1 /*

     2  * Copyright (c) 2016, 2018, 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 "oops/instanceKlass.hpp"

    36 #include "oops/oop.inline.hpp"

    37 #include "runtime/fieldDescriptor.hpp"

    38 #include "runtime/handles.hpp"

    39 #include "runtime/jniHandles.inline.hpp"

    40 #include "runtime/thread.inline.hpp"

    41 

    42 static int start_pos_offset = invalid_offset;

    43 static int start_pos_address_offset = invalid_offset;

    44 static int current_pos_offset = invalid_offset;

    45 static int max_pos_offset = invalid_offset;

    46 static int max_event_size_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::lookup(class_name, sizeof class_name - 1, CHECK_false);

    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::lookup(start_pos_name, sizeof start_pos_name - 1, CHECK_false);

    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::lookup(start_pos_address_name, sizeof start_pos_address_name - 1, CHECK_false);

    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::lookup(event_pos_name, sizeof event_pos_name - 1, CHECK_false);

   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::lookup(max_pos_name, sizeof max_pos_name - 1, CHECK_false);

   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 max_event_size_name[] = "maxEventSize";

   113   Symbol* const max_event_size_sym = SymbolTable::lookup(max_event_size_name, sizeof max_event_size_name - 1, CHECK_false);

   114   assert (max_event_size_sym != NULL, "invariant");

   115   assert(invalid_offset == max_event_size_offset, "invariant");

   116   compute_offset(max_event_size_offset, klass, max_event_size_sym, vmSymbols::int_signature());

   117   assert(max_event_size_offset != invalid_offset, "invariant");

   118 

   119   const char notified_name[] = "notified";

   120   Symbol* const notified_sym = SymbolTable::lookup(notified_name, sizeof notified_name - 1, CHECK_false);

   121   assert (notified_sym != NULL, "invariant");

   122   assert(invalid_offset == notified_offset, "invariant");

   123   compute_offset(notified_offset, klass, notified_sym, vmSymbols::bool_signature());

   124   assert(notified_offset != invalid_offset, "invariant");

   125 

   126   const char valid_name[] = "valid";

   127   Symbol* const valid_sym = SymbolTable::lookup(valid_name, sizeof valid_name - 1, CHECK_false);

   128   assert (valid_sym != NULL, "invariant");

   129   assert(invalid_offset == valid_offset, "invariant");

   130   compute_offset(valid_offset, klass, valid_sym, vmSymbols::bool_signature());

   131   assert(valid_offset != invalid_offset, "invariant");

   132   return true;

   133 }

   134 

   135 bool JfrJavaEventWriter::initialize() {

   136   static bool initialized = false;

   137   if (!initialized) {

   138     Thread* thread = Thread::current();

   139     initialized = setup_event_writer_offsets(thread);

   140   }

   141   return initialized;

   142 }

   143 

   144 jboolean JfrJavaEventWriter::flush(jobject writer, jint used, jint requested, JavaThread* jt) {

   145   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(jt));

   146   assert(writer != NULL, "invariant");

   147   oop const w = JNIHandles::resolve_non_null(writer);

   148   assert(w != NULL, "invariant");

   149   JfrBuffer* const current = jt->jfr_thread_local()->java_buffer();

   150   assert(current != NULL, "invariant");

   151   JfrBuffer* const buffer = JfrStorage::flush(current, used, requested, false, jt);

   152   assert(buffer != NULL, "invariant");

   153   // "validity" is contextually defined here to mean

   154   // that some memory location was provided that is

   155   // large enough to accommodate the "requested size".

