1 /*
  2  * Copyright (c) 2016, 2021, 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 #include "precompiled.hpp"
 26 #include "jni.h"
 27 #include "classfile/symbolTable.hpp"
 28 #include "classfile/systemDictionary.hpp"
 29 #include "classfile/vmSymbols.hpp"
 30 #include "jfr/jni/jfrJavaSupport.hpp"
 31 #include "jfr/recorder/storage/jfrStorage.hpp"
 32 #include "jfr/support/jfrThreadId.hpp"
 33 #include "jfr/utilities/jfrTypes.hpp"
 34 #include "jfr/writers/jfrJavaEventWriter.hpp"
 35 #include "memory/iterator.hpp"
 36 #include "oops/instanceKlass.hpp"
 37 #include "oops/oop.inline.hpp"
 38 #include "runtime/fieldDescriptor.inline.hpp"
 39 #include "runtime/handles.inline.hpp"
 40 #include "runtime/jniHandles.inline.hpp"
 41 #include "runtime/thread.inline.hpp"
 42 
 43 static int start_pos_offset = invalid_offset;
 44 static int start_pos_address_offset = invalid_offset;
 45 static int current_pos_offset = invalid_offset;
 46 static int max_pos_offset = invalid_offset;
 47 static int notified_offset = invalid_offset;
 48 static int thread_id_offset = invalid_offset;
 49 static int valid_offset = invalid_offset;
 50 
 51 static bool find_field(InstanceKlass* ik,
 52                        Symbol* name_symbol,
 53                        Symbol* signature_symbol,
 54                        fieldDescriptor* fd,
 55                        bool is_static = false,
 56                        bool allow_super = false) {
 57   if (allow_super || is_static) {
 58     return ik->find_field(name_symbol, signature_symbol, is_static, fd) != NULL;
 59   } else {
 60     return ik->find_local_field(name_symbol, signature_symbol, fd);
 61   }
 62 }
 63 
 64 static void compute_offset(int &dest_offset,
 65                            Klass* klass,
 66                            Symbol* name_symbol,
 67                            Symbol* signature_symbol,
 68                            bool is_static = false, bool allow_super = false) {
 69   fieldDescriptor fd;
 70   InstanceKlass* ik = InstanceKlass::cast(klass);
 71   if (!find_field(ik, name_symbol, signature_symbol, &fd, is_static, allow_super)) {
 72     assert(false, "invariant");
 73   }
 74   dest_offset = fd.offset();
 75 }
 76 
 77 static bool setup_event_writer_offsets(TRAPS) {
 78   const char class_name[] = "jdk/jfr/internal/EventWriter";
 79   Symbol* const k_sym = SymbolTable::new_symbol(class_name);
 80   assert(k_sym != NULL, "invariant");
 81   Klass* klass = SystemDictionary::resolve_or_fail(k_sym, true, CHECK_false);
 82   assert(klass != NULL, "invariant");
 83 
 84   const char start_pos_name[] = "startPosition";
 85   Symbol* const start_pos_sym = SymbolTable::new_symbol(start_pos_name);
 86   assert(start_pos_sym != NULL, "invariant");
 87   assert(invalid_offset == start_pos_offset, "invariant");
 88   compute_offset(start_pos_offset, klass, start_pos_sym, vmSymbols::long_signature());
 89   assert(start_pos_offset != invalid_offset, "invariant");
 90 
 91   const char start_pos_address_name[] = "startPositionAddress";
 92   Symbol* const start_pos_address_sym = SymbolTable::new_symbol(start_pos_address_name);
 93   assert(start_pos_address_sym != NULL, "invariant");
 94   assert(invalid_offset == start_pos_address_offset, "invariant");
 95   compute_offset(start_pos_address_offset, klass, start_pos_address_sym, vmSymbols::long_signature());
 96   assert(start_pos_address_offset != invalid_offset, "invariant");
 97 
 98   const char event_pos_name[] = "currentPosition";
 99   Symbol* const event_pos_sym = SymbolTable::new_symbol(event_pos_name);
100   assert(event_pos_sym != NULL, "invariant");
101   assert(invalid_offset == current_pos_offset, "invariant");
102   compute_offset(current_pos_offset, klass, event_pos_sym,vmSymbols::long_signature());
103   assert(current_pos_offset != invalid_offset, "invariant");
104 
105   const char max_pos_name[] = "maxPosition";
106   Symbol* const max_pos_sym = SymbolTable::new_symbol(max_pos_name);
107   assert(max_pos_sym != NULL, "invariant");
108   assert(invalid_offset == max_pos_offset, "invariant");
109   compute_offset(max_pos_offset, klass, max_pos_sym, vmSymbols::long_signature());
110   assert(max_pos_offset != invalid_offset, "invariant");
111 
112   const char notified_name[] = "notified";
113   Symbol* const notified_sym = SymbolTable::new_symbol(notified_name);
114   assert (notified_sym != NULL, "invariant");
115   assert(invalid_offset == notified_offset, "invariant");
116   compute_offset(notified_offset, klass, notified_sym, vmSymbols::bool_signature());
117   assert(notified_offset != invalid_offset, "invariant");
118 
119   const char valid_name[] = "valid";
120   Symbol* const valid_sym = SymbolTable::new_symbol(valid_name);
121   assert (valid_sym != NULL, "invariant");
122   assert(invalid_offset == valid_offset, "invariant");
123   compute_offset(valid_offset, klass, valid_sym, vmSymbols::bool_signature());
124   assert(valid_offset != invalid_offset, "invariant");
125   return true;
126 }
127 
128 bool JfrJavaEventWriter::initialize() {
129   static bool initialized = false;
130   if (!initialized) {
131     initialized = setup_event_writer_offsets(JavaThread::current());
132   }
133   return initialized;
134 }
135 
136 jboolean JfrJavaEventWriter::flush(jobject writer, jint used, jint requested, JavaThread* jt) {
137   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(jt));
138   assert(writer != NULL, "invariant");
139   oop const w = JNIHandles::resolve_non_null(writer);
140   assert(w != NULL, "invariant");
141   JfrBuffer* const current = jt->jfr_thread_local()->java_buffer();
142   assert(current != NULL, "invariant");
143   JfrBuffer* const buffer = JfrStorage::flush(current, used, requested, false, jt);
144   assert(buffer != NULL, "invariant");
145   // "validity" is contextually defined here to mean
146   // that some memory location was provided that is
147   // large enough to accommodate the "requested size".
