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 // indicates if the Attach Listener needs to be created at startup
72 static bool init_at_startup() NOT_SERVICES_RETURN_(false);
73
74 // indicates if we have a trigger to start the Attach Listener
75 static bool is_init_trigger() NOT_SERVICES_RETURN_(false);
76
77 #if !INCLUDE_SERVICES
78 static bool is_attach_supported() { return false; }
79 #else
80
81 private:
82 static volatile AttachListenerState _state;
83
84 public:
85 static void set_state(AttachListenerState new_state) {
86 Atomic::store(new_state, &_state);
87 }
88
89 static AttachListenerState get_state() {
90 return Atomic::load(&_state);
91 }
92
93 static AttachListenerState transit_state(AttachListenerState new_state,
94 AttachListenerState cmp_state) {
95 return Atomic::cmpxchg(new_state, &_state, cmp_state);
96 }
97
98 static bool is_initialized() {
99 return Atomic::load(&_state) == AL_INITIALIZED;
100 }
101
102 static void set_initialized() {
103 Atomic::store(AL_INITIALIZED, &_state);
104 }
105
106 // indicates if this VM supports attach-on-demand
107 static bool is_attach_supported() { return !DisableAttachMechanism; }
108
109 // platform specific initialization
110 static int pd_init();
111
112 // platform specific operation
113 static AttachOperationFunctionInfo* pd_find_operation(const char* name);
114
115 // platform specific flag change
116 static jint pd_set_flag(AttachOperation* op, outputStream* out);
117
118 // platform specific detachall
119 static void pd_detachall();
120
121 // platform specific data dump
122 static void pd_data_dump();
123
124 // dequeue the next operation
125 static AttachOperation* dequeue();
126 #endif // !INCLUDE_SERVICES
127
128 private:
129 static bool has_init_error(TRAPS);
130 };
131
132 #if INCLUDE_SERVICES
133 class AttachOperation: public CHeapObj<mtInternal> {
134 public:
135 enum {
136 name_length_max = 16, // maximum length of name
137 arg_length_max = 1024, // maximum length of argument
138 arg_count_max = 3 // maximum number of arguments
139 };
140
141 // name of special operation that can be enqueued when all
142 // clients detach
143 static char* detachall_operation_name() { return (char*)"detachall"; }
144
145 private:
146 char _name[name_length_max+1];
147 char _arg[arg_count_max][arg_length_max+1];
148
149 public:
150 const char* name() const { return _name; }
151
152 // set the operation name
153 void set_name(const char* name) {
154 assert(strlen(name) <= name_length_max, "exceeds maximum name length");
155 size_t len = MIN2(strlen(name), (size_t)name_length_max);
156 memcpy(_name, name, len);
157 _name[len] = '\0';
158 }
159
160 // get an argument value
161 const char* arg(int i) const {
162 assert(i>=0 && i<arg_count_max, "invalid argument index");
163 return _arg[i];
164 }
165
166 // set an argument value
167 void set_arg(int i, char* arg) {
168 assert(i>=0 && i<arg_count_max, "invalid argument index");
169 if (arg == NULL) {
170 _arg[i][0] = '\0';
171 } else {
172 assert(strlen(arg) <= arg_length_max, "exceeds maximum argument length");
173 size_t len = MIN2(strlen(arg), (size_t)arg_length_max);
174 memcpy(_arg[i], arg, len);
175 _arg[i][len] = '\0';
176 }
177 }
178
179 // create an operation of a given name
180 AttachOperation(const char* name) {
181 set_name(name);
182 for (int i=0; i<arg_count_max; i++) {
183 set_arg(i, NULL);
184 }
185 }
186
187 // complete operation by sending result code and any result data to the client
188 virtual void complete(jint result, bufferedStream* result_stream) = 0;
189 };
190 #endif // INCLUDE_SERVICES
191
192 #endif // SHARE_SERVICES_ATTACHLISTENER_HPP