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