148   const bool is_valid = buffer->free_size() >= (size_t)(used + requested);
149   u1* const new_current_position = is_valid ? buffer->pos() + used : buffer->pos();
150   assert(start_pos_offset != invalid_offset, "invariant");
151   w->long_field_put(start_pos_offset, (jlong)buffer->pos());
152   w->long_field_put(current_pos_offset, (jlong)new_current_position);
153   // only update java writer if underlying memory changed
154   if (buffer != current) {
155     w->long_field_put(start_pos_address_offset, (jlong)buffer->pos_address());
156     w->long_field_put(max_pos_offset, (jlong)buffer->end());
157   }
158   if (!is_valid) {
159     // mark writer as invalid for this write attempt
160     w->release_bool_field_put(valid_offset, JNI_FALSE);
161     return JNI_FALSE;
162   }
163   // An exclusive use of a leased buffer is treated equivalent to
164   // holding a system resource. As such, it should be released as soon as possible.
165   // Returning true here signals that the thread will need to call flush again
166   // on EventWriter.endEvent() and that flush will return the lease.
167   return buffer->lease() ? JNI_TRUE : JNI_FALSE;
168 }
169 
170 class JfrJavaEventWriterNotificationClosure : public ThreadClosure {
171  public:
172    void do_thread(Thread* t) {
173      if (t->is_Java_thread()) {
174        JfrJavaEventWriter::notify(JavaThread::cast(t));
175      }
176    }
177 };
178 
179 void JfrJavaEventWriter::notify() {
180   assert(SafepointSynchronize::is_at_safepoint(), "invariant");
181   JfrJavaEventWriterNotificationClosure closure;
182   Threads::threads_do(&closure);
183 }
184 
185 void JfrJavaEventWriter::notify(JavaThread* jt) {
186   assert(jt != NULL, "invariant");
187   assert(SafepointSynchronize::is_at_safepoint(), "invariant");
188   if (jt->jfr_thread_local()->has_java_event_writer()) {
189     oop buffer_writer = JNIHandles::resolve_non_null(jt->jfr_thread_local()->java_event_writer());
190     assert(buffer_writer != NULL, "invariant");
191     buffer_writer->release_bool_field_put(notified_offset, JNI_TRUE);
192   }
193 }
194 
195 static jobject create_new_event_writer(JfrBuffer* buffer, TRAPS) {
196   assert(buffer != NULL, "invariant");
197   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));
198   HandleMark hm(THREAD);
199   static const char klass[] = "jdk/jfr/internal/EventWriter";
200   static const char method[] = "<init>";
201   static const char signature[] = "(JJJJZ)V";
202   JavaValue result(T_OBJECT);
203   JfrJavaArguments args(&result, klass, method, signature, CHECK_NULL);
204   // parameters
205   args.push_long((jlong)buffer->pos());
206   args.push_long((jlong)buffer->end());
207   args.push_long((jlong)buffer->pos_address());
208   args.push_long((jlong)JFR_THREAD_ID(THREAD));
209   args.push_int((int)JNI_TRUE);
210   JfrJavaSupport::new_object_global_ref(&args, CHECK_NULL);
211   return result.get_jobject();
212 }
213 
214 jobject JfrJavaEventWriter::event_writer(JavaThread* t) {
215   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(t));
216   JfrThreadLocal* const tl = t->jfr_thread_local();
217   assert(tl->shelved_buffer() == NULL, "invariant");
218   return tl->java_event_writer();
219 }
220 
221 jobject JfrJavaEventWriter::new_event_writer(TRAPS) {
222   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));
223   assert(event_writer(THREAD) == NULL, "invariant");
224   JfrThreadLocal* const tl = THREAD->jfr_thread_local();
225   assert(!tl->has_java_buffer(), "invariant");
226   JfrBuffer* const buffer = tl->java_buffer();
227   if (buffer == NULL) {
228     JfrJavaSupport::throw_out_of_memory_error("OOME for thread local buffer", THREAD);
229     return NULL;
230   }
231   jobject java_event_writer = create_new_event_writer(buffer, CHECK_NULL);
232   tl->set_java_event_writer(java_event_writer);
233   assert(tl->has_java_event_writer(), "invariant");
234   return java_event_writer;
235 }