, options are not considered when defining an argument position.
 210 // The generic syntax of a diagnostic command is:
 211 //
 212 //    <command name> [<option>=<value>] [<argument_value>]
 213 //
 214 // Example:
 215 //
 216 //    command_name option1=value1 option2=value argumentA argumentB argumentC
 217 //
 218 // In this command line, the diagnostic command receives five parameters, two
 219 // options named option1 and option2, and three arguments. argumentA's position
 220 // is 0, argumentB's position is 1 and argumentC's position is 2.
 221 class DCmdParser {
 222 private:
 223   GenDCmdArgument* _options;
 224   GenDCmdArgument* _arguments_list;

 225 public:
 226   DCmdParser()
 227     : _options(NULL)
 228     , _arguments_list(NULL) {}


 229   void add_dcmd_option(GenDCmdArgument* arg);
 230   void add_dcmd_argument(GenDCmdArgument* arg);
 231   GenDCmdArgument* lookup_dcmd_option(const char* name, size_t len);
 232   GenDCmdArgument* arguments_list() const { return _arguments_list; };
 233   void check(TRAPS);
 234   void parse(CmdLine* line, char delim, TRAPS);
 235   void print_help(outputStream* out, const char* cmd_name) const;
 236   void reset(TRAPS);
 237   void cleanup();
 238   int num_arguments() const;
 239   GrowableArray<const char*>* argument_name_array() const;
 240   GrowableArray<DCmdArgumentInfo*>* argument_info_array() const;
 241 };
 242 
 243 // The DCmd class is the parent class of all diagnostic commands
 244 // Diagnostic command instances should not be instantiated directly but
 245 // created using the associated factory. The factory can be retrieved with
 246 // the DCmdFactory::getFactory() method.
 247 // A diagnostic command instance can either be allocated in the resource Area
 248 // or in the C-heap. Allocation in the resource area is recommended when the
 249 // current thread is the only one which will access the diagnostic command
 250 // instance. Allocation in the C-heap is required when the diagnostic command
 251 // is accessed by several threads (for instance to perform asynchronous
 252 // execution).
 253 // To ensure a proper cleanup, it's highly recommended to use a DCmdMark for
 254 // each diagnostic command instance. In case of a C-heap allocated diagnostic
 255 // command instance, the DCmdMark must be created in the context of the last
 256 // thread that will access the instance.
 257 class DCmd : public ResourceObj {
 258 protected:
 259   outputStream* const _output;
 260   const bool          _is_heap_allocated;
 261 public:
 262   DCmd(outputStream* output, bool heap_allocated)
 263    : _output(output)
 264    , _is_heap_allocated(heap_allocated) {}
 265 
 266   // Child classes: please always provide these methods:
 267   //  static const char* name()             { return "<command name>";}
 268   //  static const char* description()      { return "<command help>";}
 269 


