1 /*
   2  * Copyright (c) 2005, 2019, 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_SERVICES_ATTACHLISTENER_HPP
  26 #define SHARE_SERVICES_ATTACHLISTENER_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "metaprogramming/isRegisteredEnum.hpp"
  30 #include "runtime/atomic.hpp"
  31 #include "utilities/debug.hpp"
  32 #include "utilities/globalDefinitions.hpp"
  33 #include "utilities/macros.hpp"
  34 #include "utilities/ostream.hpp"
  35 
  36 // The AttachListener thread services a queue of operations that are enqueued
  37 // by client tools. Each operation is identified by a name and has up to 3
  38 // arguments. The operation name is mapped to a function which performs the
  39 // operation. The function is called with an outputStream which is can use to
  40 // write any result data (for examples the properties command serializes
  41 // properties names and values to the output stream). When the function
  42 // complets the result value and any result data is returned to the client
  43 // tool.
  44 
  45 class AttachOperation;
  46 
  47 typedef jint (*AttachOperationFunction)(AttachOperation* op, outputStream* out);
  48 
  49 struct AttachOperationFunctionInfo {
  50   const char* name;
  51   AttachOperationFunction func;
  52 };
  53 
  54 enum AttachListenerState {
  55   AL_NOT_INITIALIZED,
  56   AL_INITIALIZING,
  57   AL_INITIALIZED
  58 };
  59 
  60 template<> struct IsRegisteredEnum<AttachListenerState> : public TrueType {};
  61 
  62 class AttachListener: AllStatic {
  63  public:
  64   static void vm_start() NOT_SERVICES_RETURN;
  65   static void init()  NOT_SERVICES_RETURN;
  66   static void abort() NOT_SERVICES_RETURN;
  67 
  68   // invoke to perform clean-up tasks when all clients detach
  69   static void detachall() NOT_SERVICES_RETURN;
  70 
  71   // check unix domain socket file on filesystem
  72   static bool check_socket_file() NOT_SERVICES_RETURN_(false);
  73 
  74   // indicates if the Attach Listener needs to be created at startup
  75   static bool init_at_startup() NOT_SERVICES_RETURN_(false);
  76 
  77   // indicates if we have a trigger to start the Attach Listener
  78   static bool is_init_trigger() NOT_SERVICES_RETURN_(false);
  79 
  80 #if !INCLUDE_SERVICES
  81   static bool is_attach_supported()             { return false; }
  82 #else
  83 
  84  private:
  85   static volatile AttachListenerState _state;
  86 
  87  public:
  88   static void set_state(AttachListenerState new_state) {
  89     Atomic::store(&_state, new_state);
  90   }
  91 
  92   static AttachListenerState get_state() {
  93     return Atomic::load(&_state);
  94   }
  95 
  96   static AttachListenerState transit_state(AttachListenerState new_state,
  97                                            AttachListenerState cmp_state) {
  98     return Atomic::cmpxchg(&_state, cmp_state, new_state);
  99   }
 100 
 101   static bool is_initialized() {
 102     return Atomic::load(&_state) == AL_INITIALIZED;
 103   }
 104 
 105   static void set_initialized() {
 106     Atomic::store(&_state, AL_INITIALIZED);
 107   }
 108 
 109   // indicates if this VM supports attach-on-demand
 110   static bool is_attach_supported()             { return !DisableAttachMechanism; }
 111 
 112   // platform specific initialization
 113   static int pd_init();
 114 
 115   // platform specific operation
 116   static AttachOperationFunctionInfo* pd_find_operation(const char* name);
 117 
 118   // platform specific flag change
 119   static jint pd_set_flag(AttachOperation* op, outputStream* out);
 120 
 121   // platform specific detachall
 122   static void pd_detachall();
 123 
 124   // platform specific data dump
 125   static void pd_data_dump();
 126 
 127   // dequeue the next operation
 128   static AttachOperation* dequeue();
 129 #endif // !INCLUDE_SERVICES
 130 
 131  private:
 132   static bool has_init_error(TRAPS);
 133 };
 134 
 135 #if INCLUDE_SERVICES
 136 class AttachOperation: public CHeapObj<mtInternal> {
 137  public:
 138   enum {
 139     name_length_max = 16,       // maximum length of  name
 140     arg_length_max = 1024,      // maximum length of argument
 141     arg_count_max = 3           // maximum number of arguments
 142   };
 143 
 144   // name of special operation that can be enqueued when all
 145   // clients detach
 146   static char* detachall_operation_name() { return (char*)"detachall"; }
 147 
 148  private:
 149   char _name[name_length_max+1];
 150   char _arg[arg_count_max][arg_length_max+1];
 151 
 152  public:
 153   const char* name() const                      { return _name; }
 154 
 155   // set the operation name
 156   void set_name(const char* name) {
 157     assert(strlen(name) <= name_length_max, "exceeds maximum name length");
 158     size_t len = MIN2(strlen(name), (size_t)name_length_max);
 159     memcpy(_name, name, len);
 160     _name[len] = '\0';
 161   }
 162 
 163   // get an argument value
 164   const char* arg(int i) const {
 165     assert(i>=0 && i<arg_count_max, "invalid argument index");
 166     return _arg[i];
 167   }
 168 
 169   // set an argument value
 170   void set_arg(int i, char* arg) {
 171     assert(i>=0 && i<arg_count_max, "invalid argument index");
 172     if (arg == NULL) {
 173       _arg[i][0] = '\0';
 174     } else {
 175       assert(strlen(arg) <= arg_length_max, "exceeds maximum argument length");
 176       size_t len = MIN2(strlen(arg), (size_t)arg_length_max);
 177       memcpy(_arg[i], arg, len);
 178       _arg[i][len] = '\0';
 179     }
 180   }
 181 
 182   // create an operation of a given name
 183   AttachOperation(const char* name) {
 184     set_name(name);
 185     for (int i=0; i<arg_count_max; i++) {
 186       set_arg(i, NULL);
 187     }
 188   }
 189 
 190   // complete operation by sending result code and any result data to the client
 191   virtual void complete(jint result, bufferedStream* result_stream) = 0;
 192 };
 193 #endif // INCLUDE_SERVICES
 194 
 195 #endif // SHARE_SERVICES_ATTACHLISTENER_HPP
--- EOF ---