--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/services/threadIdTable.cpp Wed Sep 25 11:10:05 2019 -0700
@@ -0,0 +1,238 @@
+
+/*
+* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+* or visit www.oracle.com if you need additional information or have any
+* questions.
+*
+*/
+
+#include "precompiled.hpp"
+#include "runtime/interfaceSupport.inline.hpp"
+#include "runtime/thread.hpp"
+#include "runtime/threadSMR.hpp"
+#include "runtime/timerTrace.hpp"
+#include "services/threadIdTable.hpp"
+#include "utilities/concurrentHashTable.inline.hpp"
+#include "utilities/concurrentHashTableTasks.inline.hpp"
+
+
+typedef ConcurrentHashTable<ThreadIdTableConfig, mtInternal> ThreadIdTableHash;
+
+// 2^24 is max size
+static const size_t END_SIZE = 24;
+// Default initial size 256
+static const size_t DEFAULT_TABLE_SIZE_LOG = 8;
+// Prefer short chains of avg 2
+static const double PREF_AVG_LIST_LEN = 2.0;
+static ThreadIdTableHash* volatile _local_table = NULL;
+static volatile size_t _current_size = 0;
+static volatile size_t _items_count = 0;
+
+volatile bool ThreadIdTable::_is_initialized = false;
+
+class ThreadIdTableEntry : public CHeapObj<mtInternal> {
+private:
+ jlong _tid;
+ JavaThread* _java_thread;
+public:
+ ThreadIdTableEntry(jlong tid, JavaThread* java_thread) :
+ _tid(tid), _java_thread(java_thread) {}
+
+ jlong tid() const { return _tid; }
+ JavaThread* thread() const { return _java_thread; }
+};
+
+class ThreadIdTableConfig : public AllStatic {
+ public:
+ typedef ThreadIdTableEntry* Value;
+
+ static uintx get_hash(Value const& value, bool* is_dead) {
+ jlong tid = value->tid();
+ return primitive_hash(tid);
+ }
+ static void* allocate_node(size_t size, Value const& value) {
+ ThreadIdTable::item_added();
+ return AllocateHeap(size, mtInternal);
+ }
+ static void free_node(void* memory, Value const& value) {
+ delete value;
+ FreeHeap(memory);
+ ThreadIdTable::item_removed();
+ }
+};
+
+static size_t ceil_log2(size_t val) {
+ size_t ret;
+ for (ret = 1; ((size_t)1 << ret) < val; ++ret);
+ return ret;
+}
+
+// Lazily creates the table and populates it with the given
+// thread list
+void ThreadIdTable::lazy_initialize(const ThreadsList *threads) {
+ if (!_is_initialized) {
+ {
+ // There is no obvious benefits in allowing the thread table
+ // to be concurently populated during the initalization.
+ MutexLocker ml(ThreadIdTableCreate_lock);
+ if (_is_initialized) {
+ return;
+ }
+ create_table(threads->length());
+ _is_initialized = true;
+ }
+ for (uint i = 0; i < threads->length(); i++) {
+ JavaThread* thread = threads->thread_at(i);
+ oop tobj = thread->threadObj();
+ if (tobj != NULL) {
+ jlong java_tid = java_lang_Thread::thread_id(tobj);
+ MutexLocker ml(Threads_lock);
+ if (!thread->is_exiting()) {
+ // Must be inside the lock to ensure that we don't add a thread to the table
+ // that has just passed the removal point in ThreadsSMRSupport::remove_thread()
+ add_thread(java_tid, thread);
+ }
+ }
+ }
+ }
+}
+
+void ThreadIdTable::create_table(size_t size) {
+ assert(_local_table == NULL, "Thread table is already created");
+ size_t size_log = ceil_log2(size);
+ size_t start_size_log =
+ size_log > DEFAULT_TABLE_SIZE_LOG ? size_log : DEFAULT_TABLE_SIZE_LOG;
