/* * Copyright (c) 2014, 2018, 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 "classfile/javaClasses.hpp" #include "jfr/leakprofiler/chains/edge.hpp" #include "jfr/leakprofiler/chains/edgeStore.hpp" #include "jfr/leakprofiler/chains/edgeUtils.hpp" #include "jfr/leakprofiler/utilities/unifiedOop.hpp" #include "oops/fieldStreams.hpp" #include "oops/instanceKlass.hpp" #include "oops/objArrayOop.inline.hpp" #include "oops/oopsHierarchy.hpp" #include "runtime/handles.inline.hpp" bool EdgeUtils::is_leak_edge(const Edge& edge) { return (const Edge*)edge.pointee()->mark() == &edge; } bool EdgeUtils::is_root(const Edge& edge) { return edge.is_root(); } static int field_offset(const Edge& edge) { assert(!edge.is_root(), "invariant"); const oop ref_owner = edge.reference_owner(); assert(ref_owner != NULL, "invariant"); const oop* reference = UnifiedOop::decode(edge.reference()); assert(reference != NULL, "invariant"); assert(!UnifiedOop::is_narrow(reference), "invariant"); assert(!ref_owner->is_array(), "invariant"); assert(ref_owner->is_instance(), "invariant"); const int offset = (int)pointer_delta(reference, ref_owner, sizeof(char)); assert(offset < (ref_owner->size() * HeapWordSize), "invariant"); return offset; } static const InstanceKlass* field_type(const Edge& edge) { assert(!edge.is_root() || !EdgeUtils::is_array_element(edge), "invariant"); return (const InstanceKlass*)edge.reference_owner_klass(); } const Symbol* EdgeUtils::field_name_symbol(const Edge& edge) { assert(!edge.is_root(), "invariant"); assert(!is_array_element(edge), "invariant"); const int offset = field_offset(edge); const InstanceKlass* ik = field_type(edge); while (ik != NULL) { JavaFieldStream jfs(ik); while (!jfs.done()) { if (offset == jfs.offset()) { return jfs.name(); } jfs.next(); } ik = (InstanceKlass*)ik->super(); } return NULL; } jshort EdgeUtils::field_modifiers(const Edge& edge) { const int offset = field_offset(edge); const InstanceKlass* ik = field_type(edge); while (ik != NULL) { JavaFieldStream jfs(ik); while (!jfs.done()) { if (offset == jfs.offset()) { return jfs.access_flags().as_short(); } jfs.next(); } ik = (InstanceKlass*)ik->super(); } return 0; } bool EdgeUtils::is_array_element(const Edge& edge) { assert(!edge.is_root(), "invariant"); const oop ref_owner = edge.reference_owner(); assert(ref_owner != NULL, "invariant"); return ref_owner->is_objArray(); } static int array_offset(const Edge& edge) { assert(!edge.is_root(), "invariant"); const oop ref_owner = edge.reference_owner(); assert(ref_owner != NULL, "invariant"); const oop* reference = UnifiedOop::decode(edge.reference()); assert(reference != NULL, "invariant"); assert(!UnifiedOop::is_narrow(reference), "invariant"); assert(ref_owner->is_array(), "invariant"); const objArrayOop ref_owner_array = static_cast(ref_owner); const int offset = (int)pointer_delta(reference, ref_owner_array->base(), heapOopSize); assert(offset >= 0 && offset < ref_owner_array->length(), "invariant"); return offset; } int EdgeUtils::array_index(const Edge& edge) { return is_array_element(edge) ? array_offset(edge) : 0; } int EdgeUtils::array_size(const Edge& edge) { if (is_array_element(edge)) { const oop ref_owner = edge.reference_owner(); assert(ref_owner != NULL, "invariant"); assert(ref_owner->is_objArray(), "invariant"); return ((objArrayOop)(ref_owner))->length(); } return 0; } const Edge* EdgeUtils::root(const Edge& edge) { const Edge* current = &edge; const Edge* parent = current->parent(); while (parent != NULL) { current = parent; parent = current->parent(); } return current; } // The number of references associated with the leak node; // can be viewed as the leak node "context". // Used to provide leak context for a "capped/skipped" reference chain. static const size_t leak_context = 100; // The number of references associated with the root node; // can be viewed as the root node "context". // Used to provide root context for a "capped/skipped" reference chain. static const size_t root_context = 100; // A limit on the reference chain depth to be serialized, static const size_t max_ref_chain_depth = leak_context + root_context; const RoutableEdge* skip_to(const RoutableEdge& edge, size_t skip_length) { const RoutableEdge* current = &edge; const RoutableEdge* parent = current->physical_parent(); size_t seek = 0; while (parent != NULL && seek != skip_length) { seek++; current = parent; parent = parent->physical_parent(); } return current; } #ifdef ASSERT static void validate_skip_target(const RoutableEdge* skip_target) { assert(skip_target != NULL, "invariant"); assert(skip_target->distance_to_root() + 1 == root_context, "invariant"); assert(skip_target->is_sentinel(), "invariant"); } static void validate_new_skip_edge(const RoutableEdge* new_skip_edge, const RoutableEdge* last_skip_edge, size_t adjustment) { assert(new_skip_edge != NULL, "invariant"); assert(new_skip_edge->is_skip_edge(), "invariant"); if (last_skip_edge != NULL) { const RoutableEdge* const target = skip_to(*new_skip_edge->logical_parent(), adjustment); validate_skip_target(target->logical_parent()); return; } assert(last_skip_edge == NULL, "invariant"); // only one level of logical indirection validate_skip_target(new_skip_edge->logical_parent()); } #endif // ASSERT static void install_logical_route(const RoutableEdge* new_skip_edge, size_t skip_target_distance) { assert(new_skip_edge != NULL, "invariant"); assert(!new_skip_edge->is_skip_edge(), "invariant"); assert(!new_skip_edge->processed(), "invariant"); const RoutableEdge* const skip_target = skip_to(*new_skip_edge, skip_target_distance); assert(skip_target != NULL, "invariant"); new_skip_edge->set_skip_edge(skip_target); new_skip_edge->set_skip_length(skip_target_distance); assert(new_skip_edge->is_skip_edge(), "invariant"); assert(new_skip_edge->logical_parent() == skip_target, "invariant"); } static const RoutableEdge* find_last_skip_edge(const RoutableEdge& edge, size_t& distance) { assert(distance == 0, "invariant"); const RoutableEdge* current = &edge; while (current != NULL) { if (current->is_skip_edge() && current->skip_edge()->is_sentinel()) { return current; } current = current->physical_parent(); ++distance; } return current; } static void collapse_overlapping_chain(const RoutableEdge& edge, const RoutableEdge* first_processed_edge, size_t first_processed_distance) { assert(first_processed_edge != NULL, "invariant"); // first_processed_edge is already processed / written assert(first_processed_edge->processed(), "invariant"); assert(first_processed_distance + 1 <= leak_context, "invariant"); // from this first processed edge, attempt to fetch the last skip edge size_t last_skip_edge_distance = 0; const RoutableEdge* const last_skip_edge = find_last_skip_edge(*first_processed_edge, last_skip_edge_distance); const size_t distance_discovered = first_processed_distance + last_skip_edge_distance + 1; if (distance_discovered <= leak_context || (last_skip_edge == NULL && distance_discovered <= max_ref_chain_depth)) { // complete chain can be accommodated without modification return; } // backtrack one edge from existing processed edge const RoutableEdge* const new_skip_edge = skip_to(edge, first_processed_distance - 1); assert(new_skip_edge != NULL, "invariant"); assert(!new_skip_edge->processed(), "invariant"); assert(new_skip_edge->parent() == first_processed_edge, "invariant"); size_t adjustment = 0; if (last_skip_edge != NULL) { assert(leak_context - 1 > first_processed_distance - 1, "invariant"); adjustment = leak_context - first_processed_distance - 1; assert(last_skip_edge_distance + 1 > adjustment, "invariant"); install_logical_route(new_skip_edge, last_skip_edge_distance + 1 - adjustment); } else { install_logical_route(new_skip_edge, last_skip_edge_distance + 1 - root_context); new_skip_edge->logical_parent()->set_skip_length(1); // sentinel } DEBUG_ONLY(validate_new_skip_edge(new_skip_edge, last_skip_edge, adjustment);) } static void collapse_non_overlapping_chain(const RoutableEdge& edge, const RoutableEdge* first_processed_edge, size_t first_processed_distance) { assert(first_processed_edge != NULL, "invariant"); assert(!first_processed_edge->processed(), "invariant"); // this implies that the first "processed" edge is the leak context relative "leaf" assert(first_processed_distance + 1 == leak_context, "invariant"); const size_t distance_to_root = edge.distance_to_root(); if (distance_to_root + 1 <= max_ref_chain_depth) { // complete chain can be accommodated without constructing a skip edge return; } install_logical_route(first_processed_edge, distance_to_root + 1 - first_processed_distance - root_context); first_processed_edge->logical_parent()->set_skip_length(1); // sentinel DEBUG_ONLY(validate_new_skip_edge(first_processed_edge, NULL, 0);) } static const RoutableEdge* processed_edge(const RoutableEdge& edge, size_t& distance) { assert(distance == 0, "invariant"); const RoutableEdge* current = &edge; while (current != NULL && distance < leak_context - 1) { if (current->processed()) { return current; } current = current->physical_parent(); ++distance; } assert(distance <= leak_context - 1, "invariant"); return current; } /* * Some vocabulary: * ----------- * "Context" is an interval in the chain, it is associcated with an edge and it signifies a number of connected edges. * "Processed / written" means an edge that has already been serialized. * "Skip edge" is an edge that contains additional information for logical routing purposes. * "Skip target" is an edge used as a destination for a skip edge */ void EdgeUtils::collapse_chain(const RoutableEdge& edge) { assert(is_leak_edge(edge), "invariant"); // attempt to locate an already processed edge inside current leak context (if any) size_t first_processed_distance = 0; const RoutableEdge* const first_processed_edge = processed_edge(edge, first_processed_distance); if (first_processed_edge == NULL) { return; } if (first_processed_edge->processed()) { collapse_overlapping_chain(edge, first_processed_edge, first_processed_distance); } else { collapse_non_overlapping_chain(edge, first_processed_edge, first_processed_distance); } assert(edge.logical_distance_to_root() + 1 <= max_ref_chain_depth, "invariant"); }