   156   const bool is_valid = buffer->free_size() >= (size_t)(used + requested);

   157   u1* const new_current_position = is_valid ? buffer->pos() + used : buffer->pos();

   158   w->long_field_put(start_pos_offset, (jlong)buffer->pos());

   159   w->long_field_put(current_pos_offset, (jlong)new_current_position);

   160   // only update java writer if underlying memory changed

   161   if (buffer != current) {

   162     w->long_field_put(start_pos_address_offset, (jlong)buffer->pos_address());

   163     w->long_field_put(max_pos_offset, (jlong)buffer->end());

   164   }

   165   if (!is_valid) {

   166     // mark writer as invalid for this write attempt

   167     w->release_bool_field_put(valid_offset, JNI_FALSE);

   168     return JNI_FALSE;

   169   }

   170   // An exclusive use of a leased buffer is treated equivalent to

   171   // holding a system resource. As such, it should be released as soon as possible.

   172   // Returning true here signals that the thread will need to call flush again

   173   // on EventWriter.endEvent() and that flush will return the lease.

   174   return buffer->lease() ? JNI_TRUE : JNI_FALSE;

   175 }

   176 

   177 class JfrJavaEventWriterNotificationClosure : public ThreadClosure {

   178  public:

   179    void do_thread(Thread* t) {

   180      if (t->is_Java_thread()) {

   181        JfrJavaEventWriter::notify((JavaThread*)t);

   182      }

   183    }

   184 };

   185 

   186 void JfrJavaEventWriter::notify() {

   187   assert(SafepointSynchronize::is_at_safepoint(), "invariant");

   188   JfrJavaEventWriterNotificationClosure closure;

   189   Threads::threads_do(&closure);

   190 }

   191 

   192 void JfrJavaEventWriter::notify(JavaThread* jt) {

   193   assert(jt != NULL, "invariant");

   194   assert(SafepointSynchronize::is_at_safepoint(), "invariant");

   195   if (jt->jfr_thread_local()->has_java_event_writer()) {

   196     oop buffer_writer = JNIHandles::resolve_non_null(jt->jfr_thread_local()->java_event_writer());

   197     assert(buffer_writer != NULL, "invariant");

   198     buffer_writer->release_bool_field_put(notified_offset, JNI_TRUE);

   199   }

   200 }

   201 

   202 static jobject create_new_event_writer(JfrBuffer* buffer, TRAPS) {

   203   assert(buffer != NULL, "invariant");

   204   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));

   205   HandleMark hm(THREAD);

   206   static const char klass[] = "jdk/jfr/internal/EventWriter";

   207   static const char method[] = "<init>";

   208   static const char signature[] = "(JJJJZ)V";

   209   JavaValue result(T_OBJECT);

   210   JfrJavaArguments args(&result, klass, method, signature, CHECK_NULL);

   211   // parameters

   212   args.push_long((jlong)buffer->pos());

   213   args.push_long((jlong)buffer->end());

   214   args.push_long((jlong)buffer->pos_address());

   215   args.push_long((jlong)JFR_THREAD_ID(THREAD));

   216   args.push_int((int)JNI_TRUE);

   217   JfrJavaSupport::new_object_global_ref(&args, CHECK_NULL);

   218   return result.get_jobject();

   219 }

   220 

   221 jobject JfrJavaEventWriter::event_writer(Thread* t) {

   222   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(t));

   223   JfrThreadLocal* const tl = t->jfr_thread_local();

   224   assert(tl->shelved_buffer() == NULL, "invariant");

   225   return tl->java_event_writer();

   226 }

   227 

   228 jobject JfrJavaEventWriter::new_event_writer(TRAPS) {

   229   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));

   230   assert(event_writer(THREAD) == NULL, "invariant");

   231   JfrThreadLocal* const tl = THREAD->jfr_thread_local();

   232   assert(!tl->has_java_buffer(), "invariant");

   233   JfrBuffer* const buffer = tl->java_buffer();

   234   if (buffer == NULL) {

   235     JfrJavaSupport::throw_out_of_memory_error("OOME for thread local buffer", THREAD);

   236     return NULL;

   237   }

   238   jobject java_event_writer = create_new_event_writer(buffer, CHECK_NULL);

   239   tl->set_java_event_writer(java_event_writer);

   240   assert(tl->has_java_event_writer(), "invariant");

   241   return java_event_writer;

   242 }