+ _current_size = (size_t)1 << start_size_log;
+ _local_table = new ThreadIdTableHash(start_size_log, END_SIZE);
+}
+
+void ThreadIdTable::item_added() {
+ Atomic::inc(&_items_count);
+ log_trace(thread, table) ("Thread entry added");
+}
+
+void ThreadIdTable::item_removed() {
+ Atomic::dec(&_items_count);
+ log_trace(thread, table) ("Thread entry removed");
+}
+
+double ThreadIdTable::get_load_factor() {
+ return ((double)_items_count) / _current_size;
+}
+
+size_t ThreadIdTable::table_size() {
+ return (size_t)1 << _local_table->get_size_log2(Thread::current());
+}
+
+void ThreadIdTable::grow(JavaThread* jt) {
+ ThreadIdTableHash::GrowTask gt(_local_table);
+ if (!gt.prepare(jt)) {
+ return;
+ }
+ log_trace(thread, table)("Started to grow");
+ TraceTime timer("Grow", TRACETIME_LOG(Debug, membername, table, perf));
+ while (gt.do_task(jt)) {
+ gt.pause(jt);
+ {
+ ThreadBlockInVM tbivm(jt);
+ }
+ gt.cont(jt);
+ }
+ gt.done(jt);
+ _current_size = table_size();
+ log_info(thread, table)("Grown to size:" SIZE_FORMAT, _current_size);
+}
+
+class ThreadIdTableLookup : public StackObj {
+private:
+ jlong _tid;
+ uintx _hash;
+public:
+ ThreadIdTableLookup(jlong tid)
+ : _tid(tid), _hash(primitive_hash(tid)) {}
+ uintx get_hash() const {
+ return _hash;
+ }
+ bool equals(ThreadIdTableEntry** value, bool* is_dead) {
+ bool equals = primitive_equals(_tid, (*value)->tid());
+ if (!equals) {
+ return false;
+ }
+ return true;
+ }
+};
+
+class ThreadGet : public StackObj {
+private:
+ JavaThread* _return;
+public:
+ ThreadGet(): _return(NULL) {}
+ void operator()(ThreadIdTableEntry** val) {
+ _return = (*val)->thread();
+ }
+ JavaThread* get_res_thread() {
+ return _return;
+ }
+};
+
+void ThreadIdTable::grow_if_required() {
+ assert(Thread::current()->is_Java_thread(),"Must be Java thread");
+ assert(_is_initialized, "Thread table is not initialized");
+ double load_factor = get_load_factor();
+ log_debug(thread, table)("Concurrent work, load factor: %g", load_factor);
+ if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
+ grow(JavaThread::current());
+ }
+}
+
+JavaThread* ThreadIdTable::add_thread(jlong tid, JavaThread* java_thread) {
+ assert(_is_initialized, "Thread table is not initialized");
+ Thread* thread = Thread::current();
+ ThreadIdTableLookup lookup(tid);
+ ThreadGet tg;
+ while (true) {
+ if (_local_table->get(thread, lookup, tg)) {
+ return tg.get_res_thread();
+ }
+ ThreadIdTableEntry* entry = new ThreadIdTableEntry(tid, java_thread);
+ // The hash table takes ownership of the ThreadTableEntry,
+ // even if it's not inserted.
+ if (_local_table->insert(thread, lookup, entry)) {
+ grow_if_required();
+ return java_thread;
+ }
+ }
+}
+
+JavaThread* ThreadIdTable::find_thread_by_tid(jlong tid) {
+ assert(_is_initialized, "Thread table is not initialized");
+ Thread* thread = Thread::current();
+ ThreadIdTableLookup lookup(tid);
+ ThreadGet tg;
+ _local_table->get(thread, lookup, tg);
+ return tg.get_res_thread();
+}
+
+bool ThreadIdTable::remove_thread(jlong tid) {
+ assert(_is_initialized, "Thread table is not initialized");
+ Thread* thread = Thread::current();
+ ThreadIdTableLookup lookup(tid);
+ return _local_table->remove(thread, lookup);
+}