 270   static const char* disabled_message() { return "Diagnostic command currently disabled"; }
 271 
 272   // The impact() method returns a description of the intrusiveness of the diagnostic
 273   // command on the Java Virtual Machine behavior. The rational for this method is that some
 274   // diagnostic commands can seriously disrupt the behavior of the Java Virtual Machine
 275   // (for instance a Thread Dump for an application with several tens of thousands of threads,
 276   // or a Head Dump with a 40GB+ heap size) and other diagnostic commands have no serious
 277   // impact on the JVM (for instance, getting the command line arguments or the JVM version).
 278   // The recommended format for the description is <impact level>: [longer description],
 279   // where the impact level is selected among this list: {Low, Medium, High}. The optional
 280   // longer description can provide more specific details like the fact that Thread Dump
 281   // impact depends on the heap size.
 282   static const char* impact()       { return "Low: No impact"; }
 283 
 284   // The permission() method returns the description of Java Permission. This
 285   // permission is required when the diagnostic command is invoked via the
 286   // DiagnosticCommandMBean. The rationale for this permission check is that
 287   // the DiagnosticCommandMBean can be used to perform remote invocations of
 288   // diagnostic commands through the PlatformMBeanServer. The (optional) Java
 289   // Permission associated with each diagnostic command should ease the work
 290   // of system administrators to write policy files granting permissions to
 291   // execute diagnostic commands to remote users. Any diagnostic command with
 292   // a potential impact on security should overwrite this method.
 293   static const JavaPermission permission() {
 294     JavaPermission p = {NULL, NULL, NULL};
 295     return p;
 296   }
 297   static int num_arguments()        { return 0; }
 298   outputStream* output() const      { return _output; }
 299   bool is_heap_allocated() const    { return _is_heap_allocated; }
 300   virtual void print_help(const char* name) const {
 301     output()->print_cr("Syntax: %s", name);
 302   }
 303   virtual void parse(CmdLine* line, char delim, TRAPS) {
 304     DCmdArgIter iter(line->args_addr(), line->args_len(), delim);
 305     bool has_arg = iter.next(CHECK);
 306     if (has_arg) {
 307       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
 308                 "The argument list of this diagnostic command should be empty.");
 309     }
 310   }
 311   virtual void execute(DCmdSource source, TRAPS) { }
 312   virtual void reset(TRAPS) { }
 313   virtual void cleanup() { }
 314 
 315   // support for the JMX interface
 316   virtual GrowableArray<const char*>* argument_name_array() const {
 317     GrowableArray<const char*>* array = new GrowableArray<const char*>(0);
 318     return array;
 319   }
 320   virtual GrowableArray<DCmdArgumentInfo*>* argument_info_array() const {
 321     GrowableArray<DCmdArgumentInfo*>* array = new GrowableArray<DCmdArgumentInfo*>(0);
 322     return array;
 323   }
 324 
 325   // main method to invoke the framework
 326   static void parse_and_execute(DCmdSource source, outputStream* out, const char* cmdline,
 327                                 char delim, TRAPS);
 328 };
 329 
 330 class DCmdWithParser : public DCmd {
 331 protected:
 332   DCmdParser _dcmdparser;
 333 public:
 334   DCmdWithParser (outputStream *output, bool heap=false) : DCmd(output, heap) { }


 335   static const char* disabled_message() { return "Diagnostic command currently disabled"; }
 336   static const char* impact()         { return "Low: No impact"; }


 337   virtual void parse(CmdLine *line, char delim, TRAPS);
 338   virtual void execute(DCmdSource source, TRAPS) { }
 339   virtual void reset(TRAPS);
 340   virtual void cleanup();
 341   virtual void print_help(const char* name) const;
 342   virtual GrowableArray<const char*>* argument_name_array() const;
 343   virtual GrowableArray<DCmdArgumentInfo*>* argument_info_array() const;
 344 };
 345 
 346 class DCmdMark : public StackObj {
 347   DCmd* const _ref;
 348 public:
 349   DCmdMark(DCmd* cmd) : _ref(cmd) {}
 350   ~DCmdMark() {
 351     if (_ref != NULL) {
 352       _ref->cleanup();
 353       if (_ref->is_heap_allocated()) {
 354         delete _ref;
 355       }
 356     }
 357   }
 358 };
 359 
 360 // Diagnostic commands are not directly instantiated but created with a factory.
 361 // Each diagnostic command class has its own factory. The DCmdFactory class also
 362 // manages the status of the diagnostic command (hidden, enabled). A DCmdFactory
 363 // has to be registered to make the diagnostic command available (see
 364 // management.cpp)
 365 class DCmdFactory: public CHeapObj<mtInternal> {
 366 private:
 367   static Mutex*       _dcmdFactory_lock;
 368   static bool         _send_jmx_notification;
 369   static bool         _has_pending_jmx_notification;
 370   static DCmdFactory* _DCmdFactoryList;
 371 
 372   // Pointer to the next factory in the singly-linked list of registered
 373   // diagnostic commands
 374   DCmdFactory*        _next;
 375   // When disabled, a diagnostic command cannot be executed. Any attempt to
 376   // execute it will result in the printing of the disabled message without
 377   // instantiating the command.
 378   const bool          _enabled;
 379   // When hidden, a diagnostic command doesn't appear in the list of commands
 380   // provided by the 'help' command.
 381   const bool          _hidden;
 382   const uint32_t      _export_flags;
 383   const int           _num_arguments;
 384 
 385 public:
 386   DCmdFactory(int num_arguments, uint32_t flags, bool enabled, bool hidden)
 387     : _next(NULL)
 388     , _enabled(enabled)
 389     , _hidden(hidden)
 390     , _export_flags(flags)
 391     , _num_arguments(num_arguments) {}

 392   bool is_enabled() const       { return _enabled; }

 393   bool is_hidden() const        { return _hidden; }
 394   uint32_t export_flags() const { return _export_flags; }
 395   int num_arguments() const     { return _num_arguments; }
 396   DCmdFactory* next() const     { return _next; }
 397   virtual DCmd* create_resource_instance(outputStream* output) const = 0;



 398   virtual const char* name() const = 0;
 399   virtual const char* description() const = 0;
 400   virtual const char* impact() const = 0;
 401   virtual const JavaPermission permission() const = 0;
 402   virtual const char* disabled_message() const = 0;
 403   // Register a DCmdFactory to make a diagnostic command available.
 404   // Once registered, a diagnostic command must not be unregistered.
 405   // To prevent a diagnostic command from being executed, just set the
 406   // enabled flag to false.
 407   static int register_DCmdFactory(DCmdFactory* factory);
 408   static DCmdFactory* factory(DCmdSource source, const char* cmd, size_t len);


 409   // Returns a resourceArea allocated diagnostic command for the given command line
 410   static DCmd* create_local_DCmd(DCmdSource source, CmdLine &line, outputStream* out, TRAPS);
 411   static GrowableArray<const char*>* DCmd_list(DCmdSource source);
 412   static GrowableArray<DCmdInfo*>* DCmdInfo_list(DCmdSource source);
 413 
 414   static void set_jmx_notification_enabled(bool enabled) {
 415     _send_jmx_notification = enabled;
 416   }
 417   static void push_jmx_notification_request();
 418   static bool has_pending_jmx_notification() { return _has_pending_jmx_notification; }
 419   static void send_notification(TRAPS);
 420 private:
 421   static void send_notification_internal(TRAPS);
 422 
 423   friend class HelpDCmd;
 424 };
 425 
 426 // Template to easily create DCmdFactory instances. See management.cpp
 427 // where this template is used to create and register factories.
 428 template <class DCmdClass> class DCmdFactoryImpl : public DCmdFactory {
 429 public:
 430   DCmdFactoryImpl(uint32_t flags, bool enabled, bool hidden) :
 431     DCmdFactory(DCmdClass::num_arguments(), flags, enabled, hidden) { }




 432   // Returns a resourceArea allocated instance
 433   DCmd* create_resource_instance(outputStream* output) const {
 434     return new DCmdClass(output, false);
 435   }
 436   const char* name() const {
 437     return DCmdClass::name();
 438   }
 439   const char* description() const {
 440     return DCmdClass::description();
 441   }
 442   const char* impact() const {
 443     return DCmdClass::impact();
 444   }
 445   const JavaPermission permission() const {
 446     return DCmdClass::permission();
 447   }
 448   const char* disabled_message() const {
 449      return DCmdClass::disabled_message();
 450   }
 451 };
 452 
 453 // This class provides a convenient way to register Dcmds, without a need to change
 454 // management.cpp every time. Body of these two methods resides in
 455 // diagnosticCommand.cpp
 456 
 457 class DCmdRegistrant : public AllStatic {
 458 
 459 private:
 460     static void register_dcmds();
 461     static void register_dcmds_ext();
 462 
 463     friend class Management;
 464 };
 465 
 466 #endif // SHARE_VM_SERVICES_DIAGNOSTICFRAMEWORK_HPP
--- EOF ---